EDRS PRICE MF-$0.65 HC-$6.58 DESCRIPTORS* Equipment

DOCUMENTassails ED 070 574 SE 014 121 TITLE Opticalman 1 and C, Rate Training Manual. INSTITUTION Bureau of Naval Personnel, Washington, D.*C.; Naval Personnel Program Support Activity, Washington, D. C. REPORT NO NAVPERS -10206 PUB DATE 66 NOTE 184p.; Revised 1966

EDRS PRICE MF-$0.65 HC-$6.58 DESCRIPTORS *Equipment Maintenance; Instructional Materials; Mechanical Equipment; Military Personnel; Military Science; *Military Training; *Optics; Physics; *Post Secondary Education; *Supplementary Textbooks

ABSTRACT The technical subject matter of this rate training manual is written for regular navy and naval reserve personnel. Responsibilities for optical shop administration, supervision, and training are discussed in detail. Metals are studied in connection with heat treating processes. Characteristics of light are analyzed to familiarize students with interference, polarization, and double refraction phenomena. Following discussions of basic theoiies in construction, step-by-step procedures are described for the disassembly, reassembly, maintenance, and repair of submarine periscopes, ship-mounted binocular Mark 3 Mod 2, turret periscope Mark 20 Mod 6, tilting-prism telescope gunsights, and rangefinders including stereoscopic rangefinder Mark 42 Mod 27. Besides illustrations for explanation use, information on advancement and a training film list are also provided. (CC) FILMED FROM BEST AVAILABLE COPY U $ DEPARTMENT OF HEALTH EDUCATION & WELFARE OFFICE OF EDUCA TION THIS DOCUMENT HAS BEEN REPRO DUCED EXACTLN AS RECEIVED FROM THE PERSON OR ORGANIZATION ORIL, INATING IT POINTS OF VIES L OR OPIN IONS STATED DO NOT NECESSARILN REPRESENT OFFICIAL OFFICE OF f DU CATION POSITION OR POLICN

OPTICALMAN 1 & C

S . S I I v.

PREFACE

This training course was written for men of the Navy and of the Naval Reserve who are studying for advancement to the rates of Opticalman 1 and C. Combined with the necessary practical experience and a thorough shady of the related basic Navy Training Courses the information in this course will help the reader prepare for advancement-in-rating examinations. This Navy Training Course was prepared by the Training Publications Division, Naval Personnel Program Support Activity, Washington, D.C., for the Bureau of Naval Personnel. Material provided by manufacturers is gratefully acknowledged.Technical assistance was provided by the U.S. Naval Schools, Opticalmen, Great Lakes; the Naval Ship Systems Command; azu the Naval Ordnance Systems Command.

First Edition 1950 Revised 1966

Ai THIS BOOK GOES TO PRESS, THE NAVY HAS UNDERGONE A MAJOR REORGANIZATION 11,I WHICH CERTAIN BUREAUS HAVE BEEN REDESIGNATED AS SYSTEMS COMMANDS. CHECK INSTRUCTIONS AND NOTICES FOR FURTHUR INFORMATION CONCERNING THIS CHANGE. THE UNITED STATES NAVY

GUARDIAN OF OUR COUNTRY

The United States Navy is responsible for maintaining control of thesea and is a ready force on watch at home and overseas, capable of strong action to preserve the peace or of instant offensive action to win inwar. It is upon the maintenance of this control that our country's glorious future depends; the United States Navy exists to make it so.

WE SERVE WITH HONOR Tradition, valor, and victory are the Navy's heritage from the past. To these may be added dedication, discipline, and vigilanceas the watchwords of the present and the future.

At home or on distant stations we serve with pride, confident in the respect of our country, our shipmates, and our families.

Our responsibilities sober us; our adversities strengthenus. Service to God and Country is our special privilege. Weserve with honor.

THE FUTURE OF THE NAVY The Navy will always employ new weapons, new techniques,and greater power to protect and defend the United Stateson the sea, under the sea, and in the air. Now and in the future, control of the sea gives the United States her greatest advantage for the maintenance of peace and for victory inwar. Mobility, surprise, dispersal, and offenskie power are the keynotes of the new Navy.The roots of the Navy lie in a strong belief in the future, in continued 'dedication to our tasks, and in reflectionon our heritage from the past. Never have our opportunities and our responsibilities been greater.

11 CONTENTS CHAPTER Page

1. Advancement 1 2. Slop Supervision 3. Metals 34 4. Phenomena of light 40 5. Rangefinder theory and construction 44 6. Rangefinder calibration and maintenance 68 7. Stereoscopic rangefinder 84 8. Submarine periscopes 106 9. Periscope maintenance and repair 117 10. Ship-mounted binocular 129 3 11. Turret Periscope 138 12. Tilting-prism telescope gunsight repair 151

APPENDIX

1. Training film list 175

INDEX 176

1f!. READING LIST

NAVY TRAINING COURSES Machinery Repairman 3 & 2, (Chapters3, 4, 5, 6, 9), NavPers 10530-B Blueprint Reading and Sketching Nav Pars10077-B Machinery Repairman 1 & C, (Chapter 6), NavPero 10531-A

OTHER PUBLICATIONS Ordnance Pamphlet 2080 Ordnance Pamphlet 105 Ordnance Pamphlet 1858 Ordnance Pamphlet 2147 Ordnance Pamphlet 2531 Periscope-Submarine types 8B and 8C,Nav Ships 324-0447 Maintenance and Material Management(3-M) Manual, Op Nav 43P2 Bu Ships Technical Manual (Chapter9240, section II) CHAPTER 1

ADVANCEMENT

This training course is designed to help In large measure, the extent of your con- you meet the professional (technical) qualifi- tribution to the Navy depends upon your willing- cations for advancement to Opticalman First ness and ability to accept increasing responsi- Class and Chief Opticalman. Chapters 2 through bilities as you advance in rating.When you 12 of this training course deal with the techni- assumed the duties of a0M3, you began to accept cal subject matter of the opticalman rating. a certain amount of responsibility for the work The present chapter provides introductory in- of others.With each advancement in rating, formation that will help you in working for you accept an increasing responsibility in mili- advancement in rating.It is strongly recom- tary matters and in matters relating to the mended that you study this chapter carefully professional requirements of the Opticalman before beginning intensive study of the re- rating. mainder of this training course. You will find that your responsibilities for military leadership are about the same as those of petty officers in other ratings, since every REWARDS AND RESPONSIBILITIES petty officer is a military person as well as a technical specialist.Your responsibilities for Advancement in rating brings both increased technical leadership are special to your rating rewards and increased responsibilities.The and are directly related to the nature of your time to start looking ahead and considering the work.Repairing the periscope of a submarine rewards and the responsibilities of advancement is a job of vital importance, and it's a teamwork is right now, while you are preparing for ad- job;it requires a special kind of leadership vancement to 0111 or OMC. ability that can only be developed by personnel By this time, you are probably well aware of who have a high degree of technical competence many of the advantagesof advancement in and a deep sense of personal responsibility. ratinghigher pay, greater prestige, more in- Certain practical detailii that relate to your teresting and challenging work, and the satis- responsibilities for optical shop administration, faction of getting ahead in your chosen career. supervision, and training are discussed in By this time, also, you have probably discovered chapter 2 of this training course. At this point, that one of the most enduring rewards of advance- let's consider some of the broader aspects of ment is the personal satisfaction you find in your increasing responsibilities for military and developing your skills and increasing your technical leadership. knowledge. YOUR RESPONSIBILITIES WILL EXTEND The Navy also benefits by your advancement. BOTH UPWARD AND DOWNWARD. Both Highly trained personnel are essential to the officers and enlisted personnel will expect you functioning of the Navy. By each advancement to translate the general orders givenby officers in rating you increase your value to the Navy into detailed, practical on-the-job language that in two ways. First, you become more valuable can be understood and followed even by relatively as a technical specialist in your own rating. inexperienced piirsonnel.In dealing with your And second, you become more valuable as a juniors, it it to you to see that they perform person who can supervise, lead, and train others their work properly. At the same time, you must and thus make far reaching and long lasting be able to explain to officers any inportant needs contributions to the Navy. or problems of the enlisted men.

1 OPTICALMAN 1 & C

YOU WILL HAVE REGULAR AND CONTINU- not understand the precise meaning of terms in ING RESPONSIBILITIES FOR TRAINING. Even connection with the work of his own rating is at if you are lucky enough to have highly skilled a disadvantage when he tries to read official and well trained men in the optical shop,you will publications relating to his work. He is also at still find that training is necessary.For ex- a great disadvantage when he takes the written ample, you will always be responsible fortrain- examinations for advancement in rating.Al- ing lower rated men for advancement in rating. though it is always important for you to use Also, some of your best workers may be trans- technical terms correctly,it is particularly ferred and inexperienced or poorly trainedper- important when you are dealing with lower rated sonnel may be assigned to you. Or a particular men; sloppiness in the use of technical terms is job may call for skills that none of yourperson- likely to be very confusing to an inexperienced nel have. These and similar problems require man. you to be a training specialist who can conduct YOU WILL HAVE INCREASED RESPONSI- formal and informal training programs to qualify BILITIES FOR KEEPING UP WITH NEW DE- personnel for advancement and whocan train VELOPMENTS.Practically everything in the individuals and groups in the effective execution Navypolicies, procedures, equipment, publica- of assigned tasks. tions, systemsis subject to change and de- YOU WILL HAVE INCREASING RESPONSI- velopment. As a OM1, and even more as a OMC, BILITIES FOR WORKING WITH OTHERS. Asyou you must keep yourself informed about all advance to OM1 and then OMC, youwill find that changes and new developments that might affect many of your plans and decisions affect a large your rating or your work. number of people, some of whomare not in the Some changes will be called directly to youk optical shop and some of whom are noteven in attention, but others you will have to look for. the same division. It becomes increasinglyim- Try to develop a special kind of alertness for portant, therefore, to understand the duties and new information.Keep up to date on all avail- responsibilities of personnel in other ratings. able sources of technical information. Every petty officer in the Navy is a technical specialist in his own field.Learn as much as you can about the wONt of other ratings, and plan REQUIREMENTS FOR ADVANCEMENT your own work so thatit willfit in with the overall mission of the organization. In general, to qualify for advancement you AS YOUR RESPONSIBILITIES INCREASE, must: YOUR ABILITY TO COMMUNICATE CLEARLY 1. Have a certain amount of time in grade. AND EFFECTIVELY MUST ALSO INCREASE. 2. Complete the required military andpro- The basic requirement for effective communica- fessional training courses. tion is a knowledge of your own language.Use 3. Demonstrate the ability to perform all correct language in speaking and in writing. Re- the PRACTICAL requirements for advancement member that the bade purpose of all communica- by completing the Record of Practical Factors, tion is understanding. To lead, supervise and NavPers 780. train others, you must be able to speak and ;trite 4. Be recommended by your commanding of- in such a way that others canunderstandexactly ficer. what you mean. 5. Demonstrate your KNOWLEDGE bypass- A second requirement for effective communi- inga written examination based on (a) the cation in the Navy is a sound knowledge of the military requirements for advancement and (b) Navy way of saying things.Some Navy terms the professional qualifications for advancement have been standardized for thepurpose of en- in the Opticalman rating. suring efficient communication. Whena situation Advancement in rating is not automatic. calls for the use of standard Navy terminology, Meeting all the requirements makes you eligible use it. for advancement but it does not guaranteeyour Still another requirement of effectivecom- advancement. Some of the factors that deter- munication is precision in the use of technical mine which persona, out of those who take the terms. A command of the technical languageof examinations, will actually be advanced in rating the Opticalman rating will enableyou to receive are the scores made on the written examination, and convey information accurately andto ex- the length of time in service, the performance change ideas with others. Aperson who does marks, and the quotas for the rating. Chapter 1ADVANCEMENT

Remember that the requirements for ad- SCOPE OF THIS TRAININGCOURSE vancement may change from time to time. Check with your division officer or with your training Before studying any book, it is a good idea to officer to be sure you have the moat recent re- know the purpose and the scope of the book. Here quirements when you are preparingfor advance- are some things you should know about this train- ment and when you are helping lower rated mon ing course: to prepare for advancement. 1.It is designed to givo you information on To prepare for advancement, you need to be the professional (technical) qualifications for familiar with (1) the military requirements and advancement to 0M1 and OMC. the professional qualifications gi/en in the 2.It must be satisfactorily completed before Manual of Qualifications for Advancement in you can advance to OM1 or OMC, whether you Rating, NavPera 18068; (2) the Record of Practi- are in the regular Navy or in the Naval Re- Ziririctors, NavPera 760; (3) appropriate Navy serve. Training Courses; and (4) any other material 3.It is NOT designed to give you informa- that may be required or recommended in the tion on the military requirements for advance- current edition of Training Publications for Ad- ment to P01 or CPO. Navy Training Courses vancement in Rating, NavPers 10052.These that are specially prepared to give information materials are discussed later in the section of on the military requirements are discussed in the this chapter that deals with sources of informa- section of this chapter that deals with sources of tion. information. 4.It is NOT designed to give you informa- THE OPTICALMAN RATING. tion that is related primarily to the qualifications for advancement to 0M3 and 0M2. Such informa- The Opticalman rating is a general rating tion is given in Opticalman 3 & 2, NavPers ONLYthere are no service ratings. Because of 10205. the nature of the work Oriticalman perform, the 5.The professional (technical) Opticalman comprehensiveness of its scope and the diversity qualifications that Were used as a guide in the of abilities required, an Opticalman should be a preparation of this training course were those man of fairly high intelligence, good emotional promulgated in the Manual of Qualifications for stability, and high mechanical aptitude. A back- Advancement in Rating, NavPers 18068B, of ground of general and mechanical training is June 1965.Therefore, changes in the Optical- helpful. man qualifications occurring afterJune 1965 may An Opticalman is generally assigned duty in not be reflected in the information given in this optical shops aboard repair ships or tenders. training course.Since your major purpose in On occasions, however, he may be assigned duty studying this training course is to meet the quali- ashore as an instructor in an Opticalman school. fications for advancement to OM1 or OMC, it is Some Opticalman receive shore duty in recruit- important for you to obtain and study a set of ing; others are assigned duty in Naval Reserve the most recent Opticalman qualifications. training, or in the U.S. Naval Examining Center, 6. This training course includes information Great Lakes, Illinois, where they help to prepare that is related to both the KNOWLEDGE FAC- servicewide examinations for advancement in TORS and the PRACTICAL FACTORS of the rating. On occasions, Opticalmen may also be qualifications for advancement to 0M1 and OMC. assigned duty in the Training Publications Divi- However, no training course can take the place of sion, Washington, D.C., to help prepare Navy actual on-the-job experience for develOping skill Training Courses and/or other training mate- in the practical factors. The training course can rials, such as curricula and correspondence help you understand some of the whys and where- courses. fores, but you must combine knowledge with You should understand by now that the Opti- practical experience before you can develop the calman rating is a VERYimportant rating, with= required skills.The Record of Practical Fac- out which part of the mission of the Navy would tors, NavPera 760, should be utilized in conjunc- not be accomplished, particularly during emer- tion with this training course whenever possible. gencies and under certain conditions and circumstances.Remember, then, that you ARE an SOURCES OF INFORMATION important person who fills an important position It is very important for you to have an ex- on the TEAMthe United States Navy. tensive knowledge of the references to consult

3 OPTICALMAN 1 & C

for detailed, authoritative, up-to-dateinforma- practical factors and the knowledge factor's of tion on all subjects related to themilitary re- BOTH the military requirements and the profes- quirements and to the professional qualifications sional qualificationa. of the Opticalman rating. A special form known as the RECORD OF Some of the publications discussed hereare PRACTICAL FACTORS, NavPers 760, is usedto subject to change or revision from time tottme record the satisfactory completionot the practi- some at regular intervals, others as the need cal factors, both military and professional, listed arises. When using any publication thatIs sub- in the Quals Manual. This form is available for ject to change or revision, besure you have the each rating. latest edition. Whenever a person demonstrates When using any publication that his ability to perform a practical factor,appro- is kept c.-rent by means of changes, besure priate entries must be made in the DATE and you have a copy inwhich all official changes have INITIALS columns. As an 0M1 or OMC,you will been entered. often be required to check the practical factors performance of lower rated men and to report BUPERS PUBLICATIONS the results to your supervising officer. To facilitaterecord keeping,group records of The BuPers publications described here in- practical factors are often maintained aboard clude some which are absolutely essentialfor ship.Entries from the group records must, of anyone seeking advancement in rating and some course, be transferred to each individual's Re- which, although not essential,are extremely cord of Practical Factors at appropriate Inter- helpful. vale. THE QUALS MANUAL.--The Manualof As changes are made periodically to the Quals Qualifications for Advancement in Rating,Nav- Manual, new forms of NavPers 760 Pers 18068B (with changes), gives are proceed the mum when necessary. Extra space is allowedon the requirements for advancement to eachrate Record of Practical Factors for entering addi- within each rating. The Quals Manuallists the tional practical factors as they are published in military requirements which apply to allratings changes to the Quals Manual. Besure that the and the professional or technicalqualifications NavPers 760 you are using includes the latest that are specific to each rating. changes to the qualifications for Opticalman. The Quals Manual is kept current bymeans of The Record of Practical Factors also provides numbered changes.These changes are issued space for recording demonstrated proficiencyin more frequently than most Navy Training skills which are within the general scope of the Courses can be revised; therefore, thetraining rating but which are not identifiedas minimum courses cannot always reflect the latest qualifi- qualifications for advancement. Keep this in cations for advancement: When preparingfor mind when you are training and supervising lower advancement, you should always checkthe rated personnel.If a man demonstrates pro- LATEST Quals Manual and the LATESTchanges ficiency in some skill which is not listed in the to be sure that you know the current requirements Opticalman quals but which falls within thegen- for advancement in your rating. eral scope of the rating, report this fact to the When studying the qualifications for advance- supervising officer so that an appropriate entry ment, remember these three things: can be made. 1. The quals are the MINIMUMrequirements The Record of Practical Factors should be for advancement to each rate within eachrating. If you study more than the required kept in each man's service record and should be minimum, forwarded with the service record to thenext you will of course have a great advantage when duty station. Each man should also keep you take the written examinations for advance- a copy ment in rating. of the record for his own use. 2.Each qual has a designated rate level NAVPERS 10052.Training Publications for E-4, E-5, E-6, E-7. Advancement in Rating, NavPers 10052, isavery You are responsible for important publication for anyone preparingfor meeting all quals specified for advancement to advancement in rating.This publication lists the rate level to which you are seekingadvance- requiredand recommended Navy Training ment AND all quail specified forlower rate levels. Courses and other reference material to be used 3. by personnel working for advancement in rating. The written examinations for advance- NavPers 10052 is revised and issuedonce each ment in rating contain questions relatingto the year by the Bureau of Naval Personnel. Each 4 9 Chapter 1 ADVANCEMENT revised edition is identified by a letter following deal of useful information on the ealisi.ed rating the NavPers number. When using this publica- structure; how to prepare for advancement; how tion, be sure you have the most recent edition. to supervise, train, and lead other men; and how The required and recommended references to meet your increasing responsibilities as you are listed by rate level in NavPers 10052. It is advance in rating:. important to remember that you are responsible S01111) of the Navy Training Courses that may for all references at lower rate levels, as well be useful to you when you are.preparing to meet as those listed for the rate to which you are the professional. qualifications for advancement seeking advancement. to OM1 and OMC are discussed briefly in the Navy Training Courses that are marked with following paragraphs.For a complete listing an asterisk (*) in NavPers 10052 are MANDA- of Navy Training Courses, consult the List of TORY at the indicated rate levels. A mandatory Training Manuals and Correspondence Courses, training course may be completed by (1) passing NavPers 0061 (revised). the appropriate Enlisted Correspondence Course Basic Handtools, NavPers 10085 -A. Although based on the mandatory training course, (2) thisirse is not specifically required passing locally prepared tests based on the infor advancement in the. Opticalman rating, you formationgiven in the mandatory training will find that it contains a good deal of useful course, or (3) in some cases, successfully com- information rir the care and use of all types of pleting an appropriate Navy school. handtools and portable power toctis commonly It is important to notice that all references used in the Navy. whether mandatory or recommended, listedin Blueprint Reading and Sketchbig, NavPers NavPers 10052 may be used as source material loolir-B, contains information that may be of for the written examinations, at the appropriate value to you as you prepare for advancement to rate levels. OM I and OMC. NAVY TRAINING COURSES.Navy Training Mathematics, Vol. 1, NavPers 10069-C, and Courses are written for the specific purpose of Mathematics, Vol: 2, NavPers 10071-A. These helping personnel prepare for advancement in two training courses may be helpful if you need rating. Some courses are general in nature and to brush up on your mathematics. Volume 1, in are intended for use by more than one rating; particular, contains basic information that is others (such as this one) are specific to the needed for using formulas and for maldng simple particular rating. computations. The information contained in Navy Training Courses are revised from time volume 2 is more advanced than you will need to time to bring them up to date. The revision for most purposes, but you may occasionally of a Navy Training Course is identified by a find it helpful. letter following the NavPers number. You can Opticalman 3 & 2, NavPers 10205.Satis- tell whether a Navy Training Course is the latest factory completion of this training course is now edition by checking the NavPers number and the required for advancement to 0M3 and 0M2. letter following the number in the most recent Opticalman 8 & 2 and Opticalman 1 & C replace edition of the List of Training Manuals and Opticalman 3, Vol. 1, NavPers 10198; Optical- Correspondence Courses, NavPers 10061 (re- NavPsrs 10197; and Opticalman vised). C, NavPers 10198. If these courses were There are three Navy Training Courses that UsFirrmeet third class and second class ad- are specifically prepared to present information vancement requirements, you should become on the military requirements for advancement. familiar with the contents of Opttaalrt...n 3 & 2. These courses are: This new course includes revised material from BasicMilitary Requirements,NavPers the previous courses and new material. Much of 10054-A. the information given in this edition of Optical- Military Requirements for Petty Officer 3 & man 1 & C is based on the assumption MiWu 2, NavPers 10056-B. are familiar with the contents of Opticalman Military Requirements for Petty Officer 1 & 3 & 2, NavPers 10205. C, NavPers 10057-B. CORRESPONDENCE COURSES.Most Navy Each of the military requirements courses Training Courses and Officer Texts are used is mandatory at the indicated rate levels.In as the basis for correspondence courses. Com- addition to giving information on the military pletion of a mandatory training course can be requirements, these three books give a good accomplished by passing the correspondence

5 /0 ff OPTICALMAN 1 & C course that is based on the training course. chapters remain in their old positions,so the You will find it helpful to takeother corre- new and the old numbers have a definite relation- spondence courses, as wellas those that are based on mandatory training ship to each other. For example, theold chapter courses.For 24 has been renumberedas 9240, and the old example, the completion cf thecorrespondence course based on Engineering Administration chapter 95 has been renumberedas 9950. How- NavPers 10858-C is strongly ever) some of the chapters will be movedtonew recommended locations, as well as being renumbered; inthese for personnel preparing foradvancement to cases, there is no clear relationship between OMCS.Taking a correspondencecourse helps you to master the information given the old numbers and the new. Forexample, the in the train- old chapter 6 has been moved toa new location ing course or text and alsogives you a pretty good idea of how much and is now renumbered 9004. you have learned from It should be noted that fitvpte r s of the Bureau studying the book. of Ships Technical Manual may be OTHER BUPERS PUBLICATIONS.Addi- referred to by either the old chapterLumber or the wtw tional BuPers publications thatyou may find useful in connection with chapter number, depending upon whichnumber your responsibilities was in use at the time of writing. Ifyou have for leadership, supervision, andtraining include any trouble locating the matter by the number the Manual for Navy Instructors,NavPers 16108-C, and the Naval given, :leek the cross-reference sheetsgiven Training Bulletin, Nav- in the front of the first volume of theBureau of Pers 14900 (published qwarterly). Ships Technical Manual. BUSHIPS PUBLICATIONS The manufacturer's techniOal manualsfurn- ished with most eqtiipmentare valuable sources A number of publications issued of inforniation oii maintenance, And repair.The by the manufacturers' technical manse's forperi- Bureau of Ships will be of interestto you. While scopes and other optical equipment are usually you do not need to kno* everything thatis given given NavSidps numbers. in the publications mentionedhere, you should have a general idea of whereto findinformation er in BuShips publications. FILMS The Bureau of Ships TechnicalManual, Nav- Training films available to naval personnel Ships 250-000, is the basicdoctrine publication are a valuable source of supplementary informa- of the Bureau of Ships. TheManual is kept up to date by means of quarterly tion on many technical subjects.h. selected changes.All list of training films that may be undid toyou copies of the Manual should haveall changes is given in appendix I of this training made in them assoon as possible after the course. changes are received. Other films that may be of interestare listed Beginning with the quarterly in the United States Navy FilmCatalog, Nav- changes dated Weps 16-1-777. This catalog, publishedin `466, 15 July 1563, the Bureau of Ships beganto re- supersedes threeearlier publications: number individual chapters in theBureau of the Ships Technical Manualaccording to Wy- former catalog with thesame title but numbered fiarine Corps Standard NavPers 10000-A; the Supplement,NavWeps Subject Classification 10-1-172; and the Navy ClassifiedFilm Cate - System. Under this system, allchapters of the lohavPers 10001-A. Manual will eventually be partof the 9000 series When selecting a film, note its date which identifies ship design andship's material of issue subject groups. When all listed in the film catalog. Asyou know, pro- chapters have been cedures sometimes change rapidly.Thus some renumbered to conform to the 9000numbering films become obsolete rapidly. system, the old chapter numberswill be elimi- If a film is nated. In the meantime, obsolete only in part, it may still havesections you wili have to consult that are useful, but it is importantto note the sheets in the front of the firstvolume of the procedures that have changed. Manual which cross-referencethe new number- If there is any doubt, verify current procedures bylooking them ing system and the old. Someof the Manual up in an applicable source.

6 CHAPTER 2

SHOP SUPERVISION

As an OM1 or OMC, one of your major re- your shop and by each man assigned to your sponsibilities will be to supervise the repair shop.This log may be one of your own design, and overhaul of optical instruments.In order but it should contain the following pertinent to supervise optical shop work most efficiently, data: Job order and work request number, date you with rely mostly on your past experience in received, name of the activity requesting the shop work and repair procedures. In addition work, brief description of the job, name ofthe to this, you will be required to maintain certain man assigned to do the job, and thenumber of records and reports, conduct and supervise an man-hours expended. effective training program, and give accurate A MATERIAL EXPENDED RECORD is a run- estimates as to the time required to complete ning inventory of your stockpile includingsuch repair work. information as the date material was received, It is impossible to cover all the procedures the jobs on which the material was expended, and problems that arise in the work of a shop and the balance on hand.To facilitate the supervisor. By studying this section, you will preparation of stub requisitions, such data as become aware of some of the things that occur, quantities listed on the shipboard allowance list, particularly in regard to the job of setting up location of the spaces where the materials are hop procedures, and the methods by which stored, and stock numbers may be included. everyday problems are solved in an optical This record is particularly valuable on repeat shop. jobs such as the repair of small instruments. An EQUIPMENT LOG is a list of the various RECORDS AND REPORTS tools charged to you and their locationwhether in the shop or storeroom, or assigned to an As you advance in rating to OM1 or OMC, individual; the location of repair parts boxes you will be required to assume more responsi- can also be logged in this notebook.An equip- bility for the paperwork which is so necessary meet log kept up to date with adequate tool in a well organized shop. In fact, to avoid bog- descriptionsmake, model, and serial number ging down completely in the mass of details, will be of great assistance to you in making you will probably delegate some of these duties periodic inventories. to an assistant in the shop.Keeping all your A MAN-HOUR REPORT is submitted daily records up to date 11411 enable you to keep a to the head of the department through the close check on each job, each workman, and division officer. A summary of both productive each piece of equipment under your supervision. and nonproductive work may be included in this The ship will have standard forms for keeping report.Nonproductive work includes training, some of the required records; for example, shop upkeep, general drills, and special details work request forms, supplementary job order such as field day, mess cook, compartment forms, and the necessary requisitions for ob- cleaner, and master-at-arms assignments. This taining repair part and supplies.You may form, when submitted by all of the shops in the supplement these forms with shop logs andnote- department, gives the repair officer a complete boas of your own design to meet your specific picture of the wsrldng day. needs. For further information on Navy records and A WORK PROGRESS LOG is a record of all reports refer to BuShips Technical Manual, the current and completed work accomplishedby chapter 9004 00. r

a. OPTICALMAN 1 & C

CARE OF TOOLS AND EQUIPMENT or burnt, and each one likes to havehis own hammer, chisels, and screwdrivers.) Orderliness is a prime essentialof good Besides shop operation. speeding up production of work, thismethod of There must be a place for stowage will provide better care and every tool and each tool must be returnedto its cleanliness place after use. of handtools. By seeing that this practice If space permits, onecorner of the shop may is observed, the men underyour supervision be blocked off for use as will be able to find any toolat any time, without a TOOLROOM. In this wasted effort. room can be kept such tools as portablepower In an optical shop, cleanliness, drills, grinders, grinding wheels,large dividers, like orderli- pipe wrenches, C-clamps, large drillbits, spe- ness,, is a very important factor.If tools are cial files, dies, tap wrenches, and to serve their purpose mostsatisfactorily, they diestocks. A should be wiped with a cloth striker should be made responsible forkeeping containing light oil the tools in order and issuing themas required. after they have been used. Toolsaboard ships This toolroom job should be rotated and in other localities of highhumidity should among the be wiped at least once strikers to give each manan opportunity to a week (whether or not learn the names and uses of all the tools. they have been used). In applyingoil, care must be taken to see that it does Tool stowage is an important itemin the not get on the wooden optical shop.Lockers, racks, drawers, cabi- handles of screwdrivers andother tools. nets, and boxes are used for stowing An untidy shop is an unsafeshop. For this tools. The reason it is important that tools, place selected depends largelyon the USE of the machinery, tool, the frequency of itsuse, its size and shape, workbenches, and floorspaces bekept clean. and its value. Greasy and oily rags in pilesare fire hazards. Drill bits, micrometers, torch Spilled oil on benches anddecks may cause tips, com- serious injury. All equipment bination squares, gages, and the likemust be should be checked stowed so that they are protectedfrom contact to make sure that guards havebeen installed with other tools. Edged tools and and that they are kepton all moving parts of pointed tools, equipment. such as scribers, dividers, andcompasses, require special stowage to preventdamage to cut- Operating instructions and safetyprecautions should be posted at each ting edges and sharpened points. machine.It is good Particularly valuable and hard-to-gettools engineering practice to complywith all the re- should be kept locked in special quirements listed in the operatinginstructions lockers, and safety precautions. drawers, cabinets, or toolboxes.These include portable power tools, gages,micrometers, spe- SHOP HOUSEKEEPING cial pliers, wrenches, files, anddrills. Tools frequently used outside the shopshould be made tUp in kits and stowedin convenient Generally, you can givea workshop one good toolboxes.Tools used in your shop look and tell whether it is efficientand well run. may be Just make a quick marked with a distinctive color foridentification. survey for cleanliness, neat If so marked, they are noteasily mixed with tool and stock stowage, andthe condition of tools that belong to other shops. equipment. If such a survey revealsa high quality of housekeeping, it Good housekeeping requires thatbench tops can also be assumed and power equipment be kept that the shop 1s well organisedand really turns clear of unneces- out the work. sary tools and material, scrap stock,filings, dirt, and excess oil andgrease. Material and suppliesscrews,bolts, and gasket materialmust be storedin a convenient, INVENTORY OF TOOLS AND secure, and orderly place. Use cabinets, EQUIPMENT shelves, bins, and racksarranged in the shop One of the jobs of the supervisor to give the greatestpossible amount of free of an opti- working space. cal shop is to maintaina system of account- ability for valuable tools andequipment. He If shop space permits andaufficienttools are should see that custody cards available, each man should havehis own stowage are made out for drawer and toolbox in which tools and equipmentrequiring custody signa- he can keep the tures.These include such items tools that are ordinarilyused. (No man likes as portable to use a drill bit that power tools, gages, micrometers,and special someone else has nicked sets of handtools.Tools which are of a highly

8 <3 Chapter 2SHOP SUPERVISION pilferable nature should be accounted for by in- 13. Clamp workpieces securely to the ma- ventory at regular intervals.All accountable chine, particularly on drill press operations. tools issued from the toolroom should be re- (Use vises or other adequate holding devices turned at the end of the working day, unless spe- when-working on small parts.) cial permission has been obtained to keep them 14. Do not exceed the recommended depth out for a longer period of time. of cut, cutting speeds, and feeds. In making a complete inventory of tools and 15. Keep the areas around machines clear equipment, the Coordinated Shipboard Allowance of obstructions and in a nonslippe:y condition. List (COSAL) is used. The COSALis the official 16. Remove chips with a brush or other source which contains the allowance of ma- suitable toolnever by hand or with compressed chinery,equipment,accessories,tools, and air. repair parts furnished the opttoal shop. A de- 17. Always wear goggles or a face shield tailed description of the COPAL is given ini4111- when grinding, or when there is danger of fly- tar), Requirements for Petty Officer 3 & 2, ing chips. NavPers 10056-B. 18. Do not operate electrically driven portable handtools wihout a ground connection be- SAFETY PRECAUTIONS tween the metal housing of the tool andthe steel structure of the ship. When possible, use only You should ensure that the following pre- tools equipped with a properly grounded plug, cautions for the safety of personnel are known see that the grounded plug isinserted in a and observed by the operators of all types of grounded receptacle. If the tool is equipped with power-driven tools: a 2-contact plug and a supplementaryground wire, see that the ground wire is securely at- 1. Do not attempt to operate a machine with tached to the ship's structure by a clean metal which you are not familiar. contact.Where the ground wire is independent 2. Before operating a machine, see that of the tool plug, the wire should always be con- there is plenty of light to work by. nected BEFORE the plug is inserted in the re- 3. Do not operate electrically driven ma- ceptacle and should not be disconnected until chines, either stationary or portable, without AFTER the plug is pulled out. Where portable observing the proper electrical safety pre- tools are provided with grounded plugs, this cautions. sequence of connecting the ground first and dis- 4. Shut off the power supply to any machine connecting it last is automatically provided for that is being repaired or adjusted; and attach the in the arrangement of the contacts in the prescribed warning card to the switch, to ensure grounded plug and grounded receptacle.It is, that the machine will not be energized by other therefore, in the interest of safety and con- personnel. venience to install these grounded plugs on all 5. Do not allow machines to =unattended. portable tools. 6. Never lean against a machine that is running. PLANNING THE WORK 7. Keep machine guards in position at all times unless removal is authorized by the shop The optical shop supervisor, with the as- supervisor. sistance of his leading petty officers, must plan 8. Replace machine guards after repairs or each phase of each job that is assigned to his inspections have been completed and before the shop. The planning of the day's work must in- machine is started. clude the lead jobs, the assist (supplementary) 9. Do not distract the attention of a ma- jobs from other repair shops, the routine up- chine operator. keep and maintenance, and nonproductive work 10. Do not wear loose or torn clothing, such as working parties.Lack of good plan- glovesneckties, long sleeves, or rings while ning will usually result in confusion, delay, and operating a machine. sometimes failure to meet the commitments of 11. If clothing becomes caught in amachine, the shop. The supervisor must plan for the co- shut off the power immediately. ordinating of the various steps in the work. 12. When using piittible electric equipment This involves consideration of available man- around machine tools, take special care that power, equipment, materials, and the workload electrical cords are clear of moving parts. of the other repair shops.

9 IP-

OPTICAIMAN 1 & C Planning does not stop in theimp. The repair officer must know how in getting the work out.Have a place for many productive everything and keep everything inits place. It man-hours are to be availablefor repair work, is also important that your during a specific availability,to enable him storage facilities to know how much work have adequate provision for securingfor sea. can be accepted during Estimating the amount of material required that period of time.This is where estimating comes into the picture. to complete a job is your responsibility.Unless The shop supervisor you are able to estimate withaccuracy the must have the ability to givean accurate esti- amount and kind of materials required by mate of the time that each of thejobs assigned your to his shop will consume. shop, you will either be caught shortwithout To do this, he will the items you need oryou will find your shop rely heavily on his pastexperience and the experience of his leading petty cluttered with items you do not need. Ahigh officers. He must inventory level of slow moving materialsties also estimate the nonproductiveman-hours that up division funds that might be used to better will be required to meet hisshop's obligations to provide for working advantage. Remember that runninga shop is parties, mess cooks, like running a business; you mustoperate with- special liberty, etc. in a budget. Much of the guesswork in In planning the work, thecapabilities of the estimating men must be considered. can be eliminated if you make properuse of Assigning an inex- records of material expended during thepre- perienced man to a difficult jobrequires that vious quarter. an experienced man be on hand to give Include the amount of material direct required for any special work whichyou know 1 supervision at all times.If the work load of is to be done during the period the shop is light, this isa good training op- for which you portunity. are estimating.Plan and place shop orders However, if the shop hasa heavy for materials in advance with the supply workload the inexperiencedman would be of officer more value assigned to a job requiring through the division officeror department head. skills Do not bypass any of the normal supplychannels more in line with his experience. of authority. Another question to be answeredis the number of men required to accomplish Inventory levels for most consumable items the job. Too and repair parts are maintained bythe supply many men working on the same pieceof equip- department. ment is sometimes worse than Aboard some repair shipsor not enough. Each tenders, the 0M1 or OMC will assist thesupply job will have to be analyzedstep by step and officer in maintaining the inventory then the required number ofmen assigned. on optical Still another factor that must parts. Usually a high limit will bekept on hand. be considered Before the low limit is reached, theOM1 or is the necessary materialsto accomplish the OMC will request that material be needed repairs. What kindof materials, how obtained to much is needed, where is it replenish the stock and maintain thehigh limit obtainable, and how supply. In ordering, take intoconsideration the much time will be takento obtain it, are all rate of use, the balance questions that must be given much on hand, and the ex- considera- pected delay in shipment and delivery.Informa- tion.Possibly the material calledfor in the tion concerning the procurement, blueprint is no longer available.The research custody, and required in finding a suitable inventory of repair parts and othersupplies is substitute takes covered in Military Requirementsfor Petty time.These factors all must beconsidered Officer 1 & C, NavPers 10057-A, and by the supervisor of theoptical shop. in Requirements for Petty Officer 3& 2, There are some materialsthat can be kept in ROPers 10056-B. the optical shop in sufficientquantities to avoid In planning a job, the CPO delay caused by frequent tripsto the issue room. or P01 in charge For some items a 30-day of the shop must first performthe job step by supply is adequate, step mentally.This procedure will help for others, a 90-day supplymay be necessary. pre- Usually, the 0M1 vent the unintentional omission ofsome im- or OMC will know from portant step of the job. Once thesteps are out- experience where each item isin the shop; he keeps his locator file in his lined, consideration should begiven to each step head. He should to make Baru that all requirementsare taken also attach a list of thecontents to each drawer into account. or cabinet so that the rest of themen in the shop will also know where After the job has been analyzed, thesequence things are stowed. of the operations must be determined. Remember the importance of good In some housekeeping jobs the more time consumingoperations may 10 Chapter 2SHOP SUPERVISION be performed first so that the largest part of PRIORITY OF JOBS the job is completed first.In other jobs, the less time consuming operations may have to be In planning and scheduling work in theshop done before any other operation can be per- you will have to give carefulconsideration to the formed. priority of each job order. Priorities are gen- Once the planning of the work has been done, erally classified as urgent, routine, ordeferred. follow the plans carefully. However, it is also Deferred jobs do not present much of a necessary to be flexible, in order tomeet any problem, as they are usually accomplishedwhen unforeseen circumstances or make emergency theworkload of the shop is light and there are repairs.If a change in plans is indicated, the few jobs of a higher priority to be done.Also, supervisor must reevaluate the whole plan and when these jobs are approved it iswith the make such changes as he believes necessary. understanding that they will be accomplished Careful planning and the followup of these plans when the time, personnel, and equipment are will enable you to rim your shop with the ut- available. The majority of job orders will havethe most of efficiency and productivity. routine priority assigned to them. Routine jobs make up the normal workload ofthe shop, LAYING -OUT AND ASSIGNING WORK and must be carefully planned and scheduled so that the daily organization and production can A Navy optical shop is primarily concerned be maintained at a high standard. with repair work. The assignment of work The urgent priority jobs require immediate changes constantly according to the amount and planning and scheduling.Other jobs, of lower type of work being done in the shop. When the priority, may have to be set aside so thatthese workload is light, the less experienced men may urgent jobs can be accomplished. Attimes it be assigned to a complicated job under the may be necessary to assign mento a night shift -supervision of an experienced petty officer. so that these jobs can becompleted on time. When the workload is heavy the most experienced men will have to be assigned to the com- DETERMINATION OF REQUIRED REPAIRS plicated jobs and to those jobs that are of an urgent nature.At times reassignment of work When a job is delivered to the shop, one of must be made to prevent delays, to accomplish the first. things to be done is to determinewhat added new work, or to expedite emergency jobs. kind of repairs are required. This iswhere the years of practical experienceand up-to-date INFORMATION ON INCOMING J0'313 knowledge on different types of repair procedures are invaluable.During the planning Job orders generally will be received in the stage, check with some of theleading petty of- shop several days in advance of the work. The ficers in the shop for ideas on how best to ac- shop supervisor should start his planning as complish the necessary repairs. Perhaps one soon as possible to gain an advantageof time. of them may have done the samejob before. Much of the pluming may be done before the It may be possible to assign some ofthe plan- work is delivered to the shop. Jobs that have ning work to them; for examplea job of over- been done before may be planned in ache man- hauling a rangefinder may be given' to a manin ner that the necessary repair parts are on hand the shop who has demonstrated his abilityto do or the blueprints are obtained fromthe techni- this type work. cal library. Usually the activity requesting the After the necessary repairs have been de- repairs will provide the plans or blueprints termined, the shop supervisor must ascertain along with the job order. that the repair parts or materials areavailable. Another source of information is the manu- If they are not available on board, theymust be facturers' technical manuals. Many of these requisitioned through the supply department. may be found in your own technicallibrary or The activity requesting the repairs may even may be obtained from the activityrequesting have the necessary repair parts on hand.If so, the repair work.From these sources of in- they may be used by the repair activityand then formation much advance planning can be done replaced when available. Frequently, therepair. prior to the delivery of the equipment to be parts must be manufactured or possiblytem- repaired. porary repairs made to the old parts.Matters

11 t+1/6 OPTICALMAN 1 & C

of this nature must be clearedup before the job routine jobs within any set time is laid out and assigned to lessexperiencedper- as long as the sonnel in the shop. repairs are completed before theend of the availability, and in sufficient time forthe ship's SCHEDULING OF WORK force to install the repaired equipment. The estimation of time requiredto complete jobs of an urgent nature (priority) The main object in plannedscheduling of work must be is to have the workflow smoothly given considerable thought.If a last minute and to have the job comes up near the end of therepair period, next job ready without delay,since lost time or if a ship in portfor only a day or two requires between jobs lowers the overallefficiency of the an urgent repair job, the time required to make shop.Because of the variety of jobs whichyou the repairs is an important and your men will be requiredto perform, ape-. consideration. In cific work schedules must be jobs such as this, the time estimatemust be prepared to make extremely accurate to avoid thewaste which sure that all work is completed.These work would result from starting schedules must be flexible enoughto adapt to a repair job that changes in priorities, transfer could not be completed.Frequently, the final of personnel, decision will be made by the 0111or OMC in temporary breakdowns of equipment,unsched- uled ship drills, or charge of the optical shop; becauseof his ex- any other emergency that perience in repair work, his knowledgeof the may come up from time. to time. current workload, and his knowledge of The priority of job orders,as well as the the men length of time required to and machines in the shop, he shouldbe able to complete them, will give an accurate estimate of the timerequired to determine the scheduling of work.Jobs of urgent complete almost any repair job. priority will be accomplished firstbefore routine Before any estimate can be made, jobs are started. The deferredjobs or the jobs detailed of least importance are left information on the job must beon hand. Where until last; then they necessary, blueprints and manufacturer's tech- can be done or canceled, dependingupon the workload of the shop. nical manuals should be studied.A thorough It may be necessary to change study of the item requiring repairsmust be the schedule made because the job might requirerepairs or of work in the shop whennew high-priority jobs replacements in addition to those come in.Sometimes other work must betem- originally porarily set aside until these specified. A decision has. to bemade as to the urgent jobs are amount of repair work that is to bedone. De- completed.Experience, judgment, and fore- tailed procedures on how best sight are required to maintainan organised to accomplish scheduling of work in these repairs must be clearlyunderstood. In a large optical shop, in other words, one should know all order to get the mmierousjobs finished at their the details of respective times. the repair job, before starting toconsider the length of time required to do thejob. When the necessary repairshave been de- Eirl'IMAZWG TIME FOR A JOB termined, consideration may begiven to a time estimate.The optical shop supervisor must Estimating time for the completionof a job consider the various phases of the requires considerable thought andforesight. repair opera- Upon your estimate tion when calculating the time itshould take to may depend the success or perform a given operationon any part and on failure of a ship to meet itsoperational com- any specific instrument. mitments.Failure to complete a job inthe allotted time can result in considerableunneces- TEARDOWN TIME sary expense and loss of valuabletime. Each estimate that you make must' berealistic, ac- In any repair job, the instrument curate, and dependable. Anestimate, in a very to be re- real sense, is a paired is disassembled onlyas much as is guess, but it should be an in- necessary to enable the repairs to be telligent guess based on theproper use of rec- made ords and experience. without damage to other partsof the equipment. For most of the routine The teardown time is thattime required to dis- jobs that come into assemble a piece of equipmentafter it has been the shop, the shop supervisormay give a quick delivered to the shop. estimate of the probable timeof completion. The teardown time is Generally, there is no necessity then doubled to allow sufncierdtime for re- for completing assembly.ifitisnecessary to do any 12 17 Chapter 2SHOP SUPERVISION dismantling before delivery to the shop, an es- Another item that must be decided isthe timate of this time will be made by the ship's number of hours per day that will beassigned force (customer ship) or by other repair de- for personnel to work on the newjob. If it is to be a routine job, normal workinghours will partment personnel. be considered. If it is a rush job with anurgent job MISCELLANEOUS TIME ALLOWANCE priority, three shifts will be assigned to the and men will be working 24 hours a day onit. The final factor to consider in estimating In brief, the selection and assignmentof time is often overlooked. This is the time that personnel will depend upon the magnitude and falls into the category of miscellaneous. Some complexity of the new job under consideration of the miscellaneous factors are: fatigue from as well as its assignedpriority.This in turn mind and muscle exercise, personal time allow- depends upon the workload of the shop,except ances such as head calls, restbreaks, or meals, where the new job is given an urgentpriority. and such other items that would not fall into any of the other categories given here. REQUIRED PARTS AND MATERIAL The time factors that have thus far been considered are those that have to do with the over- After a decision has been made as tothe hauling of a piece of equipment or making repair extent and nature of repairs that arerequired, a parts. There are certain other factors that must check must be made to see if the requiredmate- be considered in order to make a realistic and rial and parts are on board ship. Thematerial accurate time estimate. Some of these are: the must be available before an attemptis made at shop workload of other repair shops and any time estimating the time of a repair job. Suchitems consuming errors: as gaskets, studs, bearings, andshaft keys that may be required must not beoverlooked. SHOP WORKLOAD Naval ships carry an allowance ofrepair The workload of the shop must be carefully parts for machinery and equipment onboard considered before a new job is approved for ship. A check of the ship's COSAL willshow if completion within a certain time. a certain part is supposedto be carried on After a decision has been made as to what board. There have been instances wherethis repairs or replacements are necessary, the check has been overlooked. There is certainly petty officer in charge will be able to determine no need to manufacture an itemsuch as a gear what tools and personnel should be used for the if the ship carries gears for the instrumentthat job. The next step is to check on the present and requires repair. Locating available repairparts scheduled work. If an urgent priority has been will save a great deal of time in doingthe re- given to the new job wider consideration, then pair job, and one's estimate can bemade ac- the work being done by the repairman will be cordingly. set aside with the proposed job has been completed.If the new job does not have an urgent CONSIDERATION OF THINGS priority, it must be dovetailed, in accordance THAT MAY GO WRONG with its priority, into the schedule of work being done. Experience is an excellent teacher of things Another decision must be made concerning that may go wrong when doing a repairjob. An the personnel to be assigned to the new job. experienced supervisor can avoid manyof the This new job may require experienced personnel difficulties that may arise in performingrepair who may have to be taken off other jobs. If the work. When planning and estimating arepair new job is a complicated one, a leading petty job, the possible difficulties that mayarise officer may have to be assigned to process the should be carefully considered, andextra time job through the shop, including disassembling, allowed for them. Adequate blueprints orother inspections, assembling, and tests. The number drawings should be on hand.If you have suf- of required personnel, as well as their tecimical ficient information before starting thejob, and ability, must be considered. (Sometimes, a job a clear view as to the totalamount of repair can be completed in less time by assigning more work that will be required, it is easier toavoid men to do the work. However, there arelimits.- mistakes and delays. tions as to the number of men you can put on a The repair job itself may cause a certain given job. Don't assign unneeded men.) amount of breakage or damage;and the is OPTICALMAN 1 & C

supervisor who has estimated 90minutes for removal of the parts may find assigned men cannot be excused fromthese that the whole activities, extra time must be addedfor the job actually takes 4 hours. completion of the repair job. Failure to ensure that aman fully under- stands the details of the work The factors discussed do not makea com- may result in plete list of things that maygo wrong on a re- spoiled work. While the supervisormay have pair job, but they indicate the type of se.,1 the details on the job, thisis not sufficient things if the man doing the job ruins it which will have to be considered whenesti- because of lack mating the time required to doa repair job. of information or a misunderstandingas to what should have been done. The supervisor must SUPERVISING REPAIR WORK make sure that the detailedinstructions are thoroughly understood by themen doing the actual work. Some relatively One of the most important duties ofa First inexperienced men Class or Chief Opticalman is that ofsupervising fear to appear ignorant andwant to make a good allowing by saying that they the repair work in the opticalshop. The super- understand the in- visor must instruct shop personnelconcerning structions, without fully appreciatingwhat is meant. When the job, or part of the different repair jobs which haveto be done; it, has to be he must check on the progress of thework, and done over, the original estimatedtime of completion will no longer hold true. give additional advice or instructionswhen When the unit that is to be repaired necessary; and he should check the completed consists job to see that it has been done properlyand in of a number of assembled parts,there may be accordance with his instructions. difficulties in removing the variousparts. Parts After the supervisor of the optical shop has may be rusted or foram so that it isextremely difficult to remove them. On the obtained complete information ona new job and original in- has decided what repairs or replacementsare spection of the items in need ofrepairs, the necessary, he must then decide who is to do the supervisor should watch forany indication that the unit may be difficult to job. In order to make this decision, thesuper- disassemble. Then visor must Imo," what experience themen have he should make an extra allowanceof time in his estimate to cover th's phase had with different types of repairwork, and of the repair what skills they have in operatingthe various job. machine tools. If an item fails to passany required tests The shop supervisor should after repair, additional work willbe necessary. see that all The required tests, and the items coming into the shopare properly tagged. possibility of ad- The men in the shop should be instructedto re- ditional work associated withtests, must be place any tags which have been removed considered when makingan estimate of time in order required for the repair job. to overhaul an instrument. The mixupof some items, can cause, at the very least,a lot of un- The time required to deliver theinstrument necessary contusion and lost time. to the shop should not be includedon estimated time to do a repair job in the shop.When boat STARTING THE JOB and crane service are involvedin &proposed job, this fact should be brought up for consideration The man who is going to do therepair job by the person or activity requestingan estimate must be given detailed information of the time required by the optical on how the shop. When job is to be done. The shopsupervisor should requested to estimate this time oftransportation, the supervisor of an optical shop be careftd to ass that theman fully under- shOtildmake an stands what he is going td do,so as to prevent estimate, distinct and repents fromthat for the any mistakes due to miaandersbusding of work of his own shop. Boat andcrane service in- may be unpredictable at times, and the structions. The amount of instructiondepends super- upon the Imowledge and experience of theman visor should check with the officerof the deck concerned. If he is an experienced and the crane operator beforemaking an esti- man, it may mate of this kind. be only necessary to give hima blueprint and tell him what parts have to bemade or what When planning on the requiredpersonnel for repairs are to be accomplished. There the job, a check should be madefor the possible will be inspections, drills, and worldngpartiesthatmay times when a blueprint will not beavailable. The occur which will delay the repair job. supervisor will then have to snakea sketch of If the the part or parts to bemanufactured.This 14 /1 Chapter 2SHOP SUPERVISION sketch will make the job easier and more under- The supervisor who has interest and confidence standable for the man doing the work. A thorough in his men and their work will find that men understanding of Blueprint Reading and ketch- have confidence in him as a good shop super- NavPers 10077-B, will be of great help to ?bin% the shop supervisor in performing this task. Complications may develop on some repair Inexperienced men will need additional in- job, which may require additional planning and structions for setting up the work in the machine, revised repair procedures. By observing the and information on the proper procedure in progress of the various jobs, andwhether any doing the job. Men in the shop should under- are ahead or behind the plannedschedule, the stand that they are free to ask questions if they supervisor will be able to change the schedule are in doubt about any details in doing their as- of some jobs in order to prevent "bottlenecks" signed work. Men will ask questions when they and to keep the most important jobs moving. see that it is to their advantage to do SO. In addition to giving instructions on how a CHECKING ON COMPLETED JOBS job is to be done, it is also advisable to give the men some information concerning the impor- When a job has been completed in the shop, tance of the job, the origin of the job, the part the supervisor should inspect and approve the that each person will play in accomplishing the job.Inspection is necessary to ensure that the complete repair job, and the reasons for cer- repair job or the manufactured replacement tain specifications.In general, men are in- parts will be satisfactory both to the repair terested in why a job is done, and how it is done, activity and to the ship's force that is going to and will usually turn out better work if they use and depend upon the equipmentthat has been have a clear picture of the whole job. repaired.Inspection of parts may be accomplished either visually or by means of measuring CHECKING THE PROGRESS OF WORK instruments. In addition, when applicable, shop tests are performed to check the conditionof The assignment of a job is only the first step repaired equipment. in processing a job through the shop. The super- The completed job order should show the visor of an optical shop must brow his men. He man-hours, the material used, and a full de- should have a fairly good idea of each man's scription of the work accomplished. In addition, skill, ability, and knowledge for accomplishing the necessary shop records and paperwork the repair work. should be correct and up to date. When the job The best way in which the shop supervisor has been completed, the interested parties can obtain this knowledge is to inspect the shop should be notified as soon as practicable; com- frequently and check the progress of the various pleted jobs should not be left to accumulate in jobb in the shop.In that way, the supervisor the shop, as some of the items may become will have a good idea as to which jobs, or which mined up, damaged, or lost. men, will require the most checking or in- Before releasing a completed item, the shop ending- supervisor should check to be certain that When checking on the progress of work, the (1) The correct job order is signed by a repre- supervisor should be sure that the men are ob- sentative of the requesting activity, (2) the serving proper safety precautions in regard to identification on the item and on the job order themselves and the machines that they are coincide, and (3) all manufacturers' technical operating. manuals and blueprint furnished with the job In case of any doubt, the supervisor should order are returned. check that the men azierstand his instructions properly or are doing the work correctly as in- TRAINING SHOP PERSONNEL dicated by the blueprint or drawing. if news- nry, the supervisor should provide additional The first Impression formed by a new man instructions to give a better smdersbmding of in the shop will be a lasting one. It the petty the job, or to improve workmanship. By fre- officer in charge of an optical 'hop has a well- quently talldng to the men and answering their planned program for hdroducing new men to questions, the supervisor can prevent jobs from the work in the shop, be Intaken a most con- being spoiled, as might happen it he were not structive step toward building high morale. available to give the correct details on the jobs. One of the best stimulants for the development AO, 15 OPTICALMAN 1 & C

of high morale among new men is to have them 2. Those dealing with the realize that their boss appreciatestheir feeling men's attitudes or feelings, their confidence latheorganization, of strangeness and isaware of their desire to pride in the job, and respect make good,There is often a gap betweenthe for their fellow point at which a man is workers. assigned and the time S. Those dealing with skills, that he has developed intoa satisfied worker. safe working Proper introduction to the work, habits, and quality of work. a well - planned To aid in developingmen for greater re- training program, and counselingwhen neces- sponsibilities is everyone's job. sary will turn the ill-at-easeman into a con- Each person fident and interested worker. not only must be receptive to thatwhich helps The shop supervisor will to develop himself, but mustalso help to de- find it a profitable velop those who assist him inhis work. How- procedure to review with eachnew man such ever, the petty officer in charge of matters as the mission of theship and how the a machine shop fits into the overall shop has the direct responsibilityof seeing picture; the policy an that all his subordinatepetty officers under- drills, liberty and leave; andthe man's duties stand their work and its relation and what is expected of himas an individual. to the function The supervisor should be of the optical shopso well that they auto- sincerely interested matically teach those who assistthem. ; not only with gettingacquainted with the man but in being sympatheticwith the problems that may arise in getting settled. Theinitial contact SUPPLIES should be primarily to winthe man's confidence. The supervisormay later turn the man over to This book is intended asa training guide for a qualified petty officer whois capable of the technical requirementsof your rating, so completing the introductionprocess and the information related to supply isnot included. early training that isnecessary. Usually, con- However, it is important thatyou know some- siderable informationcan be given to the new thing about supply problemsin your rating. man by an experienced petty officerselected The Military Requirements forP Officer by the supervisor to completethe introduction 2 NavPers 10056-B, andMilitary period. for Petty Officer1&CI NavPers 1 7-A, In carrying out hisresponsibility for intro- will give you most of theinformation you will ducing the new worker to thejob, the super- need for working withsupplies in the optical visor must do a certainamount of planning if shop. the instructionsnecessary for the proper in- doctrination of the new workerare to be carried out effectively. MAINTENANCE AND MATERIAL At this point, itmay be well to indicate one MANAGEMENT fundanzental difference betweenthe work of a supervisor and that of his Shipboard maintenanceprograms in the past men. The men work have varied from one command with machines and materials,while the super- to another, re- visor works through people suiting in various degrees ofoperational readi- to produce the de- ness.A relatively new, uniform sired results with themachines and materials. system of The machines may be imbedding, recording, reporting,and managing operatingperfectly and the ship maintenance is materials may be of the bestquality, but unless now in use. This system is the men who bindlethem are properly in- calle.1 the Standard NavyMaintenance and Mate- structed, adjusted to their work, rial Management (3-11)System and is designed of their place in the and cognisant to upgrade the operationalreadiness of ships. organisation and of the The 3-31 System is not to policies of the department,they will not be be considered a satisfied mortars. "cure -all" for all equipmentand maintenance The supervisor isrespon- problems. The system does, sible for developing highmorale in his shop. however, provide The first step in this a logical, efficient approach tothese problems process is attained by by lameldng a forthrightattack on electrical, properly indoctrinating eachnew lean at the mechanical, and electronic time of his entrance into thework area. There disorders. The system also produces a largereservoir of knowl- are three general areas ofindoctrination. edge about equipment 1. Those dealing withfacts, such as the disorders, which, when shipboard rules and regulations. fed back to the appropriatesources, should result in corrective steps toprevent recurrences. 16 Chapter 2 SEOP SUPERVISION

The 3-M System consists primarily of a applicable drawings are critically examined. If Planned Maintenance System (WS) which pro- the maintenance requirements are found to be vides a uniform system of planned, preventive unrealistic cr unclear, they are modified or maintenance; and a Maintenance Data Collection revised before being incorporated into the System (MDCS) to provide a means of collecting PMS. necessary maintenance and supply data, suitable It is possible that the planned maintenance for rapid machine processing. A Manhour Ac- prescribed in the PMS may conflict with that counting System, also called Exception Time prescribed in other documents such as the Accounting (ETA), is installed in the repair de- Bureau of Ships Technical Manual. Should this partment of repair type ships in conjunction with happen, the PMS supersedes and takes prece- the MDCS. dence over any and all documentation that may The 3-M System, like any other system or be in conflict with it. All tests, inspections, and program, is only as good as the personnel who planned maintenance actions should ultimately make it work.Your role in the system as a be incorporated in the PMS. P01 or CPO will include the training of lower The Planned Maintenance System is based rated personnel in its use, as well as the ached-do'upon the proper utilization of Planned Mainte- uling and supervision of maintenance. General nance System Manuals, Maintenance Require- information concerning all aspects of the sys- ment Cards (MRCs), and schedules for the ac- tem is included in this chapter but as a leading complishment of planned maintenance actions. petty officer, you should keep abreast of new developments and changes to the system. Details The Planned Maintenance System Manual on the system and changes related to it are The Planned Maintenance System Manual available in the Maintenance and Material Man- contains the minimum planned maintenance re- agement (3-M) Manual, OPNAV 43P2 (revised). quirements for each component installed for a Other sources of information include OPNAV particular shipboard department. A separate Instruction 4700.16 (revised), the Bureau of Planned Maintenance System Manual is fur- Ships Journal, and directives issued by type nished for each department. The manuals are commanders. individually compiled for each ship, thereby (NOTE: The principles and procedures in- assuring a tailored system. volved in the Standard Navy Maintenance and The Planned Maintenance System Manual is Material Management (3-M) System are the same normally kept in the departmental office and is for all ratings.Planned maintenance require- used by the department head, division officers, ments have not been determined for that equip- and leading petty officers in planning and sched- ment which the Opticalman maintains; therefore uling maintenance. The manual contains a list the examples used in this chapter are applicable of effective pages and a section for each to ratings other than Opticalman.) division or maintenance. group within the department.Information to be found on the list of PLANNED MAINTENANCE SYSTEM effective pages includes the coasiponents in- OPERATION stalled, the APL/CID number, the manufacturer of the component, and the NAVSKIPS number for The plsuming and scheduling of planned main- the appropriate manufacturer's technical man- tenance is accomplished through the Planned uaL Each divisional section contains index Maintenance System (Pin).In addition, the pages for each system, subsystem, or component PMS defines the minimum maintenance required, which requires a planned maintenance action. controls its perrik--Lz---ance, describes the methods and tools to be used, and aids in the prevention These pages are referred to as Maintenance and detection of impending casualties.These Index Pages (MIPs). Each Maintenance Index factors should prove to be a definite asset to Page contains a brief description of the main- the leading petty officer in forecasting future tenance requirements and the frequency with material requirements and in the proper utiliza- which the maintemmce is to be effected. The tion of available manpower. frequency code is: In establishing the minimum planned main- D-Daily towline requirements for each piece of equip- W-Weekly ment, the Bureau of Ships Tecimical II-Monthly manufacturers' technical mar uals, Q-Quarterly

17 AA OPTICALMAN 1 & C

S-Semiannually The Maintenance Requirement Card isone A-Annually of the primary tools of the PMS system to be C-Once each overhaul cycle used by the personnel actually performing R-Situation requirement (e.g. 100 hours maintenance tasks. Personnel assigned to of operation) maintenance tasks will remove pertinent cards In addition, an index page includes the rate(s) from the set which is maintained in the working recommended to perform the task and theaver- space; obtain the stated tools, parts, and mate- age time required. A sample Maintenance Index rial; perform the maintenance requirementas Page (OPNAV Form 4700-3) is shown infigure specified on the card; correct and reportany 2-1. deficiencies noted during the performance of The manpower available willvary from one the maintenance requirement; and return the ship to another; therefore the informationfound card to its proper place after the task has been on the MIPs regarding rates recommended to completed. perform a maintenance task and theaverage Maintenance Requirement Cards represent time required for the task requirescertain the minimum planned maintenance requirements clarification.The maintenance tasks areac- of the cognizant material bureau. The command tually performed by personnel availableand has the prerogative to increase miaimumsc capable, regardless of what rating is listedon quirements to meet local conditions.If these the MIP. The average time required,as listed changes are of a continuing nature,recom- on the MIP, does not take into account the time mended changes in the system should be sub- required to assemble the tools and materialsto mitted to the bureau. do the maintenance action nor the timerequired to clean the area and putaway the tools at the Scheduling of Planned Maintenance end of the task. That portion of the Planned MaintenanceSys- Through the use of a cycle schedule (fig. tem Manual which contains the Maintenance 2-3), the Planned Maintenance System is de- Index Pages applicable to the equipmentunder a signed to simplify the scheduling of planned specific division or maintenancegroup is called maintenance. All required planned maintenance the Group Maintenance Manual. Acopy of the actions are programmed throughout theover- Group Maintenance Manual, in additionto the haul cycle of a ship. In addition, the system is one in the departmental Planned Maintenance flexible enough to readily accommodateany System Manual, is kept in each workingspace changes in a ship's employment schedule. as a ready reference to maintenance personnel. The cycle schedule contains a list of the components for each division or maintenance The Maintenance Requirement Card group and indicates the quarter after overhaul in i bick the semiannual, annual, and overhaul The Maintenance RequirementCard (fig. 2-2) cycle maintenance requirements are to be defines a planned maintenance task insufficient scheduled.The cycle schedule also lists the detail so that assigned personnelcan perform quarterly, monthly, and situation requirements the task with little difficulty_Each Mainte- that must be scheduled every quarter. The de- nance Requirement Card lists the rate ofper- partment head,in conjunction with division =mei recommended to perform thatparticular officers and leading petty Officers,uses the task; the safety precautions thatmust be ob- cycle schedule in matins out the quarterly served; the time, tools, parts, andmaterials schedule. required for the tau& and the detailedpro- By definition, the day a ship leaves the ship- cedures for performing the task. Acomplete yard is considered to be in the first quarter set ofapplicable Maintenance Requirement after overhaul.This day could conceivably be Cards is maintained in each workingspace with near the end of the quarter.A ship is not the Group Maintenance Manual.A master set of all Maintenence Requirement Cards necessarily expected to perform all of the is kept planned maintenance listed for the firstquarter on file in the departmental alike. Ifa card is lost, or if it becomes torn after overhaul, but the amount performedmust or soiled, it can be be in proportion to the time remainingin that replaced by typing a duplicate cardfrom the particular quarter.The steps to follow in master set or by ordering one throughthe using the cycle schedule proper clientele. can best be explained by reference to figure 2-3.Consider, for le Chapter 2SHOP SUPERVISION

Itefersoce halicalsos *OM Maw wan. et Co *Nom sadier Mointenswtolardlame Wis. ll orkshop Zquipment

SwimCoe Maiwilissin Sow Immo . iae MN egad No. Mw ears

001113844875V1. Inspect oil levels in reservoirs. W-1 1193 0.3 Iona 2. Lubricate tailstock. 3. Rotate the handle on the oil filter.

UZITJ3844876V1. Operate laths by power. W-2 1C3 0.3 V-1 2. Clean and lubricate exposed surfaces(

=1112844877V1. Lubricate feed pinion bearings. W-3 ls3 0.3 loone 2. Lubricate feed sleeve. 3. Clean exposed surfaces.

num944881W1. Lubricate lathe. MI-1 0.5 W-1,1V-2 2. Inspect belt tension.

12:112TJ2841111112111. Lubricate upper spindle. M1-2 1S3 0.2 lone 2. Inspect belt tension.

ant»94488381. Lubricate the gearing and bearing. 8-1 1S3 0.3 Nona

cairn844884C1. Clean oil sumps and renew oil in . C-1 1S3 1.0 None headstock, and carriage gear cases.

bow rap bled111.....k.103214- 98.171 Figure 2-1. Maiateaaace bides Page.

19 51 OPTICALMAN 1 & C

VTEM COMPONENT M.N. WINIEN Outfit and 18" Drill Press Purnishinp A46 V-3 ..A. ..e.m.fre SLISAITSTRIN RELATED U.N. RATES SOH Equipment for Workshops None NR3 0.3

M.N. DESCRIPTION 1. Lubricate feed pinion bearings. TOTAL WIC 2. Lubricate food sleeve. 0.3 3. Clean exposed surfaces. =APSE!"TINE: 0.3 WET/ PRECAUTIONS

1. Observe standard safety precautions.

TOOLS. PARTS. MATERIALS. TEST ILOUIPMIINT 1. Oil can with Symbol2190 TIP oil 2. Rags

/ PROCEDURE

1. Lubricate Feed PinionBearings. a. Lubricate the feed pinion bearing throughsmall holes on top of hubswith 2 drops of oil. 2. Lubricate eed Sleeve. a. Rack feed sleeve to its maximum down position. b. Clean and wipe with oil. 3. Clean Exposed Surfaces. a. Rub all rust spots with an oily rag. b. Apply a light film of oil to all the unpainted surfaces. m

N 2 at .., ....

LOCATION

98.178 Figure 2- 2. Maintenance Requirement Card. Chapter 2-SHOP SUPERVISION ...... not CO SCHEDULE AS INDICATED example, the planned maintenance required for are 44/02/710 0110111111. ATTU PRIMA% the #1 main refrigeration unit. As indicated on ANAIGN[I MN EACH 1 2 3 PAGE S a 7 : GU the cycle schedule, a short description of the 0 10 II 12 maintenance required may be found on page AUXILIARY . COMPONEFT A-8 of the Planned Maintenance System Manual. ALA] TA STINT INO UNIT 113. AS II 1.12 Cl.C/117151.1$ From the cycle schedule it is apparent that the ... i1 ,2 maintenance must be scheduled as follows: A. I PORT INC UNIT A3. AS $1.12 0 LCTITI

PITO RRRRRRR CV 21 A.2 cliEsti. NADINE Al NIA I M 1 and M 2 - Each Month RRRRR XIMMIXIICY NI Q 1 - Each Quarter 05 011111. BIMINI AI MIMI A 1 01.2.3 S 1 - 2nd, 4th, 6th, 8th, 10th, and 12th quar- 4.11 M.P. AIR COOP. C 1.C31S1 Al Al NI ters after overhaul

0.4 L.P. AIR COMP. C131111 112.AI AI 01.01 A 1 and A 2 - 3rd, 7th, and 11th quarters after overhaul 0.11 WINDLASS A WINCI1211 C I.C312/ Al 11.2.01 $I 01 C 1 and C 2 - 4th quarterafter overhaul A.11 1 MAIN NIFRICI. UNIT II I A1.02 C s.ca faMG (denoted by the numeral "4" ALAS OS 4.4 3 MAIN 214210. UNIT II C 1,C211111NI NIG in parentheses oncycle A 1,02 01 0.0 1 AIR COND. UNIT C1.2111 SI SI NIG schedule) C LEIN 01 11.11 22 AIR COND. UNIT II A1.02 SI 11.2 The quarterly schedule is a visual display

0.7 ACNING MACNINI N I SI 111 consisting of two identical quarterly schedule AN LAUNDRY RRRRR CTOR SI SI forms (fig.2-4), one for the current quarter 0.11 LAUNDRY MMMMM

CONDINATION 01 and one for the subsequent quarter. The cycle 0.10 WASHITA/ MMMMM CTOR 11.2 schedule and both quarterly schedule forms are 0.11 LAUNDRY PRIM N I 01 NI contained in the same visual display holder, and

A12 DISIMITNNING NAM A1.2 01 correspond line for line. The entire display is Al called the maintenance control board and is 0. 12 COMMISSARY IOUIP. Ni 01121 NI CI.C31111NIA The MOTOR MMMMM maintained in the departmental office. 4.14 BOAT INC 01 S 1G SIG 81,111 maintenance control board shows the overall A. IS ZINO Ni status of planned maintenance within the de-

A10 A GAIL I. PRIM C1111 NI partment. The quarterly schedule has thirteen columns, 4.17 JP .11 TUC). MMMMMM A1.11 A2211 21.11 one for each week in the quarter, for the sched- A111 0/2121. DM PURIIMR AI uling of maintenance throughout the 3-month A. III TM PUMP NI NI 01 period.EIch of the weeks is divided into days OAS 01 A.20 DOIVIN PUMP P./100 AI 21.11 by tick marks (see fig. 2-4) to depict more ac- . OIINIL curately the operating schedule, thus allowing A.T I S.N. A VACUUM PUMP Al A2 maintenance requirements tobe scheduled in 0111120. OIL A.22 TRANSFIR PUMP AI C11111 conjunction with ship operations. AIR CONOITIONING A411 SI Ni 01.01 A suggested procedure for the preparation AM CONOITICNINI of a quarterly planned maintenance schedule is 11.1 MOLLS() PUMP SI *1.11 to first black out the dates which the ship is 4.1111 MOT IRCPUINT A LS 1 SI expected to be underway during the quarter, CONTROL 01.21 4.211 TINT A INIPICTIONI SI C1121 SI 111.13 then with the aid of the cycle schedule and the At 01.1.1 0.17 PIPING 4 WALI/211 01111 AI C21131 11.2 Planned Maintenance System Manual, fill out 0.20 COOLING PIMP the quarterly schedule accordingly.Monthly 4.211 COCAIN. PUMP " WISC. MING. 131.2.11 planned maintenance requirements should be 4.S0 GOUIPMENT CIIII C2I131 NIG scheduled at approximately the same time each 4.77.'OAT 10INCI4 C)171 month and other planned maintenance actions 11.114 PUMP 220 01 A311 POO MMMMM PUMP P40 Al III.21 should be scheduled at equal intervals insofar 01,A2 I. as practical.After the quarterly schedule 11.10 VACUUM PRIMING PUMP C1111 01 2.S is completely filled,in, it is a good practice to A1111 AUX VINT1LAT1ON SI 51. 111 look it over closely to see if the work load is CYCLE%maim eau num0754 (rut balanced throughout the quarter.If there ap- 98.172 pears to be less work scheduled during one Figure 2-3.-Cycle schedule. week of the quarter than the others, some of the

21 cu. II

ari

INIMITUNN MAINTENANCE SCNUULIE MU SUN Chapter 2SHOP SUPERVISION maintenance requirements should be resched- weekly schedule forms. All otherplanned main- uled to balance the work load throughout the tenance requirements which are tobe performed quarter. during a specific week are obtained from the The quarterly schedule is updated weekly. current quarterly schedule. The leading petty officer of the division or The preparation of a weekly planned main- maintenance group will cross out all maintenance tenance schedule requires you to take into con- requirements which have ler-mcomplished and sideration the available manpower, the time will circle all requirements which have notbeen involved in each maintenance task, and the accomplished. All circled requirements are ship's operations. In the assignment of specific rescheduled by drawing an arrow to a later week, personnel to maintenance tasks, it must be reas indicated in figure 2-4. membered that the average time required to The quarterly schedule is kept on board as perform a task, as listed on the Maintenance a record of all completed maintenance actions. Index Page and the Maintenance Requirement This record may be destroyed at the beginning Card, does not take into account the time re- of the second quarter following the next ship- quired to assemble the tools and materials yard overhaul period. to do the maintenance action nor the time re- The quarterly schedule is also used by the quired to clean the area and put away the tools leading petty officer of each division or main- at the end of the task.Related maintenance tenance group to prepare a weekly planned requirements(see fig.2-1) which are due maintenance schedule (fig. 2-5).The weekly should be scheduled and performed together to schedule is posted in each working space and is conserve time.Any corrective maintenance, used by the leading petty officer to assign cleaning, and upkeep to be performed is in ad- specific maintenance tasks to specific personnel. dition to the planned maintenance prescribed by The weekly schedule provides a list of the- the Planned Maintenance System. components, the Pppropriate page number of the The weekly schedule offers flexibility for all Planned Maintenance System Manual, andspaces planned maintenance actions except those which for the assignment of maintenance tasks to must be performed daily. When aplanned main- specific personnel. The daily and weekly plan- tenance task is completed, the leading petty ned maintenance actions are preprinted on the officer will cross out the requirement on the

WORKSHOP GROUP WORK SCHEDULE FOR WEEK OF if *Mai /166

MAINTENANCE OUTSTANDING REPAIRS AND P.M. COMPONENT RESPONSIBILITY PAGE MONDAY TUESDAY WEDNESDAYTHURSDAYFRIDAY SAT /SUN CHECKS DUE IN NEXT 4 WEEKS

LA THE WILSON? 6A-16064 S C-/ DRILL PRESSRoSERTS A-16W 3 M-2

. _., ,_

WEEKLY WORK SCHEDULE OPNAV FORM 44004

98.175 Figure 2-5.Weekly schedule.

23 OPTICALMAN 1 & C schedule. Maintenance that cannot be com- The shipboard installation of the Mainte- pleted on schedule is circled and rescheduled nance Data Collection System includes a central, on the basis of worklon ship operations. functional data collection center. The primary The weekly schedule is designed for con- function of the shipboard data collection center venient preparation and effective reuse. At the is to screen all documents for completeness end of each week, the leading petty officer of and accuracy before they are forwarded to the the division or maintenance group will take the data processing center.During the screening weekly schedule to the departmental office, up- process, the data collection center adds a 4- date the quarterly schedule, erase the weekly digit maintenance control number in block 9 of schedule, and prepare a schedule for the follow- each document. ing week. The effectiveness of the Maintenance Data Collection System depends initially upon the in- Feedback Report dividual performing the maintenance action and the accuracy with which it is reported. Leading The Planned Maintenance System allows for petty officers are responsible for ensuring that the correction of discrepancies in the system all forms used in connection with the Maintenance through the use of a Feedback Report (fig. 2-6). Data Collection System are complete and ac- If a discrepancy exists in the systemas in- curate. Leading petty officers should also stalled aboard your ship, a Feedback Report ensure that a form is submitted for each ap- should be originated immediately by the person plicable action and that no action is reported who discovers the discrepancy. more than once. The Feedback Report will be useful only if it contains all of the correct informationcon- Equipment Identification Code Manual cerning the discrepancy, including thereason for the recommended change..Prior to being It is essential that all personnel having any forwarded, a Feedback Report shouldbe checked responsibility for maintenance actions be infor completeness and accuracy by the leading doctrinated in the proper use of the Equipment petty officer of the division. Identification Code Manual as it contains many of the codes used in the reporting of maintenance RECORDING OF MAINTENANCE ACTIONS actions.Each major system is coded and the codes are broken down to the lowestpartneces- The Maintenance Data Collection System sary for positive equipment identification. The (MDCS) is designed to providea means of manner in which the equipment identification recording information concerning planned and code is obtained from the manual is described corrective maintenance actions.Maintenance in the following example. performed is recorded by code insufficient Assume it is desired to determine the code detail to permit the collection of a great variety for the casing wearing rings and impeller wear- of information concerning maintenance actions ing rings of a main condensate pump in a steam and the performance of the equipment involved. main propulsion system. By referring to the The use of codes in recording and reporting index pages of the Equipment Identification Code maintenance actions permits machine process- Manual, it is found that the steam main pro- ing with automatic data processing equipment. pulsion system is identified by the code "Z" The system also provides data concerning the and the subsystem (in this example the feed and initial discovery of a malfunction, how the condensate system) is identified by the code equipment malfunctioned, how many hours the "ZQ". The next step is to turn to the pages of equipment was in operation, which equipment the manual with the )1Q codes and go down the was involved, what repair parts and materials list of equipment until you come to the listing were used, what delays were incurred, the for the main condensate pump.Under this reasons for delay, and the technical specialty listing you will find the 7- digit, codes for the or work center which performed the main- casing wearing rings and the impeller wearing tenance.Each maintenance action is reported rings.The first digit of the code identifies in this manner except for routine preservation the system, the second digit identifies the sub- actions (chipping, painting, and cleaning) and system, the third and fourth digits identify the daily or weekly Planned Maintenance System equipment and the last three digits identify the actions. assembly.If the assembly requires further Chapter 2 SHOP SUPERVISION

INSTRUCTIONS ON BACK OF GREEN PAGE FROM: 0 0 Gt 1 SERIAL 47 3 TO: Ouships/Buweps Maintenance DATE Management Field Office 15 "AR' 19" BOX 604, HAMPTON ROAD DRAW...44 NORFOLK ,VIRGINIA, 2351I VIA: COM CRU DESCANT SUBJECT: PLANNED MAINTENANCE SYSTEM FEEDBACKREPORT SYSTEM EQUIPMENT FOR COMPON EN T F0RNI514IN4S LATHE SUB-SYSTEM M.R. NUMBER EQuiPMENT FOR A-i0 C-1 WORKSHOP, BU. CQNTROL NO.1-41.. in.11.7004 4884C DISCREPANCY

M. R. Description Egitipment thong. Typographical DRSafety Precaution. Missing Mitisteloomi. Technical Index Page (NIP) "1 Publications. Tools, Etc. Technical 0 Miscellaneous r--1Missing Meintainance I-1 Requirement Cord (MRC) Procedure SAFETY PRECAUTIONS LISTED DO NOT Et4SURE EQUIPMENT WILL NOT BE INADVERTENTLY STARTED. RECOMMEND TI-4E FOLLOWINGSAFETY PRECAUTION SE ADDED : TAG OPEN THE CIRCUIT BREAKERS AT THE LATHE AND ON THE SWITCH BOARD.

SIGNATURE OF C. 0. OR DESIGNATED REPRESENTATIVE Pour M R t. t.) S $3

THIS COPY FOR: ADDRESSEE 1 OPN AV Form 1700/7 (10.65)

40.101 Figure 2-6.Planned Maintenance System. F0P4baCk Report.

.25 OPTICALMAN 1 & C breakdown, the last digit identified the sub- form is a single-sheet document used to record assembly. the completion of planned maintenance actions, In addition to the equipment identification corrective maintenance actions, and authorized codes, the Equipment Identification Code Manual alterations that have been performed at the contains other codes and information of equal shipboard level by shipboard personnel.All importance.Section I of the manual contains planned maintenance actions except daily and general instructions for the preparation of forms weekly actions must be recorded on this form, when reporting maintenance actions. Other as well as on the weekly and quarterly sched- sections of the manual contain additional codes ules.Routine preservation such as chipping, as follows: painting, and cleaning should not be reported. The Shipboard Maintenance Action Form is Section IIAdministrative Organization also used to report work done aboard ship by Section IIIWork Center an outside activity which does not report under Section IV How Malfunctioned the Maintenance Data Collection System. When Section VWhen Discovered a repair activity such as a civilian contractor Section VI Action Taken or a shipyard (except for regular overhauls) Section VII Service which is not under the Maintenance Data Col- Section VIII Source lection System provides ship maintenance as- Section IX Type Availability sistance, duplicate 4700-2B documents are prepared.Block 7 of the original document is left These codes make possible the recording of blank and the code for the assisting work center a wide variety of information in a relatively is entered on the duplicate.Only those man- small space. At the data processing level, the hours actually spent by the shipboard personnel codes permit use of automatic data processing in assisting the outside activity are entered in operations which provide pertinent,direct- block 13 of the original; manhours spent by the reading, information summaries. The sum- outside activity in assisting the shipboard work maries can be profitably employed only if center are documented in block 13 of the accurate information has been recorded; there- duplicate. fore familiarity with the coding systems is a Deferred Action Form. The Deferred Action must and the importance of accuracy in the Form (OPNAV 4700-2D) is a two-sheet form recording of codes cannot be overstressed. . rye ed to report corrective maintenance actions that are deferred because of the ship's opera- MDCS Documentation tions, the lack of repair parts, or the requirement for outside assistance.The first sheet Documentation in the Maintenance Data Col- (fig. 2 -8) is used to record and report the lection System is accomplished by the com- reason for deferral and the second sheet (fig. pletion, as applicable, of one or more standard 2-9) is used to report the completion of the forms.Forms used to record and report in- deferred action. formation related to maintenance actions aboard If a corrective maintenance action is beyond ship and within repair activities include OPNAV ship's force capability and outside assistance is Form 4700-2B (Shipboard Maintenance Action), required, a work request is prepared and for- OPNAV Form 4'100-2D (Deferred Action), OP- warded. This situation will always require that NAV Form 4'100-2C (Work Request), andOPNAV an. OPNAV Form 4'100-2D be submitted.The Form 4700-2F (Work Supplement Card).De- manhours that have been expended, if any, by tailed descriptions of the entries to be madeon ship's force in connection with the maintenance these forms are listed in Section I of the action are documented on the OPNAV Form Equipment Identification Code Manual and in 47'00-2D,The manhours involved in the in- chapter 3 of the Maintenance and MaterialMan- vestigation and the removal of the equipment agement (3-M) Manual. are documented on the first sheet of the document. The manhours involved in the reinstalla- Management (3-M) Manual tion of the equipment are documented on the second sheet of the document. Shipboard Maintenance Action Form.A If a shipboard maintenance action must be sample Shipboard Maintenance Action Form deferred due to the lack of necessary repair (OPNAV 4700-2B) is shown in figure 2-1. This parts or because of the ship's operations, an

26 cif Chapter 2SHOP SUPERVISION

MAINTENANCE DATA COLLECTION OPNAY FORM 4700-26 (8-64) SHIPBOARD MAINTENANCE ACTION

A. SNIP NMC AND NULL NO./ACTIIMTV I. LENIN. ORO, 3. SNIP ACCTO. NO 3. mAtNT. CTRL. NO. U. DATE MONTH YEAR 11 . US$ Duc D_D 761 Dc70cSt6/0935"/60$6

S . EQUIPMENT ID CODI G. .C. 7. SST.K. I. WAIN ACT. ACCT. ND.'S. MALMMIC. ILii.11. LOOTS13.144N.NOEMISMODISI1, .

IA I/ 1,10 ISI /1E.1110 I I I I I 1 s I 0I t1°31;4I/I0I *I 0 1,4I I I IA. SERIAL NO. SO. EQUIP. TIME to. ION MICNTIFICTION

114111 I II I I I I F. DESCRIPTICRWREMANSIII III III _I II IIIIIII -PERMS/Here ,REverNmor AMI/Ireilvver AS ouTtalE0 ON AMC 4-16 S-/

L. SIC. 13 FOR LOCALUSEONLY ita-420-keMA 3

17.81B Figure 2-7.Shipboard Maintenance Action Form. OPNAV Form 4700-2D is prepared and the The information to be given in block F first sheet is submitted (using the appropriate (Description/Remarks) of the work request in- action taken code from section VI of the Equip- cludes the name of the component, the CID ment Identification Code Manual) and the man- number of the component, and the alteration hours expended, if any, are entered in block 13. number. If the alteration number is not ap- When the maintenance action is completed, the plicable (N/A), it must be so indicated (see fig. second sheet is submitted using the appropriate 2-10).Block F should also contain a descrip- action taken code and the manhours expended tion of the existing defects and the repairs in completing the action are entered in block required on the component. Sheet 1 of the work request is retained by the requesting activity and sheets 2, 3, and 4 Work Request.The Work Request Form are forwarded to the assigned repair activity (OPNAV 4700-2C) is a four-sheet document via the designated chain of command.Infor- which is presently used to request outside mation concerning the administrative proce- assistance from repair ships and tenders.It dures to be followed by repair activities may is planned that OPNAV 4700-2C will also be be found in chapter 4 of the Maintenance and used, at a later date, for requesting assistance Material Management (3-M) Manual. from shipyards.Part I of the work request is When the work request is accepted by the shown in figure 2-10.Part II of the work repair activity, sheet 3 of the document is request, shown in figure 2-11, is a continuation used as a job order and is sent to the assigned of part I and provides additional space for work center. Prepunched Work Supplement written descriptions, diagrams, and sketches. Cards (OPNAV 4700-2F) are also sent to the

27 OPTICALMAN 1 & C assigned work center. A sample OPNAV lead work center supervisor forwards the com- 4700-2F is shown in figure 2-12. pleted work request to his division officer. The assigned work center performs the Material Usage and Cost Data.The docu- job,records the maintenance data on Work mentation of material usage and cost data on Supplement Cards, and records the material maintenance transactions requires the joint obtained outside of normal supply channels on effort of the supply and maintenance personnel the reverse side of the card. If more than one aboard ship. The form used to document workday is required to complete the action, or material usage and cost data is determined by if assisting work centers are needed, the lead the action involved and the source of material. work center will utilize the additional Work The reverse side of the appropriate OPNAV Supplement Cards provided to record daily form (OPNAV 4700-2B, 4700-2D, or 4700-2F) manhours expended.(The lead work center is is used by maintenance personnel to report that work center which has the primary re- material obtained from outside normal supply sponsibility for thecompletion of the task channels. The reverse sides of OPNAV Forms described on the work request.) 4700-2D and 4700-2F are essentially the same When a repair job is completed, sheet 3 of as the Form 4700-2B which is shown in figure the work request is completed by the lead work 2-13.Parts and material obtained from pre- center and is signed by the man who performed expended material bins; items obtained by the maintenance.An inspector from the re- cannibalization or from salvage, that can be questing activity is contacted for final inspec- identified by a part number or stock number; tion and signs off the work request.After and consumable materials, such as lumber, obtaining the signature of the inspector, the sheet metal, and bar stock, used for manufacture

MAINTENANCE DATA COLLECTION OPNAV FORM 470040 1114147 DEFERRED ACTION I

A. SHIP NAME AND MULL NO./ACTIVITY I. MINIM. ORO. 2. SHIP ACCTO. NO. 2. MAIN'. CTRL NO. t. DATE U55 .8 DP 761 DO 009 I r I 1 0 3 6 / 6 o 36

S . EQUIPMENT ID CODS 7. MIST. O.REPAIR ACT. ACCT. NO.. IS. UNITSIS. RAMMOURS

141AI/1310141E1;110 I I SeN L91 0110101 II I I It. SERIAL NO. 110. 1171,11P/1011 SI. ALTERATION IDENTIPICATION

I I ,MIRI/I II I] I II I I I I I I I I I I I I I I I I P . DIESCRIPTIOWIRNARKIP DISColleltED ONE Thera $116Ntib Pito*, toLEA GEAR OF /9" weittLIF ceJbucritle fgoihvretIANeff Reformat/nem" A-I6 5-1. No 'PARE oN 8A1lb.

L 1210. III

N. SIG. III

/ / /

17.81D Figure 2-8.Deferred Action Form, Sheet 1.

.28 . ..

Chapter 2SHOP SUPERVISION

MAINTINANCS DATA cousenow OPNAV TOMS 470040 04411 DEFERRED ACTION 2

A. SHIT MAME AND NULL MO./ACTIVITY I. ADMIN. OM. S . *NIP ACCTS. NO. T. MAINT. CUM. 110. 4. OATS vSS30e4 AD 741 37° I 0 70 st 0

S . SOUIPNINT ID COOD S W.C., I. ASST.D.C. I.C.1O. IIVAMI ACT. Azar. NO. 1 O. SIALMOC. A 1,0. 1 I1. 11L UNITS1 II. MANSIOURIS- 1 S. 111641113101q11 lisle I I I I 1 SI" f S ER I A L 110. D.IVT01/ 11 SO. SOUIP/T11411 SI. ALTERATION IOSISTIVICATION

NISI/ 1 1 1 1 1 1 1 1 1 1 /. OS/CNITIOM /SSMAASS 1111 I 111111111111 DISCVeler0DAMTb.A4 SIWARIbNemo10&04e tiar4M OPIVwsdarie twist.E comOirer AWAITEIMMIF 284rmealeer A-li S-I. Nospill*, ON Wit,. "PARS RetinVeh FR.M Usif StEMA.1117-11m-ra SPARE, faro# Limy, 077fMeTeity.

L. ANL NI OK ONL M.SAL 141 / irekIeql/

17.81D Figure 2-9.Deferred Action Form, Sheet 2.

work are reported.Economy of effort and the MANHOUR ACCOUNTING SYSTEM elimination of duplicate recordingare highly desirable; however, when thereis doubt The Manhour, Accounting System, sometimes about reportinganitem, it should be referred to as Exception Time Accounting (ETA), reported. is designed and intended for use by the repair department of repair activities in conjunction Existing supply forms are used to document with the Maintenance Data Collection System. It the material usage and cost data of repairparts is basically a management tool and accounts or materials obtained through the normal supply for deviations from a normal 7-hour working channels. The document used is determined by day. the availability of automatic data processing The mechanics of Exception Time Accounting equipment. If the ship has automatic data include the use of codes, the preparation ofa processing equipment, DD Form 1348 is used. Master Roster Listing,. and the preparation and Iftheshipdoesnot have automatic data samission of Daily Exception Cards (OPNAV processing equipment, NAVSANDA Form 1250 is /Form 4700-2E). A sample Daily Exception Card used.Maintenance personnel are required to is shown in figure 2-14. furnish the work center code, the equipment identification code, the CID number, the main- ETA Codes tenance control number, the name of the part, and the stock number when submitting theForm Exception Time Accounting codes identify 1250 or the Form 1348 to the supplydepart- work centers, pay grades of individuals, work ment. assignments, and the categories of manhour 29 50 OPTICALMAN 1 & C

MAINTENANCE OATH COLLECTION ONA9 4700.2C 36.643 WORK. REQUEST

A SNIP NAME ANO NULL NO /ACTIVITY 1. ADMIN 0113 2 SNIP ACCTG NO 3 MAiNTCTRL NO CATE US$ 23ueN_ Jo, 741 $141cs 2 6/ 6 66 5 EQUIPMENT 10 COOL 7 9 REPAIR ACT ACCT NO 9 MAL/MRC 10 ' 12 UNITS ',/, /// /i A /le/ Ao 41 (. 1 r f elY 1 . 14 SERIAL NO ITS, III 1110 WC 17 01511110 CMPLN OATE IS ilR 1 efeA S. a 6sAv

P. DESCRIPTION/REMARKS LATHE IV" 5Plel#1610/1FLD At/ Wilde Toot. MoDEL $ Plio,rocoo/ ALTEItAriod AVA. Teen, SIIEARep FROM I D&.Ek MAI/uPAcTonz Nevi IDLER GEAR As PER sAmPLA

FOR LOCAL USE ONLY 0 N I CO ACT 1 SIO .1. I S g 34 NO 2 CONTACT

.1111.- EN / EISliraMPPRIla

17.81C Figure 2-10.Work Request, Part I. expenditures for each person reported in the Master Roster Listing system. The work center codes listed in section III The number of manhours assigned to a of the Equipment Identification Code Manual are work center for any given reporting period is used. These codes are entered inblock A of the established by the use of the Master Roster Daily Exception Card. Listing.A reporting period for the Manhour Accounting System is one month. Each work center prepares an initial roster Grade codes are assigned to all personnel of assigned personnel listing work center code, from E-1 through captain. These codes may be name grade code, and assigned labor code of found in chapter 5 of the Maintenance andMate- each individual.The roster is screened for rial Management (3-M) Manual and are entered completeness and accuracy and then forwarded in block C of the Daily Exception Card. to Data Services.Data Services prepares a Labor codes are used to identify areas where Master Roster Card Deck from the information manhours are being expended, and to what contained inthelisting. From this deck, extent. Labor codes are divided into three Data Services provides each work center with major categories: Productive, Productive Sup- a Master Roster Listing. port, and Nonproductive.Labor subcodes are Each work center supervisor verifies the also used to enable the maintenance manager completeness and accuracy of the listing. Cor- to isolate areas where excessive manhours rections are made by drawing a red line tre being expended. The codes and subcodes through the entry in error and inserting correct for the major labor code groupings are listed information above the incorrect item.The on the reverse side of the DailyException Card. roster is resubmitted to Data Services and the

LPG SS. Chapter 2SHOP SUPERVISION

MAINTENANCE DATA COLLECTION ONAV PORN 4100.2C M/ PART 11 WORK REQUEST IA. SNIP NAME AND NULL NO./ACTIVITY II. ADMIN. ORO. SNIP ACOO. NO. MAINS. Olt. NO.4. {S. I

1 1 I 1 1 1 1 1 1 1 P. DISCRIPTION/RIAtAIMS ICanIlaus41

9 PAGE 1.

17.81C Figure 2-11.Work Request, Part II.

o 861 o- 6 NA 13041 8 a REMARKS: DO NOT ENTER IF SAME AS ABOVE

IP? 4.DATE oti / 1 013 16 S.EIC

7.AWC L 1

9.HOW MAL 1 10.WHEN DISCOVERED 11.ACTION TAKEN P 12.UNITS COMPLETED 01 / I 13.MANHOURS(TENTHS) 0o 1 71 CI READY TO PICK UP () DELIVERED () Ion ,rulatfIlitottnnknsnansnisnunisnumnaisaaawaasuesesailwilsosusruserousimessuesNiusumisguliew SIIMMI41M

17.81F Figure 2-12.Work Supplement Card.

91 OPTICALMAN 1 & C

CID /APL/ L/AN 3 /0/ SOURCE FEDERALSTOCK ND. /PART NO. MATERIAL REO. MATERIAL USED CODE RE KERENCE SYMBOL /NOUN UNIT PRICE COG. MUTI WIGTITY WITS 1 WW01111.

I / SIC.P.0755'.000 3i RI st yts" i EA'" .sie / I. I I I I I I I I 4 I I I I I I I I

I I I I I I I I I I I I I I I I I I I I I I I ..: I I I ONO PORN 4700-25 (1)-114) BACK

17.81B Figure 2- 13. Reverse aide of OPNAV 4700-2B.

ClIANOC LABOR COCK TO. 0 NON-PRODUCTIVE PRODUCTIVE ABLEL TURNS OF NOUN KY TYPE OF. MANGE W) ~II IMO Off X SNORT TERM WAN TO. In 01 DIRECT LABOR 1-1 0 020 OELAYS A 3-11 1 WW1 COMM Cad PRODUCTIVE SUPPORT 5-44 2 al our( ABSENCE ASSIGNED 15-20 3 ISIINTENANCE AMIN 21-24 4 TRANSFERRED aa 241142141001 2T-33 5 Q 22 NON DUTY ABSENCE LABOR CODE 11 WOW. CONTROL 34-3. 6 OVERTIME 40-41 T 12 NANTENAKTVIDER "re°. 46-51 DATE OF MINX NMI OF MUNK SU-MI Mr- 0 St-ST 3117115661 itMO To4.1 ONO NU. 1.4 worn rows CCUltaav woo ors 1 emsIn Ian .... pal". mAINTf.011NCIL . 1.NO 0.1T000131 UN -airr 000 our run essmagemis an UUUUUUUUUUUUUUUUUUUUUUUU um UUUUUUUU pospAA0POOM000018

17.81E Figure 2-14.Daily Exception Car&

374 Chapter 2SHOP SUPERVISION

Master Roster Deck of cards is conmcted, if the individual's work center code, name, grade necessary.The completeness and. accuracy code, and assigned labor code. of the Master Roster Listing is verified in the The submisE,,m of a Daily Exception Card above manner at the end of each reporting is required at any time a person is absent period. from Ms assigned work area in excess of 20 minutes. Information to be entered on the Daily Exception Card card includes the date, the amount of time involved in the exception, and appropriate labor After the cards in the Master Deck are codes and subcodes.When the exception is verified,Data Services provides each work longer than the scheduled work shift, the card center supervisor with 25 Daily Exception is completed at the end of the shift and another Cards for each individual on the roster. The card is prepared for the remainder of the prepunched and machine printed cards reflect exception. CHAPTER 3

METALS

The Opticalman will work with metals at What are the properties which anOpticalman various times while working on optical instru- needs to understand about the metals most com- ments.Thus he should be familiar with types monly used? They include the mechanical prop- of metals, the properties of metals, and the erties of hardness, toughness, tensile strength, heat treating processes for the most common ductility, and malleability. Following is an ex- metals. planation of the meaning of these terms. There is no simple definition of metal. All The HARDNESS of a metal is that property chemical elements that possess metallic prop- which enables it to resist scratching, denting, erties are classed as metals.The metallic cutting, or erosion.It may also be defined as properties might be defined as luster, good the ability of the metal to resist penetration. thermal and electrical conductivity, and the A pion" of lead, for example, can easily be capability of being permanently shaped, or to scratcliga with a knife. But it would be difficult some extent deformed, at room temperature. to mark a piece of steel in this manner. The Other chemical elements, lacking these prop- reason is that steel possesses the property of erties, are classed as nonmetals.Some ele- hardness,and thus provides resistanceto mentscarbon, phosphorus, silicon, and sulfur, scratching and cutting. for examplebehave sometimes like metals, TOUGHNESS is that property of a metal which sometimes like nonmetals, and are known as enables it to withstand shock loading without metalloids. An alloy b defined as a substance breaking. having metallic properties, that is composed of It is thus related to strength and to ductility. two or more elements. Usually, the hardness of a metal increases as PROPERTIES OF METALS the toughness decreases. TENSILE STRENGTH is that property of a Metals and alloys vary widely in their char- metal which resists forces that would tend to acteristics or properties. Chemical properties pull the metal apart.It is measured in terms involve the behavior of the metal in contact with of pounds per square inch which represents the the atmosphere, salt water, or other environ- load that must be exerted on a cross-sectional ments.Physical properties relate to color, area in order to break the metal. density and weight, magnetic qualities, electrical DUCTILITY is that property that renders a conductivity or resistance, and heat conductivity. metal capable of being drawn into wire form, Mechanical properties relate to load carrying stamped, or hammered into sheets.In other ability, wear resistance, and elasticity. words, when the metal is placed under a severe The various properties of metals and alloys load, it deforms rather than fractures. have been determined in the laboratories of MALLEABILITY is the property of metal manufacturers and are tabulated and indexed by that permits it to be rolled, forged, hammered, various engineering societies interestedin or drawn, without cracking or breaking. metallurgical development.Charts which give CORROSION RESISTANCEthough not a properties pertaining to a particular metal or mechanical property is also of primary import- alloy are published in such reference books as ance. Corrosion resistance is the property that the Metals Handbook. The charts provide in- enables a metal to withstand chemical or formation on the physical and mechanical prop- electrochemical attack by air, moisture, soil, erties which have been determined. or other agents.

34 Chapter 3METALS

The various mechanical properties described bar. The types of structural steel are: may at times be desirable, and at other times steel, medium steel, high tensile steel, special be undesirable, depending on the purpose for treated steel, and stainless steel. which the metal is to be used. But resistance to Mild steel is used when structural strength corrosion is always a highly desirable char- is of no great importance, and when a great acteristic. deal of flanging, shaping, and other shop operations are involved. TYPES OF METALS Medium steel is similar to mild steel in its The metals with which you work can be di- workability. But, it is harder and stronger than vided into two general classifications, ferrous mild steel and is used when structural strength and nonferrous.FERROUS metals are those is required. that are composed primarily of iron.NON- High tensile steel, usually referred to as FERROUS metals are those that are composed RTS, contains small additions of Various alloys primarily of some element or elements other that give the steel extra hardness and toughness. than iron.Nonferrous metals or alloys some- Special treated steel, known as STS, contains times contain a small amount of iron as an a small percentage of chromium-nickel; and the alloying element or as an impurity. product has been specially treated to obtain hardness and toughness. FERROUS METALS Stainless steel, referred to as SST, is generally designated by the percent of chromium A few examples of ferrous metals include and nickel; for example, an 18-8 stainless is an pig iron, cast iron, ingot iron, and wrought iron. alloy containing 18 percent chromium and 8per- Carbon steel and the various alloy steels cent nickel. structural as well as tool steelare also considered as ferrous metals, since they are com- NONFERROUS METALS posed ofirontowhichrelativelysmall percentages of carbon and other elements have As an Opticalman you may work with various been added as alloys. types of nonferrous metals. Some of the major Pig iron is composed of about 93 percent types and their uses are discussed in this sec- iron, from 3 to 5 percent carbon, and varying tion. amounts of other elements. It is comparatively Copper and copper alloys rank high among weak and brittle, and has a limited use. commercial metals with respect to desirable The term cast iron may be applied to any properties. Copper is ductile, malleable, hard, iron in which the carbon alloy is more than 1.7 tough, strong, wear resistant, machinable, and percent. Cast iron has high compressive weldable. Also it has high tensile strength, strength and good wear resistance, but it lacks fatiguestrength, and thermal and electrical ductility,malleability,ancl impact strength. conductivity.Copper is easy to work, and al- Wrought iron is made from pig iron bya though it becomes hard when worked, it can process of puddling, squeezing, and rolling. easily be softened (annealed) by heating it to a This process removes many of the impurities, cherry red and then letting it cool. Annealing is and gives the wrought iron a type of fibrous the only heat treating procedure that is applied internal structure which promotes workability. to copper. Ingot iron is a commercially pure iron Lead is a heavy metal, weighing about 710 (99.85 percent), easily formed and possessing pounds per cubic foot.Yet lead is soft and good ductility. malleible. It is available in pig and sheet form; Of all the different metals and materials sheet lead is rolled up on a rod so that the user which you will use while in the Navy, by far the can unroll and cut off the amount required. The most important is steel. Steel is manufactured surface of lead is grayish in color, but scraping from pig iron by decreasing the amount of the surface will show that the color of the metal carbon and other impurities present. About 15 is actually white. Because of its softness, lead pounds of manganese, an indispensable addition can be used in various jobs. Sheet lead is used in the production of steel, is added to each ton for bench tops.where a great deal of acid is of pig iron. used.Lead lined pipe is used for systems that Most of the, steel you use will be in the form must carry chemicals.Alloyed with tin, in of structural shapes, such as sheet, plate, and various proportions, it produces a soft solder.

90 C) OPTICALMAN 1 & C

Lead is often added to metal alloys to improve mechanical property or a combination of prop- machinability. In working with lead, remember erties. A metal part is heat treated in order to that its dust, fumes, or vapor can be highly make it softer, more ductile, stronger, harder, poisonous. or more resistant to wear.These properties Zinc is used often as a protective coating, are developed as needed to improve the useful- known as galvanizing, on steel and iron. Zinc ness and safety of a part for a definite purpose. is also used in soldering fluxes, in die castings, No one heat treating operation can produce all and as an alloying element in making brass and these characteristics, and the improvement of some bronze. some properties must be accomplished at the Tin has many important uses as an alloying expense of other properties. element. Remember that it can be alloyed with There are different forms of heat treating. lead to produce soft solders; and alloyed with Common forms used by the Navy include: an- copper, it produces bronze.Tin base alloys nealing, normalizing, hardening, tempering, and have a high resistance to corrosion; they also stress relieving.The particular process used have a low fatigue strength, and a compressive is determined not only by the physical properties strength which will accommodate light or me- to be developed or modified, but also by the dium, but not heavy, loads. composition of the metal. Ferrous metals may Tin, like lead, possesses a good resistance be hardened, tempered, annealed, and normal- to corrosion; it has the added advantage of be- ized. Most nonferrous metals can be annealed, ing nonpoisonous.But when subjected to ex- and many can be hardened, but they are never tremely low temperatures, it has a tendency to tempered or normalized. (For nonferrous decompose. Aluminum is easy to work and has metals, the hardening process is usually re- a good appearance. Although light in weight, it ferred to simply as heat treatment.) has a high strength per unit weight, but its While all heat treating processes are simi- tensile strength is only 1/3 that of iron, and lar in that they involve heating and cooling, they 1/5 that of annealed mild steel.In its pure differ in the temperatures to which the metals state, aluminum is soft, and has a strong af- are heated, the rate of cooling, and the cooling finity for gases.The use of alloying elements medium.In addition, some of these processes overcomes these disadvantages. not only effect changes in physical properties, True brass is an alloy of copper and zinc. but also alter the surface composition of the Additional elementsaluminum, lead, tin, iron, metal. manganese, or phosphorusmay be added to For all metals, time and temperature are give the alloyspecific properties. the important factors in the heat treating opera- Bronze made of 84 percent copper and 16 tion.Usually, the atmosphere surrounding the percent tin was the best metal available before metal during heating, or during heating and cool- steelmaking techniques were developed. Many ing, is also critical. complex bronze alloys, containing additional elements such as zinc, lead, iron, aluminum, ANNEALING silicon, and phosphorus, are now available. Monel is an alloy in which nickel is the Two main purposes of annealing are (1) to predominate element.It contains from 64 to relieve internal strains, and (2) to make a metal 68 percent nickel, about 30 percent copper, and soft enough for machining.Practically all small percentages of iron, manganese and co- metals, ferrous and nonferrous, may be an- balt.It is harder and stronger than either nealed, and no elaborate equipment is essential. nickel or copper, and has high ductility.It has It is possible to produce good anneals by using many of the qualities of stainless steel, which a heating torch or a furnace. The basic process it resembles in appearance, and its strength consists of heating the metal to a specified and high resistance to atmospheric corrosion temperature, holding it at that temperature for make it an acceptable substitute for steel in a a specified length of time, and then cooling it system or service where atmospheric corrosion slowly to room temperature.Both the tem- resistance is of primary importance. perature of the operation and the rate of cooling HEAT TREATING PROCESSES depend upon the metal being treated, and the purpose for which it is to be used. Metals in a solid state can be heated and Annealing temperature for any metal should cooled to change or improve a physical or be slightly above the recrystallization point of

36 414 Chapter 3METALS the metal. Cast iron ordinarily must be heated carbon steels generally do not require normal- to a point between 1400° and 1500° F. Pure izing, but giving them a normalizing treatment aluminum can be annealed at temperatures from will cause no harmful results. 625° to 700° F, but aluminum alloys require The process of normalizinglike other heat somewhat higher temperatures, depending upon treatment processesconsists of three steps: their composition.Pure copper can be an- heating the metal to a specified temperature, nealed at temperatures from 800' to 1200° F; soaking it (that is, holding it at this tempera- most brasses (copper-zinc alloys) require an- ture), and cooling it. In normalizing, the speci- nealing temperatures of from 475° to 650° F. fied temperatures are, for each metal, a point Nickel-chromium alloys, which can withstand from 100° F to 150° F above the transforma- extremely high temperatures without appre- tion range.The holding time depends upon the ciable damage, must be heated to annealing thickness of the metal, but must be long enough temperatures between 1800° and 1950' F. to allow for uniform heating throughout.The Soaking or hold time depends upon the mass metal should be allowed to cool evenly to room and the composition of the metal.Also, the temperature in still air. rate at which a metal is cooled back to room temperature depends upon the composition of HARDENING AND TEMPERING the metal.Alloys whose constituents precipitate on slow cooling from the solid solution The primary purposes of HARDENING opera- temperature are of the age hardening type. tions are to harden metal and, at the same time, Precipitation itself is a form of age hardening increase the tensile strength.In steel, how- treatment; if the hardening constituent; if the ever, the hardening process increases brittle- hardening constituent of an alloy is in excess ness; and, the rapid cooling of the metal from of the amount soluble at room temperature, the the hardening temperature sets up severe in- excess amount will precipitate, causing an internal stresses. To reduce brittleness, and to crease in hardness and strength. relieve internal stresses, steel must be tem- Rapid cooling suppresses precipitation, and pered after it has been hardened.Although the alloy remains soft at room temperature. hardening and tempering are separate steps For metals whose constituents precipitate after in the heat treatment of a tool steel, the value or during fast cooling, it may be necessary to of each procedure depends upon the other. furnace-cool the metal in order to produce The hardening treatment for most steels complete softening. consists of heating to the correct temperature, Cooling methods also differ according to the soaking it the required length of time, and then type of metal concerned.Pure aluminum can rapidly cooling it in oil, water, or brine. A be cooled in air; pure copper can be cooled in point to remember is that too rapid a cooling air,or quenched in water.Steel must be rate will increase the danger of cracking or furnace-cooled, and the cooling rate must be warping. The addition of alloys permits a kept slow, to produce maximum softness. slower rate of cooling, and several steels In annealing, avoid overheating the metal (high-speed tool steels) may be cooled in air. being treated. Overheating will cause increased The temperature to which you must raise grain size. There is also danger of burning the steel for hardening should be about 50° to 100° metal and, in ferrous metals, decarburizing the F above its upper critical point.This is to surface if a protective atmosphere is not pro- ensure that every point in it will have reached vided. critical temperature and to allow for some slight loss of heat when the metal is transferred NORMALIZING to the cooling medium. Remember that it is cooled rapidly by quenching in oil, fresh water, Normalizing is a heat treating process simi- or brine. Quenching firmly fixes the structural lar to annealing, but it is applied to ferrous changes which occurred during heating, and thus metals only.The purpose of normalizing is to causes the metal to remain hard. refine internal grain structure, and to relieve If allowed to cool too slowly, the metal will stresses and strains caused by welding, forg- lose its hardness. On the other hand, to prevent ing, uneven cooling of castings, machining, too rapid quenchingwhich would result in and bending.Where steel is to be hardened, warping and crackingit is sometimes neces- it is advisable that it be normalized first; low sary to use oil instead of fresh water or salt

37 OPTICALMAN 1 & C water for high carbon and alloy steels. (Note: Tools with cutting edges are not tempered Salt water gives a faster quench but does not above 650° F; the hardness required for pene- necessarily give a higher hardness. Hardness tration is lost if a hardened steel is heated is dependent to an extent upon the quenching beyond this temperature. However, the tough- medium; however, an oil hardening steel will ness and shock resistance of the steel improves not be harder if quenched in brine.) as it is reheated beyond 650° F. When reheats In cooling, you have to bring carbon steel to beyond 650' F are enployed, the operation is a temperature somewhat below 1,000' F in less frequently called TOUGHENING. You will soon than 1 second; and from this point downward, a learn, by trial, the temperature at which a tool rapid cooling rate must still be maintained. must be tempered. Table 3-1 gives the tempera- Alloys added to steel increase this 1-second tures for tempering various plain carbon steel limit for lowering the temperature; therefore, tools. alloy steels can be hardened in a slower quenching medium. Table 3-1.Temperatures for Tempering Although all ferrous metals can be hardened Various Plain Carbon Tools. by heat treatment, the degree to which they can be hardened varies considerably. For example, Degrees Tool such ferrous metals as pure iron, wrought iron, Fahrenheit and low-carbon steels contain very little hardening element (carbon), and this type of heat 400' Hammer faces, machine treatment will have little appreciable effect in cutting tools hardening them.Cast iron can be hardened, 460* Tape and dies but here, too, the effect is limited. If cooled too 480' Punches, reamers, dies, rapidly, cast iron forms a hard and brittle knives white iron; if cooled too slowly, it forms a gray 500° Twist drills iron that is soft and brittle under impact. 520° Drift pins, punches 540° Cold chisels Some nonferrous metals and alloys can be 550° Screwdrivers, springs hardened by cold working and rolling.These processes increase the strength of nickel al- The following description of a common loys, copper, and wrought brass; some aluminum method used to harden and temper chisels will alloys and several copper base alloys are help to clarify the meaning of hardening and hardened by an aging process. tempering. Bring 2 1/2 to 3 inches of the cutting TEMPERING, also called DRAWING, is a edge of the tool up to hardening temperature. process generally applied to steel to reduce Then, using tongs to hold the chisel, quench by brittleness and relieve stresses developed dur- plunging 1 1/2 to 2 inches of the heated end into ing the hardening process. Tempering always the quenching medium. Jiggle the tool rapidly, follows, never precedes hardening.It differs using an up-and-down, forward-and-backward from annealing, normalizing, and hardening in motion; and, as you do so, make sure you keep that the tempering temperatures are always the point immersed 1/2 inch in the quenching BELOW the lower critical point. As it reduces medium. brittleness, the tempering process also softens When the metal has cooled down to a black the steel.One property must be sacrificed to heat (900' to 950° F), remove the tool from the some extent in order that another property may quench tank.Then quickly polish the tapered be improved. High speed steel is an exception end with an emery board and watch the temper since tempering high speed steel increases itt: color "run out" until the desired color appears hardness to a limited extent. (usually peacock to dark blue). Then quench the Tempering is accomplished by heating the entire tool. hardened steel to a temperature below the criti- It is well to remember that every chisel you cal range, holding this temperature for a suffi- see is not a water-hardened chisel. Many are cient time to penetrate the whole piece, and manufactured from special alloys and are oil- then cooling the piece in water, oil, or air. hardened. Most chisels of this type have di- The tempering temperature for hardened steel is rections for treating stamped on the shank as determined by the degree of hardness and follows: 1350 W 400 or 1600 0. The first means toughness desired. to heat to 1,350° F, quench in water and temper Chapter 3METALS at 400° F. The secondmeans to heat to 1,600° F, no less than 1 hour for each inch of thickness and quench in oil.It is not necessary to temper of the thickest section. Then allow the part to this tool, as it is a special alloy. Other alloy cool very slowly to room temperature.The chisels will have different directions stamped on cooling rate should not exceed 200° F per hour the shank. Generally, it is safe to assume that an for any metal.Since the majority of stress unmarked chiselis a carbon steel water- relief occurs during the first hour after the hardened tool. part attains the proper temperature, it is essential that hold time be counted from the time STRESS RELIEVING the metal, not the furnace, reaches the stress relieving temperature. Remember, slow cool- Stress relieving is a heat treating process ing is essential.If the part is cooled rapidly, in which uniform heating is essential, but the new internal stresses develop, defeating the temperature to which the part is raised is not purpose of the treatment. as high as that required for annealing and nor- In steel, stress relieving is often the final malizing.The purpose of stress relieving, as heat treatment. Here the stress relieving tem- the name implies, is to relieve stresses devel- perature is at least 50° F, but not more than oped in metals juring mechanical working or 100° F, below that of the preceding heat treating solidification. temperature. A temperature of 750° relieves Stress relieving involves temperatures below about 50 percent of the stress in a steel cast- the transformation point of ferrous metals. The ing, while a temperature of 1,000° F relieves main factors in stress relieving are the tempera- more than 90 percent.Typical practices for ture of the treatment and the time the part is stress relieving common metals are presented held at that temperature. Stress relief becomes in table 3-2. more effective as the temperature is increased. For example, with gray cast iron, the percentage Table 3-2.Stress Relieving Data of stress relief at temperatures below 750° F is negligible.Above this temperature, the per- Tempera- Hold time centage of residual stress relieved increases Material ture ( ° F)(hours per inch rapidly with increase in temperature. However, thickness) if the temperature closely approaches the transformation range, structural changes will begin Gray cast iron... 950 1 to occur. As a rule, when stress relieving is Low carbon steel. 1,150 1 applied, structural changes are not desirable. Carbon-molybdenum Consequently, the temperature selected should steel 1,250 2 give the greatest possible stress relief with the Chrominum-moly- least possible change of properties. For gray bdenum steel... cast iron,the stress relief temperature is (0.5 Cr-0.5 Mo). 1,250 2 950° F.At this temperature from 60 to 90 (2 Cr-0.5 Mo).. 1,325 2 percent of the original internal stress is re- ( 9 Cr-1 M o ).. 1,400 3 lieved and a minimum of structural change Copper 300 1/2 occurs. Brass: Stress relieving is accomplished by heating (70 Cu -SO Zn). 500 1 the metal slowly and uniformly to a predeter- (60 Cu-40 Zn).. 375 1/2 mined temperature. The rate of heating should Bronze (90 Cu-10 not be less than 400° F per hour for most Sn) 375 1 metals.When the metal attains the desired Stainless steel.. 1,550 2 temperature, hold or soak at this temperature Monel 550 2

39 CHAPTER 4

PHENOMENA OF LIGHT

There are many strange phenomena about YOUNG'S EXPERIMENT light, some of which you studied in Opticalman 3 & 2, NavPers 10205. It would be to your ad- Young went further into the theory of inter- vantage to go back and review the chapter on ference to prove he was right by conducting an characteristics of light which will help you to experiment. He took a piece of black paper and have a better understanding of the information put two narrow slits in it, as in figure 4-1, about on light in this chapter. Information on interfer- 1 mm apart. Behind the black paper he placed a ence, polarization, and double refraction follows. source of light 3 or 4 meters away. When he looked through the slits at the source of light, INTERFERENCE OF LIGHT WAVES he could see a series of dark and light bands, The wave nature of light has been substanti- as shown in figure 4-2. When he put a red filter ated by various -studies of light interference. between the light source and the slits, the series These studies have also produced other interest- of dark and light bands became red and black. ing light facts. Interference in light waves gives us a direct and accurate means for measuring wavelengths. Credence to Einstein's theory of relativity, on the other hand, was provided by unsuccessful endeavors to measure variations in lightvelocity by theinterference methods. Einstein contended that the velocity of light is constant and unaffected by the motions of anob- server. The first man to become interested in the effects of interference was Thomas Young, in 1801. He had the idea that if light were a form of wave motion it must act the same way water would, if subjected to the proper conditions. Since water can show the effects of interference, he felt sure he could produce the same effects with light. To show he was right, he took two similar trains of water waves. He said that if the elevations of cne wave coincide with the eleva- 148.1 tion of the other wave, they must together pro- Figure 4-1.Double-slit interference. duce a greater wave; but, on the other hand, if the elevation of one wave coincides with the de- Figure 4-3 shows the same double-slit inter- pression of the other wave anci fills up that ference, but this time we use a monochromatic depression, the waves cancel each other out. light source(s). (A monochromatic light source From this we get the two phases of interference, is a single wavelength of a very small range of constructive and destructive. wavelengths). Slits Xi and X2 are parallel to the Young's theory shows he had come to believe source ,and both must be the same distance from in Huygens' wave theory of light; his theory was it. When light from the source reaches the slits, opposed to Newton's corpuscular theory. the slits can then be considered new light sources 40 Chapter 4PHENOMEN OF LIGHT

FRESNEL'S EXPERIMENT The criticism of Young's experiments made Augustin Fresnel feel he should prove Young's experiments were right. Many who saw Young's experimentswerestillunconvinced.They thought that the spreading of light as it passed through the slit was not due to wave motion but to reflections from the flat edges of the slit. To prove this was not true, Fresnel constructed a device which used the sharp edges of two razors for the edges of his slit. Then he constructed 148.2 another exactly the same width, but this time he Figure 4-2.Fringes from double-slit used the flat and polished backs of two razors. interference. When the experiment was completed, he proved that it made no difference about the edges of the slits. With this experiment, and others, Fresnel helped to make the wave theory become generally accepted. POLARIZATION The first man to know the meaning of polarization was Fresnel. He knew that transverse waves vibrate at right angles to the direction of propagation (spreading of light). At the same time, he also knew that transverse waves could be polarized and that longitudinal waves could not be polarized. Huygens could not explain polarization because he thought light consisted of longitudinal waves. The following example illustrates the theory of polarization. Suppose that a rope is passed through two slats of a picket fence: if the rope is vibrated parallel with the slats, transverse waves would be able to pass through; but if the rope is vibrated at right angles to the slats, the waves would not be able to pass through, as il- lustratedinfigure 4-4. Polaroid films and tourmaline act in the same way as the slats in the fence, except that they act on light waves. By using two polaroid films, you can cancel out

148.3 Figure 4-3.Double-slit interference wave- front diagram. because they are producing new wave fronts. As the new wave fronts become larger, part of the waves produce constructive interference and make bright bands of reinforced light. While this is happening, the other wave fronts produce destructive interference and make the dark bands of light. These bands of light are hard to 148.4 see, unless you use a screen of some type to Figure 4-4.Mechanical similarity of project them on. polarization.

41 OPTICALMAN 1 & C the light completely. The first film will let some Another method of producing polarized light of the light pass and the second film, if turned is when sunlight is scattered by the earth's at- 90° to the first, will eliminate all remaining light. mosphere and is partially polarized. Because This type of polarization is used on some sunlight is partially polarized we have to use optical instruments today. With a filter of this polarized filters on our cameras. type, the amount of light through the filters can be adjusted by rotating one of the polaroidfilms. This is helpful, inasmuch as the Navy does not DOUBLE REFRACTION have to use two filters, such as one dark and one light. We can adjust a polaroid filter so that There are some transparent crystals that can we have either light or dark. This is the princi- produce a double image. One of these crystals pal of the variable density filter, which actually is called calcite (sometimes called Iceland spar). consists of two polarizing filters one of which is The double image is produced when each ray of rotatable. light is split into two rays by the crystal and the When you look through one polaroid film, you two rays are bent or refracted through different see what is called plane polarized light; that is, angles (fig. 4-6). We know then that since the you see vibrations parallel to one plane. Ordi- two rays are bent different amounts the in- nary light, as we see it everyday, is unpolarized dices of refraction in calcite must be differ- light, because it consists of many waves vibrat- ent. This double image is what we call double ing in different directions. refraction. One method of producing polarized light, and the simplest, was discovered by Sir David Brew- ster in 1808. His method involved usage of the reflecting surface of glass. He discoveredthat if light were reflected at a particular angle the reflected light would be plane polarized. Brewster's law stated that maximum polarization of light by reflection is obtained when the reflected and refracted rays are at right angles (fig. 4-5).

148.6 Figure 4-6.Double refraction in a medium. We know that some crystals do not have equal properties in all directions. If unpolarized light falls on a crystal such as calcite in any direction except parallel to the optic axis, the vibrations will occur in two directions at right angles to each other in the crystal. The two rays that are split are called the ordinary ray and the extraordinary ray. Since the velocities of the two rays are different, the indices of refraction must also be different. One of these rays (ordinary ray), in which the index of refraction is constant and independent of the angle of incidence,is like ordinary refraction with glass. For the extraordinary ray, the index of refraction varies with the angle of incidence. You do not always get double refraction from Figure 4-5.Maximum polarization accord- a crystal such as calcite, because there is one ing to Brewster's law. 148.5 particular direction where there is no double 42 Chapter 4PHENOMENA OF LIGHT refraction. When you do not get double re- rectionistheoptic axis of thecrystal. fraction, both rays are traveling with the The opticaxisisnot a singleline but same velocity and the index of refraction the direction ofall such lines which are is the same forboth. This particular di- parallel.

43 CHAPTER 5

RANGEFINDER THEORY AND CONSTRUCTION

Unless you are firing pointblank at your animals, such as lions, bears, wolves, and target, you must elevate the gun above your line people, have their eyes in the front of their heads. of sight (LOS) in order to secure a hit. The Because their two fields of view overlap, they exact angle of gun elevation depends chiefly on have depth perception, and can estimate relative the range.Successful gunnery requires, then, distances. Hunted animals, such as rabbits, have that you have some means for measuring the their eyes far around toward the sides of their distance from gun to target, quickly and ac- heads. That gives them a wide field of view, so curately, without leaving your own ship. Optical they can spot an enemy approaching from almost rangefinders are used for this purpose and you any direction. But the overlap of the two visual will be working on them from time to time. fields is slight, and they have little or no depth perception. RANGEFINDER THEORY Rangefinding with the help of instruments is more recent.It started in the Nile valley, about You have seen a rangefinder, perhaps many 4,000 years ago.This was fertile valley, so times. Rangefinders arG constructed in various that agriculture was highly profitable. But every lengths and diameters. Mounted at each end of spring the Nile river flooded, and washed away the cylinder are end windows that allow the pas- all the fences and boundary 9atkere.The sage of light into the instrument, with eyepieces Egyptians had to develop a system of GEOMETRY located in the center of the tube. The operator (literally: earth-measure) to find out whose field looks into the eyepieces, turns aknob, and reads was where. on a scale the distance between his ship and Practical geometry is based largely on the some object several thousand yards away. To measurement of lines and angles. Letus review someone with no knowledge of optics, that might some of the more basic principles. seem a little mysterious. But you shciuld already have a good knowledge of the basic theory of the ANGULAR MEASURE rangefinder. Rangefinders are as old as the human race. Everybody knows what an angle is; still it is Your two eyes serve as a very effective range- not easy to readily define the term. An angle finder at short distances. Your two pupils cor- may be defined as a measure of the amount of respond to the end windows of an optical range- turning necessary to bring one line or plane finder, andyourinterpupillarydistance into coincidence with or parallel to another, as corresponds to its base length. When you change in figure 5-1. Here, we start with the line AB, fixation from one object to another at a different then pivot this line at point A, and swing it distance, you automatically change the angle at around to position AC. The line, in rotating from which your two lines of sight converge. By sub- its first position to its second, has generated the consciously noting that change of convergence angle BAC. angle, ycni come up with an accurate estimate of relative distances.(Assuming, of course, that THE DEGREE both objects are within range of your steroscopic vision.) To measure any quantity we must use UNITS, Here is something you need not remember, which are defined in terms of some arbitrary but it maybe of passing interest.Predatory standard.(A unit is any determinate amount

44 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

RADIAN. For some purposes, as you will see later, the radian is a more convenient unit than the degree.

THE RADIAN In figure 5-2, the angle between the two radii is one radian.Consider first the radius OA;measure its length, r. Now, startingat C point A, lay off on the circumference of the SECOND POSITION circle an arc whose length is equal to r, and 148.7 mark point B at the end of it. Draw the radius Figure 5-1.Angular measurement. OB.Then the angle between the two radiithe angle A0Bis one radian.The two arms of (as of length, time, heat, value)) adopted as a this angle intercept an arc whose length is equal standard of measurement. The fundamental to the radius of the circle. unit of angular measure is the DEGREE. We There are as many radians in a circle as can best define it in terms of rotation. Imagine there are radii in its circumference.The a circle, with one radius drawn in.Let us circumference of a circle is equal to x times pivot that radius at the center of the circle and its diameter. [ In geometry s (the Greek letter turn it through one complete revolution, back to Pi) represents a constant; 3.14159+. ] Since the its original position.That radius, in making diameter is twice the radius the radius will go one complete revolution, has generated an angle into the circumference 2 it times. So, there are of 360°. Or we can look at it another way. We 2 s radians in a circle. can divide the circumference of our circle into How many degrees in a radian? Since there 380 equal parts, and mark off the divisions. A are 360° in a circle, there are360 radius, in rotating from one mark to the next, 2 degrees (or will generate an angle of one degree. 57.2956°) in a radian.(This and all other A degree is a fairly small uniteach of those equivalents based on the value of w are only 380 angles in the circle is one degree. But with approximate, since w is an indeterminate num- the help of optical instruments, we canmeasure beran endless decimal.) Reducing 57. 2956° to even smaller angles, or measure large angles degrees, minutes, and seconds, we get: more precisely.To make convenient smaller 1 radian equals 57°17'44. 8" units, we can divide each degreeinto 80 To make that figure easier to handle, we MINUTES, and each minute into 60 SECONDS. can convert it into seconds.Then we ;lave: Then our system of angular measurement shapes 1 radian equals 206,265 seconds up like this: 360 degrees equal one complete circle TRIANGULATION 60 minutes equal one degree What does all this geometry have to do with 60 seconds equal one minute rangefincling? We will show you. The ancient The second is our smallest independent unit farmers in the Nile valley discovered th°t when of angular measure; to measure more precisely you have to measure a distance that ytv "aunt than by seconds, you will have to use decimal reach directly, you can use the principle of fractions of a second. triangulation. We use that principle in rangefinding. Modern surveyors still use the principle CIRCULAR MEASURE of triangulation to measure distances they cannot get at directly. Astronomers use it to measure Circular measure is the measure of an the distance of the sun and planets, and some of angle with its vertex at the center of a circle the nearer stars. in other words, the angle formed by two radii. Figure 5-3 illustrates the principle of tri- In circular measurement, we define an angle in angulation, and shows the fundamental triangle of terms of the relationship between the length of arangefinder. You are at point A; another the radius and the length of arc intercepted by ship is at P; you want to measure her range the two radii.The unit of circular measure without leaving your own ship.A surveyor used in conjunction with the rangefinder is the would do it by laying off a line AB, of convenient

45 OPTICALMAN 1 & C

triangle are equal respectively, to the three RADIAN angles of the other.)The two triangles in figure 5-4 are similar. In any pair of similar triangles, the relationship between corresponding parts is constant. Measure the lines AB and BC (in fig. 5-4), and then divide the length AB by the length BC; if your measurements are accurate, your answer will be 0.9397. Do the same thing with the corresponding parts of the smaller triangle;measure DE and EF, and divide DE by EF.Your answer will be 0.9397 again. If you divide AC by BC you will get 0.3420. You can do the same thing with corresponding parts of the smaller triangle, or of any triangle similar to these two; the answer will always be the same.

148.8 Figure 5-2.Radian measurement. length, at a right angle to the line of sight AP. He would measure this line AB,as accurately as possible, with his tape measure. Then he would set up his transit at point B, anduse it to measure the angle ABP. He would then have all the data necessary to calculate therange AP. You should have a good knowledge of the principle of triangulation, but we willrun through it just for review.It's all based on the principle of similar triangles.(Two triangles are similar when the three angles ofone D F

A 148.10 Figure 5-4.Similar triangles. Remember that this will only hold true with lai any triangle that has an angle of 90°. 3 Look back at figure 5-3. Now, it is obvious how we can solve that whole triangle, and cal- I culate the range AP, by measuring only those THIS ANGLE AND THE parts of the triangle that are on your own ship. A/PARALLACTIC ANGLE How? By comparing APB with some similar ARE IDENTICAL triangle we are already familiar with. We know B c that angle A is a right angle, and we measured THE SUM OF THE THREEANGLES OF ANY angle B using a surveyor's transit. Wecan TRIANGLE WILL EQUAL ISO. easily calculate angle P, because we know that in any triangle the sum of the angles is equal 148.9 to 180°. Now, if you wanted to, you could draw Figure 5-3.The fundamental triangle ofa a small triangle similar to ABP, measure its rangefinder. sides, and calculate the ratio of the various 48 57 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION parts.You would know that the corresponding substitute tan 8 for tan Z. P. AB corresponds parts of ABP would have the same ratio. to the base of our rangefinder; let B represent But we do not need to go to all that trouble. the base in yards, and R the range AP in yards. Mathematicians have calculated all these ratios Now our formula is: for us, and listed them in table of trigono- metric functions. Tan 0 = How can we calculate the range from the R facts we know about the triangle in, figure 5-3? After a little thought you can see that the We can do it by setting up an equation that con- range will always be large when compared with tains the term we want to know (AP, the range) the base of the rangefinder, and therefore the and other terms that we already know. What do angle 8 will always be very small. Now this we already know? We know the length of the may be surprising, but it is true: for very small side AB, and the value of all three angles. angles, the tangent of the angle is almost exactly We know that, in a right triangle, the side equal to the angle itself, WHEN WE EXPRESS opposite one of the acute angles, divided by the THE ANGLE IN RADIANS. So, if we express 0 side adjacent to that angle, is the tangent of in radians, then: that angle. We can apply that formula to the triangle in figure 5-3: 0it tanL P = ApAB There you have the RANGEFINDER FORMULA. Thit suppose we want to express 0 in seconds, So we have an equation that combines our rather than radians. We know that there are unknown (the range, AP) and other quantities 206,265 seconds in one radian. Therefore, if we that we know. If we solve it for the range, AP, 'express 0 in seconds: we get: 0= 206,265 seconds AP = AB From/thatformula, we can calculate the value We know AB, by measurement, and we know of the parallactic angle, 0, for any given range- angle P; we can look up tan P in a table of tri- finder at any given range.But the job of the gonometric functions, and solve the triangle. rangefinder itself, of course, is to measure 0, So, using the method of a surveyor, with his and convert it into yards of range for us. transit and tape measure, you can calculate the Let us go back for a minute to your personal range of a target without leaving your own ship. rangefinderyour own two eyes.How does it But you can do it much more quickly with a work? Though you probably do not realize it at rangefinder. the time, you estimate the relative distance of In figure 5-3, the points A and B correspond two objects by comparing their parallactic to the two end windows of your rangefinder; the .angles.Since a nearby object has a greater line AB corresponds to the base of the range- parallactic angle than a distant one, you know flder and is always constant for that particular that the object with the greater parallactic rangefinder. We cannot measure the PARAL- angle is closer than the other. LACTIC ANGLE (angle P) directly, because its Of course there is a limit to the usefulness vertex is aboard the other ship. But if we con- of your personal rangefinder, because there is struct an imaginary line BC parallel to AP, then a limit to your STEREO-ACUITY.To the angle 0 (Theta) will be identical with the paral- average trained observer, two parallactic angles lacticangle, and can be easily measured. will appear to be equal unless the difference The rangefinder can give us all the informa- between them is 12 seconds or more.Since tion we need to solve the triangle and calculate the base of your personal rangefinder is short the range. (65 mm is average), its effectiveness is limited Using the triangulation formula to comparatively short ranges. How can we extend that range? Let's con- tanL A: sider two distant objects, whose parallactic angles are 1 second and 2 seconds, respectively. P is the parallactic angle, and since we are To the naked eyes, of course, they will appear going to measure the identical angle 0, we can to be at the same distance, because the difference

47 OPTICALMAN 1 & C in their parallactic angles is too small to de- one near each eyepiece.Now you have the tect.You cannot tell which of these objects system shown in figure 5-6. is closer unless you find some way to increase We have used a penta prism at each objec- the difference between their parallactic angles tive, to reflect rays from the target onto the to 12 seconds or more. optical axis. We have added two prisms Now suppose that you mount two 12X (12 (numbered 7) that reflect the rays to the ob- power) telescopes side by side and parallel, server's eyes. We now have a system that will with the centers of their eyepieces about 65 increase your depth perception tremendously. millimeters apart.You can look through one itmagnifies your target and effectively in- of these telescopes with one eye, and the other creases your interpupillary distance. By using one with your other eye.The telescopes will this system you can easily estimate the relative magnify both objects 12 times and thus increase distance of two objects, even at a great distance. their parallactic angles to 12 seconds and 24 But estimating relative distance is very different seconds, respectively.The difference is now from measuring actual distance. To make this 12 seconds, and you can estimate the relative system into an effective rangefinder we will distance of the two objects. have to add a measuring device. You could also extend the range ofyour The two diagrams in figure 5-7 are sche- depth perception if it were possible to increase matic drawings of a coincidence rangefinder your interpupillary distance.You can easily the type with a single eyepiece. The cross at see that, for an object at any given distance, C represents a coincidence prism.It enables increasing the base of the triangle will increase you to see through both telescope systems at the parallactic angle. once, with one eye; youf field of view appears The optical rangefinder uses both these to be split by a horizontal line; the lower half means to extend the range of your depthper- of the image is formed by one of telescopes, ception. It provides you with a magnified image the upper half by the other. of the target.It provides you with two lines of Look at the upper diagram in figure 5-7. sight through its two end windows, whichare The rangefinder has been turned so that ray A much farther apart than the pupils ofyour eyes. from the target is at a right angle to the optical By using a rangefinder with a magnification of axis.After reflection in the left penta prism 24X, and a base length 100 timesyour inter- L, ray A will coincide with the axis; it will pupillary distance, you can increaseyour depth strike the center of the coincidence prism at C, perception by a factor of 2,400. and will be reflected to the observer's eye at E. If your target were at infinity, all rays from OPTICAL CONSTRUCTION OF THE a given point on it would be parallel. The ray RANGEFINDER entering the right penta prism, R, would behave like ray Bit would be reflected along the axis, You can easily understand the construction and after reflection at the coincidence prism it of a rangefinder if you compare it with other would coincide with ray A. To the observer, the instruments you have already studied. In figure two halves of the image would appear to coincide 5-5 you see two simple gunsight telescopes, and form one unbroken image. laid out with all their elements ina straight But actually your target will be at a definite line.The two eyepieces (doublets) face in- distance. The broken line B' represents a ward; the two objective lensesare at the ends ray from a target at a definite distance.It of the line.Since you now have two lines of will strike the face of the right penta prism sight, through two separate telescopes,you at a slight anglethe parallactic angle, 0. After have the essential elements of a rangefinder. reflectionin the penta prism it will diverge But to make it useful, you will haveto add a from the axis at the angle 0, and after reflec- few features.Your two lines of sight are tion in the coincidence prism it will fail to pointing in opposite directions; actually,you coincide with A.The observer will see a want them to converge on a single object., You broken image of the target; half the image will can do that by adding two reflecting surfaces be displaced to one side. on the optical axisone beyond each objective In the lower diagram (part B of fig. 5-7), to deflect the lines of sight forward. Tomake we have inserted a pair of measuring wedges; the incident nays enter youreyes, you must think of them as a pair of thin prisms. A add two more reflecting surfaces to theaxis, prism, of course will deviate a ray of light

48 5.9 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

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1 2 3 4 5 5 4 3 2 1

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148.11 Figure 5-5.Teliscopic system of a rangefinder. toward its base. If we choose our prisms care- help to make the instrument more accurate, and fully, we can make them deviate the ray B' convenient to use, and provide an easy means through angle g .Then, after the ray passes of calibrating it. through the measuring wedges, it will lie on the optical axis, and the observer will see an un- TYPES OF RANGEFINDERS broken image of the target. The Navy uses two types of rangefinders: If necessary, we could actually measure the COINCIDENCE type, and the STEREOSCOPIC ranges that way. We could select, by trial and type.The two instruments have many features error, one or more prisms that would make the in common; each consists of two telescopes, one image halves coincide. Then, if we knew the de- in each half of the instrument. Both types meas- viation of those prisms, we would know e, and ure the parallactic angle, and calculate the could calculate the range.But a system like range from that measurement.The principal that would be slow, and it would keep the oper- difference is in the way the target image is ator pretty busy. presented to the operator's eyes. Actually, rangefinders use a simpler prin- The COINCIDENCE RANGEFINDER has a ciple.The measuring wedges are so mounted single eyepiece.The operator's field of view that you can rotate them on the axis by turning is split by a horizontal line; the upper half is a knob. The deviation will vary with the amount formed by one of the two telescopes, the lower of rotation. By turning the rangingknob you can halt by the other.To operate the coincidence rotate the wedges until their deviation is equal rangefinder, the operator turns the ranging to 0 .We can mount a scale in this system, to knobthus rotating the measuring wedgesuntil indicate the amount of rotation. And, by suitable the two halves of the image coincide. He can tests on targets at known distances, we can then read the range, in yards, on the scale. calibrate that scale to show the range in yards. When the rangefinder is not set to the proper This is the basic principle of the range- range, the operator sees a broken target; half finder. There is more to it than that, of course, the image will be displaced to one side, as in but the other elements are acces8ories. They figure 5-8.

148.12 Figure 5-8.Basic optical system of a rangefinder.

49 OPTICALMAN 1 & C

COMPENSATOR WEDGES

B' BEFORE INTRODUCTION OF WEDGES A AND B' AFTER INTRODUCTION OF WEDGE!

148.18 Figure 5-7.The rangefinder principle. The STEREOSCOPIC RANGEFINDER hastwo 5-9may appear to be closer or farther away, eyepieces.In ranging with this instrument the than the target.By turning the ranging knob, operator makes use of his own stereo-acuity and this rotating the measuring wedges, the his ability to estimate the relativedistance of operator can make the target appear tomove objects. When he looks through theeyepieces in either direction.When the target and the he will see a single, unbrokenimage of his target. diamonds appear to be at the same distance, Superimposed on that image he will the rangefinder is properly set, and theoper- see a pattern of reference marks. (This pattern ator can read the range on the scale. is engraved on the reticles in the twotelescopes In naval use, the stereoscopic rangefinder of the rangefinder.) Figure 5-9 showsa typical has largely replaced the coincidencetype.If reticle pattern for a stereoscopic rangefinder. the operators are thoroughly trained, thereis To the operator, this reticle patternwill no significant difference in the accuracy of the appear to be spread out in spacesome of the two types.But when ranging on aircraft, or vertical marks will appear to becloser than under conditions of poor visibility,a skilled the diamonds; others willappear to be farther operator can usually get better results with away. (This is an illusionor"artificial" the stereoscopic rangefinder. stereoscopic effect.The patterns of the two reticles are similar but not identical.By COINCIDENCE RANGEFINDER viewing a separate reticle with eacheye, you get an effect of stereopsis, and thepattern The main optical system of the coincidence appears to be spread out in space.) rangefinder includes these elements: end win- To the rangefinder operator, the center dows,end penta prisms or end reflectors, row of reference marksthe diamonds, in figure measuring wedges or compensator wedges,

50 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

I I I I

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148.14 55.294 Figure 5-8.Field of view of the coincidence Figure 5-9.Field of view in a stereoscopic rangefinder. rangefinder. correction wedge, main objective lenses or ob- deviate the incident rays, they provide a means jective lens groups, coincidence prism, main of compensating for slight inaccuracies in the eyepiece group, astigmatizers, and color filters. reflecting angles of the penta prism, or else- Some instruments also have change of magnifi- where in the instrument.There is an index, cation lenses.Figure 5-10 shows the optics of and in some instruments a graduated scale, on a typical coincidence rangefinder, Refer back to the outer edge of each end window, or on its this illustration as we describe the principal frame, to show the setting.(On some range- elements. finders, the left end window is piano- parallel; only the right end windowisusedfor corrections End Windows on these instruments.) The end windows are set during the final An end window is mounted in the front of each inspection of the rangefinder, after it is manu- end box of the rangefinder. These windows are factured, and after each overhaul.When the tightly sealed around the edges, and thus help rangefinder has become thoroughly stabilized at to keep dirt and moisture out of the instrument. normal temperature, the inspector checks the Although the two surfaces of each window have internal adjustment, and then rotates one or both been ground optically flat, they are not quite end windows to secure a correct reading on an parallel. Each end window is actually a prism, accurately known range, It should not be neces- though a prism of extremely small angle. sary to reset the end windows in service. . By a suitable rotation of an end window, you can make its deviation zero in the plane of End Penta Prisms or End Reflectors triangulation, or you can deviate the incident rays slightly, to either the right or the left. (As you The penta prisms or end reflectors (often remember from your study of plane geometry, called penta reflectors) deviate the line of sight a line and a point determine a plane. The plane through an angle of 90°. (In most rangefinders, of triangulation is the plane determined by the the deviation in the right penta prism or end halving line of the rangefinder and the sighting reflector, although constant, is slightly less point on the target) Since the end windows can than 90°. We will explain why a little later in

51 MAIN OPTICAL SYSTEM ELEMENTS TRAINER'S TELESCOPE SYSTEMFIRSTEND WINDOW REFLECTING PRISM MAIN OPTICAL SYSTEM ELEMENTS RIGHT END REFLECTOR CORRECTIONLEFT ENDOBJECTIVEEND WINDOW REFLECTOR WEDGE GROUP SYSTEM ELEMENTS MAINASTIGMATIZERSCOINCIDENCE OPTICALRAYEYEPIECE FILTERS GROUP PRISM TRAINER'SOBJECTIVEERECTING RETICULE REFLECTING REFLECTING PRISM COMPENSATORRIGHTRIGHT END OBJECTIVE WINDOW WEDGES GROUP INSIDE RANGE SCALE CORRECTION SCALF SCALE ILLUMINATING PRISMSYSTEM "N.SCALEINSIDESCALEILLUMINATOR REFLECTING INDEXLAMPRANGE SEALING PRISM SCALE WINDOWS ELEMENTS SCALECORRECTIONEYEPIECECORRECTIONILLUMINATOR OBJECTIVESREFLECTING GROUP. SCALE SCALSEALING PRIINDEX WINDOWS Figure 5-10.Optics of the coincidence rangefinder. TRAINER'SSCALETRAINER'SSCALE RHOMBOIDDOVEOBJECTIVE OBJECTIVE AND PRISMEYEPIECE INSIDE PRISM SCALE GROUP READER PRISM 148.15 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION this chapter.) A penta prism, by reflecting the image twice, produces an erect, normal image. We could not use a plane mirror or a right- angle prism for this purpose, because the image would be reverted. In addition, the deviation of a right-angle prism is not constantit is 90° only if the incident light is normal to the first surface. In large, long-base rangefinders, the objective lens must be quite large to make the field of view wide enough.In these instruments we use end reflectors, rather than penta prisms. An end reflector consists of two plane mirrors, rigidly mounted together at an angle of 45° .(The L rangefinder in fig. 5-10 uses end reflectors, rather. than penta prisms.) The path of light within it is the same as that in a penta prism. ,,A Figure 5-11 shows the path of light through a penta prism. A study of this diagram will show you that the deviation is constant, regardless of the angle of incidence.Although the light is 148.16 refracted at both outside surfaces, the two re- Figure 5-11.Principle of the penta prism fractions are equal and in opposite directions. and end reflector. Since we can disregard this surface refraction, you can see that an end reflector works in Figure 5-12 illustrates the action of a single exactly the same way. measuring wedge.It is mounted on the long- In a long-base rangefinder, the end reflector itudinal axis Of the instrument, between the ob- has two advantages over the penta prism. First, jective lens and its image plane. As you can a penta prism of sufficient size would be very see in the illustration, the deviation of the wedge expensive. Second, and more important, a large is constant. But the displacement of the line of end reflector responds quickly to temperature sight, at the image plane, depends on the position changes; after a change in temperature, the end of the wedge along the axis.For any angle 0, reflector stabilizes within a short time. A large and therefore for any range, there is a certain penta prism, on the other hand, responds slowly, position of the wedge on the axis that will make since glass is a poor conductor of heat.For the two images coincide. We can use this sys- some time after a temperature change, various tem to measure ranges by rigidly attaching a parts of a large penta prism would be at various pointer to the wedge, and allowing that pointer temperatures, with resulting distortion and inac- to travel over afixed scale. Wecan calibrate curacy. that scale by marking the position of the pointer when we make coinnidence on targets at ac- Measuring Wedge or Compensator Wedges curately known ranges. All of the newer instruments ude a pair of Look back at figure 5-7 and review the compensator wedges.The two compensator function of the measuring wedge or compensator wedges are mounted on the axis of the right- wedges. To summarize: they are thin, achro- hand. telescope outboard of the objective. Figure matic prisms, that can be used to deflect the 5-13 shows a single prism in the position of the line of sight in one telescope back through the compensator wedges. angle 0, so that the two images coincide. There are two general types of deviating wedges: The incident ray, as usual, diverges from the (1) a single measuring wedge, mounted so that axis by the angle 0 .The prism will deviate you can slide it along the optical axis of the that ray toward its base. For any given angle instrument; and (2) two compensator wedges, so 0, we can select -a prism with exactly the de- mounted that when you turn the ranging knob the viation necessary to make the incident rays two wedges rotate equally and simultaneously, parallel to the axis when they strike the objec- in opposite directions, about the optical axis. tive.When the rays are parallel to the axis at

53 OPTICALMAN 1 & C

IMAGE PUNE MEASURING WEDGE

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148.17 Figure 5-12.Action of the single measuring wedge. theright objective (as they are at the left to reduce the parallactic angle to zero. We objective), the two images will coincide. will have to eliminate the vertical deviation As we have said before, we coulduse this entirely; otherwise the halving line will fail system to measure ranges by trial and error. to split the imagethe images will be spread If we had a large assortment of prisms handy out, or they will overlap. we could try them out, one by one, untilwe By using two wedges, rotating through equal found one with exactly the deviationnecessary angles but in opposite directions, we can keep to make the rays parallel to the axis. The the horizontal deviation and eliminate the verti- paired compensator wedges make ranging pract- cal deviation.Figure 5-15 shows how com- ical by providing a continuously variable de- pensator wedges work. You can understand the viation. principle easily if you remember that a prism Any prism, as you know, will deviate the always deviates the ray toward its base. incident rays toward its base.With the base Since the range is always large compared toward the target (as in fig. 5-13),or toward to the base of the rangefinder, the parallactic the operator, all the deviation will be ina angle is always small. The compensator wedges, horizontal plane.If the base were up or down, therefore, are prisms of very low powerthe all the deviation would be in a vertical plane. angle is sometimes so small you can not tell If we turn the base to some angle betweenzero which side of the disk is its base. For this and 90°, the rays will be deviated both hori- reason a small mark is etched at the edge of zontally and vertically at the same time. most wedges.It represents a line from the Figure 5-14 shows what happens when you center of the base to the apex of the prism. rotate a single wedge about the optical axis. Earlier in this chapter, we told you that the We have used a screen to intercept the deviated deviation in the right-hand penta prism or end ray, to show what happens to it.The line AO shows the total deviation of the ray toward the base of the prism, CA is the vertical component of the deviation, BA the horizontal component. If you keep the wedge at a fixed distance from the screen, then the total deviation OA will be constant, regardless of the angle of rotation. But as you rotate the wedge the horizontal and vertical components will change. The horizontal 55.293 component of deviation, BA, is the one we need Figure 5-13.Action of the compensator wedges. 54 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

NO TIE FIRST TIE MK NAVE 10111 KKK NAVE WELKE WOK BENDS KB ROTATED K BEEN NOTATEDTMRONCN TIE PAY EXACTLY TIE SANE fll IIKKES IN OEM MAT NIT IN MKS C0OSITI mans TIE SECOND WOK INDS TIE FEW WOK DENS TIE PAY KIN. TIE FIRST WOK TIE PAY TO TIE MK ENDS TIE PAY DE RESULT IS II AND A UM TIE SECOND WOK OK 55. 295 NO BENDING TO TIE MKT. 110 10 TO TIE MINT. AT AIL Figure 5-14.Effect of rotating a single THE SHOED WOK THE miAT IS A NAME wedge. MIK TIE PAY WINK TO THE WAIT. DOWN AND A UME reflector is less than 90°. To understand why, TO TIE MINT. first consider what would happen if the deviation TIE RESULT IS A ENDING TO II were exactly 90°. Then, for a target at infinity, Ralf. the incident ray would be deviated parallel to the optical axis.Since the parallactic angle is 148.18 zero, we would need no deviation in the com- Figure 5-15.Refracting a ray of light with pensator wedges to make the two images coin- two compensator wedges. cide.For a target at infinity, we would turn the base of one wedge up and the base of the the axis after deviation by the penta prism or other one down, as in part B of figure 5-15. end reflector. They would require no deviation For a target at the minimum measurable at the wedges; we would turn one wedge base up range, the incident rays would deviate from the and the other wedge base down.At minimum optical axis, toward the operator, at the maxi- range we would have maximum deviation toward mum parallactic angle. To make them parallel the operator, and we would compensate for it by to the axis we would require maximum deviation turning both wedge bases toward the target. In away from the operator; consequently we would this system, as you can see, we need 180° of turn the compensator wedges so that both their rotation of the wedges to cover the full span of bases were toward the target.Obviously no measurable ranges. And consequently the rangefinder can measure a range greater than calibrations will be spread through 180° on the infinity, or less than the 1111111113113111 measurable scale. range.To cover the whole span of measurable ranges, we need only rotate the wedges through Correction Wedge 90 °; and all measurable ranges will be crowded into 90° on the scale. The correction wedge provides a means for We could read the scale more accurately if correcting errors in alignment. Like the meas- we could expand the calibrations to cover 180°. uring wedge, the correction wedge is a thin prism We can do that quite easily, )ust by making the of low power. In some instruments it is achro- deviation in the right penta prism or end re- matic; in others it is a simple prism.It is flector less than 90° (by making the angle be- located in the left-hand telescope, and mounted tween the two reflecting surfaces less than so thatitcan be rotated by the operator. 45° ).Now, rays from a target at Infinity will Rotation of the wedge, of course, deviates the be deviated away from the axis, back toward line of sight, both vertically and horizontally. the target.To make the images coincide we The deviation in the plane of triangulation is would turn the wedges so that both bases were the most useful; errors in horizontal alignment toward the operator.For a target at mean are corrected by adjustment of the opticalbars, range, the Incident rays would be parallel to or adjustment of the height adjuster linkage

Z50 OPTICALMAN 1 & C which raises and lowers the end of the optical bar. Rangefinder operators sometimes disagree as to when the two halves of the image coincide. A An operator may find that he habitually makes H an error in ranging, and that this error is fairly constant.With experience he can learn B the usual amount of his habitualerror, and adjust the correction wedge to correct it.

Coincidence Prism T. TOP HALF, RIGHT IMAG H.tAIDDL E, RIGHT IMAGE B. BOTTOM HAL F, RIGHT IMAGE The coincidence prism is the element that TL, Mi, 11,, S9i4L ARV( FOR LEFT IMAGE suppresses opposite halves of the two images, and presents the composite image to theoper- 148.19 ator's eye.At the same time, it erects the Figure 5- 16. Principle of the coincidence image. prism. The coincidence prism is built up of several smaller prisms cemented together and mounted objectives are made and mounted with the near the center of the instrument.The coin- greatest of precision.If the focus of the ob- cidence prism is complex; it is difficult to de- jectives are not exactly alike, the magnifica- scribe, and almost impossible to represent tion of the image in the right and left eye will satisfactorily in a drawing.To understand it, differ and the range readings will be incorrect. we suggest that you first read through the rest Lack of uniformity in the focus of objectives is of this section; then get a cemented coincidence readily detected when a target is observed that group in your hand, and study it carefully. is not in the center of the field. The right and Figure 5-16 shows, in a two-dimensional left objective lenses are therefore selected and drawing, the path of light through a simple coin- adjusted to give the same focus. They arecom- cidence prism. The prism in the drawing is posed of a positive lens of crown glass and a made up of two smaller prisms, cemented at negative lens of flint glass. The objective mount- the surface AB. Before cementing, half ofthat ing and the spacing between them must be care- surface, CB, was silvered.The two sets of fully adjusted to give the correct focus, and they rays entering the prism from the two range- must be held firmly in their mounts without finder telescopes are labled.Follow the rays strain. to see what happens to the right-handimage. The top half will strike the silvered surface, Eyepiece Group and be reflected up out of the prism; the bottom The eyepiece group is used to view, and to half will miss the silvered surface, andpass on magnify, the composite image reflected by the thrOigh to the eyepiece, formingthe bottom half coincidence prism. The eyepiece has a focusing of the composite image. The top half of the left mount; the usual focusing range is from plus image will be reflected, at the silvered surface 2 to minus 4 diopters. toward the eyepiece, and will form the top halt You will find several different types of eye- of the composite image. The bottom half of the pieces in the various marks of Navy range- left image will miss the silvered surfaceand finders. The two most common are: pass on out through the top of the prism. 1. The, orthoscopic eyepiece (composed of The middle rays meet at the halving line, a cemented triplet and a single lens). in the center of the image. By careful adjust- 2. The achromatic eyepiece (composed of ment of the two telescope systems,we can re- two cemented doublets, with an air space between duce the width of the halving line practically them).The newer instruments are provided, to zero, and thus make coincidencemore ac- almost exclusively, with the achromatic eye- curately. piece. Objective Lenses Astigmatizera The function of the objectives is to form The two astigmatizersone in each tele- real images of the target on the reticles. The scopeare mounted on the objective side of the

58 6/ Chapter 5RANGEFINDER THEORY AND CONSTRUCTION coincidence prism. You can throw them simul- a pair of rotating compensator wedges, to mea- taneously to the IN position, where they inter- sure the parallactic angle; it shows the result cept the rays just before they reach the coin- on a scale calibrated to indicate the range in cidence prism, or to the OUT position, off the yards.The two instruments differ in the way .suds, where they have no effect on the image. the operator determines when the wedges are Each astigmatizer is a simple lens, but correctly set.In the coincidence rangefinder with its surface ground to cylindrical, rather he makes two half-images coincide; in the than spherical shape.As you may remember, steroscopic rangefinder he depends on his own a cylindrical lens produces an elongated image stereoscopic vision. the image of a single point will appear as a The stereoscopic rangefinder has two eye- line.The astigmatizers are useful when you pieces; the operator's right eye sees the image are ranging on a searchlight at night.Here formed by the right-hand telescope; his left eye your target image is practically a point of light. sees the other one.The two images fuse to- You would have to manipulate the rangefinder gether, just as they do when you look through very carefully to get that point image exactly a pair of binoculars. on the halving line, and even then you could In each of the two telescopes, in the focal never be sure you had made exact coincidence. plane of the objective lens, is a reticle. The When you throw the astigmatizers to the IN images of these two reticles, like the two target position, the two half-images of the search- images, appear to fuse and form a single image. light become vertical lines of light, perpendic- The two reticles are similar, but not identical. ular to the halving line as in figure 5-17. To Consider, for a moment, a single mark near make exact coincidence you need only turn the the center of each reticle.The operator sees ranging knob until the two half-images form a a separate mark with each eye; he fuses the single, unbroken vertical line. two images so that he sees a single mark. But rays from corresponding points on the two marks, as they enter the two eyepieces, are not parallel; they diverge at a small angle.This angle corresponds to a parallactic angle.To the operator, viewing the two marks stero- scopically, they appear as a single mark located at a finite distance in space. Rays from the target, reaching the two eyepieces through separate telescopes, also diverge at a small anglethe parallactic angle of the target.If the parallactic angle of the reticle 148.20 marks is smalldr than that of the target, the Figure 5-17.Astigmatized half-images of fused reticle image will appear to be more a searchlight. distant than the target; if the parallactic angle of the reticle is greater than that of the target, Color Filters the reticle will appear to be closer. By rotating the compensator wedges you can The color filters are mounted between the change the apparent parallactic angle of the coincidence prism and the eyepiece. You will target.In the coincidence rangefinder you re- find various color assortments in the various duce it to zero; in the stereoscopic rangefinder marks of rangefinder. 'These filters have the you make it equal to that of the reticles. The same function they have in a telescope:they target and the reticle mark then appear to be serve to dim a too brilliant image; they help to at exactly the same distance.The amount of reduce haze; under some conditions they in- rotation of the wedges necessary to make the crease the contrast of your target against its two angles equal is a measure of the paral- background. lactic angle of the target; consequently, the scale can be calibrated to show the range in STEREOSCOPIC RANGEFINDER yards. Figure 5-18 shows the optics of a stero- Like the coincidence rangefinder, the stero-. scopic rangefinder. As you can see, they are scopic rangefinder uses a measuring wedge, or similar to those of the coincidence type, except

57 6a OPTICALMAN 1 & C

ENO WOW MINT ADJUSTER MOTIVE ADJUSTER TAIMPENSATORKOK RUT END WINOOV7 ILLUMINATOR ILLUMINATION REFLECTOR MONT ADJUSTER WITTTAMP amom INTVINAL ADJUSTER PINTA. POSY Pl."-.. COMMOTION SCALE MTV*

COMO RAMADTKINS LOT RETICLE RETICLE LIFTr4i2:17lig NOW ADJUSTER LENS SYSTEM REFLECTOR Mrwri ROW MOM IM SCALE I osligra I MOff END NADINS RIN SOMA 011Orip_ RIFLECTOR ,...... MOOS PRISM fitsus '.-SCALe Name *x_ILLUINNATINS PRISM LENT WIDOW WV META LVO SCALE WOES Efr* WO WISMOVIS 111 EVE LENS 00010Von sou P RIEROCIO ORION

MIONSOID PROM ILIYE "111/ GROUP euisi; RAY FILTER LEFT ERECTOR LDS AUXILIARY SYSTEM LENS WOO LEFT OCULAR PROM

LIFT EOM, STOUP IVO TSAI

55.300 Figure 5-18.Optics of the stereoscopic rangefinder. for the central elements. We will list the princi- finder. The operator, by turning the knob and pal parts in two groups: thus tilting the height adjuster, can raise or 1. End windows, end reflectorsor penta lower the left-hand target image. prisms,measuring wedge or compensator The stereoscopic rangefinder uses its height wedges, objective lens groups, correction wedge, adjuster for aligning the two optical systems in eyepiece groups, and color filters. the horizontal plane, and its correction wedge 2. Height adjuster, ocular prisms, reticles, for vertical alignment. rhomboid prisms, collective lenses, and erector lenses. Ocular Prisms In some instruments the erectors alsoserve as change-of-magnification lenses. There is no The two ocular prisms, one for each tele- astigmatizer; since there is no halving line,you scope, are mounted near the center of the do not need it. Allthe elements :ngroup 1 above instrument. Each prism reflects the image are the same as those of the coincidence range- twice, and presents an erect and normal image finder. We will not describe them again. The to the eyepiece.In the newer, double-purpose elements in group 2 are foundonly in the stereo- rangefinders, the prism elevates the line of scopic type: sight so that, if the lines of sight from the end windows are horizontal, the operator must look Height Adjuster downward in order to see the target. image. What happens when a ray of lightpasses through a flat plate of glass?If the ray is normal to the surface, it passes through without any change. Hit strikes the surface at a smaller angle, the emergent ray is displaced toone side, though it is still parallel to the incidentray. Figure 5-19 illustrates this principle. In the stereoscopic rangefinder, the height adjuster is a flat disk of glass in the left-hand optical system.The disk is mounted in bear- 55.299 ings, and connected to a knob outside therange- Figure 5-ILPrinciple of the height adjuster. 58 64, Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

(In the Mk 42, the operator's line of sight is the vertical marks for reference, the operator downward at an angle of 25° from the vertical.) can estimate the spot in units of error, which can then be converted to the equivalent in yards Reticles for that particular range. The spacing, from center to center, between The reticles are piano- parallel glass disks any two adjacent marks in the same row, corre- with reference marks etched on them. They are sponds to five mils in deflection.Thus the usually mounted in the focal plane of the ob- operator can quickly make deflection spots with- jective lenses. In some rangefinders, each out training the rangefinder off his target. (A reticle is cemented to a convex-plano lens. In mil is a unit of measurement for angles, much most of the recent instruments you will find smaller than a degree-1/6400 of the circum- several sets of reference marks engraved on ference of a circle.) the reticles. Figure 5-20 shows a typical reticle pattern.(We've added the lettering and arrows Rhomboid Prisms to help explain the pattern. On the reticle itself you will see only the vertical marks and the The rhomboid prisms provide a variable diamonds.) interpupillary adjustment. They are so mounted As we have told you, the two reticles are that the distance between their forward faces slightly different; the operator fuses the two remains constant.They pivot about a point at reticle images stereoscopically. AU the dia- the center of the forward face; thus the distance monds appear to be at the same distance; the between the rear faces is variable, and can be operator can use any one of them as a reference set for the operator's interpupillary distance. mark in measuring the range. All the marks in Each collective lens (sometimes called field any one horizontal row appear to be at the same lens) gathers light from a rhomboid prism and distance.But the various rows appear to be bends it toward the eyepiece lens. at various distances: to the operator, the upper rows appear to be more distant than the dia- AUXILIARY OPTICAL SYSTEMS monds; the lower rows appear closer than the diamonds. The marks in the first rows above In most rangefindersboth coincidence and and below the diamonds are so spaced that their stereoscopicyou will find several auxiliary apparent distance from the diamonds is equal to optical systems, in addition to the main system. 50 units of error.(A unit of error is the Some of these are used in ranging; others pro- greatest theoretical distance by which a range vide a means for adjusting the main optical sys- reading may be wrong.) The second rows from tem. The principal auxiliary systems are: the the diamonds appear to have a range difference internal adjuster system, the adjuster scale of 100 units of error. reading system, the main scale reading system, In ranging, the operator rotates the com- and the trainer and finder telescope system. pensator wedges until the diamonds and the target appear to be at the same distance. He need MAIN SCALE READING SYSTEM not change this setting to measure the distance The main scale reading system is used to from the target of a burst or splash. By using read the two range scales:the internal scale

I Hr 5 MILS I ....._____ I . '1

50 UNITS A 1 oi) leATOSR 100 UNITS OF ERROR VzOF 5 MILS OF ERROR f "1 , I I I I I 5 MILS I I I 4 IA- 55.304 Figure 5-20.A typical reticle pattern.

59 OPTICALMAN 1 & C connected to the wedges, and the external scale of the rangefinder, enters through a. windoW, is mechanically linked to them.In some instru- reflected from the reflector plate, and illumi- ments the system is so arranged that theoper- nates the left target mark. Since this mark is ator can see the scale alongone side of the in the focal plane of the right objective, rays field; in others, an assistant rangefinderoper- from the mark will be parallel atter they pass ator reads the scale through an auxiliary tele- through the right objective. Some of this light scope built into the rangefinder. As shown in will be reflected by the right reflector, and be figure 5-18, the reading telescope consists of lost; the rest will pass through.At the same an arrangementof prisms, a transparent scale, time, the right target mark is illuminated by an objective lens, a field lens, and an eye lens. the right reflector, and sends out rays which The window in the illuminating system protects become parallel after passing through the left the airtight seal of the rangefinder. objective. The external range scale isa second dial, At each end of the adjuster tube is a small mounted near the outside of the rangefinder penta prism.Ordinarily these prisms are tube, so that it can be read througha window swung out of the way, so as not to interfere without artificial light. with the operation of the main optical system. The internal scale is the more importantof By turning the internal adjuster drive knob, the two; normally the operator willread only you can crank the two penta prisms into p.Isition. the internal scale.The external scale is pro- This operation automatically closes t:;% EltzttArs vided for use if the illuminating circuit for the over the end windows, to keep external light 4.mt internal scale should fail. In inspectinga range- of the system. finder you should check to be sure that both scales give the same reading.If they do not, If the two objectives of the internal adjuster you will probably find some lost motion in the system are so mounted that their optical axes mechanical linkage; or the coupling betweenthe coincide, then the two sets of rays from the external scale and the wedgesmay be out of two internal targets will both be parallel to that adjustment. aids. And, after reflection at the two small penta prisms, the two sets of rays will still be INTERNAL ADJUSTER SYSTEM parallel to each other.In the stereoscopic rangefinder, the operator will see one target The internal adjuster system providesan with each eye, and the two images will fuse artificial target, inside the instrument,which stereoscopically. can be used to check the range scale. The optics Remember that the deflection in the right- are so arranged that the light from the artificial hand penta prism or end reflector is usually target, on entering the two main telescopes, less than 90°.This angle differs somewhat in appears to come from infinity, or fromsome different marks of rangefinders. The angle of selected standard range.The range scale is deviation of both internal adjuster penta prisms set for this known distance, and then thewedges is 90°.So there is one prescribed range at are adjusted to give coincidence (or stereo- which the scale must be set in order to check scopic contact) on the artificial target. its calibration with the internal adjuster system. A study of figure 5-21 will showyou how the The operator sets the range scale at thispre- system works. The system consists of two ob- scribed distance, and then sights through the jective lenses,located in an adjuster tube eyepiece (or eyepieces).In the stereoscopic mounted alongside the main optical tubeof the rangefinder the image of the artificial target rangefinder.The objectives are of the same must appear to be at the same distance as the focal length, and they are so spaced thateach is ranging mark on the reticles.If it doesn't, at the front focal point of the other.Cemented the operator must turn the correction knob to each okective is a reticleon which the arti- until it does. He repeats this operation five ficialtargetusually two vertical linesis times, then sets the median correction on the etched.Thus each target is in the focal plane range scale.(With a coincidence rangefinder, of the opposite objective. A transparentre- of course, the operator must adjust the scale flector plate is mounted outboard of eachob- so thatletwo half-images of the artificial jective. targets make coincidence at the halving line First, consider the left-hand reflector alone. when the range scale indicates the prescribed Light from a small lamp, mountedon the outside range.)

60 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

INTERNAL INTERNAL TARGET TARGET ILLUMINATION INTERNAL TARGET ILLUMINATING LAMP WINDOW INTERNAL LINES ENGRAVED INTERNAL INTERNAL ON LENS INTERNAL TARGET TARGET TARGET TARGET PENTAPRISM COL%IMATING CONDENSER PENTA-PRISM WEDGE LENS

ma ..\\%P.: ...... -...... 1.:."'' 7.Z...7z....a -...... -...... Z':-.. fan . ...?..,-..... \ INTERNAL INTERNAL INTERNAL INTERNAL TARGET TARGET TARGET TARGET OBJECTIVE CENTERING i1ROR MIRROR (HAL F TONE (HALF TONE LENS DISK MIRROR) IsIIRROR)

END REF LECTOR END REFLECTOR 148.21 Flicure U.Internal adjuster system. On the stIrboscui)ic rangefinder, the internal example, that a target at a range of 6,000 yards adjtmsment is asiltr to 'make if the ranging moves 18 yards toward you. How much does mark on the reticle is centered between the two that change the parallactic angle? In the Range- vertical lines of the artificial target. Hit is not finder Mk 42, the parallactic angle would in- centered, turn the internal target adt.ister knob Irease by only 0.00014 degrees.Yet, under (sornotimes called the collimator knob) to center Is.vorable conditions, tr:s rangefinder can de- it. The artificial targot should never appear to tect that small a change in the parallactic angle. touch the ranging mark; if it does it will inter- The elements of the rangefinder must be fere with your stereoscopic judgement. made and assembled with extremo precision. Any small errors that may A3 present after ADJUSTER SCALE READING SYSTEM assembly can be eliminated .y adjustment of the end windows.in addition, the instrument The correction wedge of the internal adjus er is provided with several ch:^10 and adjustments system is similar to a single measuring wedge, to facilitate accurate rangirg.The knobs by The adjuster scale reading system enables ye.1 which theseadjustments tre made vary in to determine the position of this wedge. On some ,rmaition on the different marks of rangefinder, instruments the position of this wedgeIsshown and sornetlmvp ^n affierent modifications of the on a scale attached to it; on others it is iei- same mark.Ittaaaver, the knobs are always cated on a dial similar to the outside ranrr labeled. scale. The system includes a source of illumt nation, and lenses for magnifying the scale. On STEREOSCOAIC RANGEFINDER all rangefinders later than the Mk 28, the scale OPERATION is graduated in units of error.

RANGEFINDER OPERATION In the next sections we will discuss the operation of the stereoscopic rangefinder. The It is obvious that rangefinders are precision operation of the coincidence type isquite instruments, since the parallactic angles they similar; we will tell you later how it differs. measure are extremely small.T";ppose, for These are the four basic adjustments of the

61 OPTICALMAN 1 & C

stereoscopic rangefinder, in the order in which in use.If parallax is present, a smallerror the operator makes them: in the interpupillary settingcan cause serious 1. Interpupillary adjustment. errors in ranging.The greater the parallax 2. Focus adjustment. of the instrument, the larger theerrors will 3. Height adjustment. be.Parallax is present, you remember, when 4. Internal adjustment. the image formed by the objective does not lie Interpupillary Adjustment exactly in the plane of the reticle. No matter how carefully you adjust the rangefinder during Figure 5-22 shows how the rhomboid prisms overhaul, a small amount of parallax will nearly enable you to adjust the spacing of theeyepieces. always be present. Parallax is sometimes Since the image is reflected twice in each prism, caused by temperature changes; more often, by it emerges unchanged.You can see that by variations in range. The objective is positioned pivoting the two rhomboid prismson the axis so that when a target is at median range its A-A you can adjust the distancesbetween the image will fall in the plane of the reticle. Thus eyepieces. Moving the prisms on this axisdoes if a target is_at extreme range, its image will not change the length of the path of light,nor fall short (on the objective side) of the reticle; change the orientation of the imagein any way. if the target is at close range its image will A small knob or lever, locatednear the eye- fall beyond (on the eyepiece side of) the reticle. pieces, controls the interpupillary adjustment. When a target is at short range, too small If you do not know yourown interpupillary dist- an interpupillary adjustment will result in short ance, it might be a good idea to measure itnow. range readings; too large an adjustment will Use an accurate interpupillometer andmeasure make the readings too long.For a target at to the nearest 1/4 millimeter. Then,whenever extreme range you have the opposite effect: you use or inspect a rangefinder, you can set a large interpupillary adjustment will make the the interpupilla:7 adjustment to theproper value for your eyes. range readings too short; a small one will make them too long.Figure 5-23 shows what The operator must make this adjustment happens when the image fills on the eyepiece very carefully, to within 1/4 millimeter of the side of the reticle. proper setting for his eyes.He should then tighten the locknut, if there isone, to keep the Focus Adjustment setting from changing while the rangefinderis The purpose of the focus adjustment, of course, is to bring the target image sharply into view.Make the adjustment by turning the knurled focusing rings below the eyeguards. The focusing scale is calibrated in diopters. You remember the proper procedure for focusing any telescope:turn the focusing collar to the minus end of the scale, look through the eyepiece, and then turn the collar back toward plus until the image is sharp. This method helps reduce eyestrain in using the rangefinder; the eyes accommodate more readily to a minus setting than to a plus setting. Focus the eyepieces one at a time.Keep both eyes open while you focus; whenyou are focusing one eyepiece, have someonecover the other end window, if practicable. Ofcourse if you know the proper setting for yourown eyes, and know that the focusing scale of therangefinder is correctly calibrated, youcan instantly set the eyepieces to the proper focus foryour eyes. 55.298 Although it seems obvious, operatorssome- Figure 5-22.Interpupillary distanceadjustment times forget that changing the focus will not

62 68 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

LEFT RIGHT END WINDOWS TELESCOP E TEI.ESCOPE

OBJECTIVE LENSES

BAND OF RAYS ENTERING EYE BANDS OF RAYS ENTERING WHEN I.D. IS SET TOO NARROW. BANDS OF RAYS ENTERING EYE EYES WHEN I.D. IS SET TOO WHEN I.D. IS SET TOO NARROW. WIDE. CENTER OF BLURRED TARGET CENTERS OF BLURRED CENTER OF BLURRED TARGET IMAGE. TARGET IMAGES. IMAGE.

RETICLES

PLANE OF TARGET IMAGE

ERECTING LENSES

EYEPIECE LENSES OBSERVER SEES A BLURRED HERE THE I.D. IS CORRECTLY IMAGE OF TARGET BUT USES ALL ADJUSTED. EXIT PUPILS OF EXIT PUPIL. OBSERVER'S PUPILS

OBSERVER USES ONLY THE OUT. EYEPIECE LENSES SIDE HALF OF EACH EXIT PUPIL, HERE THE I.D. IS SET TOO THE TARGET IMAGE IS BLURRED, NARROW. AND THE RANGE READING IS TOO LONG.

/ I \,OBSERVER USES ONLY THE IN- HERE THE I.D. IS SET TOO EYEPIECE LENSES .. SIDE HALF OF EACH EXIT WIDE. PUPIL, THE TARGET IMAGE IS BLURRED, AND THE RANGE EXIT PUPILS READING IS TOO SHORT.

148.22 Figure 5-23.Errors caused by parallax and incorrect interpupillary adjustment remedy haze, or darkness, or fogged end by rotating the height adjuster knob. You will windows.The operator should determine the not have to make this adjustment very often, diopter setting for his own eyes, on each instru- but you should check it each time you use the ment he uses, under the best possible conditions. rangefinder, or whenever you have trouble in He should use that predetermined setting when fusing the two images. conditions are unfavorable for accurate focusing. There are two ways to make the adjustment. In one of these, you aim the rangefinder at the Height Adjustment horizon.. Keep your eyes on the horizon, and notice the reticle marks without looking at them The height adjustment secures thi horizontal closely.Turn the ranging knob until you break alignment of the images in the two rangefinder your stereoscopic fusion of the reticle images, telescopes. You can change the height adjustment. and see two separate images of the recticle OPTICALMAN 1 & C

pattern.(You will need a little practice before you can do this easily.) Turn the height adjuster knob slowly until the two center marksof the reticle patterns are at exactly thesame height above the horizon. If you are working in the shop,you can use the other method. Cover one of the endwindows of the rangefinder and look throughthe other eyepiece.Train and elevate your rangefinder on some fixed target, and adjust it so that the bottoin point of the center reticle markbarely touches the top of the target.Now cover the opposite end windoW.Train the rangefinder, A B without elevating or depressing it, tobring the other reticle mark over thesame target. Turn 148.23 the height adjuster knob until the bottom ofthe Figure 5-24.Reticle and adjuster target. mark barely touches the top of the target.This is the more accurate of the two methods,but the correction scale reading each time. Deter- of course it requires that the rangefindermount mine the median reading. be absolutely stable. 5. Set the correction scale to the median reading. To that reading, add (or subtract)your Internal Adjustment calibration offset. Now, unless temperature or other conditions change, the rangefinder is The internal adjuster system providesan properly adjusted. artificial target inside the instrument, by which you can check the accuracy of the range scale seWngs. In using the internal adjustersystem, Other Adjustments the operator will see a target consistingof two vertical lines, with the center mark of thereticle On some instruments you will have to make between them.He then turns the correction a few additional adjustments; you will not find knob until the target lines and the reticle mark all of them on all marks and mods ofrange- appear to be at exactly the same distance, and finders. sets the Indicated correctionon the correction 1. Headrest adjustment.Adjust it so that scale. your forehead rests comfortably against it when Figure 5-24, part A, shows the type of internal your eyes are at the normal eye-distance. (At adjuster target in the RangefinderMark 42 normal eye-distance, the rubber eyeguards will Mods 4 and 5. Figure 5-24, part B,represents rest lightly around your eyes, and exclude all the target in Rangefinder Mk 42 Mods6, 8, 9, external light.) 10, 11, 12, and 13. In the figure the dottedlines 2. Color filters. These have thesame func- represent the target. (The reticle marksoutside tion as in the coincidence rangefinder.Use the target are not visible whenyou use the in- them when you need to cut glare or haze,or ternal adjuster.) These are the stepsin making when you want to increase the contrast of the the internal adjustment of the Mk 42rangefinder: target against its background. 1. Set the range scale to 6,000 yards. (The 3. Searchlight filters.These filters, pro- range of the internal target is usually marked vided on most stereoscopic rangefinders,are on a small plate near the range knob, and in- extremely dark. Use them when rangingon a dicated on the range scale bya small star.) searchlight aimed at your ship. Set the correction scale at its mid-position 4. Change of magnification.Some range- marked "60". finders are provided with two degrees of magni- 2. Turn the adjuster penta prismsto the fication.Always use the higher magnification "in" position. unless you need a wider field of view. 3. Illuminate the internal adjustertarget. 5. Reticle rheostat. This controls the illum- 4. By turning the correction knob,range ination of the two reticles.When ranging at stereoscopically on the internal adjustertarget. night, adjustthe reticle illumination to the Repeat this operation five times, andrecord minimum usable brightness.

64 70 Chapter 5RANGEFINDER THEORY AND CONSTRUCTION

Now look back at figure 5-18. See if you can identify all the parts, and describe their function. But do not try to memorize the details of the optical system; the details will vary considerably between the various Marks and Mods. Concen- CORRECT HALVING trate on general principles. Here is a summary of the steps in preparing a steroscopic rangefinder for use:

1. Set the interpupillary adjustment. DUPLICATION DEFICIENCY 2. Set the focus. 3. Adjust the headrest. 4. Check the height adjustment; readjust it if necessary. 5. Make at least five internal adjustments, and use the median correction. 8. Use a filter if visibility is poor. 7. When ranging at night, adjust the reticle illumination. 148.24 Figure 5-25.Effects of duplication and COINCIDENCE RANGEFINDER OPERATION deficiency.

In most respects the operation of the coin- MECHANICAL CONSTRUCTION OF cidence rangefinder is similar to that of the RANGEFINDER stereoscopic type.Make these adjustments: The structural frame of a modern naval 1. Set the focus. rangefinder consists of three long tubes: 2. Check the halving adjustment; readjust if THE OUTER TUBE is made of seamless necessary. drawn steel, heavily wrapped with insulating 3. Make five internal adjustments; use the material to help minimize the effect of temper- median correction. ature variations on the working parts of the 4. Use a filter if visibility is poor. instrument.The outer tube is gastight; it is 5. If ranging on a point of light at night, turn filled with helium or nitrogen under slight pres- the astigmatizers to the "in" position. sure. The gas serves two purposes: it retards aging of the optical glass and cement bykeeping All these adjustments are the same as those oxygen away from them; and since it is dried of the stereoscopic rangefinder, except the halv- before the instrument is charged, it prevents ing adjustment and the use of astigmatizers. condensation of moisture on the inner surfaces. The HALVING ADJUSTMENT secures proper Near each end of the outer tube is a ring, by alignment of the two half-images, so that the which the rangefinder is attached to its mount operator sees a single unbroken image, without in a director or turret. Figure 5-26 shows the duplication or deficiency (see fig. 5-25). mechanical construction of a typical stereo- In making the halving adjustment, select a scopic rangefinder. target with a small and clearly defined top, of a THE INNER TUBE, mounted within the outer shape that will not "telescope" easily. (A pyr- tube, is the main structural frame of the instru- amid or diagonal is most useful; avoid a mast ment; like the outer tube, it is made of seamless or other vertical structure.) Use the elevation drawn steel.Between these tubes is a gas- control to move the halving line slowly up and filled space, which helps to insulate the optical down over the top of the target. Look closely elements against temperature changes.The for any duplication or deficiency. inner tube carries most of the optical and Be sure that, unless you are ranging on a mechanical working parts; the only important point of light at night, the ASTIGMATIZERS are exception is the eyepiece group, which is mounted "out."If they are "in," they will give you a on the outer tube. The inner tube is mounted blurred and streaky image, and make ranging in the outer tube on two bearings; the right- impossible. handbearingpermitsa small amount of

85 OP'11CALI/LAN 1 & C ...riatrna.olMAirvrAVIIC, 11 . &Mir:

Chapter 5RANGEFINDER THEORY AND CONSTRUCTION movement along the axis of the rangefinder. inner tube so that it will not be distorted by Thus if the outer tube expands or contracts temperature changes. because of temperature changes or external Temperature changes, of course, result in stresses, it will not distorthe inner tube. expansion or contraction of metal and glass. In an instrument as long as a rangefinder, this THE OPTICAL TUBE or OPTICAL BAR is a could easily result in serious misalignment of short, rigid tube machined from specially treated the optical parts. As you can see, naval range- steel with a low coefficient of expansion. It is finders are specially constructed to minimize perfectly balanced, and bearing-mounted in the this effect.

11,

67 CHAPTER 6

RANGEFINDER CALIBRATION AND MAINTENANCE

The primary job of the rangefinderoperator ranging knob. The buzzer is usedto signal when is to measure ranges accurately, consistently, a range setting is made. The buzzer is sounded and with reasonable speed. To do this jobsuc- only while the target and reticle are actually cessfully he must have a thorough knowledge of in stereoscopic contact. rangefinder adjustments, and continued practice Practice ranging on moving targets should in making them. The Opticalman's primary' job be done when ranges are being simultaneously is repairing the rangefindernot operating it. measured by some other means, if possible. But the OM can do his job more efficiently by Such practice will help develop skillas a becoming thoroughly familiar with the operating smooth, fast rangefinder operator, and this skill technique, and by developing maximum skillas a 15 invaluable when calibrating the instrument. If rangefinder operator. Here are some tipson a rangefinder is not available for frequentprac- rangefinder operation: tice, use a stereo trainer. Careful tests show Do not spend too muchtime on one range set- that, in the early stages of training, a mancan ting. If you make a setting carefully and confi- learn as well on the stereo trainer as on the dently, it will probably be accurate; ifyou make rangefinder. a setting hesitantly and then back off a little and Avoid these common errors that cause try again, it may not be as accurate. . inaccurate ranging: There are two ways to make the range setting: 1. Interpupillary distance inaccurately set. by making the original setting too long, and then 2. Focus improperly set.(If one of the turning back to the target; or by making the images is slightly blurred,it will, decrease original setting too short, and then working for- stereo perception.) ward to the target. Decide which of these methods 3.Height adjustment improperly set. (This is easier for you. On stationary or slow-moving also decreases stereo perception.) targets always make the setting in the same di- 4.Internal adjustment made carelessly, or rection, whether measuring ranges or calibrat- made with the range scale incorrectly set. ing the rangefinder. For a fast-moving target, 5.Pressing face too hard against the rubber tracking can be done more smoothly by making eyeguards. the settings in the direction of target motion. 6. Eyepieces or end windows being dirty. When the range rate is low (that is, therange 7. Covering the target withthe ranging mark is changing slowly), you may not notice when the of the reticle. (This interferes with stereoscopic target drifts out of stereoscopic contact withthe judgment. The ranging mark shouldappear just reticle. Under such conditions it is advisable to above the target, not superimposedon it.) break contact, deliberately and frequently.But keep the break small; simply turn the ranging RANGEFINDER ACCURACY knob a short distance, then remake the contact. The operator of a stereoscopic rangefinder For a skilled operator it isunnecessary to makes his range setting bybringing the target and bracket both sides of the target, except under the ranging mark of the reticle to thesame ap- very difficult conditions. (When the range rate is parent distance. When do the two distances ap- high, the target motion itself will break the pear to be the same? When the two parallactic stereoscopic contact.Simply bring the reticle angles appear to be the same. The accuracyofa back on again.) stereoscopic rangefinder islimited by the On most rangefinders there is a range-signal stereo-acuity of its operator. Two angles will ap- button (buzzer) mounted at the center of the pear to be the same, even to a trained operator, 68 73 Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

CORRECT ANGLE MINUS 12 SECONDS

CORRECT ANGLE

CORRECT ANGLE PLUS 12 SECONDS

B ft . I MINIMUM MEASURED RANGE I

TRUE RANGE

MAXIMUM MEASURED RANGE Figure 6-1.Possible errors in measuring the parallactic angle. 148.25 if there is no more than 12 seconds difference piece of the rangefinder). The greatest theoreti- between them.So when even the most skilled cal distance by which a range reading may be operator makes stereoscopic contact with a tar- wrong (for a given rangefinder, at a given range) get, his measurement of its parallactic angle is a useful unit of measurement. We call it the may be off by as much as 12 seconds in either UNIT OF ERROR (U.O.E.). In figure 6-1, the direction. distances AT and BT are each equal to one unit Look at figure 6-1. Let us assume that a of error. (As you can see, BT is slightly longer skilled operator is using a stereoscopic range- than AT. But the difference is so small, com- finder (LR represents its base line) to range pared to the error itself, that we can disregard it.) on the target at T. The angle LTR is the true The unit of error also provides a unit for parallactic angle of that target. When the oper- measuring range errors when we spot bursts or ator turns the ranging knob until the target splashes. (We cannot measure these errors di- makes stereoscopic contact with the reticle, he rectly in yards, since the apparent distance is ready to read the range on the scale. But the between the various rows on the reticle varies parallactic angle he has measured may be in with the range.) The U.O. E. also can be used to error by as much as 12 seconds in either direc- measure the relative skill of individual operation. And this error will be undetectable; no tors, since the size, in yards, of an operator's matter how skilled the operator may be. habitual error also varies with range. Conse- If he makes the maximum undetectable error quently, the correction scale is calibrated in on the short side, he will actually measure angle units of error. (For a given rangefinder, working LAR (the true parallactic angle of the target, at a given range, we can easily convert units of plus 12 seconds). The range scale will then show error into yards.) the target to beat A, rather than its true position If the range error causedbyoneunit of error T. If the operator makes the maximum undetect- is a variable number of yards, what determines able error on the long side, the range scale will it? Four things: show the target to beat B, rather than at its true First, of course, the stereo-acuity of the position. So a stereoscopic rangefinder does net rangefinder operator. In order to derive a con- give the exact position of the target. If the range venient formula, we assume a constant value- scale shows the target to be at T, it is actually 12 secondsfor the stereo-acuity of all trained somewhere between A and B. operators. When the range scale shows the range to be Second, the magnification of the rangefinder. LT, we know that reading may be wrong, in Remember that errors are caused by undetec- either direction, by a certain distance. The range table differences in angles AT THE OBSERVER'S error may be any distance that does not change EYE. The apparent parallactic angles are in- the parallactic angle (as seen through the eye- creased by the magnification of the instrument. OPTICALMAN 1 & C

Third, the range. Figure 6-2 shows two Where: identical rangefinders, ranging on targets at e is the range error, in yards, due to one two different ranges.In each case the angular unit of error unit of error (U.O.E.) is the same, butthe range B isthe base length of the rangefinder error caused by it is much greater atthe longer M is the magnification of the rangefinder R is the range TARGET AT 58.2 is a constant, valid only when the /LONG RANGE operator's stereo-acuity is 12 seconds, and when both B and R are expressed in YARDS. RANGE ERROR CORR ESPONDING When using this formula, ALWAYS express TO 1 U.O.E. the base length in YARDS. The base length of IS LARGE some rangefinders is normally stated in feet or meters which must be converted into YARDS RANGE ERROR before the formula can be used. CORRESPONDING Apply the formula in a sample problem. The TO 1 U.O.E. TARGET AT Mk 14 rangefinder has a base length of 1.094 IS SMALL _0. yards, and a magnification of 11 X. What is the or SHORT RANGE value, in yards, of its unit of error at 1,000 yards? Substitutein the formula: 1 U.O.E. 1 U.O.E. e =1.09458.2 (MOO \ 2 X 11 1,000/ 58.2 1.094X 11x 1 = 4.83 yards 148.26 So, for this rangefinder, the range error Figure 6-2.How a range error equal toone due to one unit of error is 4.83 yards at 1,000 U.O.E. changes with range. yards.What is it at 2,000 yards? You have already found the value of 58.2; for any given range.The range error increases with the BM SQUARE of the range in thousands of yards. rangefinder tha quantity remains constant (un- (For example, assume that for a givenrange- less you changethe magnification). Then finder the unit of error is equal to a range error (2 0002 of 1 yard at a range of 1,000 yards. Then at e = 4.83 x -4.2-A-Aw) 2,000 yards the error will be 4 yards; at 3,000 1,uuu yards it will be 9 yards; etc.). Fourth, the base length of the rangefinder. 4.83 x 4 In figure 8-3 are two rangefinders of different = 19.32 yards base length, ranging on targets at the same range.Although the angular unit of error of For each rangefinder, the units of error must the two instruments is the same, itcauses a be converted into yards. There are three ways to greater range error in the short-base range- do this: finder. When spotting the fall of shot in range, the 1. By using the tables provided for many operator reports the range error in units of rangefinders (in the OP's that describe them) error. But before he can use that measurement that show the value of the unit of error at vari- to correct the elevation of the guns, it must be ous ranges. converted ipto yards. Use the formula: 2. By calculating the value of the unit of error for any particular range by using the formula.First find the value of the constant 58.2 e= ( R )2 58.2. Then express the range in THOUSANDS BM BM

70 Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

WON NI WWI

WASU015 SANE MON WE ANGLE OF III "OSMIUM COWMEN' THE ANGLE OF COWMEN('

MIT IASI meet* WIS IANCIEFINOil

148.27 Figure 8-3.11bw range error cfne tO one17.1118.ViOrlan Web base length of the rangefinder. OF YARDS,/411,X0it, and multiply by the In chapter II, We developed the basic range- predetermined value of 38.2. /War *Minim A B (1) 3. By solving the forniula for a numbisr of ranges, and then drawing a curve, plotting the itiglie.that with very small angles, such value of the unit of error against therange. as the parallactic angle of a rangefinder target, Thereafter you can make the conversion by that equation is true when we express e in radii.- spotting the range on the curve, and then reasi ens, and express B and R in yards. tog the corresponding value for the unit of Now consider the actual target at T'.(R, error. you remember, is the measured range, and e la the mug, error, in yards.) To understand how to derive the unit-of- Ear the target at T', the rangefinder formula error formula, look at figure 8-4. In this if: diagram, B is the base of a rangefinder that is' ranging on a target that appears to be at T. Reis the apparent range of that target, and is its apparent parallactic angle. Now suppose (9i atiresSed in radians.) Now, if we sub- that in measuring the range the operator has tritot eqvitlpn (2) from equation (1) we get: made the maximum theoretical error on the near side.Then the target actually lies at T. Its actual range is R + e, rather than R as B shown on the range dial. And its actual paral- 1-4"T RB+e lactic angle is 4 (the Greek letter Phi). (3) .71 OPTICALMAN 1 & C

e0. 0000582 X R2 B The expression on the right is a fraction; you can multiply both numerator and denominator of any fraction by the same number without changing its value.So multiply both parts of the fraction by a million. Then: e 58.2 X R2 B X 1, 000, 000 58.2 R2 e= BX1, 000, 000

58.2- R 2 X e - B 1, 000 And there you have the unit -of -error formula for a rangefinder with a magnification of one. A magnification of 2 X will double the apparent parallactic angle, and therefore cut the error in half; a magnification of 3 X will triple the apparent parallactic angle, and therefore cut the 148.28 error to one third; etc.For large angles that Figure 6- 4. Diagram to develop the approximation would be,way off; for very small unit-of-error formula. angles, such as the parallactic angle of a rangefinder target,it is almost exactly true.So, Simplifying the expression on the right: since the error is inversely proportional to Be the magnification, we can put M directly in the "6 74 R(R+ e) (4) denominator of the formula. Then: 58.2 R12 And, since e is always small compared with R, e BM A, 000 we can say with sufficient accuracy that: There is the formula for unit of error, ar- 0 -sb=Be9 rived at by a series of approximations. But the EC error caused by those approximations is so Remember that in figure 6-4, we assumed small, compared to the range error, that we that the operator had made the maximum the- can ignore it.And that formula works for all oretical error (12 seconds) in measuring the Navy rangefinders, both stereoscopic and coin- parallactic angle 0. Then cp is 12 seconds cidence. less thane , and: Now we can make a couple of conclusions about the theoretical accuracy of rangefinders: - st = 12" 1. The precision increases proportionately as you increase the base length and the mag- We cannot substitute 12 seconds in equation nification. (3) because, you remember, 9 andare both 2. The precision decreases proportionately expressed in radians.But we can make the as the square of the range.This means that substitution if we first convert 12 seconds to you can expect four times the error if you radians.(Divide it by 206,265the number of double the range. seconds in one radian.) Then, making the sub- But do not forget that these conclusions stitution, we have: are only theoretical.They represent the best 12 eB performance we can expect from any range- 206,265 =a2 finder.Its precision in actual practice will be Now, if you perform the division on the left influenced by many things, including visibility, side of the equation and then solve for e, you vibration, target contrast, heat waves, and, of have: course, the skill of the operator.Only under

72 77 Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

the most favorable conditions can the precision these effects are mostly small, and they are of a rangefinder approach its theoretical value. too elusive to be considered in practice.If a rangefinder has two magnifications, you can use RANGEFINDER CALIBRATION the same calibration offset for both. But always use the highest magnification when you are Complete and accurate calibration data for calibrating the instrument. each rangefinder in service is essential.Cor.4 When you calibrate a rangefinder, keep these rect gun elevation depends primarily on correct points in mind: measurement of the target range, If the range- 1. Rangefindererrorsincreaseas the finder readings are inaccurate, the initial salvos square of the range. For that reason, calibra- will be off in both range and deflection (since tion errors that appear insignificant at short drift varies with range).Subsequent analyses range will become seriousat long range. of firings may lead to erroneous or conflicting 2. When you calibrate a rangefinder against conclusions.Before we can rely on a range- a known range, the probable error of the known finder for accurate measurements, we must range must be considerably less than the prob- calibrate it by comparing its readings with other able error of the rangefinder.If the known measurements of known accuracy. (The internal range has been measured from some point other adjustment cannot serve the purpose of a com- than the rangefinder you are calibrating, do not plete calibration, since it checks the range scale forget to apply a suitable correction. at only one specified range.) 3. Besides the theoretical error, practical Although rangefinders are calibrated at as- considerations limit the accuracy of the range- sembly, and after each overhaul, their calibra- finder: heat waves, range rate, vibration, varia- tion should be checked at every opportunity. tions in target contrast, etc. Errors can develop from two sources: (1) a 4. Rangefinders are more accurate at high slight shift of the end windows (this is rather magnification.An instrument with a choice of rare), or of the optical parts of the internal magnification should be calibrated at its highest adjuster system or the main optical system. power. (2) characteristic personal errors of individual 5. After a sudden change in temperature, operators. wait several hours before you begin calibra- To correct for the constant errors (range tion.When you are going to calibrate a turret error and U.O. E.) we find in a rangefinder, we rangefinder, turn on the turret blowers several determine an appropriate offset of the correc- hours ahead of time. tion scale (called "calibration offset" or "index 6. Variations in the density of the gas in- correction"), and apply it to the correction side the instrument (called STRATIFICATION) scale after the internal adjustment. We can will cause some inaccuracy when ranging on make a preliminary calibration of the range- overhead targets.(This effect is very small finder by adjusting its end windows. fine cali- when helium is used as the charging gas.) bration for each individual operator must be '1.Because of the limitations of lens de- made by applying his calibration offset to the sign, rangefinders are more accurate at the correction scale. But when you find that all the center of the field than at its edges. operators of a particular rangefinder require fairly large calibration offsets in the same di- CALIBRATION ON MOVING TARGETS rection,it is a good idea to readjust the end windows. Calibration on moving targets is the method Whenever you make repairs that involve most often used to calibrate a rangefinder any major optical part between the end windows against radar.It is suitable for air, surface, and the reticles of a stereo rangefinder, or or shore targets. between the end windows and coincidence prism Although rangefinder errors vary as the of a coincidence rangefinder, the instrument square of the range, radar error is constant at should be completely recalibrated. all ranges. At long ranges a properly calibrated If the rangefinder is properly adjusted, a radar is. far more accurate than the range- single calibration offset (for one particular finder, and we can therefore use it as a standard operator) will be good at all ranges.Under for calibration.But do not forget that range- certain atmospheric conditions you may get finder errors become very small at short range. long or short readings at different ranges; but At short range a normal internal adjustment

73 7 OPTICALWAN 1 itiC provides a more accurate calibration than a setting.In the rangefinder calibration log find check against radar. the calibration offset that seems most suitable On some ships, differential synchros are under the existing conditions.If it is plus, add wired to the radar and rsuigefinder, and indicate it to (or if it is minus, subtract it from) the directly the difference in the readings of the median internal adjustment. Set the correction two instruments.If this system its not available, on the correction scale of the rangefinder, and you will have to record a series of radar and enter it on the recording sheet in the apace rangefinder ranges simultaneously. Figure 6-5 marked "LA. Used." shows a form that might be used for this pur- 4. Track a single moving target simul- pose. taneously with rangefinder and radar. The The procedure for calibrating a rangefbxler radar operator tracks continuously; the range- against radar on a moving target is as follows: finder operator indicates by buzzer when he is 1. Unless the two instruments are in the "on target."Record both the rangefinder and same station, or connected by a differential the radar ranges whenever the buzzer sounds. synchro, connect them by telephone. Use a separate recording sheet for each instru- 2.Carefully make all the preliminary ad- ment; label each sheet with the correct instru- justments of both rangefinder and radar. ment name. 3. Record your internal adjustment settings 5. Record at least 9 readingsand prefer- on the recording sheet, and find the median ably as many as 15on each run.

RANGEFINDER StOltDISO alitET NangefinderE3NAdar0 Location,.Ranie 1 OperatorRea- .m.,Ratorder pimaL R,Date4213L_-___

Plumber 1 Run Number 2 eRun number Run Number 4 Tap t Air Tapt Tppgat Air 11.,ret Air O. RANGES ORO. RANCESIERROENO. RANGES ERRONC. RANGES ERRO UOE U fo I') 6 ) , Settinra 1 11, 410 rin - i1 12. 000 4 I- 1 11, 800 - 161 8. 500 - 4 01 211. 250 A-2 12, 100 0 2 11. 550 - 6 2 8, 550 - 3 2 61.5 119, 850 -43 12. 100 - 1a 11, 250 - 5 1 8, 525 - 61.5 4In,970 - 74 12, 000 - 34 10, 850 -64 8, 600 4 601411114t 510, 900 -6 /5 11, 900 - 3 5 10, 625 5 8 700 4 - 5 60.5 611, onn - ,76 11, 900 - 1 10, 350 2 6.8, 500 - 6 61.5 711. 100 3.J 11, .95o - 1.7 10, 100 -67 8, 425 4 7 8 in, Ann 58 11. 700 0 9. 800 - 4 8 8, 400 - 211 ,8 8 9 10,400 -4g 11,500 - 19 9,750 0 9 8,400 - 2 Mediar 6i 1010, 150 - 6JO11, 250 2 -49 9, 625 - 4lo 8, 125 - Calib - Al 9, 600 11. 9, 900 4al11, 250 1 - 511 8, 300 , Offse 3 ? .12. 9,Ann 0 12 11, 110 2 -2 9, 450 .- 62 8, 300 - 58.5 13 9, 700 1-111 11, 100 - 1 9, 250 -15011 8, 325 - 2 14 9. 150 - 614 10, 900 0 114 9, 125 - 1114 8, 350 0 11 9. 325 - 4 5_ 10,600 - 2 5 8, 925 - 16 15_ 8, 375 .' 1 Magliftm WyPill. -4 Median Error -1 Median Error -6 Median Error -3 Calibration Calibration Calibration -3 Calibration -3 Offset Used "3 Offset Used -3 Offset Used Offset Used Corrected Corrected Corrected Corrected Calib. Offset Calib. Offset -4 Calib. Offset-9 Calib. Offset -6

148.29 Figure 8-50Rangefinder recording sheet.

74 RADICLE FIND= urrate.r1vr4 Lltilt1 LAVAL Otniimiaw Inv Wawa Mavv www anon of the stereoscopic rangefinder.The It is obvious that rangefinders are precision operation of the coincidence type isquite instruments, since the parallactic angles they similar; we will tell you later how it differs. measure are extremely small...i.:ppose, for These are the four basic adjustments of the

81 ,47

Chapter 6RANGEFIND3R CALIBRATION AND MAINTENANCE

6. Find the error of each rangefinder read- The procedure for calibrating on any fixed ing by comparing it with the corresponding target is as follows: radar reading.Convert this difference into 1. Make all preliminary adjustments care- units of error, using any of the three methods fully.Make at least five internal adjustments, previously described (the formula, a curve. or and record the median correction. the tables in the OP).Record each error cna 2. Set the range scale at the known range the rangefinder recording sheet; put short er- of the fixed target. rors in the minus column and long errors in S. Range on the target with the correction the plus column. knob, and record the settings. 7.Find the median of these errors, and 4.If the range scale is properly calibrated, enter it on the recording sheet in the space .here will be no differonce between the median marked "median error."If it is long, mark of the settings on the fixedtarget andthe median it plus; if it is short, mark it minus. This of the settings on the internal target of the figure is the calibration offset.(De sure you rangefinder. use the MEDIAN, not the mean or average, If stationed at a naval shipyard, you should since occasional wild ranges do not affect the be able to pick out a few easily recognizable median. To find it: check off the highest error, objects !or use as ranging standards. Use the then the lowest, then the next highest, etc., until ground plan of the yard to determine the dis- only one number is left; that is the median.) tance of those objects from the optical shop. 8. Add a plus (or subtract if minus) median If stationed on a repair ship, you will find error to the calibration offset used; the result fixed markers suitable for ranging. If not, is the corrected calibration offset. Enter it in ask your department head about setting up some the proper space on the record sheet. markers. 9. Enter the result of each run separately If necessary you can use the sun, the moon, on the rangefinder calibration log.(Fig. 6-6 or a star as a fixed target, by setting the range shows a sample log form.) Be sure you enter scale at infinity.You can use the moon either the CORRECTED CALIBRATION OFFSETnot day or night; you can use the sun if the range- the MEDIAN ERROR nor the CALIBRATION finder has searchlight tatern.If you use a OFFSET USED. star, you will have to make a very accurate 10. Determine the calibration offset to be height adjustment.This method is useful only used by each operator pending further tests. when observing conditions are good, and the Consult the rangefinder calibration log for a operators are thoroughly experienced. Experi- particular operator, list his corrected calibra- ments show that when inexperienced operators tion offset for each individual run taken on at range on an infinity target, they get about three least three previous calibration days, and find times the spread of readings that they get on the median. Use results from more than three targets at a finite distance. days if necessary, to include at least nine individualruns; or if you suspect that the RECORDKEEPING results from runs on a particular day may be unreliable. Calibration results are likely to vary from day to day. To get a reliable calibration offset, CALIBRATION ON FIXED TARGETS the operator should calibrate his rangefinder at every opportunity, and determine the median offset from several days' readings. Using the The simplest way to calibrate a rangefinder median of several days' results will tend to is by calibrating on fixed targets. Range on a nullify the effect of errors made on any one fixed target at a known distance. By comparing day. the scale reading with the known distance, you To get the full benefit of rangefinder cali- can determine the rangefinder error at that bration, the operator must keep accurate rec- range. ords, and apply the results systematically. You can sometimes use radar to range on These records are valuable not only for cali- a radar beacon.Alongside each radar beacon bration, but for determining the relative skill is a visible marker that makes a convenient of operators as well. By comparing the unit of target for the rangefinder.This method is error spread on the individual recording sheets most useful at long ranges. of various operators, you can get an idea of

75 SO CORWIN NATO LOUT DAN. CAUUN MOM WAN UAW ON VINSILIIT ON MAL ClIONISTANaS OMIT RANK

(

148.30 Figure 6-6.Rangefinder calibration log sheet. their relative proficiency: the smaller the spread will take careful handling of the rangefinder to or scatter, the better the operator. preserve your delicate adjustments.No one should be permitted to touch a rangefinder RANGEFINDER MAINTENANCE except the qualified operators and the qualified opticalmen. Because of its size, a rangefinder looks like So that the operator will handle his instru- a rugged piece of gear.' But you know it is a ment gently, be sure that all the knobs and levers delicate instrument that must be handled with can be turned smoothly, without jerking or forc- care. When you overhaul it, you will align the ing.The internal parts of the instrument nor- elements within extremely small tolerances.It mally require no lubrication, except during a 76 fri r

Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

complete overhaul.To keep oil and oil vapor DRYING AND CHARGING THE from reaching the lenses, apply lubricantvery RANGEFINDER sparingly to the parts that extend into the rangefinder. Check the rangefinder mounts regularly Rangefinders are charged with dry gas, and frequently, and lubricate them whenever under about two pounds pressure. The primary necessary. . purposeof charging is to keep moisture from condensing on the optical surfaces; the secon- As much as possible, protect the rangefinder dary purpose is to protect the optical elements from bad weather.Put canvas boots or metal from the aging effect of oxygen. In charging the covers over the end boxes of turret rangefinders rangefinder you pass compressed gas from a and over the whole body of exposed instruments, cylinder, through a pressure-reducing valve and to protect them from rain and spray. If a a dryer, into the instrument.Before the final rangefinder is unavoidably or accidentally ex- charging, dry the instrument thoroughly, either posed to rain or spray, clean it thoroughly and by flushing it with dry gas o r by repeatedly draw- promptly.Take off the covers in good weather ing a vacuum of about 22 inches. to keep moisture from condensing inside them. The Navy uses two different gases for range- But protect the optical elements from direct finder charging: nitrogen and helium. Nitrogen sunlight; it ages the glass and cement, and has one marked disadvantage: it tends to stratify introduces temporary inaccuracy because of into layers of different indices of refraction. unequal heating. When you elevate the instrument to range on aircraft, light rays will be refracted in passing Clean a rangefinder the same way you would from one layer of nitrogen to another, thus caus- clean a big telescope.Wipe the body with a ing a small error in range setting.For this clean, dry cloth.Gently remove any grit or reason, antiaircraft rangefinders are always salt from the outside optical surfaces with a charged with helium, whichhas much less ten- clean camel hair brush.Finally, polish the dency to stratify. surfaces with lens tissue.If there is grease But because its molecules are considerably on the surfaces, add a drop or two of alcohol smaller than those of nitrogen, helium has a to the tissue. greater tendency to leak.The gas purity of helium-filled instruments should be checked Thoroughly experienced rangefinderperson- every two weeks. You canuse a special helium- nel will be able to find the cause of any minor purity gage for this purpose.If the gage is not difficulty, and correct it.But the less exper- available, you can check the helium purity by ienced operators will probably call on you for making two internal adjustmentsone when the help. Here is a list of minor rangefinder rangefinder is level and one when it is elevated troubles; you should be able to recognize them 90°. There will always be a difference between and correct them without hesitation: the two settings.But if you make the check every two weeks, and find that the difference 1.Bulbs loose, burned out, or in wrong suddenly increases, you can assume that the receptacles. helium is no longer pure. 2. Rheostat turned too low. Some instruments are designed for helium, 3. Range scale set at wrong range during others for nitrogen. Always charge an instru- internal adjustment. ment with the gas it is designed for.Helium 4. Adjuster knob turned .only partly into and nitrogen have different indices of refrac- position. tion.You .know that refraction in an optical 5. Reticle lights on when making internal element depends on the ratio of its index of re- adjustment. fraction to that of the surrounding atmosphere. 6.Change-of-magnificationknob between If you put one gas in an instrument designed !or two positions. another, you will change the optical charac- 7. Color filters part way in. teristics of the whole system. On instruments 8. Neutral of polaroid filter unintentionally designed for HELIUM, the charging nipples are turned in. always painted ORANGE or YELLOW. 9. Height adjustment incorrect. Opticalinstruments should be recharged 10. Astigmatizers unintentionally turned in. every 12 months with dry gas. It is much harder 11. Searchlight filter in. to dry out a damp instrument than it is to keep 'R'

77 OPTICALMAN 1 & C

moisture from condensing in the first place. Follow these rules: 1. Recharge optical instruments before the conclusion of each overhaul of a ship alongside a repair ship or tender, or at a shipyard. 2. Recharge each instrument at intervals of 12 months whether or not it appears to need recharging. 3. When an instrument shows any sign of condensation on an internal surface, RECHARGE IT AT ONCE. Use an Optical Instrument Dryer of the portable type. (This dryeris improperly named; actually, it is a gar dryer, not an instrument dryer.) The dryer contains a quantity of silica gel, which absorbs moisture from the 148.31 gas passing through it. A part of the silica gel Figure 6-7.Setting the regulator valve. has been impregnated with cobalt chloride, which serves as a moisture indicator. When the indicator begins to turn pink, take the gel out of the dryer, and bake the moisture out of it in an oven. Then return it to the dryer for further use. Here are three important precautions to remember about drying and charging: 1. Do not use any cylinder gas to charge an optical instrument if the pressure in the cylinder has fallen below 400 pounds per square inch. 2. Instrument drying is most effective at high temperatures. Never try to dry an instrument when the temperature is below freezing. 3. To ensure complete drying, .repeat the exhausting and charging cycle several times. Here are the steps to follow in drying and charging the Rangefinder MK 42: 1. Attach the regulator valve to the helium 148.32 'cylinder, using a left-hang thread adapter. Figure 6-8. Connocting the hose to the inlet. 2.Connect the short hose to the outlet side of the dryer.Use the long hose to connect the inlet side of the dryer to the regulator valve on the cylinder. 3. Open the cylinder valve.Set the regulator valve between 7 and 10 pounds pressure. (See fig. 6-7.)Run a small quantity of gas through hoses to be sure they are dry. Then close the cylinder valve. 4. Remove the inlet-valve plug from the rangefinder, and connect the short hose to the inlet.(See fig. 6-8.) 5. Open the cylinder valve and build up 5 pounds. pressure. in the rangefinder.This is the maximum safe pressure rou can put in a rangefinder. While you maintain this pressure, use a liquid soap solution to test all plates and 148.33 connections for leaks. (See fig. 6-9.) Figure 6-9.Testing for leaks. Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

6. Attach the hose of the helium-purity after the rangefinder has been subjected to indicator to the outlet valve of the rangefinder, rough treatmentfor example, prolonged main- and adjust the mechanical and electricalzeros battery firing. I of theindicator.Open the cylinder valve. 7. Run helium, at 5 pounds pressure, through STEREOSCOPIC RANGEFINDER therangefinder and the helium-purity indi- INSPECTION cator. (See fig. 6-10.) 8. When the helium-purity indicator shows The checklist in figure 6-11 might be used 97.5 percent helium by volume, close the valves in your inspection of the stereoscopic range- and disconnect the dryer from the rangefinder. finder.But do not let the checklist limit your inspectiona list made up beforehand cannot RANGEFINDER INSPECTION include every possible condition.Record all pertinent information, whether or not you have Rangefinders must be inspected regularly made a space for it on your checklist. to keep defects from developing unnoticed. CLARITY OF SCALES.The scales must be The operator should check these items fre- clean and readable.The internal and external quently. range scales are especially important; the two 1. Cloudiness of exposed optical surfaces. must read the same within one unit of error. 2. Supply of lens tissue at the rangefinder If they do not, look for lost motion in therange- station. knob linkage. 3.Cleanliness of eye guards. CLARITY OF IMAGE& Check the definition 4. Lubrication of mount. in both fields.At the best possible focus, both 5. Helium purity(in antiaircraft range- reticle patterns and both target images should finders). be equally clear.In every telescope system The Opticalman should make a complete the image will be sharper in the center of the inspection every 3 months, and immediately field than at its edges. But if the image is

r; a

148.34 Figure 6-10.Running helium through the rangefinder and the purityindicator.

79 OPTICALMAN 1 & C

STEMOSCOPIC RANGEFINDER INSPECTION SHEET

Daft

Mod Saki No.

OARITY OF SCALES

CARRY OF IMAGES: Left side sla

MOISTURE : End windows

Eyepiece

Gas

RANGE OF ADJUSTMENTS No. of turns No. of bans clockwise counterdocktvise adiustined

Conction knob

Internal target side adiustment

ACCURACY OF INTERPUPILARY SCALE

FOCUS

FROM: Variable density So- Other

QARITY OF INTERNAL TARGET:

RETICLE ILLUMINATION AND STRAY UGHT:

Left side %hi side PARAUAX CAUMIATION

INPUT MECHANISM

0 SATISFACTORY 0 REPAIR DESIRAILE 0 REPAIR URGENT inspsdsdby Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE sharper in one of the rangefinder telescopes than it is in the other, you can be sure there is a shifted element or a dirty surface somewhere in the optical system. Look through the end windows for dust, smudges; and moisture. MOISTURE.If there is condensed moisture on one of the inner optical surfaces, you can often see it by looking through the end window. If you see any sign of condensation, dry and recharge the rangefinder promptly. (Do not forget to look for moisture in the eyepiece assembly, which is often outside the gas seal.)Even if there is no sign of moisture, check the date on which the instrument was last charged, to see if it is time for recharging. DIPVERGENCE. Dipv ergence is sometimes called UP-AND-DOWN DIVERGENCE, or STEP. 148.36 In a properly aligned rangefinder, the rays Figure 6-12.Using the comparator to test for emerging from the two eyepieces are parallel, dipvergence. or nearly so.If they are not, the operator will suffer from eyestrain; in extreme cases he will hard against the eyeshields.Check the focus not be able to fuse the two images. To test for and IPD scales again, to be sure they have not dipvergence elevate the rangefinder toward changed. clear sky, so that you see nothingbut the reticle FOCUS.Set the rangefinder at its highest pattern. Hold your head about 6 inches from the'power, and set the two diopter scales at zero. eyepieces.Look at the center reticle marks, Use an auxiliary telescope to look through the and break their stereoscopic fusion as you do eyepieces and focus the auxiliary telescope to when checking the height adjustment. The two give a sharp image of the target and reticle. marks should appear to be at the same height, Now shift to low power. The target and reticles with an allowable error of one fourth the height. should still be in sharp focus, without resetting The dipvergence test is easier if you have a either the auxiliary telescope or the diopter comparator; set it over the eyepieces, as in scale of the rangefinder. figure 8-12. The allowable error is 30 minutes MAGNIFICATION.Useaclynameterto in divergence and 10 minutes in height.To check the exit pupil, the eye distance, and the bring the error within tolerance, align the eye- magnification on each side of the instrument as piece prisms by moving their adjustable locking shown in part A of figure 6-14. (When checking bolts, as in figure 6-13. RANGE OF ADJUSTMENTS.Checkthe limits of the various adjustments. In each, the correct adjustment should fall within the middle third of the total availible motion.(At extreme temperatures the correction scale may read outside these limits.)If there is no scale on theadjustment, count the number of turns available between the correct setting and each of the two stops.Check the adjustment mechanism for erratic action; there should be no catching or binding, and no lost motion.. Adjust the interpupillary distance (IPD) scale during each overhaul.During the inspection, check for lost motion between the eyepieces and the scale pointer.If there is no lost motion, it can usually be assumed that the adjustment is still correct.Set the scale and the focus; look 148.37 through the eyepieces, pressing your face fairly Figure 6-13.Adjusting the eyepiece prisms. OPTICALMAN 1 & C

for equal magnification during an overhaulin side of the rangefinder.If necessary, unlock the optical shop, put an aperture stopover the the objective cell and adjust it to remove paral- objective to increase the definition, as in part lax (fig. 6-16). B of fig. 6 -14.) To change the magnificationon CALIBRATION. Check the calibration on the one side of the rangefinder, loosen the setscrew longest available known range, then at short that holds the erecting-lens cell in place. With range, and finally at an intermediate range. a scribe, reach through the adjustment hole in INPUT MECHANISM.Rangefinders equip- the optical bar and rotate the cell, as in figure ped with input and output mechanisms must be 6-15. When equal magnificationon both sidesof tested electrically. The two synchro units must the rangefinder is obtained lock the cell in place be set to electrical zero when the range reads by tightening the setscrew. 10,000 yards. FILTERS.Examine the filters for cleanli- SHOCK TESTING.When you makea tent ness and ease of operation.Then make this that might be influenced by mechanical shock teat: With the clear filter in the line of sight, the internal adjustment, for examplestrike range on a fixed target and make stereoscopic each of the rangefinder bearings with a soft contact. Then throw the filters in, one ata time. hammer, at each of four points 90° apart. None of the filters should break stereoscopic Then repeat the test.If the results are signifi- contact with the fixed target.If one of them cantly different, they may indicate thatone or does, you will know that the filter's surfaces more of the internal elements is loose in its are not parallel; replace it With a new filter. mounting. INTERNAL TARGET. The central portion FINDER'S TELESCOPE. Check to see that of the internal target should be sharply defined the target image, when it is centered in the and well illuminatedin other words,easy to rangefinder field, is also centered lathe finder's range on. telescope.In the finder's telescope the target ILLUMINATION.Make this test at night; image, the crosslines or circle, and the inside a daytime check will give unsatifactory results. scale, should all be in focus at the same diopter The illumination of the two reticles should be setting. approximately the same.There should be a Bear in mind that all these inspection tests minimum of stray light and ghost images in the are intended only to supplement the calibration system.If you see stray light lathe instrument, exercisesnot to substitute for them. Some remove one bulb at a time until you find the one maladjustments of the rangefinder are so elusive that is causing the trouble. Youcan sometimes that it takes a complete overhaul to find them. remove ghost images or stray light simply by But they show up as a historyofbad ranging and adjusting a bulb in its housing. erratic internal adjustment settings. When the PARALLAXRange on a fixed target ata record shows sudden large changes in the cor- distance of 2,000 yards or more, anduse an rection settings, you can be fairly sure that auxiliary telescope to check for parallaxon each trouble is developing.

148.38 148.39 Figure 8-14.Checking magnification witha re 6- 15. Rotating the erecting-lens dynameter. Chapter 6RANGEFINDER CALIBRATION AND MAINTENANCE

coincidence rangefinder.Here are a few more tests, which apply to the coincidence type only: ASTIGMATIZERS.With the astigmatizers out, range on a slender, vertical target that makes good contrast against its background. Then range on the same target withthe astigmatizers in. The two readings shouldbethe same. HALVINGTurn the halving adjuster knob through its entire travel, and count the turns. Then turn back half way. The instrument should be approximately in the halving position. Roll the rangefinder in its bearings, and then recheck the halving adjustment. LEAN. Range on a target at the right-hand side of the field, and make a careful halving adjustment.Swing the rangefinder in azimuth to bring the target to the left-hand side of the field. The halving adjustment should still be correct. COMPENSATOR SETTINGRange on a target near the minimum range, and make a careful 148.40 halving adjustment.Then range on a target Figure 6-16.--Adjusting the objective. near the maximum range. The halving adjustment should remain correct. (You neednot know Rangefinder operators will make only the the true range of the two targets.) . simple adjustments; casualty analysis is your LEAN IN THE INTERNAL ADJUSTER TAR- job.It is up to you to decide, on the basis of GET.Range on the LA. target, and then turn your inspections and the calibration logs, when the halving adjustment until the target is almost serious trouble exists, and what should be done hidden under the halving line. Make 10 internal about it. adjustment readings at this setting, and find the COINCIDENCE RANGEFINDER median. Rotate the halving adjustment until the INSPECTION halving line covers only a small part of the target.Make 10 internal adjustments at this set- With a few obvious exceptions, such as inter- ting, and find the median. The two median pupillary distance setting, the inspection tests readings should be the same, within one unit of just described will apply equally well to the error.

83 CHAPTER 7

STEREOSCOPIC RANGEFINDER

This chapter describes the disassembly, re- either is turned in the plane of triangulation, the assembly, and collimation of the stereoscopic angle reflected will not remain a constant. To rangefinder Mark 42 Mod 27. A detailed discus- avoid this difficulty, the end reflectors used in sion of one particular instrument is used to the rangefinder are of the pentagonal prism type, illustrate the repair of a whole class of instru- shown in figure 7-2. They have two reflecting ments. After you have mastered one Mark of surfaces. With this type reflector, if the angle rangefinder, and gained practical experience in between reflectors is 45° they always reflect the shop, the information provided by Ordnance at an angle of 90°, even when rotated. The right Pamphlets and drawings will enable you to repair end reflector, however, does not reflect an angle any rangefinder. of 90° but is constructed to reflect a fixed angle The first major section of this chapter will of 89° 49' 6". describe the principal components of the range- The end reflectors used in the Mark 42 rangefinder Mark 42 Mod 27. The second major section finder are of the built-up type, withtwo silvered will be on the complete disassembly, reassem- glass mirrors mounted to a steel block. The bly, and collimation of the rangefinder. mirrors used on rangefinders Mark 42 Mods 25, 26, and 27 are front surfaced aluminized mirrors. The mirrors have plane parallel surfaces, DESCRIPTION OZRANGEFINDER MARK 42 and are of sufficient thickness to retain their shape, but are not so thick that changes of tem- Rangefinder Mark 42 and all Mods are of the perature will affect them by causing internal stereoscopic, wandermark type, with change-of- distortions. The block is made from a solid magnification input mechtudam. The only differ- piece of steel having an expansion coefficient ence between the various modifications of the approximately the same as that of the glass. Mark 42 lies in the general arrangement of The mirrors rest on three raised spots which certain units. The function of any given unit is are carefully finished and polished. A steel the same in all modifications. Figure 7-1 shows spring plate with three similar spots holds the a cross-sectional view of the Mark 42 Mod 27 mirror firmly to the steel block, yet it is free rangefinder. to expand and contract with temperature changes, The main structural elements consist of without introducing any strain or stress in the three tubes: The inner and outer tubes which reflectors. The underside of each steel block form a double-walled main tube, and an optical has a three-point bearing, with a ground and bar (tube) mounted inside the innertube. Locate lapped finish. The steel blocks are bolted to the these three tubes in figure 7-1. brackets fastened to the ends of the inner tube. The only effect of the movement of these reflectors, due to slight deformations of the inner tube, END REFLECTORS is to throw the images out of adjustment in height, which can be readily corrected by the It is essential in a rangefinder that the rays height adjuster, as will be explained later. Two of incidence to the finder be reflected at fixed end reflectors are shown in figure 7-2; one is angles in the instrument; this is the function of shown assembled and fastened in position in its the end reflectors. If a single prism or mirror mount, while the other is broken down into its with total reflection is used at each end, and congxrnent parts. 84 Chapter 7STEREOSCOPIC RANGEFINDER

OBJECTIVES of travel. By pivoting on an axis through their front surfaces, the two rhomboid prisms provide The functon of the objectives is to form real an interpupillary adjustment. images of the target on the reticles. The ob- The two eyepiece lenses have separate focus- jectives are made and mounted with great pre- ing mounts, so that each may be adjustedto pro- cision.If the focus of both objectives is not vide the observer with a sharp image. exactly the same, the magnification of the image The color filters are so mounted that turning seen by the right and left eyes will differ and the a single knob will bring the filters of the same range readings will be incorrect. Lack of uni- color into each field. In the rangefinder Mk 42 formity in the focus of objectives is readily de- Mod 27 the filters are arranged in this order: tected when a target is observed that is not in red, yellow, clear, and polaroid. the center of the field. The right and left objec- The eyepiece assembly is mounted on the tive lenses are therefore selected and adjusted outer tube of the rangefinder. The outer tube is to give the same focus. They are composedof a subject to greater changes due to temperature positive lens of crown glass and a negative lens than either of the othertubes. But the position of of flint glass. The objectives are mounted in the eyepiece is somewhat less critical than that steel frames and separated by steel spacing of the other optical groups. The eyepiece has no rings. The objective mountings and the spacing part in the delicate measurements made by the between them must be carefully adjusted to give rangefinderit serves only as a magnifier, to the correct focus; the objectives must be held help read those measurements. Since the eye- firmly in their mounts without strain. piece assembly is completely outside the main To disassemble the objective, first unscrew gas seal of the rangefinder, you can remove and the objective ring, as shown in figure 7-3. Re- clean it without breaking the seal. move the positioning bolt (shown just to the right of the repairman's thumb in fig. 7-3) and slide ERECTING LENS SYSTEM the objective mount out of the optical tube. Un- screw the two locking rings from the objective The erecting lens system has three functions: cell. Back off the set screw and remove the re- (1) it provides an erect image of the target; (2) taining ring.Slip out the lens elements and it effectively extends the focal plane of the eye- spacers. Figure 7-4 shows the two objectives piece to coincide with the focal plane of the ob- after disassembly. jectives at the reticles; and (3) in some rangefinders it provides a means for changing the EYEPIECE PRISMS magnification.In the rangefinder Mk 42, the erecting system provides a choice of either 12 The two eyepiece prisms, which reflect the or 24 power. two lines of sight into the eyepiece, are located The erector lenses are mounted in erector in the center of the rangefinder.(They are slides. The two slides fit into the optical tube; marked No. 27 in fig. 7-1.) each slide is connected by a bar to the change - Figure 7-5 shows the two eyepiece prism of- power disk. The change -of -power lever ro- mounts of the Mk 42 Mod 27 rangefinder. (The tates the disk; as it rotates, the rods move the repairman has removed the left prism mount, by slides toward or away from the eyepiece prisms. taking out the two adjustable locking bolts and Spring stops hold the disk in either of its two one screw.) alternate positions.

EYEPIECE ASSEMBLY RETICLES Refer back to figure 7-1 to identify the prin- In assembling a rangefinder, the reticles are cipal parts of the eyepiece assembly: the two fixed in the focal planes of the erectors. The rhomboid prisms (No. 28), the color filters (28), objectives are then moved in or out until their and the eyepiece lenses (29). The eyepiece focal plane (on a target at a range of 2,000 yards assembly is covered in Opticalman 3 & 2, Nav- or more) coincides with the plane of the reticle Pers 10205; you should already be familiar with markings. "Each reticle is mounted in a frame; the functions of its parts. The rhomboid prisms, this frame can be rotated about the axis, and can with two reflecting surfaces in each, offset the be moved in any direction along the axis. Because rays without changing their direction or length the reticle has these two motions, it can be

85 OPTICALMAN 1 & C

1. END WINDOW WEDGE 10. INTERNAL ADJUSTER REFLECTOR 2. END REFL ECTOR 11. INTERNAL ADJUSTER LIGHT 3. INTERNAL ADJUSTER PRISM 12. INTERNAL ADJUSTER CONDENSING LENS 4. END BOX 13. INTERNAL ADJUSTER OBJECTIVE RETICL E 5. OUTER TUBE 14. INTERNAL ADJUSTER CORRECTION WEDGE 6. INNER TUBE 15. SEARCHLIGHT FIL TEN 7. INNER TUBE SUPPORT 16. MAIN BEARING 8. INNER TUBE BEARING 17. OBJECTIVE L ENS 9. INTERNAL ADJUSTER ALIGNMENT WEDGE

rotated to level its markings, and its center optical axis. The rotation of the two wedges is mark can be aligned with the optical axis of the equal, and in opposite directions, so there will rangefinder. The frame is so mounted that you be no vertical deviation of the image. The wedges can remove it without disturbing the other optical are rotated by either the range knob or the parts of the instrument. change-of-range input mechanism. Eachreticle,is a piano- convex lens, with its There are two range scales. A glass scale plane surface toward the objective. The convex (No. 33 in fig. 7-1) is securedtothe mount of the surface helps to converge light toward the erec- two wedges. The telescope for viewing this scale tor, and thus ensures full illumination of the is attached to the outer tube of the rangefinder. whole field. The markings are etched on the This scale reading telescope is located about plane surface; the etched lines are filled v4than 2 1/2 feet to the right of the eyepieces; your line opaque material, which ,makes them easier to of sight through it is, parallel to that through the see. When the reticle illuminatot is being used oculars. for night ranging, light passes through a lucite The external range scale is located in the rod to the edge of the reticle. The light 12 then change-of-range gear box. The scale can be reflected toward the eyepiece from the inner sur- viewed along a line of sight parallel to that face of the filled lines. through the oculars; or if a prism is swung into COMPENSATOR UNIT position, the scale can be viewed along an axis at an angle of 45° to that of the oculars. The compensator unit of the Mk42 is mounted between the right objective and the right end CHANGE-OF-RANGE INPUT window. It consists of two achromatic wedges Mk 42 rangefinders are fitted with a change- so mounted that you can rotate them about the of-range input mechanism. When ranging on a Chapter 7STEREOSCOPIC RANGEFINDER

18. HEIGHT ADJUSTMENT KNOB 21.EYEPIECE PRISMS 19. CORRECTION SCALE 28.EYEPIECE RHOMBOID PRISMS 20.HEIGHT ADJUSTMENT PLATE 29.EYE LENSES 21.INTERNAL ADJUSTER CORRECTION KNOB 30.INTERNAL ADJUSTER TARGET CENTERING PLATE 22. OPTICAL BAR SUPPORT 32. COMPENATING UNIT 23. OPTICAL BAR LOCK STUD 33. INHEit RANGE SCALE 24. RANGEFINDER RETICLE 34. OPTICAL TUBE 25. ERECTING LENSES 43.INT. ADJUSTER TARGET CENTERING KNOB 26. COLOR FILTER

148.41 Figure 7-1.Cross-sectional view of rangefinder Ml 42 Mod 27. moving target, a computing device introduces the shaft (No. 38) will cause rotation of the differen- estimated change of range into the range finder. tial. Motion of the differential will be transmitted The change of range is introduced by rotation of to the cam (58); motion of the cam is transmitted the input shaft; a range conversion mechanism through a follower and a sector to the compen- converts the estimated change into actual rota- sator unit (32). tion of the shaft. Since the input shaft and the ram knob are At ranges between 2,000 and 72,000 yards, connected to the compensator unit through differ- one revolution of the shaft changes the range ential gears, it is possible to rotate either the setting by 50 yards. Counterclockwise rotation shaft or the knob without causing a rotation of the (viewing the shaft from its outer end) increases other. But the rotation of either of them, or the the range reading; clockwise rotation decreases simultaneous rotation of bothof them, will result it. At ranges below 2,000 yards, or above 72,000 in rotation of the compensator wedges. yards, one rotation no longer corresponds to a 50-yard change in range reading, but will vary RANGE TRANSMISSION depending on bow low or bow high the range reading is. The two synchro generators (No. 56 in fig. The change-of-range mechanism is housedin 7-6) are operated by thedifferential. These gen- a gear box, which is mountedon the outer tube of erators instantly transmit range readings from the rangefinder. Figure 7-8 illustrates the ar- the rangefinder to the gun director. Betweenthe rangement of the shafts, the differential,the, limits of 2,000 aid 72,000 yards, rotation of the cam, and the compensator. A rotation of either generator rotors is directly proportional to the the range 'mob (No 37 in fig. 7-6) or the input change in range.

87 OPTICALMAN 1 & C

END REFLECTOR ASSEMBLY

I rvit t T. INT ERNAL ADJUSTER I 000 mmiTa. 11111 --mignmr

TP Pp

148.42 Figure 7-2.Rangefinder Mk 42 Mod 27 end reflector.

OC.ri t-,^ ' 148.44 Figure 7-4.Objective mounts, disassembled. T='1*-A, r!,I; 4- On the range knob is a spring-actuatedpush- lie - e button, by which the operator can control alight or other signal on the range indicator, to show when the range is to be read. The height adjuster provides a means for moving the left-hand image up or down to bring 148.43 it to the same apparent height, in relation to its Figure 7-3.Removing the objective ring. reticle, as the right-hand image.

88 Chapter 7STEREOSCOPIC RANGEFINDER

CORRECTION WEDGE

The correction wedge, controlled bya knob, rotates about the line of sight on the rangefinder axis.It corrects known errors of therangefinder, and habitual errors of the individual '"'4"1:::-.z operator.

The correction scale is secured to thecor- rection wedge mount. An increase in thecor- rection scale reading will causea decrease in the range scale reading. The telescope for viewing the correction scale is mounted just to the left of the main oculars; the line of sight 148.45 through it is parallel to that through theocu- Figure 7-5.Removing the left eyepiece lars. prism mount.

SYNCHRO GENERATORS CHANGEOFRANGE INPUT SHAFT

-..---- ,N% NMI NM N

1111111, wuuu 1 EXTERNAL 61RANGE ,47dff-frf RANGE KNOB V,..7 SCALE A

% OF INST. COMPENSATOR UNIT

148.48 Figure 7-ILChange-of-range mechanism (schematic), rangefinder Mk 42 Mod 27.

The height-adjustment unit is mountedonthe END WINDOWS inner tube of the rangefinder; its mount passes through an opening in the optical bar, and holds The two functions of the end windows are to the adjustment glue on the optical ;xis. Since provide a transparent, gastight seal and to pro- the glass itself is a disk with parallel faces, its vide a means for correcting the accumulated longitudinal position is not critical. But it must errors of the entire optical systemof the range- be far enough from the objective to lerall the d finder, Each window is an optical wedge withan converging rays pass through the lens. extremely small angle; rotation of a window will OPTICALMAN 1 & C cause a small change in the apparent parallactic 2. Loosen the locking ring of the telescope, angle. and unscrew the eyepiece mount from the body. Remove the eyepiece doublets by taking out the OVERHAUL setscrew and unscrewing the retaining ring and In this section of the chapter we will cover diaphragm. Figure 7-7 shows these parts. the disassembly, reassembly, and collimation of the rangefinder Mk 42 Mod 27. We are using the Mk 42 Mod 27 because it covers everything that will be found in other rangefinders. Most of the repairs made on the rangefinder will be performed on the parent ship, since it is a large instrument and hard to handle. (NOTE: Overhaul only to the extent needed to make repairs.)

DISASSEMBLY Before you begin disassembly, takethe cover plate off the wiring box, and remove all the electrical connections. Tag and number each wire and cable as you disconnect it, to help en- 148.47 sure correct replacement. Next.release the gas Figure 7-7.Correction-scale telescope, with pressure through the outlet valve before begin- eyepiece disassembled. ning to disassemble the rangefinder.(Note: During the dieassembly and reassembly proce- 3. Take out two setscrews, and remove the dures, be careful not to damage the machined telescope prism mount. Unscrew the retaining bearing surfaces.) ring to free the sealing glass. The first items to remove are the END- 4. Remove the cap plug and illuminator hous- REFLECTOR ASSEMBLIES; follow these steps ing from the correction-wedge mount. This in removing them: exposes the sealing glass plate. Remove the 1. Remove. 14 screws from the endbox flange plate and the lucite illuminator rod. cover plates, and remove therplates. 5. Turn the assembly so it will pass through 2. Back off the 12 securing bolts at each end the opening in the tube, and carefully remove it, box. as in figure 7-8. The insert in the figure shows 3. Remove the securing bolts and lift off the how to disconnect the swivel pin socket from the end boxes. You will need help for thisit is a drive shaft. two-man job. 8. Disengage the drive shaft and pull it out 4. Disengage thikontrol rods from the inter- through the correction-wedge opening. nal adjustor-prism assemblies by removingone 7. Remove 14 screws from the correction- securing screw at each end of the rangefinder. wedge knob plate, and lift off the knob and plate. 5. Now remove the two end reflector brac- 8. Remove the spring stops from the side of kets. the correction-wedge assembly. Now free the Next remove the headrest by biking out the wedge cell by taking out the three screws. twp screws that secure it, and remove the rubber 9. Remove the setscrew from the wedge eyeguards of the oculars. Loosenthe interpupil- cell; unscrew the retaining ring, and take out lary and filter scales, so you can rotate them to the wedge. get at the faceplate screws. Remove the face- 10. On the opposite side of the wedge assem- plate screws and the faceplate. Remove the face- bly, free the mount and scale by unscrewing the plate support by taking out the 18 screws that two :ocking rings and the ball bearing ring. (See secure it. fig. 7-9). Removal of the CORRECTION-WEDGE AS- 11. Remove the two screws that secure the SEMBLY is the next step. scale index bracket, and take off the bracket. 1. Remove the six screws by whichthe scale Now remove the six screws that engage the reading telescope is mounted, and tift out the ADJUSTER-PRISM SHIFT to its shaft; lift out telescope. the prism shift. Disconnect the shaft by reaching FILMED FROM BEST AVAILABLE COPY

Chapter 7STEREO::: ;OPIC RANGEFINDER

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148.50 Figure 7-10.Removing the change -of- magnification unit.

these posts can be seen protruding through the 148.48 sides in fig. 7-10.) Figure 7-8.Removing the correction-wedge Now remove the RETICLE ASSEMBLIES as assembly. follows: (Refer to fig. 7-1 as needed.) 1. Remove the 14 screws that secure the illuminator plate, and lift it off. 2. Remove the four screws from the reticle ttri. mount, as in figure 7-11 and lift out the whole hie 411: reticle assembly. 3. Unscrew the clamping ring and pull out the lucite illuminator rod. 4.Loosen the four eccentric screws, and remove the four clamping screws. Lift out the reticle mount. (Fig 7-12.)

148.49 Figure 7-9.Removing scale from the correction-wedge mount. in through the faceplate opening and releasing the lockscrew. Next set the CHANGE-OF-MAGNIFICATION KNOB at 12 power and then remove the assembly as follows: 1. On the change-of-magnification shift, release the arms fvom the erecting-lens mounts. Remove the screw from the center of the disk, and lift off the whole unit as in figure 7-10. Detach the remaining spring bracket. 148.51 2. Remove two screws from each lens-mount Figure 7-11.Releasing the reticle mount guide post, and lift out the posts. (The ends of assembly.

91 OPrICALMAN 1 & C

148.52 Figure 7-12.Reticle mount removed from assembly. 148.54 Figure 7-14.Removing the adjuster knob. 5. Back offthe setscrew on the reticle mount. Unscrew the retaining ring with a pin 4. Remove the guide screw and pull out the wrench, and remove the reticle. control arm shaft. (Fig. 7-15.) Remove the SEARCHLIGHT FILTER KNOB by taking out the six screws that secure it to its shaft. Free the shaft by reaching in through the right reticle opening and releasing the lockscrew; withdraw the shaft. Remove the HEIGHT-ADJUSTER ASSEMBLY as follows: 1. Remove the 12 screws that secure the assembly to the tube. Turn the assembly through approximately 90°, and lift out. 2. Remove the two pivot screws from the unit. Detach the cell mount by freeing the control arm from the shaft, as in figure 7-13. Ch.

148.55 Figure 7-15.Removing the control-arm shaft.

5. Remove the six screws from the retaining ring on the cell mount, and take out the adjuster glass. Take out the TARGET-CENTERING AD- JUSTMENT, and remove the two illuminator plates. Remove the internal target assembly. Take out the four screws that secure the internal- adjuster target, and lift it out of its assembly. 148.53 Unscrew the inlet-valve plug from the Figure 7-13.Releasing th% control arm, GASSING -PLUG MOUNT. This exposes the locknut for the internal gas-line connection; use a pin 3. Drive out the taper pin that secures the wrench to unscrew the nut. Now remove the six adjustment knob, and remove the knob. (See fig. screws from the gassing-plug mount, and lift it 7-14.) off.

92 q7 Chapter 7STEREOSCOPIC RANGEFINDER

Free the INTERNAL-SCALE R E A DING TELESCOPE by taking out the six screws that secure it. Turn the telescope while withdrawing it, so that the prism mount will safely clear the 0 (iv opening. Now disassemble the CHANGE-OF-RANGE 0 ASSEMBLY as follows: 1. Back off the range-knob lockscrew, and pull off the knob and its pushbutton. 2. Removetherange-scaleilluminator housing. Remove 17 screws from the gear box cover, and lift it off (fig. 7-16). L'OtL 4, fliPt 148.57 Figure 7-17.Removing the scale.

148.56 Figure 7-16.Removing the gear-box cover. 3. Free the range-scale index by taking out 148.58 four screws; lift the index from its dowel pin. Figure 7-18.Removing the gear housing. 4. Carefully mark the position of the scale, to help ensure correct replacement when re- bly, drawing the wires up through the housing assembling. Take out the four screws that secure (fig. 7-19). the scale, and remove it (fig. 7-17). 10. Unscrew the plug cap and take out the 16 5. Release the internal-scale gear bracket screws that secure the compensator. Turn the by taking out four screws; remove the bracket compensator to the right to disengage it from and its tension spring. the drive shaft: then lift it out. 6. Release the change-of-range gear houb- 11.Pull the shaft from the range drive gear ing by taking out three screws. Drive out the assembly. Remove 12 screws from the assem- two taper pins (see insert of fig. 7-18). Disengage bly, and carefully lift it out. the drive shaft and lift out the gear housing, as 12. Remove the remaining 19 screws to re- in figure 7-18. lease the support. 7. Through the holes in the range-knob Take off the end counterweights, and pull the housing gear, take out four screws to release rubber gaskets from the inner side of all the the gear; then remove it. openings. Remove the support cap and lock stud 8. Remove four screws from under the . of the right m bearing. Now check carefully housing, and take out the input drive gear. to be sure the inner tube is clear and free for 9. Remove the four bracket lugs and then safe withdrawal. Withdraw the tube and set it on carefully lift out the synchro generator assem- blocks for further disassembly.

93 9 y OPTICALMAN 1 & C

11. Now release the internal adjuster tube bracket on the right, and remove it from the tube. 12. Withdraw the optical bar from the inner tube. 13. Remove the two slide tubes from the optical bar.(Use a threaded plug wrench.) 14. Take out two screws from each slide tube, and remove the lens mounts. 15. Back off the setscrew on eachlens mount (fig. 7-20), and screw out the threaded cell.

148.59 Figure 7-19.Removing the synchro generator assembly. Disassembly of the INNER TUBE is next, to disassemble follow these steps: 1. Remove four screws at each end of the tube, and swing out the searchlight filters. This will expose the screws that secure eachfilterto its control rod. Remove these screws andtake off the filters. 14"';' 2. Disengage the searchlight filter control rods at each end of the tube, andremove them. 148.60 3. Take out four screws to release thecon- Figure 7-20.Releasing the threaded cell. trol gear assembly (near the center of the tube, and a little to the right). Remove the control 16. Remove the setscrew from the front of gear assembly. the cell. Unscrew the retaining ring with a pin 4. Just inside the correction-wedgeopen- wrench, and remove the front lens and the ing, you will find a screw-head taper pin. Back separating ring. (Always protect the lenses from it off. Now pull out the left adjuster rod,and dust and scratches by wrapping them carefully remove its sliding support. in lens paper. Mark the lenses showing the di- 5. Release the right adjuster-rod support rection of light on each one, as in fig. 7-21.) (the locking pin is just inside the compensator opening) and remove it. 6. By releasing a screw, break the offset coupling to free the two right rods. Thenremove the adjuster-gear housing at the left centerof the tube. 7. Unscrew and remove the two objective mounts for the correction-scale reading telescope. 8. Remove the four hold brackets for the gas line, and withdraw the line. 9. Remove six screws at each end of the tube, and remove the small rod guides. Then slide out the tube bracket assemblies. t 10. Unscrew the cap and lock stud to free the optical bar. Slide the barover to the right, 148.61 off its support bearing. Figure 7-21.Erector cell, disassembled. 94 ?ssi Chapter 7STEREOSCOPIC RANGEFINDER

17. Back off the other setscrew, and unscrew 1. Remove the center screw from each the retaining ring; then remove the rear lens. filter mount, and release the holding clamp. 18. Remove the left section of the internal 2. Remove the clamping screw from each adjuster tube bracket. filter mount, and remove the mounts. Now remove and disassemble the EYEPIECE 3. Remove the setscrew from the density PRISM MOUNTS as follows: control knob, and take off the knob. Now remove 1. Take out the two screws that secure the the gear pinion from the back of the plate. tension spring, and remove the spring. 4. Remove the density control lockscrew 2. Remove the two screws from the base of and nut, and lift out the shaft. the mount, as in figure '7-22. 5. Remove two screws from the two guide brackets, and lift off the gear rack. 6. Release the right gear bracket by removing three screws from the faceplate (fig. 7 -24). -.. le a -41 ad

44 148.62 Figure 7-22.Removing screws from base of mount. 3. Remove two screws fromtheangle bracket. The bracket is now free; lift it off. 148.64 4.Finally, remove the two screws from the Figure 7-24.Releasing the right gear bracket. holding clamp (fig. 7-23) and lift out the prism. 7. Back out the setscrew in the interpupillary adjustment knob, and remove the knob. 8. Remove the large washer screw from the left gear bracket, and remove the coupling and bracket from the faceplate. 9. Take out the setscrew in each eyeguard ring, and unscrew the rings. 10. Remove the setscrew from each knurled ring; take out six screws from each retaining plate, and unscrew the diopter rings. You can now remove the eyepiece slides. 11. Remove the setscrew from each slide. Then remove the retaining ring, lenses, and spacing rings. 12.Lift both index dust rings off the faceplate. Take out the four screws that secure the right eyepiece prism mount; disengage the coupling and lift out the prism mount, as in figure 148.63 7-25. Remove the left prism mount in the same Figure 7-23.Releasing the holding clamp. way. 13. Remove the two binding post screws on Now disassemblethe FACEPLATE AND each rhomboid prism mount, and remove the COLOR-FILTER ASSEMBLY as follows: holding-down plate and clamp.

95 /Do OPTICALMAN 1 & C

5. Release the holding-down plate, andremove the prism. Next disassemble the INTERNAL RANGE- SCALE TELESCOPE as follows: 1. Unscrew the eyeguard ring. Back off the setscrew and unscrew the index and diopter ring. 2. Take out two screws to free the focuiing key from its slot, and remove the eyepiece cell. 3. Remove two lockscrews, and unscrew the prism mount from its housing. 4. Use a pin wrench to unscrew the sealing- glass retaining ring; remove the glass. 148.65 5. Take out three screws to release the Figure 7-25.Removing the right eyepiece holding-down plate; then lift off the prism and its prism mount. clamp. 6. Back off the lockscrew that secures the 14. Mark the position of each filterin its objective cell, and remove the cell. Take out mount, so you can put it back in the same place. the setscrew, and remove the retaining ringand Remove the securing clamps, and takeout the lens. filter disks. Figure 7-26 showsa filter mount 7. Unscrew the retaining ring and diaphragm disassembled. of the eyepiece cell. Remove the doublets and spacing rings. To disassemble the CORRECTION-SCALE READING TELESCOPE do the following: 1.Loosen the locking ring and unscrew the eyepiece mount. 2. Remove the retaining ring setscrew;un- Ni screw the retaining ring and diaphragm. Then remove the eyepiece doublets. 3. Remove two screws from each securing clamp of the prism, and remove the prism. Re- move two setscrews to release the prism mount. 4. Unscrew the sealing-glass retaining ring, and remove the glass. Now disassemble the INTERNAL-ADJUSTER TARGET ASSEMBLY as follows: 1. Remove two pivot screws from the target- 148.66 centering adjustment, and remove the mount. Figure 7-26.Filter mount, disassembled. 2. Free the centering plate from the mount by backing off the setscrew and unscrewing the Now disassemble the END REFLECTORS, ring. Remove the plate. referring back to figure 7-2 to identifyparts: 3. Remove the screw that secures thecen- 1. On each end reflector bracket,remove tering knob; take off the knob and the five stop two screws from the split bearingon the prism rings. pivots. Lift off the bracket. 4. Remove the four screws thatsecure the 2. From each bracket, take out thethree plate and shaft, and lift out the plate and shaft. adjustable locking bolts, andremove the reflec- 5. Remove three screws from each internal- tor mount. Release the spring tensionscrew on adjuster target assembly, and remove the target each end of the mount. illuminator mount. Remove the holding-down 3. Remove two screws to releasethe clamp, and take off the reflector glass. holding -down side clamp. Lift out thereflectors. 6. Unscrew the retaining ring at the other end 4. On each prism bracket,remove five of the mount, and remove the diffusing glass and screws and lift off the shield. Take out three spacing ring. screws, then the eccentric bolt, and detach the 7. Remove the retaining strap from the tar- mount. get assembly, and back off the fine adjustment 96 Chapter 7STEREOSCOPIC RANGEFINDER screw to release the reticle mount. Backoff a setscrew and unscrew the reticle cell from the mount. 8. Remove the setscrew from each end of the cell; remove the retaining ring and the reticle target. 9. Loosen the setscrew in the opposite end of the mount, and unscrew the objective cell. Disassemble the cell by taking out its setscrew and unscrewing the retaining ring. 10. At the wedge-cell end of the target assembly, remove the two retaining strap screws. Loosen the fine adjustment screws, and slide out the wedge-cell mount. 11. Free the wedge-cell from its mount by backing off a setscrew in the lug. Disassemble the cell by taking out the setscrew and retaining ring. The SEARCHLIGHT-FILTER can bedisas- sembled next by removing two split bearing caps, and taking off the pivot bearing of each assembly. 148.67 After removing the lockscrew near the base, you Figure 7-27.Removing the compensatorscale. can unscrew the cell with a pin wrench.Remove the setscrew to release the retaining ring; remove the ring, and take out the spacingring and filter. Now disassemble the COMPENSATOR UNIT as follows: 1. Unscrew the plug cap. Take out the 16 screws that secure the compensatorassembly to the outer tube. Turn the assembly to theright to disengage it from the drive shaft, andthen lift it out of the rangefinder. 2. Remove the eight screws that hold the lucite illuminator rod, and remove it from the outside surface of the compensator. 3. Remove the scale index by taking out the two screws that hold it. 4. Remove the two screws that hold the scale in place; then liftitoff, as in figure 7-27. 148.68 5. Remove the counterweight from above the Figure 7-28.Removing the wedge cells. scales. Remove three screws from the support ring (under the scale and counterweight), and 8. Unscrew the locking ring on each gear remove it. segment, and remove the ball bearing. If neces- 6. Remove the two wedge-cellsone from sary, remove the gear bracketby taking out the each side of the compensator mountas in figure three screws that secure it. 7-28. To disassemble a wedge-cell, back out the Remove the END WINDOWS from the end setscrew, screw out the retaining ring, and re- that secure move the wedge. boxes by removing the four screws 7. Remove the two stop screws from the the cover plate, and liftitoff. Remove the compensator unit. Remove the three screws and clamping ring and scale, and unscrew the mount. clamps through the hole in each gear segment, If it is necessary to remove the wedgefrom its and lift the two segments off the assembly, as mount, apply slow heat to soften the sealing in figure 7-29. compound. 97 OPTICALMAN 1 & C

Reassembly of the Optical Bar Use a threaded plug wrench to slide inthe two erecting lens mounts. Secure the two mounts in the bar by means of their guide postsand screws.Replace the change-of-magnification shift and arms, then the spring bracket. Attach the two eyepiece prisms temporarily by means of the adjustable locking boltsand screws. Slide in the two objective lenses at the ends of the bar, and fasten them with the position bolts. Turn on the two locking rings, thenthe securing rings. That is as far as you proceee now. You will make the final setting of the locking rings When youcollimate theoptical bar. Correction Wedge And Compensator Unit After attaching the drive gear, put the scale 148.69 index bracket in place. Set in the ball-bearing Figure 7-29.Removing thegear segments. ring, and insert the mount and scale in theoppo- site side of the assembly. Now attach thetwo locking rings; the smaller ring locks themount REASSEMBLY AND COLLIMATION to the bearing; the larger ring locks the mount to the assembly itself. Secure the wedge cell with In general, you can reassemble therange- three screws; then attach the two spring stops. finder by following the disassemblydirections in First set the ball bearing in place in eachseg- reverse. In the following sections a fewpointers ment, and lock it with the ring. After attaching that will be helpful during reassemblyare given. the two gear brackets to the unit, replace the gear segments and secure each of them with Height Adjuster three screw. id clamps. Be sure the gears mesh properi.Replace the two stop screws. Insert the shaft, and secure it in placewith Put each wedin its cell, and secure it with the the slot key. Attach the controlknob,and drive in retaining ring and setscrew. Replace thetwo the taper pin. After replacing the glassplate in cells in the compensator unit, andsecure it its cell, secure it in the assembly withtwo pivot temporarily with three screws. (You willsecure screws. Then attach the control arm. it permanently during collimation.) Aftersetting in the support ring and the two counterweights, secure the scale with two screws. Now attach the Target Centering Adjuster scale index and the lucite rod. Now you are ready to collimate thecompen- Insert the shaft in the air-pressuredia- sator, the correction wedge, and the main optical phragm, and turn the shaft backone full turn bar. Use a Mk 4 telescope collimator,or a Mk 2 from the bottom. Attach the shaft andthe knob support to the plate with four spotting-glass collimator which has been adapted screws. After for use with the Mk 42 rangefinder.Collimate securing the centering plate andretaining ring the compensator first. in the mount, engage the mountto the shaft cou- COLLIMATION OF THE COMPENSATOR.- pling and attach it with two pivotscrews. Set the four heavy stop rings against the The compensator is positioned in the rangefinder pin for a clock- at an angle of 25°, therefore it will haveto be wise stop; then add the remaining thinwasher and the spring, so that the lug of the collimated at that angle. Set the crossline of the washer engages collimator telescopes at an angle of 25°,as in in the hole in the knob. Before attachingthe knob, be sure that the doweled shaft and figure '7-30. Use a level protractorset at an the locking angle of 25°. Use an auxiliary objectiveto get a rings are properly engaged. You willhave to sharp image of the protractor; rotatethe tele- apply pressure from the bottom ofthe shaft to scope until its crossline is parallel to the edge attach the knob screw. of the protractor scale. 98 103 Chapter 7STEREOSCOPIC RANGEFINDER

4rtk

148.72 Figure 7-32.Bringing the vertical linesinto coincidence. 148.70

Figure 7-30.Adjusting the collimator .. telescopes. Mount the compensator on parallel bars. Re- move the left wedge.Set the scale at 1,591 yardsthe zero setting for the Mk 42. Lock the scale at this position with a temporary wedge, as in figure 7-31.

.44- .14d'

148.71 Figure 7-31.Locking the scale. Rotate the right wedge until its vertical lines 148,73 are parallel to those of the collimatortele- Figure 7-33.Correction wedge mountedfor scope, as in figure 7-32. collimation. Replace the left wedge and rotate it to bring both sets of crosslines into coincidence. Now scale at 60. Now, with the collimator crosslines remove the temporary wedge. still at an angle of 25°, rotate the correction COLLIMATION OF THE CORRECTION wedge until its vertical line is superimposed on WEDGE.Place the correction wedge on the par- that of the collimator telescope, as infigure allel bars, as in figure 7-33. Set the correction 7-34. 99 OPTICALMAN 1 & C

screws, superimpose the intersection of the collimator crosslines on the center diamondof the reticle, as in the insert of figure7-36.

148/76 Figure 7-36.Centering the diamond.

Now rotate the optical bar through 180°. Sight through the telescope, and observethe posi- 148.74 tion of the diamond in relation to the Figure 7-34.Aligning the correction crosslines. wedge. It will probably be off the intersection.To center the diamond on the mechanical axis of theoptical Collimation of the Optical Bar bar,loosen the screws, as in figure 7-37.

Mount the main optical baron the collimator, in the brackets adapted for thatpurpose. Figure 7-35 shows theoptical bar mounted in its brackets.

148.77 Figure 7-37.Adjusting the reticle. Now repeat the test, and makea further ad- _NJ justment if necessary. Figure 7-38 showsthe path of the diamondson a properly collimated reticle when the optical bar is rotatedthrough 148.75 360°. Figure 7-35.Optical bar, mountedon the collimator. To adjust the right reticle,reverse the optical bar on the collimator and repeat thecollimation procedure. Replace the eyepiece prisms, andset the Remove the eyepiece prisms, andinsert the diopter scales at zero. Set the main faceplate left reticle. By turning the telescopeadjusting assembly in place on the opticalbar. Use a 100 /o5 Chapter 7STEREOSCOPIC RANGEFINDER

9. Secure the prism adjuster-gear housing (to the left of the eyepiece opening) withfour screws. 10. Set the control-gear housing in place(at the right of the eyepiece opening). /Or 11. Slide in the searchlight-filter control %% rodsone through each end of the tube.Engage A them with the control-housing gear. 12. Replace the two internal adjuster rods. The left rod, and the innersection of the right rod, engage in the gear housing. 13. Attach the outer section of the right internal adjuster rod in its coupling. Replace the two sliding supports. 14. Attach each of the searchlight filters to 148.78 its control rod. Twist each filter counterclock- Figure 7-38.Diamonds properly collimated wise until it is secure in its base in the tube. through 3600 rotation. Assembly of the Outer Tube dynameter to check the two eyepieces for equal magnification. Put an aperture stopover the ob- Now replace the inner tube in the outer tube, jectives, one at a time, and check for definition. and lock it in position. Then follow these steps: Check the two telescope systems for equal mag- 1.Replace the rubber gaskets in all the tube nification. To adjust the magnification, follow the openings. 2._ Mount and secure the faceplate support. directions given in chapter 6 under magnifica- surfaces a t'.on. (Do not forget to give all machined Now correct for true lines of sight. First, thin coat of grease during reassembly.) replace the reticles.Set on the faceplate, and 3. Lisert ana engage the adjuster-prism take a reading with a comparator. The diamonds shaft. Secure it with the small lockscrew atits must lie in the same horizontal plane. To adjust inner end. the dipvergence, follow the directions given in 4.Positiont h e change-of-magnification chapter 6 under dipvergence. knob on its stop, and secure it with eight screws. 5. Engage the searchlight-filter knob drive shaft, and secure it with its inner lockscrew. Replacing The Optical Bar Replace the knob. 6. Replace and secure the height-adjuster To replace the optical bar in the inner tube, assembly. follow these steps: 7.Replace thetarget-centering adjust- 1. Remove both reticle assemblies from the ment, and secure it with its six screws. optical bar. 8.Insert the two internal-adjuster target 2. Replace the bar in the inner tube, and assemblies, and secure each with its four move it up to its bearing. screws. 3. Mount the right internal adjuster tube. 9. Attach the gassing-plug mount. Align 4. Lift the optical bar onto its bearings; the inlet-valve opening with the gas-line connec- push it into place, and lock it there. tion, and secure the line with the locknut. After 5. Mount the left internal adjuste_ tube, and attaching the gassing-mount plate, replacethe secure it with two screws in each bracket. inlet-valve plug with a plug wrench. 6. Secure both tube-bracket assemblies, 10.Set the change-of-magnification knob at one in each end of the inner tube. 12 power. Then replace the two reticle assem- 7. Insert the gas line, and secure its four blies, and secure each with its four screws. brackets. Put the valve in position in the line; 11. Set the correction-knob assembly in you will connect it later. place,reaching through the correction-wedge 8. Secure each of the two objective mounts opening to engage the drive shaft. for the correction-scale reading telescope with 12. Replace the correction-wedge assembly; four screws. then reach through the opening with a wirehook 101 /46), OPTICALMAN 1 & C

to engage it to its drive shaft. Securethe with its 16 screws. Insert the lucitervd, attach the lug cap. 13. Mount the correztion- scalereading telescope and secure it with sia screws. 14. Replace the gear-boxsupport, and secure it with its 19 screws. Sec..re therange drive assembly with 12 screws. Engage thedrive shaft. 15. Carefully connect thecompensator assembly to its drive shaft, andsecure it in place. 16. Replace the internal-scalereading telescope. (Turn it at an angle to work it throughthe 4 opening without banging its prism mount.) I' 17. Attach the wires for the contact switch; 148.79 then replace the synchro generatorassembly and secure it with its four bracket lugs. Figure 7 -39. Checking the faceplate position. 18. Secure the range-knobgear in place. 3.Set the height adjuster at midthrow, and After setting in the drivegear, replace the gear check the height adjustment againstyour outside housing. target. The inserts in figure 7-40 showan im- 19. Carefully mesh thegear segment with proper adjustment. To bring the two target the range drive assembly, andengage the bevel images to the same height, raiseor lower one of gear to the synchro generator. Insert thetwo the images by rotating the correspondingrind taper pins in the gear brackets, and tapthem into reflector. place;then secure the brackets withtheir screws. 20. Mesh the input drive shaft,and secure it in place. Replace the internal-scalegear bracket and its tension spring. 21. Set the range scale inplace with the gearing at the extreme stop, and withthe scale oo0oo set accordingly. Replace the scaleindex on its dowel pin, and secure it withfour screws. 22. Mount the main faceplateand color-filter assembly, and secure it with 18screws. 23. Replace the two counterweightsat the .1 ends of the rangefinder. 24. Connect each end reflectorto its control rod, and secure the end-reflectorbrackets. FINAL CHECKING Now the rangefinder is ready forfir. it check- 148.80 ing on an outside target. Mount therangefinder Figure 7-40.Checking the height adjustment. where it has an unobstructed line of sight toward 4. Now check for tilt of field. Trainthe a target at an accurately knownrange eif 2,000 yards or more. Then follow these rangefinder to bring the external target intothe steps: extreme left of the field. If necessary,use the 1. Use a comparator,as in figure 7-39, to height adjuster to bring the two target images check the alignment of the reticle to diamonds. If exactly the same height relative to theleft-hand the faceplate is notsquare with the line of sight, adjust it. diamonds, as in the inserts of figure 7-41.Then train the rangefinder to bring the targetto the 2. Train the rangefinderon the outside tar. extreme right of the field. A difference in height get, and use an auxiliary telescopeto cheek for parallax. To remove parallax, of the target images relative to theright-hand release the lock- diamonds, as in the inserts of figure 7-42,shows ing ring on the objectivemount, and adjust the tilt of field. Correct it by rotation of the end position of the objective. reflector, as in figure 7-42.

2 /o Chapter 7STEREOSCOPIC RANGEFINDER 3. Check the height of the light beam on each side, as in figure 7-43. To adjust the height of the beam, loosen the three adjuster pentaprism bracket screws and turn the eccentric 0 0 0 0 0 bolt, as in figure 7-44.

148.81 Figure 7-41.Checking for tilt of field.

148.83 Figure 7-43.Checking internal target light. 11111116,,

_A s

148.82 Figure 7-42.Correcting tilt of field. z

5. Range on your external target, and carefully read the range through the internal-scale reading telescope. Compare the reading of the 148.84 external scale; it must be the same, within one Figure 7-44.Aligning the adjuster penta- unit of error. Now secure the gear-box cover in place, and prism bracket. attach the range scale illuminator housing. Re- 4. Examine loth targets for lean. If one of place the range knob and its electrical push- them appears to lean, as in the insert of figure button, and secure the knob with its lockscrew. 7-45, adjust the internal target objective on the INTERNAL ADJUSTMENTS OPPOSITE side. The position of the target objective is controlled by the two screws shown in To adjust the internal adjuster system, fol- figure 7-45. Slack off one of them and tighten the low these steps: other. 1. Set the correction scale at 60its mid- 5. Check the internal targets for true stereo- position;use temporary illumination for this scopic reading. Set the internal adjuster scale reading. at 80, the range scale at 6,000, and the target- 2. Set the range scale at 6,000 yards; cut in centering knob at midthrow. Now sight through the internal-adjuster prism shift, and illuminate the eyepieces without moving the range knob. the internal targets. The internal targets should make stereoscopic 103 OPTICALMAN 1 & C

148.87 148.85 Figure 7-47.Aligning the Mk 8 telescopes. Figure 7-45.Adjusting the internal-target objective. 3. By adjusting the rangefinder bases,superimpose the image of the center diamondon the contact with the center diamonds of the reticles. image of the collimator crossline intersectionas If they do not, adjust the auxiliary internalad- in figure 7-48. juster wedge as in figure 7-46, and thenrepeat the test. LJ

148.86 148.88 Figure 7-46. -Rotation of the auxiliary Figure 7-48.Checking alignment with the internal adjuster wedge. first collimator. 4. Rotate the rangefinder through 180°,and Replace all and cover plates on compare the second collimator, as in figure the rangefinder. Replace the windows andscales 7-49. The allowable error is 4 minutes.If in the end boxes; mount the endboxes and secure them in place. all previous adjustments were made correctly, the error should be within that tolerance.If Now you are ready to check the alignment it is not, it may be that the end reflectorsare of the mechanical and opticalaxes of the range- not properly seated, or that the reticle is im- finder. Follow these steps: properly collimated. Find the error, andcorrect 1. With the rangefinder hoistedup out of the it. way, line up two Mk 8 telescopes, as in figure 5. Hoist the rangefinder out of the 7-47, so that their reticle images way again, are superim- and recheck the collimator alignment.Lower the posed. rangefinder onto its blocks, and repeat the test. 2. Lower the rangefinder ontoa solid base Now range once more on a target atan ac- withitsleftend between thecollimators. curately known distance. With the correction

104 !a9 Chapter 7STEREOSCOPIC RANGEFINDER

Charge the rangefinder with helium, following the direction in chapter 6 under drying and charging. Finally, connect the wiring system. First, secure the connection blocks in the wiringbox; then reconnect the individual wires, as tagged. Replace the junction boxes and cable clamps. At- tach the illuminator housings, cables, and sock- ets. Check the reticles for equal illumination; if necessary, adjust the slots in their houtOngs.

148.89 r Figure 7-49.Checking alignment with ., the second collimator. ,4)1117. wedge and height adjuster at midposition, make stereoscopic contact with your target. Read the internal scale, and check the result with the known distance.If there is an error, cor- rectit by rotating the end windows, as in 148.90 figure 7-50, using the engraved scale as a Figure 7-50.Rotating the end window. guide. Replace the end-box cover plates and se- Now give the rangefinder one final range cure them with 14 screws each. check. Then it is ready for use.

105 /10 CHAPTER 8

SUBMARINE PERISCOPES

It is pointless to compare the effectiveness periscope.Doughty's invention was not the of the Navy's optical instrumentstosay one is result of study and research but was the result more useful or more essential than another. But of necessity.During the campaign of the Red we can say this:if a rangefinder or a gtmsight River, while he was serving aboard the monitor telescope on a surface ship becomesa casualty, Osage, Confederate cavalry on the banks of the the ship can carry on; buta submarine with no river kept up a steady series of surprise attacks periscope is out of effective action. We might upon the Union ships, which had no way of add that of all the Navy's opticalinstruments, seeing over the banks.This led Doughty to the submarine periscope iswe of the largest, seek some new method of watching the shores. heaviest, and most complicated. He took a piece of lead pipe, fittedit with In action against another ship, the effective- mirrors at either end, and ran it up through the ness of a submarine depends on its ability to turret. This makeshift periscope provided sight keep out of sight. The onlyreason for building for the crew of the Osage. a ship capable of submerging is that itcan get The earliest periscope, other than a col- within striking distance of another ship without lapsible one designed late in the nineteenth being seen.Yet at the same time, the men in century by Simon Lake and known as an omni- the submarine must see the other ship.To do scope or skalomniscope, was a fixed tube. Soon, so, they depend on the periscope. however, provision was made to allow the tube Optically, the submarine periscope isno to be raised and turned by hand.This was more complicated than a large rangefinder. fairly satisfactory when the boatwas traveling But because the periscope has several functions at a low rate of speed, but with increased speed instead of just one, and because its designer the pressure was apt to bend the tube and throw has had to solve a number of specialproblems, the image out of line. Improved design resulted the mechanical systems are intricate. in a double tube, the outer one to resistpressure and the inner one to house the lens systems. PERISCOPE DATA DEFINITIONS The earliest submarineswere built without To ensure a uniform method of definitionson provision for periscopes and therefore,when submarines, a standard system of nomenclature submerged, were forced togrope their way is used in all correspondence, specifications, blindly. and plans relating to such instruments. In 1854, Marie Davey,a Frenchman, de- The periscope nearest the bow is called the signed a sight tube for a submarine.The tube No. 1 periscope. This is normally the observa- contained two mirrors, one above the other,at tion periscope.The next periscope aft of the a 45° angle and facing in opposite directions. No. 1 periscope is called the No. 2 periscope. These mirrors, while providingsome degree of This is normally the attack periscope. Insome sight to the submerged ship,were faulty at best; newer type submarines, the periscopes are in 1872, prisms were substituted for mirrors. mounted side by side instead of fore and aft. Before the War Between the States, the sub- In these submarines, the starboard periscope is marine had not had a placeamong the ships of No. 1, normally the attack periscope, and the naval warfare. An American, Thomas H. port periscope is No. 2, normally the observa- Doughty, USN, was the inventor of the original tion periscope.

106

IM1116111111111111 Chapter 8SUBMARINE PERISCOPES

The term "ALTIPERISCOPE" is applied to 6.If the outside diameter of the upper head instruments having the combined qualities of section is less than two inches, this diameter, altiscopes and periscopes; they are also some- in inches, is added to the design designation, times calledaltiscope-periscopes and alti- separated from the preceding symbols by a azimuth instruments.With the altiperiscope, diagonal mark. the upper prism is movable on a horizontal axis, 7.If the instrument is an altiperiscope, and so that by turning it, the observer can raise or if its field of view can be raised enough to in- lower his line of sight. clude the zenith, the letters HA (meaning high The term "UNIFOCAL" designates an in- angle) are added to the design designation. strument with only one magnification; a BI- Here is a typical design designation: FOCAL instrument offers a choice of two mag- 91KA40T/ 1.41411A nifications.All of the periscopes in use today are of the bifocal type. Decoded, that means: The NIGHT PERISCOPE is especially designed for use in dim light; it has high light 91 K A 40 T 1.414 HA transmission and a large exit pupil. An ATTACK PERISCOPE is designed to allow Serial number of the the submarine to get as close as possible to the design enemy without being seen. The diameter of its The manufacturer, head sectionthe part that rises above the Kollmorgen surfaceis reduced to an absolute minimum. The term "AZIMUTH CIRCLE," as applied Type of instrument: to a periscope, refers to the graduated ring bifocal altiperiscope mounted below the packing gland in the conning Length of the optical tower. This is title except for periscopes which system, in feet incorporate the electrical and electronic (E and E) adapter; on this type of periscope the azimuth Coated optics circle is on the E and E adapter. The azimuth Outside diameter, in circle is used for taking bearings through the inches, of the upper periscope. head section DESIGN DESIGNATION High angle Submarine periscopes are under the tech- Each individual instrument is assigned a nical cognizance of the Bureau of Ships. They registry number (the same as a serial number have no Mark numbers. Instead, each separate on other instruments). You will findthe regis- design, or modification of a design, is assigned try number cut or stamped on each periscope at a DESIGN DESIGNATION made up of the follow- its eyepiece end, and on all of its detachable ing symbols: fittings, such as the training handles.On the 1. A serial number foreach design, or eyepiece box of each periscope you will find a modification; these numbers are assigned by nameplate, which shows the design designation, BuShips. the registry number, and some of the optical 2. A letter indicating the manufacturer, using characteristics, such as magnification and field this code: of view. KKollmorgen. S Sperry. 3. A letter showing the type of instrument: THEORY AND DESIGN Abifocal altiperiscope. Hhigh-power altiperiscope. Basically the periscope is a tube, with re- N night periscope. flecting elements at the top and bottom, to raise 4. A number showing the length of the opti- the observer's line of sight.But the actual cal system, in feet (to the nearest foot). design isnot thatsimple.The periscope 5. The letter T may be used to show that the designer must solve several special problems optics have been treated (by filming) to increase that are not encountered in the design of other their light transmission. optical instruments. He must make a

107 OPTICALMAN 1 & C

compromise between conflicting requirements. Here are some of the problems: First of all, the periscope has to be relatively long, as you can see in figure 8-1.It must be long enough to rise above the surface mhile the submarine is still far enough belowto be invisible to surface craft.Optical lengths of periscopes in service run to 40 feetor more. Another important requirement isthat the upper head sectionthe part that sticks out of the watermust be as slenderas possible, to escape detection by the enemy, and to createa minimum wake. The wake of the periscope,if seen by the enemy, would not only reveal the submarine's presence, but also would indicate its course. When the periscope is not inuse,it is lowered, for protection, into a well (fig. 8-1). But when the submarine is maneuveringinto attack position, it will use its periscope,fully elevated, while underway submerged.During that time, the periscope will be dragged through the water at high speeds.The periscope, in spite of its slender construction, must berigid enough to resist the bending effect of the water PERISCOPE IN OBSERVING POSITION pressure that results from its own drag. The IN CONNING TOWER optical system must beso designed that the bending effect will not distortor displace the target image. Another requirement is that the periscope must be able to scan the whole horizon; itmust be provided with somemeans for sweeping through 360 degrees in azimuth. Witha modern PERISCOPE WELL periscope, the submarine captainsweeps the horizon by rotating the entire instrument. It would obviously be impractical to make the periscope an integral part of the hull.And BUMPER IN BOTTOM because the periscope must be raisedand OF PERISCOPE WELL lowered and rotated, it cannot be weldedto the hull;it must pass through an opening in the hull.The design and packing of that opening create another serious problem.The packing must admit no water into the submarine,even 148.91 under tremendous pressures.Yet the packing Figure 8-1.Vertical section through a must be so designed that the periscopecan be submarine, with periscope elevated. freely raised, lowered, and rotated within it. The periscope itself must be completely direct contact with the sea. And yet the leakage waterproof.Since the submarine is so de- through them must be zero. pendent on its periscope, there must bepositive The problems we have listed so far have assurancethat the internal optical surfaces been strictly mechanical. But thereare optical will not fog up.This is done by keeping a problems too. The optical system must present pressure of 7 1/2 psi of nitrogen in the peri- to the observer a normal, erect image, bright scope at a suitable dewpoint. The head window enough to be useful. The field of view must be and its bezel, and the joint by which thehead is reasonably wide, so the observercan find his secured to the upper part of the tube,are in target quickly.

108 Chapter 8SUBMARINE PERISCOPES

The problem of image orientation is not OPTICAL DESIGN OF THE SUBMARINE hard.All you need are two prismsone at the PERISCOPE top of the tube and one at the bottomfacing in opposite directions. We will consider first the principal optical problem:securing a true field of useful width Field of view is a harder problem. In one in spite of the small head windowand the long design the tube is 40 feet long; light enters it narrow tube.The periscope designer solves through a head window a trifle more than an the problem by combining simple optical sys- inch wide.If there were no optical system in tems such as the astronomical telescope. the tube except the two prisms, the field of An astronomical telescope produces anin- view would be about one-tenth of one degree. vertedimage.Ithasonly two principal Buttheoptical system is so designed that elementsan objective and an eyepiece; thisis thetruefield of the image will be around a valuable feature for use in aperiscope, since 30°. we are trying to hold the numberof elements Remember that all the light that forms the to a minimum. We need not worryabout the image must come throughthat small head inverted image if we use two astronomical window.So we must keep to a minimum not telescopes in series.The first will invert till only the amount of glass in the system, but also image; the second will reinvert it. the number of elements. In any telescope, the magnifying poweris equal to the focal length of the objective divided Another problem is incorporating some range by the focal length of the eyepiece; andthe measuring device into the periscope system magnifying power is equal to the apparent field itself.This is normally incorporated into the divided by the true field.For example, sup- attack periscopes as a stadimeter. The stadim- pose that an object, when viewedby the naked eter is the more important of the periscope's eye, subtends an angle of5°. The same object, two ranging devices.The less important one when viewed through a telescope, appearsto being the telemeter, which is covered later in subtend an angle of 30°. You know at once this chapter. that the magnifying power of the telescopeis The periscope stadimeter uses the same 6 X. principle as the hand-held stadimeter covered Our problem is to take a fairly wide true in Opticalman 3 & 2Z NavPers 10205. It gives a field and reduce it to a narrow apparent field, double image, and has a built-in calculator. so that the image will travel asfar as possible However, it contains no mirrors; it uses an en- down the periscope tube.You have probably tirely different system to give you a double looked through the wrong end of a telescope at image. You know that when the target and the some time or other.You remember that the eyepiece of a telescope are fixed, the image will objects you saw looked very small and far off move if you move the objective at a right angle (and consequently the true field of view was to the axis.The periscope stadimeter uses much larger than the apparent field). this principle to displace the two parts of a The main optical system of the submarine tele- double image.The objective lens of the lower periscope consists of two astronomical main telescope is SPLIT VERTICALLY into scopes. We call them the UPPERMAIN TELE- two halves,withasmall space between SCOPE and the LOWER MAIN TELESCOPE. them. The upper main telescope is backwardsits eyepiece is at the top of the tube. Suppose we To use the stadimeter, you first set the want a true field of 30°. And suppose that our actual target height on the dial.Then, as you upper main telescope has amagnifying power of turn the ranging knob, half the lower main ob- 15 Xthe focal length of its objectiveis 15 jective rises (relative to the target image), times that of its eyepiece.Since the upper and the other half is lowered. As a result, you telescope is backwards, its actual magnifying will see a double image of the target, and the power will be 1/15 X, and its apparentfield farther you turn the ranging knob, the farther will be 1/15 the true field. Thus our30° true the two images will separate. When you bring field will be reduced to only 2° as it leavesthe the top of one image into line with the bottom upper telescope, and that narrow beam can pass of the other, you can read the range on the down the periscope tube for a considerable stadimeter dial. distance.

109 /141 OPTICALMAN 1 & C

(In Opticalman 3 & 2, NavPers 10205,we defined the objective as the lensnearest the target.If we apply that definition to theupper main telescope of the periscope, then it isnot really backwards. It is a normal telescope with a short-focus objective anda relatively long-focus eyepiece.But we are accustomed to working with telescopes whose magnifying power is more than one.We are used to the idea that the short-focus lens is theeyepiece, and the long-focus lens is the objective.The men who work with periscopes hold on to that ideathey call the upper lens of theupper telescope the eyepiece, even though there is noeye within 40 feet of it.We will go along with them.Keep that in mind so you will not be c onfused.) The lower main telescope is in the normal positionits objective is toward the target,and the focal length of its objective is greater than that of its eyepiece.Its magnifying power, therefore, is greater than one. In the example given, we assumed that theupper main telescope had a magnifying power of 1/15 X. Now, if we give the lower telescopea magnifying power of 15 X, the magnifying power of the two together will be:

1/15 x 15 1 The upper telescope reduced the truefield of 30° to an apparent field of 2°. The lowertele- scope, with a magnifying power of 15 X, will bring the field back to an apparent field of 30°, equal to the true field of the instrument. In figure 8-2 you can follow the path of light rays through the periscope we have described. Part A shows the action of the twotelescopes alone; in part B we have added the two prisms, to bend the line of sight twice through 90°.In the figure, the broken line represents the optical axis.The two solid lines show the path of A two rays from the center of the field;as they strike the first lens, they are parallel to the 148.92 axis. The two dotted lines represent two Figure 8-2.Path of rays through a periscope. diagonal rays, one from each extremeedge of the field.The angle between them is the true bending, the angle between them is the angle at field of the instrument. which the light diverges as it leaves theupper To illustrate the path of rays throughan telescope.These two rays limit the distance instrument, we can choose therays that are between the two telescopesthe objective of meat convenient for our purpose. We willuse the lower main telescope must be close enough the two diagonal rays that cross in front of the to the upper system so that these tworays will upper eyepiece because those two happen to fall on it. pass through the center of the upper objective. As you can see in figure 8-2, thereare two Since they pass through the objective without real images within this periscope. In part B of Chapter 8SUBMARINE PERISCOPES figure 8-2, we have put two real images at the field of its upper telescope is 2°. If the diam- reflecting surfaces of the prisms, simply be- eter of the objective of its lower telescopeis cause that makes it easier to follow the rays. 4 inches, what is the inter-objective distance? You will not find this situation in an actual Substitute in the formula: periscope, since any tiny flaw in the reflecting 2 2 surfaces would show up as a part of the final L= ---6 =114'5 inches image. 1 .01746 The sample periscope design we have described has a magnification of one.Since the The inter-objective distance of this periscope magnifying power of the periscope is equal to is about 9 1/2 feet. the proauct of the separate magnifying power To find the length of the entire optical sys- of its two telescopes, you can see that there tem, we must add the length of the two tele- are two ways to enlarge the image; we can scopes.Theoretically we could make the tele- decrease the reduction of the upper telescope, scopes any length, just by increasingthe focal or we can increase the magnifying power of length of their objectives. But the APERTURE the lower telescope. We might decrease the of the objectives is limited by the diameter of reduction of the upper telescope from 1/15 to the tube.Therefore we cannot increase their 1/7.5.Then the magnifying power of the whole focallength beyond certain practical limits system would be: without cutting the illumination below a useful level. 1/7.5 x 15 =2 Or, we could increase the magnifying power of the second telescope to 30 X. Then: 1/15 x 30 = 2

Thefirst method would require that we shorten the tube, since the rays from the first A telescope would then diverge at an angle of 4°, rather than 2°.The second method would decrease the illumination of the system, since it r would reduce the diameter of the exit pupil. Which method we would actually use would de- L pend, of course, on what we wanted our design to accomplish. Figure 8-3 shows how we can calculate the 148.93 inter-objective distance between the two main Figure 8-3.Calculation of the inter- telescopes.Part A of the figure shows the two objective distance. objectives of the periscope in figure 8-2, and the path of the diverging rays between them. In practice we have found that each telescope We want to calculate the distance L between the can be about the same length asthe inter- two objectives. Part B of figure 8-3 shows objective distance without decreasing the illum- the triangle we will have to solve to find L. ination too seriously. So the total length of our You can see that: periscope will be three times its inter-objective distance, or about 28 1/2 feet. L r It is obvious that the design of any periscope tan is limited by several factors: Where L is the inter-objective distance, r Is HALF the diameter of the objective of the lower Length of the tube. telescope, and 0 is half the apparent field of the Diameter of the tube. upper telescope. Magnifying power required. For a sample problem, let us use the peri- Diameter of exit pupil. scope we have already descrit.b.eil. The apparent Angle of true field. OPTICALMAN 1 & C

Now suppose we have to design a periscope that angle to calculate the inter-objective dis- with the following characteristics: tance. The formula is: Length of tube: not specified. Diameter of tube: 5 inches. Field: 40 degrees. L.-tanr 6 Thickness of tube walls: about 1/4 inch. Exit pupil: 5 millimeters. Where L is the inter-objective distance,r is Magnifying power:between 1.2 X and half the objective aperture, and 0 is half the 1.5 X. apparent field of the upper telescope. We have only two variables to work with: the tube length (which is not specified), and the Substituting: magnifying power (which must be between 1.2 X and 1.5 X).Now calculate the tube length for 2 2 each of these two magnifying powers. tan 1 12'.02095 9.95.58inches We willstart by finding the magnifying power of the lower telescope. It is determined The inter-objective distance is approximately by two things:the aperture of its objective, 7 feet 11 1/2 inches.The length of the whole and the size of its exit pupil. The inside diam- system will be three times that, or 23 feet eter of the tube is 5 inches minus 1/2 inch, 10 1/2 inches. or 4 1/2 inches.The lens mount and its sup- You can see that all the characteristics of porting tube will take up approximately another a periscope are interdependent.If we favor half inch, which limits the aperture of the ob- one of them we will have to sacrifice one of the jective to about 4 inches, or 101.6mm. For others.The periscope we have designed is a convenience, let us call that 100 mm.Then rather short one. However, no length was speci- what isthe magnifying power of the lower fied.So if we want to, we can make it even telescope if the exit pupil is 5 mm? Youre- shorter, and either increase the size of the exit member that pupil or decrease the diameter of the tube. What will be the length of the specified peri- diameter of objective scope when its magnifying power is 1.5 X? The Magnifying power = reduction of the upper telescope is: diameter of exit pupil 20 Then: --I:5-=13.33 100 Since the true field is 40°, the angle of beam is: M- -20 X 5 40_30 13.33 Since the magnifying power of the finished periscope will be 1.2 X, the reduction in the The inter-objective distance is: upper telescope must be: 2 2 20 L- tan---6-- 1 30' =.0281978.37 inches -18.67 X 1.2 - 6 feet 4.4 inches And since the true field of the periscope will and the length of the entire system willbe three be 40°, the apparent field of theupper tele- times that, or 19 feet 1.2 inches. scope will be: To increase the length of the tube beyond the limits we have calculated, we would have to add 40° =20 24' more telescope systems.To keep the image 18.87 erect we could add one terrestrial telescope, or two astronomical telescopes, or one Gali- That is the angle at which rays diverge from the lean telescope. Of course, the addition ofmore objective of the upper telescope. Wecan use telescopes is always objectionable, since it cuts

112 /17, Chapter 8SUBMARINE PERISCOPES down the illumination by reflection and absorp- TELEMETER LENS tion.However, there is often no other way in which we can design a periscope of the required The telemeter is one of the range-finding de- length. vices of the submarine periscope. It is essentially a reticlea piano- convex lens with suit- AUXILIARY TELESCOPES able markings engraved on its plane surface. In the longer periscopes such as the type 2 The two auxiliary telescopes each add one real you will find two additional astronomical tele- image to the periscope system. The engraved scopes. We refer to them, respectively, as the surface of the telemeter lens is mounted in the UPPER AUXILIARY TELESCOPE andthe real image plane of the upper auxiliary tele- LOWER AUXILIARY TELESCOPE. The two scope, and its markings therefore appear super- auxiliary telescopes are mounted above the main imposed on the target image. The telemeter is telescopes.Usually each of them has a mag- placed in the upper auxiliary telescope so it will nification of one; their only function is to length- vibrate WITH the field of view, thus eliminating en the system and to carry the image down movement BETWEEN the telemeter and the through the narrow, tapered section at the top target. of the tube. The markings on the telemeter lens appear In all periscopes in service you will find a on the image as horizontal lines, by which you Galilean telescope at the very top of the optical can read the angular height of the target. (The systemabove the upper auxiliary telescope. value of the graduations depends, of course, on Since it is relatively short, it does not lengthen whether you are using high power or low power.) the tube too much. The Galilean telescope pro- The telemeter system is similar in principle to videstheperiscope with its CHANGE-OF- a telescope w.a mil scale engraved, on its POWER mechanism.Since it forms an erect reticle. By observing the number of graduations image, it can be thrown in or out of the system that span the height of the target, you can read without changing the orientation of the target its angular height. Then, if you know its actual image. height, you can calculateits range by the In practice, the submarine captain always formula uses the highest magnification of the periscope for measuring the range and bearing of his tar- h get, to aim his torpedoes. He will use the low R= power only for observation. Since the two lenses of the Galilean telescope are moved on Where R is the range in yards, h is the actual or off the axis by a fairly long change-of-power height of the target in yards, and 0 is its angular control system, we =not be sure they will height, as shown by the telemeter. always come to rest in exactly the same place You can see that a submarine captain must on the axis.But in measuring target bearing, be an expert in recognizing other ships, and he we must have maximum accuracy.We must, must know their dimensions by using the table therefore, design the periscope to give low of masthead heights. And you can also see that power with the Galilean telescope IN, and high the telemeter never provides an instantaneous power with the Galilean telescope OUT. We can range reading; it always involves a calculation. do that by mounting the Galilean telescope back- In ranging with the telemeter, the submarine wards, like the upper main telescope. Its short- captain always measures the angular HEIGHT of focus divergent lens will be toward the target; the targetnever its angular LENGTH.The its long-focus convergent lens will be toward the reason for this is that the angular length of a observer. ship depends on its course angle. Butthe angu- Let us see how that actually works. In one lar height, at any given range, is constant. typical periscope design, the high power is 6 X; the low power is 1.5 X. The Galilean telescope COLOR FILTERS has a reducing power of 4 (or a magnifying power of 1/4 X).With the Galilean telescope Like most of the Navy's larger optical in- OUT, of course, the power of the periscope is struments,the periscope has a color filter 6 X. With the Galilean telescope IN, the power mount. It is located between the observer's of the periscope is: eye and the lower eyepiece lens.(It is outside 1/4 x 6 = 1.5 X the eyepiece window, so it can be cleaned or

113 7lk OPTICALMAN 1 & C repaired without breaking the gas seal of the zontal, and 10° below the horizontal. A sun periscope.)The colors are clear, yellow, red, filter located in the head section may be moved and green.The polaroid filter can be attached in or out of the optical path while the peri- to the color filter mount, so that, if necessary, scope is in high power. At night the telemeter you can use it in combination with one of the may be red-illuminated for better observation. colors. When not in use, the polaroid filter There are also attachments provided for mount- can be attached to the eyepiece box end of the ing a camera adapter to the eyepiece box periscope itself. for taking photos while the submarine is submerged. The 8B periscope also contains a means of PRINCIPAL COMPONENTS OF THE de-fogging and de-icing the head window of the TYPE 8B PERISCOPE periscope by use of a heated head window. The men on submarines at times have to The submarine periscope system 8B is a stand watch at the periscope when the sub- general purpose instrument consisting of a marine is submerged. To make this job a little type 8B periscope, an Electrical and Electronic easier the periscope system incorporates a (E and E) Adapter, and several externally training torquer, which is operated from the mounted control or connection boxes. righttraining handle and is used to aid in The type 8B periscope is a night service training the periscope.This is done by use of instrument of 36-foot optical length and 7 1 /2- a motor, which when turned on will help turn inch outer diameter, exclusive of the eyepiece the periscope. After about 15 minutes on and faceplate assembly, handles, and other con- watch, having to turn the periscope by hand trols on the eyepiece box.All electrical con- would wear the man out.With the power nections to the periscope are made through the torquer to assist him, this will not happen. E and E adapter. The power torquer is to be used as an assist The optical system in the 8B periscope con- to help turn the periscope and is not to be used tains a tilting head prism that is capable of alone.If used correctly, it will be like using elevating the line of sight 60° above the hori- power steering in a car.

OUTER FOCUSING TUBE KNOB BLINDER ATTACHMENT GRIP FOR LINE OF SIGHT ELEVATION EYEPIECE 11 FACEPLATE LEFT ;'RAINING RIGHT TRAINING HANDLE HANDLE SUN FILTER RELEASE EYEPIECE BOX BUTTON

TELEMETER GRIP FOR RHEOSTAT MAGNIFICATION--ww- KNOB CHANGE

POWER ASSIST E BE ADAPTER SWITCH

148.94 Figure 8-4.Eyepiece box.

114 1/94 Chapter 8SUBMARINE PERISCOPES

seal.The outer tube itself is made out of corrosion-resisting steel.

INTERNAL FRAMEWORK ANTENNA AS/822 The internal framework of the system consists of three main parts:the head skeleton, the body skeleton, and the eyepiece components. All of the internal optics are supported and positioned by this framework.The shafts and linkages from the eyepiece box, which are used to operate the mechanisms, are also supported by the internal framework.

- OPTICAL SYSTEM

The optical system of the 8B periscope con- OPTICAL sists of three main components: the head as- WINDOW sembly, optical relays, and the eyepiece and faceplate assembly.The head assembly contains a tilting prism, which is operated by rotating shafts and gearing from the left train- ANTENNA ing handle. A 2-speed and a 36-speed synchro are also incorporated, for precision measurement of the relative elevation of the line of sight. RADAR ANTENNA For low-power operation, movement of the right training handle mechanically causes two lenses (Galilean cubes) to rotate into position just below the head prism.These lenses act as a reverse telescope to decrease the periscope magnification. When the periscope is in the high power operatingposition, further movement of the right training handle causes a sun filter to rotate into place. The focusing knob on the side of the eyepiece box, shownin figure 8-4, mechanically moves the focusing erector lens 148.95 near the base of the tube. This knobprovides Figure 8-5.Head section. for the +1.5 to - 3.0 diopter focus range for the observer, and also provides for camera focus. EXTERNAL CASING There is also a sextant switch located on the left training handle, for taking sextant readings The external casing of the periscope system while submerged. consists of four main sections: the outer head, the outer tube, the eyepiece box, and the E and E adapter.The joints between the outer head HEAD SECTION and the outer tube and between the outer tube and eyepiece box, consist of an "0" ring, a Information on various components of the bronze coupling, two setscrews, and a gasket head section is not included in this course be-

115 1.24 OPTICALMAN 1 & C

cause it is classified.Figure 8-5 shows the Magnification: head section. High power 6 X The following are the design characteristics Low power 1 5 X for the 8B periscope: True field of view: 6 X 8° Weight 1,537 pounds 1.5 X 32 ° Outer diameter of main Exit pupil diameter tube 7 497 inches 6 X and 1.5 X 7 mm Overall length of peri- Maximum elevation, line scope with model F621 of sight 60° stub antenna 39 feet Maximum depression, line Optical length of periscope36 feet of sight 10°

116 /4./ J CHAPTER 9

PERISCOPE MAINTENANCE AND REPAIR

This chapter describes the general mainte- FOGGING OF OPTICAL SURFACES nance procedures you will use most often on the submarine periscope, and the procedure for Maintenance of the installed periscope is removing the periscope from the submarine and limited almost entirely to elimination or pre- transferring it to the optical ship. Detailed invention of fogged optical surfaces. All windows, formation on the submarine periscope is classi- cover plates, and input shafts must be kept water- fied and is not included in this course. You tight and gastight.Gas pressure within the will find that information in the Maintenance periscope must be maintained at 7 1/2 pounds Technical Manual Submarine Periscope Type per square inch (psi) at 70° F, to prevent all 8B and 8C, Nav Ships 324-0447. possibility of "breathing" when the pressure changes.(Pressure will vary from 7.1 psi at 60° F to 7.9 psi at 80° F.The pressure will HANDLING AND STORAGE vary even more at extreme temperatures.) The gas used for charging the instrument must be so dry that no condensation can occur at any A modern submarine periscope, in spite of temperature that the periscope may conceivably its size (up to 50 feet in length) and weight (up encounter in service. to 2,000 pounds) is a fragile instrument. When Fogging inside the periscope can be prevented moving it from one place to another, be con- by keeping the dewpoint of the charging gas ex- stantly alert to protect it from bending, vibra- tremely low. Since there is no control possible tion, or shock.Periscopes are shipped and over the dewpoint of the air outside the peri- stored in sturdy boxes, and are secured by scope, fogging of the external surfaces is fairly clamps.These clamps prevent endwise move- common. Fortunately, it is easy to correct. ment within the box. The bottom of the periscope well is likely When you remove a periscope from its box, to be considerably colder than the air in the be sure to put the clamps back in the box so they conning tower. When the periscope is raised to can be used again. When returning a periscope the observing position, especially if the air in to its box for reshipment, be sure that all the the submarine is fairly humid, condensation may clamps are in place.See that all accessories occur on the eyepiece window, and sometimes are either mounted on the periscope itself, or on the color filters.The observer's breath carefully secured inside the box. sometimes causes condensation on these sur- When moving a periscope in its box, always faces. The fogging usually disappears after the hoist or support the box at more than one point. periscope has warmed up for a few minutes.If preferablyat the quarter pointsto prevent it does not, it may be necessary to open the color needless stresses on the periscope tube.If a filter housing, to let the air circulate freely in- periscope is shipped by rail, the box should be side.In stubborn cases, remove the color filters securely chocked in the car. For highway ship- and wipe the eyepiece window with lens tissue. ping a reach truck should be used if available. The type 8B has a heater, which will keep the The box should be so loaded on the truck that eyepiece from fogging up, and a device which the overhanging end contains the upper, lighter heats up the head window to prevent fogging. end of the periscope. Thenameplate of the ship- External fogging of the head window is ping box should always be at the heavy end. much less likely, though it may occur if the

117 OPTICAI2vIAN 1 & C temperature of the sea water is below the dew- 2.If submarine personnel report that the point of the air at the surfaces. If when the peri- periscope is fogging, and the fogging is found scope is first raised, the image is clear, but to be INTERNAL, cycle the instrument and re- clouds up a few minutes later, moisture is prob- charge it. ably condensing on the head window as it dries. 3. Each time the periscope is disassembled To correct this condition lower the periscope or overhauled, or when the gas seal is broken far enough to wet the head window, and then for any reason, the instrument must be cycled raise it again. and recharged. 4. When inspecting a periscope, larefully INTERNAL FOGGING measure the pressure of its charging gas.(At- tach a gage to the outlet connection even if the periscope has a built-in pressure gage.)If the Internal fogging is far more serious than test shows a pressure of 4 psi or less, cycle external fogging, and of course it is much easier and recharge.(f the pressure is between 4 and to prevent than to correct. Prevention requires 7 1/2 psi, charge to 10 psi with nitrogen (dried only that all fittings be airtight, and that the in- by a silica-gel dryer or by the cold trap method) strument be kept fully charged with very dry and then bleed to 7 1/2 psi. nitrogen. If internal fogging does occur, the 5.If it is convenient, make a dewpoint test periscope must be dried out by a process called of the charging gas when inspecting the peri- CYCLING.An outline of the cycling procedure scope.(The dewpoint test is described later in is: this chapter.) The dewpoint of the charging gas 1. Slowly charge the periscope to highpres- should be -50° C or less.If the dewpoint of the sure (about 100 psi for scopes sealed with gaskets charging gas is appreciably higher than that, and 50 psi for scopes sealed with "0" rings). cycle and recharge. (Never look in the periscope while it is being Every periscope in service is provided with charged.) at least one inlet/outlet connection, controlled 2. Test for leaks by coating all fittings with by a valve. And each periscope is provided with soapsuds. some means for ensuring drculation of the dry- 3. Release the pressure, and draw a low ing gas within the instrument. In many designs, pressure vacuum (about 2 mm of mercury). the gas passes through the inlet valve (which 4.Close valves, and maintain the vacuum is always at the bottom of the instrument), for 3 hours.If the pressure rises noticeably, through a charging pipe, to the head section. redraw the vacuum; continue until the periscope From the head section it passes downward can hold its vacuum for 3 hours. (A rise in pres- through the optical tube and external casing to sure is not necessarily due to a leak; it may be the outlet valve.In other periscopes the gas due to water vaporizing inside the periscope.) passes upward through the optical tube to the 5.Charge with dry nitrogen to 10 psi; then head section, and then downward in the space bleed to 7 1/2 psi. between the optical tube and the external cas- You can cycle and recharge the periscope ing. without removing it from the submarine, PRO- VIDED THE TEMPERATURE IS57.° F OR CHARGING GAS HIGHER. At temperatures below 50° F, the vapor pressure of water is too low to permit The drying and charging gas for submarine thorough drying.If you have to cycle a peri- periscopes is NITROGEN, prepared in accord- scope when the temperature in the submarine ance with Navy specifications. The specifica- is below 50° F, remove the periscope and take tions require that the nitrogen be delivered in it to the optical shop. cylinders charged to 1,800 pounds per square When is it necessary to cycle the periscope? inch.The nitrogen must be entirely free from Follow these rules: acid, dust, and objectionable impurities, and it 1. Each time a periscope is dried and re- must be at least 99.5 percent pure. CAUTION: charged, attach a tag to show the date and pres- DO NOT USE A CYLINDER AFTER ITS PRES- sure of recharging. When inspecting the instru- SURE HAS FALLEN BELOW 400 psi.(When ment, check the date on the tag. If the periscope pressure in a cylinder is below 400 psi, oil and has not been re atarged in the preceding 6 months, dirt in the bottom of the cylinder will be dis- check the scope and recharge it if necessary. charged into the periscope.)

118 413 Chapter 9 PERISCOPE MAINTENANCE AND REPAIR

DRYING EQUIPMENT Since the indicator crystals are not sufficiently reliable to show the condition of the In drying or charging a periscope, the gas silica gel, the gel must be baked immediately from thd cylinder must pass through a special before each use, regardless of the color of the drying device before it enters the periscope. indicator crystals. Use a covered panorkettle; Either of two drying devices can be used. The bake for 2 hours at a temperature of 500° F. most reliable of these is the COLD TRAP.It Silica gel tends to be dusty, the purpose of consists of a coil of tubing immersed in a bath the filters in the dryer and its outlet line is to of acetone and dry ice. The temperature of the keep the dust from entering the periscope. Even cooling mixture will be around -70° C or less. so, some dust may pass through.This is ex- Any moisture in the drying gas will condense tremely objectionable, since dusting off one of on the inside walls of the copper tubing, until the internal surfaces of a periscope is a major the dewpoint of the gas is reduced to the tem- operation.So whenever it is possible use the perature of the coil. The gas that emerges from cold trap rather than the silica-gel dryer. the cold trap is extremely dry. Dry ice can usually be made aboard a repair DEWPOINT TEST ship or tender with the help of a Snow Man, if you have one.The Snow Man is a small, com- The dewpoint of a gas is tested by letting the pact, automatic machine, which makes dry ice gas flow against a cold surface and gradually from carbon dioxide gas.From one 50-pound reducing the temperature of the surface until cylinder of CO2 gas, the Snow Man will make moisture condenses on it.When condensation about ten 12-ounce cakes of dry ice. begins, the temperature of the surface is equal If neither dry ice nor the means of making to the dewpoint of the gas. it is available, use a SILICA-GEL DRYER. Fig- Figure 9-2 shows the equipment required for ure 9-1 shows a Mk 3 instrument dryer modi- a dewpoint test. The numbers in the figure cor- fied for use with the submarine periscope. Note respond to those listed here: the filter units inside the cylinder, and the Cuno 1. A centigrade thermometer, with a range Filter in the outlet line. from minus 100° C to plus 50° C. 2. Three 200-m1 pyrex Erlenmeyer flasks, each silvered on the bottom and part of the side.

TO PERISCOPE If the silver is outside, it must be copper plated INLET PLUG and coated with acetone-resisting enamel.If the silver is inside, it must be coated with clear lacquer. 3. Two pieces of glass tubing (total about 12 inches), bent to form an inlet and outlet tube as shown in the figure. CUNO AIR LINE FILTER TYPE DSA

SCREEN AND SPACING RING

GLASS WOOL FILTER UNIT

ABSORBENT COTTON FILTER

SCREEN AND FROM NITROGEN TANK SPACING RING

148.96 Figure 9-1.Mk 3 instrument dryer, adapted 148.97 for periscope use. Figure 9-2.Dewpoint testing equipment.

119 OPTICALMAN 1 & C

4.Four feet of rubber tubing. 5. A two-hole rubber stopper to fit the Erlen- meyer flasks, and hold the inlet and outlet tubes. 6.Half a pound of dry ice.(Not shown.) 7. A one-liter pyrex beaker, big enough to contain one of the Erlenmeyer flasks immersed in 2 inches of cooling mixture. 8.Half a liter of acetone. 9.Soft apiezon wax, for sealing the fittings. To make a dewpoint test, follow these steps: i.Heat the Erlenmeyer flasks on a hotplate to drive out all moisture. 2. Assemble one of the flasks with the rubber stopper, the inlet and outlet tubes, and the rubber tubing.The inlet tube should almost touch the bottom of the flask.(Leave the two other flasks on the hotplate to keep them warm and dry.) 3. Connect the rubber tubing to the outlet connection of the periscope. Use the soft apiezon wax to seal all the connections: one at each end of the rubber tubing, two at the top of the rubber stopper, one between the stopper and the flask. 4. Openthe periscope outlet valve very slightly, to permit an extremely light flow of gas through the apparatus. To detect alight flow of gas, hold the outlet tube of the flask close to your lips.If the escaping gas can be felt with your finger, the flow is too strong. 5.Pour the half-liter of acetone into the 148.98 beaker. Figure 9-3.Cycling equipment. 6. Immerse the Erlenmeyer flask in the acetone, to about an inch above the silvered in the figure correspond to those listed here, sides.Try to keep the flask from touching the except as noted: bottom of the beaker. 1. A vacuum gage (Stokes-Flosdorf Mano- 7.Put the thermometer into the acetone, meter). and hold it or clamp it so that its tip is about 2. Vacuum gage fitting for the inlet con- 1/4 inch from the bottom of the beaker.(If the nection of the periscope. (Not shown.) thermometer touches the sides or bottom of the 3.Cenco Hyvac pump. beaker, it will give a false reading.) 4.Cenco Hyvac pump fitting for the outlet 8. Slowly add powdered dry ice to the ace- connection of the periscope. (Not shown.) tone, stirring constantly.Carefully watch the 5. A pressure gage, with a range from zero silvered surface of the flask, under the end of to 150 psi.(Not shown.) the inlet tube. When the surfacebegins to cloud, 6. A Mk 3 instrument dryer, adapted for quickly read the thermometer. Recordthe tem- use with the periscope (as in fig. 9-1). perature. 7.Freshly baked silica gel.(Not shovm.) 9. Repeat the test twice more, using the two 8. Reducing valve for the nitrogen cylinder. other warm, dry Erlenmeyer flasks. The highest 9.Soft apiezon wax. (Not shown.) cf the three thermometer readings is the dew- 10.Pyrex thermos jar, with an inside dia- point of the charging gas. meter of 2 3/4 inches, and an inside depth of 12 inches. The thermos jar should be surrounded CYCLING EQUIPMENT with half-inch cork insulation, and secured in Figure 9-3 shows some of the equipment a metal container. The joint betwe en the insula- needed for cycling a periscope. The numbers tion and the flask should be sealed with wax. Chapter 9PERISCOPE MAINTENANCE AND REPAIR

11. Fifteen feet of 3/8-inch copper tubing, 5. Remove the outlet plug of the periscope, coiled to 2 1/2 inches outside diameter, and and release the internal gas pressure, if any, inserted in the flask. by opening the air outlet valve. When all the 11A. Wire screen. pressure is released,close the outlet valve. 12. A Cuno air filter,in the line between the nitrogen tank and the copper coil. 6. Remove the inlet plug, and secure the 13. Half aliter of acetone.(Not shown.) hose fitting in the inlet connection. 14. Three pounds of dry ice. (Not shown.) 7. Insert the zero to 150 psi gage in the 15. Snow Man dry ice machine. air outlet fitting and use an offset screwdriver toopen the outlet valve, as in figure 9-4. 16. Cylinder of CO2. 8. Connect the nitrogen cylinder, through 17. Nitrogen cylinder. the reducing valve and the dryer, to the inlet The above list includes all the equipment connection of the periscope. If you are using for BOTH methods of drying. If using the cold the cold trap dryer, pour half a liter of acetone trap method, you will not need items 6 and into the flask, and stir 3 pounds of powdered 7.If using the silica-gel dryer, you will not need items 10, 11, 13, 14, 15 and 16. dry ice into the acetone. Run gas slowly through Remember: DO NOT use the silica-gel dryer the dryer and charging lines for about a minute unless the cold trap method is impracticable. before making the connection to the periscope. 9. Close the reducing valve on the nitrogen CYCLING PROCEDURE cylinder.Open the main valve, and set the If inspection of the periscope has shown reducing valve for a pressure of 10 psi. Then thatcyclingand recharging are necessary, open the inlet valve of the periscope. follow these steps: 1. Carefully measure the temperature in the conning tower of the submarine and the temperature of the outside air. If either is below 50° F,remove the periscope and take it to the optical shop for cycling. 2.If conditions are satisfactory for cycling aboard the submarine, elevate the periscope from its wellhigh enough to give easy access toitsinlet/outlet connection.Be sureall required equipment is aboard the submarine. Do not try to run in long vacuum or pressure lines from outside. 3. Turn the stadimeter handwheel to the observing position, as shown by the stamped numerals on the stadimeter housing. To ensure easy reassembly of the stadimeter, set the number 58 on the height scale dial opposite the value 2.2on the range scale dial.(In periscopes with no course-angle scale, set the number 15 on the height scale dial opposite the value 220 on the range scale dial.) Remove the four bolts from the stadimeter housing and lift off the stadimeter assembly, working carefully so as not to bend the transmission shaft. (The stadimeter will be found on attack scopes only.) 4. Remove all the other external projection fittings from the eyepiece box, including the training handles, the focusing knob, and the color filter attachment. This will give access toallthe packing glands, so you can test 148.99 them for leakage. Figure 9-4.Opening the outlet valve.

121 .1.24 OPTICALMAN 1 & C

10. Slowly build up the pressure. Remember the periscope and deposit it on the optical that strong gas currents in the periscope may surfaces. It takes a major overhaul to repair deposit dust on the optical surfaces, and a this damage. sudden increase in pressure may throw the 18. When the pump is operating properly optical system out of line. Raise the pressure open the inlet valve,so the manometer can in 4-pound steps, holding each value for about indicatethe vacuum in the periscope. Keep 5 minutes before increasing it. The pressure pumping until the manometer shows a pres- should build up to 100 psi (50 psi for scopes sure of 4 mm or less (2 mm, if it is possible sealed with "0" rings)inabout 2 hours. to pumpit down that low). Then close the 11. When the gage in the outlet connection outlet valve, and secure the pump. shows a pressure of 100 psi, close the inlet 19. Hold the vacuum for 3 hours, and then valve of the periscope. Close off the nitrogen read the manometer. Any rise in pressure shows pressure atthe cylinder,and remove the that drying is incomplete, and so will require charging line fitting from the periscope inlet more pumping. connection. 12. Now check the periscope for leaks. If IMPORTANT: if you continue pumping, start possible submerge the entire lower end, in- the pump and let it run a few seconds BEFORE cluding the whole eyepiece box, in a container opening the outlet valve. of water. If that is not possible, coat all con- 20. When the periscope will hold a vacuum, nections and packing glands with heavy soap- close both theinlet and outlet valves, and suds, and watch for bubbles. At the periscope disconnect the pump and manometer. head, soap the edge of the window, the bezel 21. Now the periscope is ready for charg- frame screwheads, the gasket, the connection ing. Run nitrogen through the dryer and con- between the head and the taper section, and necting lines for a few seconds, then connect the bolts that secure that connection. If there the line to the input fitting of the periscope. is any sign of leakage, eliminate the leakbefore If a cold trap dryer is being used, add more drawing a vacuum. A leak through a packing dry ice to the acetone, to bring the mixture gland can sometimes be stopped by tightening up to the top of the coil. the gland. If necessary, release the gas pres- 22. Insert the pressure gage in the air sure (slowly, over a period of 2 hours), re- outlet connection, and open the outlet valve. place the faulty packing or gasket, and repeat 23. Slowly open the inlet valve, and grad- the pressure test. ually build up the pressure to 10 psi. Then 13. When you are satisfied that the periscope close the inlet valve, and shut off the nitrogen isgastight,close theair outlet valve and pressure at the cylinder. Disconnect the nitrogen remove the pressure gage from the outlet inlet fitting, and replace the inlet plug. connection. 24. Close the outlet valve, and remove the 14. Open the outlet valve slightly, to release pressure gage. Connect the dewpoint test ap- the pressure slowly and gradually overa paratus to the outletfitting, and a dewpoint period of 2 hours. When all pressure has been test. If the dewpoint is higher than minus 50° released, close the outlet valve. C, you must repeat the cycling procedure from 15. Connect the mercury manometer fitting the beginning. to the inlet connection. 25. If the dewpoint is satisfactory, bleed 16. Connect the evacuating fitting to the the pressure VERY SLOWLY, through the outlet airoutlet connection. Keep all leads short, valve,to 7 1/2 psi.If the periscope has a with as few joints as possible, to reduce the built-ingage, thisiseasy.Ifit does not possibility of leakage. have a built-in gage, bleed a small amount of 17. Start the Cenco Hyvac pump, and then gas, close the outlet valve, insert the gage open the outlet valve. Do not leave the pump in the outlet connection, open the valve, and unattended while it is drawing the vacuum. read the gage. Then close the valve, remove Ifthe pump should stop, or show signs of the gage, and continue bleeding, with frequent stopping, quickly grab the hose, kink it, and pressure checks, to 7 1/2 psi. close the air outlet valve to prevent the periscope. 26. The cycling procedure is now complete. vacuum from drawing air back through the, Secure all the cycling equipment. Replace the pump. The air that is drawn back will carry outletplug, and all the external fittings of oiland oilvaporfromthe pumpinto the periscope.

192 Chapter 9PERISCOPE MAINTENANCE AND REPAIR

SAFETY PRECAUTIONS DURING CYCLING Providing an access for drainage may be accomplished in a number of ways, depend- Hereisalistof safety precautions to ing on the periscope involved. remember and observe during cycling: On Type 2A periscopes: (Reference NAV- 1. Neverlet the periscope vacuum draw SHIPS 324-0293) Remove the stadimeter houshig air back through the pump. to gain access to the eyepiece skeleton re- 2. Use a reducing valve to lower the pres- taining screw. Remove the retaining screw and sure of gas from the charging cylinder. lead washer to permit drainage. 3. When using a silica-gel dryer, bake the On Type 8 periscopes: (Reference NAVSHIPS silica-gel for 2 hours at 500° F, immediately 324-0292) Remove the bottom eyepiece flange before use. Do not rely on the color of the to gain access to the eyepiece skeleton retain- indicator crystals. ing screw. Remove the retaining screw and 4. Be sure that the filter in the charging lead washer to permit drainage. line is clean and tight. On Types 2D, 2E, 2F, 8B, 8C, 8D, and 5. Be sure that all connections are tight. 8L periscopes: (Reference NAVSHIPS 324-0487, 6. Bleed out all lines before charging the 0515, 0442) Remove down to E & E adapter periscope. on8B,8C,and 8L periscopesto prevent 7. Never trytocycle a periscope at a entrance of water when the periscope is being temperature below 50° F. flushed. Remove and/or loosenhe lower door 8. Be sure the periscope is tight before sufficiently to permit drainage. releasing the pressure. A proper vacuum can Prior toflushing, movable optical com- never be drawn on a leaking periscope. ponents, such as the Galilean lenses and stadi- 9. Always take the dewpohit test from the meter lens, should be moved aside. Also, the air outlet connection of the periscopenever head prism should be rotated to provide maxi- from the inlet connection. mum clearance for the stream of water and/or 10. Alwayschargethe periscope slowly, filling hose. A large volume of fresh water building up the pressure gradually. In building directed as a gentle stream through the head up the 100 psi pressure (50 psi for scopes window opening is preferable to a high pres- sealed with "0" rings) always take a full sure stream from a nozzle. 2 hours, and take another 2 hours to release 2. After all sea water has been drained and it. theperiscope flushed thoroughly, seal the 11. Never use a nitrogen cylinder after the drainage hole and permit the scope tofill pressure has dropped to 400 psi or less. with fresh water. Actuate the operating controls 12. To ensure a complete seal, use spiezon a number of times to permit the fresh water soft vacuum wax around the hose fittings of the to enter all possible areas. Preventthe entrance inlet and outlet connections. of additional sea water if possible. 3. The flooded periscope should be returned CARE OF A FLOODED PERISCOPE to an optical repair facility as soon as possible for overhaul.

Occasionally the head or head window of REMOVING A PERISCOPE a periscope will be broken by striking some object in the water, or by the shock of depth To remove a periscope from a submarine charging, and the periscope will fill up with and transport it to the optical shop of a tender, sea water. It is essential that no time be lost follow these steps: in removing salt water from the periscope, 1. Removing a periscope from a submarine as corrosion damage begins almost immediately. can be done only in a sheltered harbor, since In the event of flooding the following procedures rolling of either ship is likely to seriously are recommended: damage the periscope. The submarine should 1. As soon as possible after flooding, the be moored alongside the tender on the side periscope should be drained of sea water and from whichit will be easiest to move the flushed with fresh water. This can be ac- periscopeinto the optical shop.If there is complished by removing the head window and a cover plate over the steady bearing of the providing a means of drainage and venting of. submarine (at the top of the periscope open- trapped air at the bottom of the periscope. ing.), remove the plate. OPTICALMAN 1 & C

2. Elevate the periscope high enough to 9-5) to the outer tube above the hoisting clamp. attach the slings. You will need free access The safetyclampswill keep the periscope toat least 2 feet of the outer tube below the from slipping downward within the hoisting point where the taper section is joined to it. clamp. 3. Bolt a forged steel hoisting clamp around 4. The slings must be long enough to clear the outer tube, at least 12 inches below the the periscope head, and they must be attached jointbetween the outer tube and the taper toa spreader bar of sufficient width to keep section. (The hoisting clamp is marked No. 2 them from fouling the head. Put the hook of infig.9-5.)The hoisting clamp should be the lifting crane in the hook opening of the lined with emery cloth with its smooth side spreader bar, as in figure 9-5. next to the outer tube of the periscope. Since 5. Raise the periscope to observing position, the friction between the clamp and the outer and transfer its weight to the lifting crane. tube must support the weight of the periscope, 6. Now remove all parts of the periscope donot try to use a clamp that fits poorly. that project beyond the diameter of the outer And never use a clamp containing setscrews. tube.Figure 9-6 shows these parts.First, Bolt one or two safety clamps (No. 3 in fig. remove the two training handles by removing the four hinge bracket bolts. 7. Remove the focusing knob assembly by taking out four lockscrews. 8. Remove thecolor filter assembly by pulling outward on the two spring-actuated plunger knobs. 9. Remove the stadimeter housing. (Follow the directions given earlier in this chapter.) 10. Remove the eyepiece attachments, which are secured to anchor screw pins projecting from the eyepiece box. 11. Now check to be sure the lifting crane is holding the weight of the periscope. Slack off the hoisting yoke. 12. Remove the lockscrews from the cover ring, and unscrew the cover ring with a spanner wrench. Then remove the hoisting yoke body, the phosphor bronze locating collar, the lower ball bearing race, the ball bearings and retainer, and the upper ball bearing race. (These parts are identified in fig. 9-6.) Be especially careful to protect all these parts from dirt and grit. 13. Remove the split ring and the ring cover. 14. Slack off thehull stuffing box gland. 15. The periscope must be hoisted vertically; before hoisting, check to be sure that the crane boom is directly above the periscope. Attach a hinged clamp with handles to the outer tube above the deck opening of the submarine. While thecraneishoisting the periscope, use the handles of the clamp to rotate the periscope back and forth, to be sure it is not binding. If there is any tendency toward binding, stop hoisting at once, and do not start again untilyou have found the trouble and 148.100 corrected it. Figure 9-5.Clamps and slings attached to 16. Hoist the periscope clear of the sub- the outer tube. marine and transport it in a vertical position

124 4) Chapter 9PERISCOPE MAINTENANCE AND REPAIR

OUTER TUBE OF PERISCOPE

(OVER RING

SPLIT RING

UPPER TALL BEARING RACE

BALL BEARINGS AND RETAINER

LOWER BALL BEARING RACE

LEFT TRAINIAG HANDLE PHOSPHORBRON/E LOCATING COLLAR

GREASE FITTING HOISTING YORE 100Y

OPENING FOR WIRE ROPE SLEEVE

HINGE IRACIET

SPRING-ACTUATED LIMISCREWS FOCUSING 10101 ASSEMBLY

POLAROID FILTER ASSEMBLY

HINGE IRA(RET

EYEPIECE SOX

RIGHT TRAINING HANDLE

COLOR FILTER ASSEMBLY

ANCHOR SCREW PINS

STADIMETER HANOWNEEL

STAIMMETER HOUSING ASSEMBLY

148.101 Figure 9-8.External parts to be removed from the periscope. tothe upper deck of the tender. To place 17. Slowly lower the periscope toward a the periscope in. a horizontal position on the horizontal position, rolling the hinge carriage deck, first secure the lower end in a hinge (which carries the weight of the lower end carriage (see fig. 9-7). Roll the carriage under of the periscope) in the proper direction along the periscope, and turn it so that its clamp the deck. Figure 9-7 shows the hinge carriage, section is vertical. Lower the periscope into and the lower end of the periscope, in horizontal the clamp opening of the carriage, to within position. 4inches of the deck. Line the clamp and 18. When the periscope is nearly horizontal cap with emery cloth, with the smooth side move the clamp carriage into position under toward the outer tube of the periscope. Close it,with the upper half of the clamp hinge the clamp cap and bolt it to the clamp section of open. Lower the periscope into the clamp; the carriage. close upper halfof the clamp, and secure

125

./34 OPTICALMAN 1 & C

_-44111110

.'1'

148.102 Figure 9-7.Hinge carriage at horizontal 148.103 position. Figure 9-8.Upper part of periscope in clamp carriage. itwiththeswingingwingnut.(Seefig. 9-8.) analysis sheet and refer to them while over- 19. Remove the hoisting clamp and safety hauling the periscope. Remember, disassemble clamps from the periscope. only to the extent necessary to make needed 20. Bolt a spreader bar onto the outer tube repairs. Refer to the 8B periscope technical of the periscope, between the two carriages. manual for the detailsthat are needed to 21. Roll the periscope, on its two carriages, overhaul this periscope. to the in-board transfer opening of the upper deck. INSTALLING A PERISCOPE 22. Put the hook of the chain fall of the overhead track in the hook opening of the After the overhaul and collimation are com- horizontal lifting spreader bar. Transfer the pleted, install the periscope in the submarine weightof the periscope to the chain hoist, by following these steps: and remove the two carriages. 1. Remove the packing gland and thepacking 23. Lower the periscope to the overhead assembly (see figs. 9-10 and 9-11) from the chain hoists of the main deck. Transfer the hull casting of the submarine. weightof the periscope to the chain hoists 2. Transport the periscope from the optical of the main deck,attaching a hook in the shop to the submarine by reversing the procedure shackle at each end of the horizontal lifting used to move it to the optical shop. spreader bar, as in figure 9-9. 3. Lower the base of the periscope a short 24. Roll the periscope into the optical shop, distance into the hull casting of the submarine. and lower it onto the separated channel optical Apply grease freely to the outer tube of the benches. Remove the spreader bar and lifting periscope asitenters the guide bearings. clamps. 4. Attach the hinged clamp and handles to the outer tube of the periscope. Rotate the CASUALTY ANALYSIS ANDREPAMS periscope back and forth while lowering it, to check for binding. Hold a casualty analysis as you would for 5. When the periscope has been lowered any other optical instrument by checking for tothe observing position,replace the hull chipped or broken lenses and dirt on leases. packing assembly. Ordinarily, you will use Always check the periscope collimation before Garlock chevron packing, as shown in figure beginning to overhaulit.This will help to 9 -10.It consists of an upper metal packing determine what might be wrong with the instru- Rag,a ringof Garlock chevron packing, ment. Record allfindings on the casualty a lantern ring, two more rings of chevron

128 /6/ Chapter 9PERISCOPE MAINTENANCE AND REPAIR

BOAT DECK

UPPER DECK

MAIN DECK

148.104 Figure 9-9.Periscope transferred to overhead chain hoist of main deck. packing, a lower metal packing ring, a filler flaxpacking, assembled as shown in figure ring, and the metal packing gland.In reas- 9-11.This will stop the leak, but has the sembly step 10 pack the cavity around the disadvantage of making the periscope harder lantern ring with grease. to train. Cut the flax packing rings with square 6. Assemble the Garlock chevron packing ends,and measure them tofitthe inner assembly loosely on a work bench or table, circumference of the hull casting, rather than and measure thedistance from the upper the outer circumference of the periscope. As surface of the upper packing ring to the inner you bring up the packing gland, be sure to shoulder face of the packing gland. Now, in check for uniform clearance with a feeler gage. the hull casting of the submarine, measure the This is especially important with flax pack- distance from the lower face of the lower ing,since the gland is not brought all the guide bearing to the lower face of the extension way up against the extension ring. ring. This second measurement should be 1/16 - 8. Assemble the azimuth circle and auxi- to 3/32-inch longer than the first, to provide liary circle attachment to the extension ring. the clearance shown in figure 9-10. If there Train the periscope on the forward and after isinsufficientclearance,replace the filler bench marks of the submarine, to be sure the ring with a shorter one, or cutit down on azimuth circle reads correctly on the lubber's a lathe. line. 7. Assemble the Garlock packing assembly 9. Reassemble the hoisting yoke, and fill in thehull casting, and bring the packing itwith mineral grease, GradeII medium. gland hard against its shoulder. Now with a 0.006 - 10. Now, while raising and lowering the inch feeler gage, check the clearance between periscope, fill the lantern ring cavity, through the outer tube of the perioscope and the inner the external grease fitting of the hull cast- circumference of the packing gland. The clear- ing, with mineral grease, Grade II medium. ance should be uniform all the way around. 11. Assemble all the external parts of the Note: At this point we will discuss packing eyepiece box, following the disassembly steps leakage. When leakage occurs through the Gar- in reverse. lock packing, you will be expected to fix it. The 12. Train the periscope several times through usual cause of leakage through the chevron pack- 360°,and watch the azimuth circle.If the ing is distortion of the packing ring, which opens periscope grinds againstit, the circle has up a crack between the packing and the peris- been improperly mounted. Remount it in the cope. Usually the leakage can be stopped Iby proper position. While training the periscope, removing the packing and replacing it, or by listen for grinding in the guide bearings. If adding an extra packing ring.If the leakage you hear grinding,itprobably means that continues,replace the chevron packing with chips of metal have fallen into the bearings OPTICALMAN 1 & C

HULL CASTING

HULL CASTING LOWER STEADY LOWER BEARING STEADY BEARING

716 CLEARANCE FLAX

PACKING RING PACKING RING

CHEVRON PACKING LANTERN RING

LANTERN RING

CHEVRON PACKING PACKING RING

PACKING RING FLAX

FILLER RING

GLAND

EXTENSION EXTENSION RING RING 148.105 148.106 Figure 9-10.Garlock chevron packing. Figure 9-11.Emergency flax packing. during assembly. To correct this, the peri- stadimeterinthe observing position,to be scopemust bewithdrawn,the outer tube sure there is no double image at the Infinity scratches smoothed down, and the guide bear- reading. Check the focusing adjustment; the ings cleaned and repacked. range of diopter setting should be frcdn -3 to + 1 1/2 diopters. 13. Check the periscope training handles, 14. When the periscope is in satisfactory the altiscope, and the power shift, to be sure condition, report to the submarine officer and they are all functioning properly. Check the ask him to inspect it for approval. CHAPTER 10

SHIP-MOUNTED BINOCULAR

The ship-mounted binocular is used by the +60°. There are also locking devices that will quartermaster or signalman in conjunction with hold the binocular assembly in any desired visual signaling operations on many ships. The position. For vertical adjustments a handcrank Navy uses both the Mark 3 Mod 1 and the Mark on thecarriage assembly permits vertical 3 Mod 2 ship-mounted binocular.Except as movement through a maximum range of 8 inches. noted herein, the only difference in the two Mods is that the Mod 1 binocular is secured to BINOCULAR ASSEMBLY a C-shaped bracket on the elevating carriage The binocular assembly contains the optics by a means of a dove-tailed plate, whereas the required to obtain the desired magnification Mod 2 binocular housing is fitted with trunnions and provision is made to install an illuminated which are secured to a U-shaped yoke on the reticle if required.An illuminated reticle is elevating carriage.The procedures for disas- not provided for binoculars used aboard ship. sembly and reassembly are the same for both Eyeguards are provided to exclude stray light the Mod 1 and Mod 2. from the observer's eyes when sighting through In this chapter we will discuss the Mark 3 the eyepieces.Two focusing knobs located on Mod 2 (fig. 10-1).Information is provided on each eyepiece enable the eyepieces to be in- the means of mounting the binocular assembly dividually adjusted to accommodate eyes of un- and the construction of the binocular assembly equal vision.Each focusing knob is provided itself.Step-by-step procedures are given for with a diopter scale which is graduated from the disassembly, reassembly, and charging of -3 to +1 diopters in 1/2-diopter increments. the binocular. An interocular knob, located below the right eyepiece, is adjustable from 56 to 74 milli- GENERAL DESCRIPTION meters, and provides adjustment of the interpupillary distance of the eyepieces. To control The ship binocular consists of four main the brightness of the field of view, an INCREASE assemblies; the binocular, carriage, pedestal, DENSITY control knob is provided on the front and bulkhead bracket.The pedestal and bulk- of the binocular just below the left eyepiece. head bracket assemblies are used toeither By turning this knob left or right you can con- deck mount or bulkhead mount the binocular trol the brightness.Inlet and outlet connections assembly. The binocular and carriage as- are provided to evacuate and fill the binocular semblies are secured together and are employed assembly with dry nitrogen. on both types of mountings.A gray canvas cover protects the binocular assembly from the BULKHEAD BRACKET ASSEMBLY weather. The bulkhead bracket assembly is used to CARRIAGE ASSEMBLY mount the ship binocular on any vertical surface which allows the binocular assembly to be An azimuth scale and an elevation scale are rotated 360° in azimuth and elevated through mounted on the carriage assembly; these permit a range of 8 inches without anyobstructions. the binocular assembly to be positioned in The bulkhead bracket assembly is slotted at azimuth and elevation.The elevation scale is each Bide to accept swivelling eyebolts of the graduated in 1-degree increments from -10° to carriage assembly. (See fig. 10-1.)

129 OPTICALMAN 1 & C

PEDESTAL ASSEMBLY sembly; the image travels through either a compensator lens or a polarizing filter as re- The pedestal assembly (fig. 10-1) may be quired by the viewer.The two porro prisms used where deck mounting of the ship binocular invert the image to an erect position (as viewed is desired. The carriage assembly is inserted through the eyepieces).The objective lenses through the large hole of the pedestal assembly; in the ship binocular are air spaced doublets slotted holes at the top of the pedestal accept which have a spacer ring between them. The the swivelling bolts of the carriage assembly. eyepiece consists of three lenses:the triplet field lens, doublet center lens, and the singlet DESIGN CHARACTERISTICS 'ye lens.

The design characteristics of the Mark 3 VARIABLE DENSITY FILTER Mod 2 binocular are: Magnification 20 power Each barrel contains one adjustable and one Clear aperture of ob- fixed polarizing filter to control the intensity jective 120 mm of light entering the binocular assembly. The True field of view 3°30' INCREASE DENSITY control rotates the adjust- Eye distance (at zero able polarizing filter to obtain the desired light diopters) 22.5 mm intensity,With the INCREASE DENSITY con- Apparent field (approx.). 70° trol set to the OUT position, the control rod Exit pupil 6 mm contacts the filter stop, which swings the fixed Interpupillary distarice.. 56-74 mm polarizing filter out of position so that the Maximum elevation of compensators will be inserted in the binocular line of sight 60° assembly line of sight. The detent locks either Maximum depression of the fixed filters or the compensators in the line line of sight -10° of sight. Overall binocular length FOCUSING MECHANISM (sunshade extended)....20.375 inches Overall binocular width.. 22.5 inches The eyepieces are of the internal focus type. Height above bulkhead bracket or pedestal The eye lens is mounted and sealed in the lens Extended (eyepiece housing assembly; the center lens and the field LOS) 35.375 inches lens are mounted in a lens mount which may be Retracted (eyepiece positioned axially for focusing. When the diopter LOS) 27.375 inches knob is rotated through a range of +1 to -3 Component weight diopters, a cam control will adjust the lens Binocular assembly...51 pounds mount to produce the proper correction for the Carriage assembly... 105. 5 pounds individual observer. Pedestal assembly.. 66 pounds Bulkhead bracket MECHANICAL OPERATION assembly 29 pounds On the top of the light filter assembly housing PRINCIPLES OF OPERATION is the headrest; it slides onto the headrest support shaft to provide fore and aft adjustment and The ship binocular is used to magnify distant is locked into position by a locking nut. A hinge objects whose details are indistinguishable, so assembly is also provided to allow upward and that the viewer may see them with greater downward movement of the headrest. detail., A handwheel is provided for locking the binocular in azimuth. Rotation of the handwheel OPTICS clockwise will cause locking action by forcing the brakeshoe against the undercut portion of the The general arrangement of the optics con- elevation shaft. tained in one of the two identical barrels in the binocular assembly is illustrated in figute 10-2. MAINTENANCE AND REPAIR The objective lenses form a normal inverted This section discusses preventive mainte- image of the object entering the binocular as-.. nance and corrective maintenance for ship 130 /SS Chapter 10SHIP-MOUNTED BINOCULAR

1. BINOCULAR ASSEMBLY 2. CARRIAGE ASSEMBL Y 3. BULKHEAD BRACKET 4. PEDESTAL ASSEMBL Y

5.SWIVELLING EYEBOLTS

69.18 Figure 10-1.Ship binocular. binocular.The amount of preventive mainte- PREVENTIVE MAINTENANCE nance that ship personnel carry out will determine how much corrective maintenance you will Proventive maintenance of the ship binocular have to do when the ship binocular is brought includes routine inspection and cleaning pro- to the optical shop for repair. cedures which are performed under shipboard 131 )43 OPTICALMAN 1 & C

!LW

9 k

A IIle L__

A PO TivE ItlJti NO Oil ill:i vf I I I. I .ARIA(Ilf D(NSIII I it TE it , l'ORR'DPRISPAS !UL' 1111.k:1A1 OUT; Cf NTC41 INS I SII INS 148.108 Figure 10 -2. Arrangement of optics. conditions.Preventive maintenance procedures and oil from the rubber components, wash them should be performed without exposing the in- with a mild soap and water solution.Note: ternal elements of the ship binocular to at- Rubber will deteriorate if not kept dry. mospheric conditions. Two types of fogging (external and internal) The ship binocular should be inspected by may be encountered when using the ship binoc- qualified personnel to ensure its operational ular. External fogging is a temporary condition capability. Perform the following inspection that will disappear as the lens surface becomes tests at least every six months: warmer. To immediately remedy this condition, 1. Check that the binocular assembly is wipe the eyepiece and objective lenses with lens capable of being elevated from a -10° position paper. Internal fogging indicates that a seal through a +60 position without binding. has been impaired at some point, allowing water 2. Ensure that the carriage assembly yoke vapor to enter the binocular.If internal fog- has smooth rotation through 360° in azimuth. ging occurs, the binocular will have to be taken 3. See that the three locking devices: head- to the optical shop for repairs and recharging rest, binocular elevation, and azimuth function with dry nitrogen. (The procedure for recharg- smoothly and lock securely. ing will be given later in this chapter). 4. Check that all controls operate smoothly but offer enough resistance to indicate a snug CORRECTIVE MAINTENANCE fit between their respective shafts and packing rings. The overhaul of the ship binocular will be 5. Be sure that all external optical surfaces performed ONLY in an optical repair shopwhere are clean. adequate facilitiesand equipment for over- 6. Check that the rubber visors slide snugly haul,repair, and collimation are available. along the objective mount and examine all rubber The ship binocular should be overhauled only components for any signs of deterioration. when necessary due to a malfunction of moving 7. Check all external fastenings for tight- parts, separation of cemented lenses, a break ness.After a period of excessive vibration in a seal allowing water vapor or dirt to enter or when shock conditions have been experienced, the binocular assembly, or destruction or misa- recheck the fastenings. lignment of optical parts. The objective and eyepiece lenses may be 'f a seal has been broken, it will be neces- cleaned using lens paper or a soft, lint-free sary to disassemble the binocular to the extent cloth which may be moistened withalcohol to re- required toclean and dry alloptical and move grease.Unnecessary cleaning should be mechanical parts.Inspection and replacement avoided.Wipe metal surfaces to remove ac- of all packing rings, and gaskets as necessary, cumulation of salt or dirt.To remove grease should be accomplished during the overhaul 132 -

. /31 Chapter 10SHIP-MOUNTED BINOCULAR procedures.Immediately following the reas- If both objective lenses from both barrels are sembly procedures,the binocular assembly removed at the same time, it is advisable to should be charged with dry nitrogen. keep the lenses and other components of the The following checklist may be used to de- left and rightlens mounting arrangements termine the extent of repairs necessary to re- separated and identified so that they may be return a damaged ship binocular to satisfactory placed properly.) operating condition: 4. Next remove the optics housing from the 1.Inspect theexterior of the binocular light filter housing.First remove retaining assembly for physical damage. ring (73) that secures the light filter assembly 2. Ensure that the interocular handle oper- to the optics housing. ates smoothly without binding or excessive 5. Next detach spring (84) from the detent looseness. arm. 3. Check for proper operation of the IN- 6. Now remove the light filter assembly CREASE DENSITY control. from the optics housing. 4. View a distant object (approximately 1/2 7. Remove screws to detach retaining plate mile) and adjust focus control of eyepiece to from filter housing. ensure proper definition for each eye. If proper 8. Remove washers (78 and 81), polarizing definitions cannot be obtained, either an adjust- filters (79), and compensating filters (82) from ment of the diopter controls is necessary or housing. the optics of the binocular assembly are de- 9. Remove screws to detach clamp (76), fective. and gear assembly (70 and 71) from filter hous- 5. Check that the elevation, azimuth, height ing. mechanism, and locks operate smoothly. 10. Remove retaining rings (74), and po- 6. Check for internal gas pressurn. larizing filters (75) from filter housing. 11. Now separate the prism housing from the OVERHAUL lightfilterhousing. First remove screws Disassemble the ship binoculars ONLY to the securing sector gears (95) and sleeve bearing extent required for replacements, repairs, or (96) allowingseparation of the two prism adjustments. Use appropriate illustrations and housings from the light filter housing. general arrangement drawings while disassem- 12. To disassemble the INCREASE DENSITY bling. These will help you determine the extent control (47) and the interocular knob assemblies of disassembly.Clean the top of the bench (48) follow theorder of index numbers in that you will be working on and have all the figure 10-3. toolsthat you will need within easy reach. 13. Refer to figure 10-3 and remove the appropriate screws to separate the prism hous- DISASSEMBLY ing from the eyepiece housing. 14. Now disassemble the prism and plate Before disassembling any component from assemblies by removing the appropriate acre' s the binocular assembly open the OUTLET screw to separate the prism and plate assembly from (top of right barrel) to release the internal pres- the housing. sure if parts within the binocular seal are to be 15. Remove items(37 through 39) from removed. prism plate. Disassemble the binocular assembly as fol- 16. Loosen screws and remove retaining lows (refer to fig. 10-3): strap (41) and clamp pad (40). 1. To disassemble the objective lens assembly remove ring (56) and the preformed 17. Remove prisms (42) from supportplate. packing (62) from the objective lens housing. Wrap prisms in lens paper and store in safe 2. Unscrew ring (57) and remove spacer place. (58) from the crown objective lens, and remove 18. Now disassemble the left and right eye- crown lens (59) and wrap inlens paper and store piece housing assemblies. Loosen setscrew in a safe place. and remove diopter knob (25). 3. Remove spacer (60) and objective flint 19. Next loosen screws and remove bearing lens (61) from housing and also wrap flint lens sleeve (30) and items (27 through 29, 31, and in lens paper and store in a safe place.Note: 32).

133.. ./58 71 87 85 78 79 73 70 .0.. 68 67 84,...,186188--._. 1 IS li/83 / C.) _?\..,(*) 75 - --176 ...., 77 74 2 /917e. 90.\ 55 61 62 65 57 59 7 10-1 54 56 .,-;;;;,. 13 4v iri 12 11 I 97 46 38 \ 37 ,..40 9 25 34 33 92 SI 95 94 96 :is) 47 46 Figure 10-3.Binocular assembly. 53 / 50irqN\ 148.110 Chapter 10SHIP-MOUNTED BINOCULAR

20. Disassemble items (16 through 25) fol- between 0.002 and 0.005 inch.If it is not, shim lowing the order of index numbers stawn in with flat washer (49) to obtain required endplay. figure 10-3. 14. When assembling focusing mechanism Disassembly of the ship binocular is now insert assembly consisting of bearing sleeve completed.The next step is to repair or re- (30), diopter shaft, and cam control (32) into place parts that are worn or damaged. diopter shaft bore of housing (with eyepiece lens assembly, 19 through 22, secured in the REASSEMBLY housing).With the flange of the bearing sleeve (30) held securely against the eyepiece lens Reassembly procedures are essentially the housing, measure end play of shaft (between reverse of disassembly.Old packing should shaft assembly, cam control, and eyepiece lens be replaced and parts which were sealed with housing,18 through 22).End play should be glyptal should be carefully cleaned before re- between 0.001 and 0.005 inch. Disassemble and sealing with fresh compound. shim between bearing sleeve and diopter shaft Match-marks noted or made at disassembly with flat washer (27) to obtain desired end play. will assist in proper orientation and mating of 15. To set diopter knob to correct mounting parts.Extreme care should be exercised to position with respect to its diopter scale and prevent oil or moisture from contacting parts the reference mark on the eyepiece casting, it to be mounted inside the binocular assembly. will be necessary to establish the zero diopter To reassemble the binocular assembly, do position for each eyepiece. the following : Insert a test reticle in place of item 37 into 1. Apply a bead of Navy approved sealing housing(39). The test reticle should have compound, approximately 3/32 inch in diameter, markings on the side closest to the objective to junction of outside diameter of crown objec- end of the binocular. Assemble the prism plate tive lens (59) and housing. assembly to theeyepiece housing. Set an 2. Assemble spacer (58) and ring (57) in auxiliary telescope which has been focused to cell housing.Ring shall be installed to ensure suit the viewing eye of the observer against metal to glass contact between items 58 and 59. the binocular eyepiece. Rotate the diopter shaft 3. Apply a thin film of Navy approved high until the image on the test reticle is in sharp vacuum grease to all preformed packing. focus. Position the diopter knob (25) on the 4. Apply a thin film of adhesive to the diopter shaft so that the zero marking on the housing shoulder and eyepiece lens (17). knob coincides with the reference mark on the 5. Press fit filter housing shaft (89), grooved casting.Secure the knob with the setscrews. pin (90), and shouldered pin (91) into optics Remove the test reticle and insert the optical housing assembly. window (37). 6.Stake shoulder pin (87) to detent arm (88). 16. With the eyepiece assembly correctly 7.Press fit bearing sleeve (70) into spur set and using an auxiliary telescope adjusted gear (71). to the viewer's eye, the objective cell assembly 8. Press two straight pins (44 and 45) into can be brought into focus. Screw the objective right-hand support plate. cell in or out to bring a distant object in focus 9. Apply approved cement to items 40 and 41. (a collimator with an infinity target may be 10. Press fit two straight headless pins used).Secure the objective cell with ring (56). (99) into binocular housing to a height of 3/16 inch. COLLIMATION 11. Press knob stop cushion (100)into binocular housing. Two collimating telescopes are aligned on a 12. Align hole of interocular knob (48) with surface plate with their axis parallel, as in hole of gear shaft (94) and insert a dummy figure 10-4. Two reticle collimating telescopes pin. Check that end play of ear shaft is between are aligned opposite the collimator to establish 0.002 and 0.005 inch.If it is not, shim with a true reference lir.e of sight.The reticle flat washer (49) to obtain desired end play: image of each collimator is superimposed upon Remove dummy pin and press in groove pin (46). that of its opposite collimating telescope. The 13. Align hole of filter knob (47) with hole binocular is inserted and secured (with each of adjustment shaft (93) and insert a dummy eyepiece focused at infinity) as shown in figure pin.Check that adjustment shaft end play is 10-5.

135 "0 OPTICALMAN 1 & C

COLLIMATOR

COLLIMATOR+

COLLIMATING TELESCOPES

148.110 Figure 10-4.Collimation adjustments. Each collimator employs a reticle with a If the intersection of the reticle image falls rectangle. This graphically indicates the toler- beyond the limits of the rectangle, the binocular ance limits within which the optical and me- is out of adjustment. chanical axis of the line of sight must fall. To bring the binocular into collimation, two The image of the collimator is viewed through eccentric buttons (65, fig. 10-3) are provided the collimating telescopes.If the vertical and ineach objective of the optics housing and horizontal crosshairs of the reticle image inter- must be turned in conjunction with each other sect within the limits circumscribed by the to enable horizontal and vertical adjustment rectangleofthe collimatingtelescope,the of the objective barrels. When adjusting the binocularis aligned both optically and me- objective barrels, loosen the square flanged chanically. ringsecuring theobjective lens assembly.

COLLIMATING SHIP BINOCULAR COLLIMATOR TELESCOPES

148.111 Figure 10-5.Collimation setup.

136 Chapter 10SHIP-MOUNTED BINOCULAR

Retighten the flanged ring after collimationis 3. Remove theinlet plug and insert an completed. adapter connected to the nitrogen source. NOTE: On the Mod 1 binocular, a double- 4.Introduceand circulatedry nitrogen eccentric ring and lens mount must be rotated through the binocular until all air has been with respect to each other to bring the reticled discharged.Replace the OUTLET screw and image to its optimum position within therec- washers in the right barrel of the binocular. tangle. Turning the eccentric ringmoves the ob- 5.Charge the binocular to a pressure of 5 jective lens mount perpendicular to the optical psi.NOTE:Do not put more than 5 psi in the axis of the binocular. Turning the objective mount ship binocular. turns the lens on its mechanical axis and, there- 6.Tighten large INLET screw and remove fore, rotates the optical center of the lens. adapter.Replace inlet plug in the valve assembly. SEALING, DRYING, AND CHARGING 7.After a period of no less than 24 hours, check with a pressure gage to determine if The ship binocular shall be dried andre- there has been any significant gas leakage. Any charged with dry nitrogen whenever internal loss in internal pressure requires a recheck of fogging occurs or a seal has been broken. Pro- the binocular seal to determine the source of the ceed with the following steps: gas leakage. 1. Remove OUTLET screw and washer from 8. After correcting the taus e of gas leakage, right barrel of the binocular. if any, recycle the binocular (steps 1-7), then 2. Back off large INLET screw of gas inlet bleed off the gas to obtain an internalgage valve (67, fig. 10-3) to allow the entranceof dry pressure of 2 psi. Retighten the OUTLET nitrogen into the binocular. screw and replace the INLET plug. CHAPTER 11

TURRET PERISCOPE

Turret sight telescopes include all the gun thereby permitting the line of sight tobe rotated sight telescopes used on naval ships.Like through an arc of 30° in elevation, from 15° be- gun sight telescopes, they provide the observer low a plane perpendicular to the axis of the with an accurate lineof sight from gun to periscope. target.The gun sight controls the angle be- The objective lens is a cemented doublet. It tween the axis of the gun bore and the line of is carefully fitted into a threaded cell in the sight through the telescope. upper head assembly at the top of the optical In the turret periscope, unlike some of the tube. The lens is held in the cell with a threaded- gun sight telescopes, the eyepiece axis is the in retaining ring and lock ring. By means of a same as, or parallel to, the line of sight to the lock ring the objective cell is secured in the target. We can divide telescopes into two upper head assembly in the position where paral- classes: those in which the main optical system lax between a distant object and the crossline is direct, and those in which it is indirect. is eliminated.The crossline lens is convexo- In the direct type, all the lenses are in a straight plano (the convex surface faces the objective). line: the optical axis of the telescope. The etchings are on the plane surface, and the The optical system of the indirect type is lens is located in the second focal plane of the basically the same except that the axis of the objective.The front and rear erector doublets eyepiece is at right angles to that of the rest are alike and each is held in a threaded cell in of the system.In front of the eyepiece is a the upper and lower section of the optical tube right angle prism, to deflect the line of sight. and secured in position. The eyepiece prism is In front of the objective is either another right a right angle prism with the hypotenuse surface angle prism or a mirror, to deviate the line of silvered, coppered, and painted with a backing sight again. paint. It is fitted into a stationary prism mount Instruments with the indirect type of optical which is bolted and "doweled" in position in the system are often mounted with the axis of the lower head casting below the optical tube. main tube in a vertical position. For that reason, The sealing plate seals off the main casting, they are usually called periscopes, rather than so that you can overhaul the eyepiece and color telescopes. filter assembly without disturbing the other parts.The color filter assembly is of the ro- GENERAL DESCRIPTION tating type.There are four disks: red, yellow, clear, and polaroid.The eyepiece contains a An example of the turret periscope we have field lensdoublet and an eye lens doublet, chosen is the Mark 20 Mod 6.Figure 11-1 mounted in an eyepiece tube. shows two views of it. Figure 11-3 is a schematic diagram of the Figure 11-2 is a diagram of the optical sys- Mark 20 Mod 6 periscope. The main body tube tem.In front of the objective is a prism. The is of cold-drawn seamless steel tubing, 1/4 objective, or tilting prism, is a right angle inch thick.Its inside surface is nickel plated. prism with the hypotenuse, surface silvered, The outside has an undercoat of corrosion re- then protected with copper"and a backing paint. sisting paint, and a finishing coat of paint. The It is fitted into a prism mount which in turn is main body tube is threaded at each end, for at- secured in ball bearings so that the prism may taching the two end castings.The mounting be rotated through an arc of 15° in elevation, sleeve isshrunk onto the main tube;it is

138 4/3 Chapter 11TURRET PERISCOPE

EYE PRISM

148.112 Figure 11-2.Periscope Mark 20 optical system. The middle section holds the front erector cell. The lower section contains the rear erector cell.The optical tube is secured at the upper main casting, but its lower end is a sliding fit over a tube that is integral with the bottom casting.That arrangement lets the outer tube expand and contract, when the temperature changes, without deforming the optical tuba. The optical tube is provided with a spacer frame, in which a ball bearing is held against the main tube by spring tension.This frame and its bearing keeps the optical tube on its axis, but permits relative motion between the two tubes when the temperature changes. The handwheel, which controls the angle of the objective prism, is located on the bottom casting, to the left of the eyepiece. Its movement is limited by stops to a rotation of about 300° which is equivalent to a 30° change in the line of sight. Situated on the right side of the filter housing is a knurled knob which can be rotated to bring the desired ray filter or clear glass into position.An arrow on the top of the knob and four engraved designations on the plate around the knob indicate which filter is in position.For each of these four positions there is a detent to hold the filter mount firmly in place. The knurled knob on the left side of the ray 134.101 filter housing is designated "density."The Figure 11-1.Periscope Mark 20. rotation of this knob turns the polarizing plate nearer the eye, while the lower plate remains carefully machined and polished to provide a fixed, and so varies the light transmission of mounting surface parallel to the optical axis of the combination from the maximum to the mini- the periscope. mum. When the planes of polarization of these The optical tube assembly is made up of two plates are parallel, that is, when the trans- three sections.The upper section contains an mission is at the maximum, they are oriented inner tube which holds the crossline lens cell. to reduce to a minimum the intensity of the light

139 OPTICALMAN 1 & C

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1. Mounting Sleeve 11. Gas Outlet 20.Packing Rings, Upper and 2. Azimuth Ring 12. Gas Inlet Lower 3. Azimuth Hole in Azi- 13. Eyepiece Sealing Clamp Ring muth Ring 14. Filter Housing Packing Ring 4. Azimuth Ring 15. Filter Control Knob Two Rubber Gaskets Covers 16. Density Knob 21.Cover Clamp Ring 5. Lower Head 17. Screws to Remove Filter 22.Upper Head and Optical 6. Upper Head Cover Housing Cover Tube Clamp Ring (Left- 7. Handwheel 18. Setscrew to Remove Hand Thread) 8. Handwheel Crank Eyepiece from Cover 23.Upper Head Casting 9. Handwheel Stop 19. Screw to Remove 24.Objective Prism 10. Upper Window Handwheel 25.Objective Prism Mount

148.113 Figure 11-3.Schematic drawing, periscope Mark 20 Mod 6.

140 Chapter 11TURRET PERISCOPE

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26. Sextuple Screw and 34.Lower Head Bolts to 41. Upper Tube Lock Upper Bearing Tube (3 Bolts) Screw 27. Sextuple Screw Nut 35.Filter Housing Bolts 42. Lower Tube Lock 28. Antibacklash Gear (2 Bolts) Screw Sector 36.Azimuth Ring Clamp 43. Focusing Ring 29. Prism Bearing Caps Bolts 44. Diopter Scale 30. Objective and Objective 37.Sextuple Screw Bearing 45. Focusing Retaining Cell and Lock Nuts Rings 31. Objective Cell Lock 38.Drive Shaft 46. Filter Turret Retaining Ring 39.Two Spiders and Spring- Plate and Screw 32. Lower Prism Mount and Loaded Antishake Ball 47. Filter Index Roller Holding Screws Bearings 48. Filter Retaining Rings and Bevel Gears and 40.Upper and Lower Shaft Lock Screws Bearing Couplings 49. Eyeguard Ring 148.113 Figure 11-3.Schematic drawing, periscope Mark 20 Mod 6Continued.

J41 OPTICALMAN 1 & C

reflected from a horizontal specular surface at the polarizing angle. The gas inlet and outlet valves located on the base casting opposite the ray filter housing are marked with plates reading "gas inlet" and "gas outlet."These valves are provided for the purpose of circulating dry gas, such as nitrogen or air, through the periscope to prevent moisture from condensing on the lenses or to remove any moisture that might collect. The inlet valve connects directly to the optical tube and conducts the dry gas into it.Provision is made to circulate the dry gas from the optical tube to all parts of the instrument. The Mark 20 Mod 6 turret periscope has the following optical characteristics: Magnification 8 power 148.114 Angular Field 50 Figure 11-4.Releasing the eyepiece and Exit pupil 5 mm color filter assemblies. Eye distance 33 mm will expose three packing ringsone of brass OVERHAUL and two of rubber (gaskets). Remove them. 6. With the special wrench (fig. 11-7) loosen Disassemble the turret periscope ONLY to the retaining ring that secures the upper end the extent required for replacements, repairs, casting.Remove the casting to expose the or adjustments.Use appropriate illustrations elevation prism. Cover this prism at once with and general arrangement drawings while disas- lens tissue, and secure the tissue so it will not sembling.These will help you determine the come off. extent of disassembly.Clean the top of the 7. Use the special spanner wrench to loosen bench that you will be working on and have all the packing clamp ring at the eyepiece end of the tools that you will need within easy reach. the instrument.Remove the brass ring and rubber packing rings (gaskets). DISASSEMBLY 8. As you look into the lower end of the periscope body, you will see the heads of three The first step in disassembling the turret periscope is to release the gas pressure from the main tube.Refer back to figure 11-3 when nelessary, and follow these steps: 1. Remove the rubber eyeguard. 2. Remove nine screws from the edge of the eyepiece and color filter assembly (fig. 11-4), and lift off the eyepiece and color filter mount. 3. Remove two bolts to free the lower half of the color filter assembly from the periscope body (fig. 11-5). 4. At the eyepiece end of the periscope, remove the screws that secure the end plate. Re- move the end plate.(You may have to tap it gently with a rawhide mallet, to break the waterproof seal.) 5.With a special spanner wrench (fig. 11-6), loosen the packing clamp ring at the objective end of the periscope. Move the ring along the 148.115 body as far as the polished steel bearing; this Figure 11-5.Freeing the lower half of the color filter assembly.

142 4/7 Chapter 11TURRET PERISCOPE bolts that secure the lower main casting. Re- ring has a left-hand thread.) Now withdraw the move the three bolts, and take the casting off prism mount and the main optical tube. As you the body. withdraw the tube, the ball bearing on the leg of the spacer frame will fall into a recess in the periscope body.Gently lift the tube and %. work the bearing over the step at the end of the recess.Remove the ball bearing and tension spring from the holding bracket. 11. With a prick punch, mark both the segment and the rack of the prism elevation mechanism, so you can reassemble them in the same relative position (fig. 11-8). 12. Remove the screws frwn the objective prism. 13. By turning the elevation shaft, bring the prism to a position of maximum deflection. With a rolling motion, remove the mirror and its shaft and bearings from the assembly. 14. The elevation shaft is supported on the optical tube bracket by a split bearing. Remove the upper half of this bearing.Slip the shaft and its coupling collar off the elevation worm shaft. 148.116 15. Remove the locking nut, figure 11-9, and Figure 11-6.Packing clamp ring spanner holding nut from the outer end of the elevation wrench. worm shaft. 9.Inside the end of the body are two large 16. Remove the setscrew from the worm rings,to which the lower main casting was shaft bearing retaining ring.Remove the re- bolted.The first ring is threaded; unscrew it taining ring with the special tool provided for from the tube.Lift out the second ring. it.Unscrew the worm shaft from the elevation 10. At the objective end, use a special wrench rack guide block. See figure 11-10. to remove the prism mount. (CAUTION: this

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148.117 148.118 Figure 11-7.End casting retaining ring Figure 11-8.Reference marks on segment wrench. and rack. OPTICALMAN 1 & C

the optical tube from the prism mount with a pair of strap wrenches. Remove the prism mount. 21. Find the seam where the two halves of ri the optical tube are joined. Scribe a line across the seam, so you can reassemble the two halves of the tube in the same position.Use strap wrenches to start the thread, and then unscrew the two halves of the tube. 22. Remove the crossline lens mount lock screw.Hold the tube with a strap wrench, and use a fiber grip wrench to loosen the crossline lens mounts. Unscrew the mount. 2s. At the other end of the tube, remove the lock screw that secures the erector mount. Un- screw the erector mount, and remove the two lens mounts from it. 24. Remove the objective from its mount. 25. Remove the color filter mount from the eyepiece assembly. 26. Use an adjustable pin wrench to remove 148.119 the lock ring from the eyepiece mount (fig. 11- Figure 11-9.Removing the elevation worm 11). With the same wrench, remove the retain- shaft locking nut. ing ring.Now turn the focusing ring off the mount. Remove the focusing key guide with a 17.Remove the elevation rack guide block. pair of tweezers. Remove the lock screws Under one side of the rack, you will find three spring-loaded ball bearings.They allow for adjusting the tension on the block so it will travel smoothly. 18. Remove the collar bearing from the upper end of the elevation shaft. 19. Release the objective mount lock ring. Back off the ring a few turns, and thenunscrew the whole objective mount from the optical tube. 20. Remove the lock screw Llrn the optical tube, where it joins the pr:Im mount. Loosen t

148.121 148.120 Figure 11-11.Removing the eyepiece Figure 11-10.Removing the worm shaft. mount lock ring.

144 'It9 Chapter 11TURRET PERISCOPE from the focusing key, and remove the key with a pair of tweezers. 27. Pull up the eye lens mount draw tube, and free it from the adapter tube. 28. Find the small lock screw at the base %. of the eyepiece adapter, figure 11-12, and remove it. Unscrew the adapter tube with afiber grip wrench. 29. Disassemble the eyepiece cell. 30. Remove the four screws that secure the eye prism, and remove the prism.

148.123 " Figure 11-13.Sealing window retainer. 3. Lubricate the eyepiece mount and insert it in the adapter. Be sure to line up the focusing key screwholes with oblong opening.Replace the focusing key, and secure it with its two screws. Replace the focusing key guide. 4.Fit the focusing ring over the lens mount, 148.122 and engage its helical slot with the focusing Figure 11-12.--Eyepiece adapter lock screw. key guide. Screw on the focusing ring,and replace its retainer and lock ring. 31. Remove the eight screws from the seal- 5. Replace the color filter mount on the eye- ing window retainer, shown in figure 11-13, and piece assembly. Be sure that the filter you put lift off the retainer. Remove the sealing window. under the eyepieoe opening matches the name on the indicator dial. 6.Fit the string of wax around the edge of CASUALTY ANALYSIS the color filter housing. Join the two halves of the housing, and secure them with seven screws. The casualty analysis of the turret periscope 7. Replace the objective in its mount. Re- consists of inspecting the instrument after disas- place the front erector mount in the erector sembly and recording the repairs needed to put tube. the instrument back into service. By using the 8. Replace the crossline lens mount in its casualty analysis sheets, you can determine the position in the optical tube, and screw it up to cost of repair and the man-hours required to do the registration mark you made during disas- the job. sembly. Secure it with its lock screw. 9. Screw the head prism mount to the upper REASSEMBLY AND COLLIMATION section of the optical tube. Use a pair of strap wrenches to tighten it until you align the regis- 1. Replace the eyepiece adapter, tighten it, tration marks you made during disassembly. then secure it with its lock screw. Secure the mount in this position withits lock 2.Fit a string of wax on theeyepiece lens screw. seat. Reassemble the eyepiesce, and remove 10. Insert the objective mount in the head the excess wax. prism mount.

145 OPTICALMAN 1 & C

11. Insert the erector tube in the lower half of the optical tube, and secure it with its lock screw. 12. Now take the upper part of the optical tube to the periscope collimator Mark 3, and place it in a telescope holder. 13. Sight through an auxiliary eyepiece, shown in figure 11-14, and screw the objective lens mount in or out until you bring the collimator crossline into sharp focus on the periscope crossline, free from parallax.Secure the adjustment by tightening the objective mount lock ring.

148.125 Figure 11-15.Adjusting the front erector lens. 20. Fitthe elevation shaft collar to the worm shaft.(Caution: the collar is keyed; there is only one position in which it will fit.) vv. 21. Fitthe elevation shaft into itssplit bearing on the optical tube. Replace the upper half of the bearing, and secure it with its two screws. 22. Now you are ready to replace the elevation prism. Engage the teeth of the gear segment with those of the rack so that you line up the 148.124 punch marks you made during disassembly, Figure 11-14.Removing parallax. iigure 11-17. 23. Replace the two bearing bracketsover 14. Join the two halves of the optical tube. the bearings of the prism shaft, and secure them Sight through an auxiliary telescope, and adjust with the four bearing screws. Now test the action the erector lens with a special hollow wrench of the prism by rotating the elevation shaft (fig. 11-15) until you see the crosslinesin sharp through its full travel. focus, free from parallax. 24. Replace the spring and ball in the long 15. Now take the instrument back toyour leg of the support bracket.Insert the optical workbench.Secure the lower optical tube in tube in the body. Remember that you have to position by replacing the lock screw. ease the ball bearing over the recess inside the 16. Replace the rear erector lensmount in body.Fit the key on the prism mount bracket the erector tube.Replace the lock ring. (You willadjust both,later,atthe collimator.) 17. Under the elevation rackare three spring controlled ball bearings.Replace the springs first, then the ballbearings (fig. 11-16). Replace the rack on its bearings, and thread theworm shaft into the rack. 18. Replace the lower worm shaft bearing retainer, and screw it into the prism mount with its special wrench. Secure it with its lockscrew. 19.Fit the bearing over the upper end of the worm shaft, and secure it with the retaining 148.126 nut and locking nut. Figure 11-16.Elevation rack bailbearing.

146 /5/ Chapter 11TURRET PERISCOPE

148.127 Figure 11-17.Engaging the segment and rack. into the notch on the end of the body. See figure 11-18. 25.Replace the head casting clamp ring, the packing rings, and the packing clamp ring 148.129 on the body. (See fig. 11-19.) Screw the prism Figure 11-19.Clamping and packingrings. mount clamp ring over the end of the body, and End with tightenit with its special wrench. Turn it 27. Screw in the threaded ring. counterclockwise to tighten it. the three holes and the cut-out of bothrings in 26. In the eyepiece end of the body, insert line. the ring with the three threaded holes, but with 28. In line with the key on the inside ofthe no threads around its rim, shown infigure 11-20. lower casting, make a registration markwith a Fit the cut-out around the optical tube. lead pencil, as shown in figure 11-21. Continue the line on the outside of the casting.Use it to guide the key into the notch on thebody (fig.

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148.128 148.130 Figure 11-18.Reassembly of the optical Figure 11-20.Replacing the unthreaded tube in the periscope body. ring.

147 OPTICALMAN 1 & C

11-22).Secure the casting to the body by re- 32. To check the collimator alignment, put placing and tightening its three bolts. the telescope holder in the fixture, and rotate it (fig. 11-23). Both lines of sight must coincide

S 6.

148.133 Figure 11-23.Checking collimator 148.131 alignment. Figure 11-21.Lower casting key registration mark. 33. Carefully level the platform with an 29. Under the sealing window, place a gasket accurate spirit level, figure 11-24.You will of 1/64 inch thickness.Replace the window, use this platform for deviating the line of sight and put a gasket of 1/16 inch thickness over it. 90° to the horizontal collimation tube. Turn the Replace the window retainer, and secure it. spirit level to several different positions, to be 30. Secure the eyepiece assembly to the sure the platform is accurately leveled. body by two screws inserted from the top, and 34. Put a true 90° penta prism on the plat- by two bolts inserted from the bottom. form, as shown in figure 11-25. The crosslines 31. Bolt the fixture for holding the periscope of "A" and "B" must superimpose. into place on the collimator. 35. Mount the periscope in its fixture, and set the focusing ring at zero diopters.Sight into the eyepiece through an auxiliary telescope. The collimator and periscope crosslines must be in sharp focus, and without parallax. If the

148.132 Figure 11-22.Continuation of the 148.134 registration mark. Figure 11-24.Leveling the platform.

148 152 Chapter 11TURRET PERISCOPE

zontal. The crosslines must superimposein all three positions.When they do, collimation is complete.If the crosslines do not superimpose then you will have to adjust the segment gear until all three crosslines superimpose. 37. Turn the prism to maximum deflection. With the packing ring, retaining ring, and clamp ring in place, fit the head casting over the end of the body. Tighten the retaining ring withits special wrench. Secure the whole assemblyby tightening the packing clamp ring with the special spanner wrench. 38. Remove the eyepiece unit. Cut a gasket to fit the end plate. Replace and securethe end plate over its gasket. 39. Now replace the periscope on the collimator and check to see if any of theadjustments 148.135 have moved. See figure 11-26. Figure 11-25.Superimposing the crosslines. SEALING, DRYING, AND C HA RGING periscope crossline is not sharp, turn the focus- You have been sealing the periscopeduring ing ring until it is.Then look at the diopter the reassembling so there will not be anyneed scale.If the reading is minus, unscrew the to repeat those steps now. The nextsteps will rear erector lens and bringit back.If the be drying the periscope to removemoisture scale reading is plus, move the rear erector which gathers inside the instrument, andthen lens forward.(You will have to remove the charging the periacope. eyepiece prism to get at the crossline mount.) 1. Connect the nitrogen to the inletvalve When you get the correct adjustment, secure the of the periscope and start the gas.Unscrew rear erector by tightening its retainingring. the inlet valve screw and let the gasbuild up Secure the eyepiece prism. to 5 pounds pressure. 36. Now rotate the elevation prism handle 2. When you have 5 pounds pressure, un- to pick up the collimator crosslines through the screw the outlet valve screw alittle and let 0° (horizontal) line of sight. Tilt the mirror to the gas circulate slowly through the systemfor 15° above horizontal and then 15° below hori- 5 minutes.

, " 7140-',`it4y

1UPPOOT FIXTURE

148.136 Figure 11-26.Periscope Mk 20 installed on periscopecollimator Mk 3. 149 OPTICALMAN 1 & C

3. When you have completed drying the to a pressure of 2 pounds, and secure both system, close the outlet valve screw and charge valves. the periscope to a pressure of 5 pounds (at this 5.Replace the eyepiece, andboltit time test for leaks as you would forany other on. gastight instrument). 6. Take the periscope to the collimator for 4. Now, after the test for leaks is completed, a final check. open the outlet valve and let the gas bleed down 7.Replace the rubber guard.

-4

150 CHAPTER 12

TILTING-PRISM TELESCOPE GUNSIGHTREPAIR

This chapter contains information on the faces of these prisms are silvered to ensure repair and overhaul of the Mark 67 and Mark complete reflection. The head prism controls 68 telescopes. They are mounted on the twin the elevation of the line of sight by rotating 5-inch antiaircraft gun mount. The Mark67 on a horizontalaxis. The deflection prism and Mark 68are identical except that one rotates on an axis at right angles to thatof isthe"mirror image" of the other. The the head prism, and controls the deflection Mark 67is mounted on tho left of the gun of the line of sight. mount,forthe use of tEe pointer and the The objective is an achromatic cemented checker.The Mark 68ismounted on the doublet. The cross line lens is piano- convex. right, for the use of the trainer. See figure The plane surface carries the cross lines,and 12-1. faces the objective. The cross lines are in the back focal plane of the objective. The image TELESCOPES MARK 68 AND MARK 67 formed by the objective is nearly erect, since the image has been nearly inverted by the The Mark 68 telescopes are large, mounted two prisms. in fixed position, and project through ports The erecting system consists of a pair of in the gun mount shield. Since the telescope cemented doublets. Thefilters are located positionisfixed,the observer can follow between the two erectors. There are threeof rapidlymoving targets without changing his them: yellow, red, and a pair of polaroids. body position.Rotating prisms elevate and Like those of the Mark 74 telescope,they deflect the line of sight to follow the target. are held in a common mountwhich you can The prisms are rotated by input shafts and rotateto bring the desired filter into your gears driven by the sight mechanism.The line ofsight.The roof prism deviates the lineof sight can move within these limits: line of sightthrough 90°, and provides an erect image in the focal plane of the eyepiece. Elevation: 85° The reflecting surfaces of the roof prism are Depression:15° carried at the same angle as the reflecting Deflection: 20° either side surface of the deflection prism. Becauseof this, the roof prism elevates the line of sight These telescopes have a fixed power of about 35° above horizontal, so that the observer 6X, and a true field of 7°30'.The diameter looks downward into the eyepice. of theexit pupil is 0.20 inch, and the eye distance is 1.30 inches. The optical system Figures 12-3 and 12-4 show two views of of the two instruments is identical, except that the Mark 67 telescope's, and figure 12-5shows the Mark 67 is"left-handed" and the Mark the general arrangement of its parts. Refer 68 is "right-handed." Figure 12-2 is a diagram to these figures as you read thefollowing of the optics in the Mark 67. description. The head prism and deflection prism are The body casting is made of bronze; it is bothright angle prisms. But since not all about 4 feetlong, andits walls, at most the incident light strikes the entrant-lightfaces points, are -10.18 inch thick. It is irregularly at a right angle, you cannot depend entirely shaped to house the optical parts, the input on internal reflection. Thehypotenuse reflecting mechanism, and the mounting surface. The OPTICALMAN 1 & C

gastight. The input shafts are sealed with stuffing boxes.. The objective window protects the optics [MARK 67 1MARK 681 from dirt and moisture. It fits into a recessed seatin the front outboard end of the main casting,and is held between silicon rubber gaskets by the window retainer. Fastened to the window flange of the body casting is the window-wiper frame, which supports a window- wiping attachment Mark 6. The driving shaft of the wiper is connected by a flexible shaft 148.137 to a 110-volt motor mounted on the inboard Figure 12-1.Telescopes Mark 67 and Mark 68. end of the body casting. The de-icer is a

OBSERVER'S EYE

EYEPIECE OS OPTICAL SYSTEM

ERECTOR CROSSLINE LENS DEFLECTION PRISM FOCAL PLANE 4 Ib2. .; 11 411 HEAD PRISM

ROOF PRISM FILTER// OBJECTIVE LENS

148.138 Figure 12-2.Optical system, telescope Mark 67. mounting pad flange is a little less than 1 foot cylindrical heater fixed to the top of the window wide, and is integral with the casting. The wiper. Two cables from the junction box carry small square flanges at the inboard endare current to the electrical units of the heater. drilled for attaching the inputAnackets of the The wiper operating rod is the only part heated. sight.The access openings into the casting Figure 12-6 is a diagram of the elevation are closed with caps and covers, and sealed mechanism. A long elevation shaft, mounted with screws and gaskets to keep the instru- in ball bearings, connects a trunnion of the '57152 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

WIPER -ROO OEFLEC Tiou DRIVE WINDOW- WIPER COLOR FILTER WINDOW KNOB WIPER OE IGER HOUSING MOTOR BOX

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t R T; C. AL rCRI :0 44 LAC N %! ..; PADS i Ntr PADS HEAD PRISM 148.139 Figure 12-3.The Mark 67 telescope, front view.

DE 1::ER UNITS WINDOW -WIPER ATTACHMENT voN::::,w.WPER MLTD4 BOT

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FLr C. I 'ON ILLUMINATOR m0,.4, P:.;,s GAS INLET VALVE '2R C T 148.140 Figure 12-4.The Mark 67 telescope, rearview. head-prism mount with the wormwheel segment. sight is splined at one end for attachment to (You can see the end of the elevation shaft, theinputshafting from the gun mount. It with a hexagonal nut and cotter pin, near the turns in ball bearings; the stuffing box at the middle of fig.12-5.) The input shaft on the input end forms a gastight seal. The worm

153 DEFLECTION -GEAR COVER DOUBLET FIELD DOUBLET EYELENS FOCUSING RING COLOR-FILTER KNOB CROSSLINEILLUMINATOR OBJECTIVE LENS WINDOW-WIPERASSEMBLY DIAPHRAGM LENS COLOR-FILTER MOUNTFILTER LENS ILLUMINATORCROSSLINEWINDOW LENS PRISM -MOUNTDEFLECTIONHOUSING PRISM PRISM-MOUNTHOUSING DEFLECTION PRISM COUNTERBALANCE DEFLECTION SEALING PLATE VARIABLE DENSITY OUTLET SCREWINNER OPTICAL OUTEROBJECTIVE OPTICAL LENSTUBE DEFLECTIONWHEEL SEGMENT WORM DEFLECTION PRISM MOUNT SHAFT ERECTOR LENS SYSTEM TUBE CELL HEAD PRISM COVER COVER DEFLECTIONWORM 13 ELEVATION COUPLING SHAFT DEFLECTION POINTER SHAFT MOUNTING SURFACES BUSHING THREADED COUPLING STOP PRISM-MOUNTBRACKET ELEVATION WORM13 SHAFT ERECTOR-LENS MOUNT STOP BLOCK PRISM WINDOW-WIPER FRAME HEAD PRISM GEAR SEGMENT PLUNGER 8 SPRING WINDOW WORMDEFLECTION MOUNT a SHAFT GEAR HOUSINGDEFLECTION- Figure 12-5.The Mark 67 telescope, general arrangement. COLLARS 148.141 NOTE - ISTELESCOPE, TO OPPOSITE MARK HAND 68 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

ANTIBACKLASH SPRING N ,STRAP STOP CAP ///

COUNTERBALANCE

ELEVATION WORM AND SHAFT

DEFLECTION SHAFT

ELEVATION WORMWHEEL SEGMENT 148.142 Figure 12-6.Elevation mechanism. gear on the input shaft operates the sector, mounts; the front erector lens mount is located which in turn rotates the long elevation shaft. in the inner optical tube, the rear one is located Notice theantibacklash device. The tension in a separate bushing in the main casting. of its spring is adjustable. By referring to figure 12-5 again, you can Figure 12-7 shows the input end of the see how the roof prism, the color filter as- deflection mechanism which drives the deflec- sembly, and the eyepiece assembly are mounted tion prism. The end of the shaft is splined in the housing. Notice the sealing plate be- for attachment to the input shafting from the tween theeyepiece and the telescope body. gun mount. The shaft moves in ball bearings, It is there so you can overhaul the eyepiece, and is sealed by a stuffing box. The mechanism if necessary, without opening the main casting. uses a pair of bevel gears to rotate the long The Mark 67 Mod 1is the same as the deflectionshaft.Find the end of the s;laft Mark 67,except for minordifferencesin in figure 12-7. Now look at figure 12-8 and curvatures and indexes of refraction of some find the other end of the shaft, to understand ofthe lenses. We doubt if you can tell the how the two drawings are related. difference when you overhaul them. But be Figure12-8 shows the deflection prism carefulthe optical parts are not interchange- mount. A worm mounted near the end of the able from one to the other. The same thing long deflection shaft operates the wormwheel is true of the Mark 68 and the Mark 68 Mod 1. segment, which in turn rotates the prism on its trunnion. (In this picture, you are looking at the OVERHAUL edge of the segment.) Your inspection should show you exactly The outer opticaltubeissupportedin what is wrong with the instrument. Repair cylindrical bearings in the main casting. There only the damaged parts. Complete disassembly is a lock ring to hold it in place, and a set- is a long, complicated job. You will often find screw to keep it from turning. (Keep refer- that all you need is an overhaul of the eye- ring back to fig.12-5, to locate the parts piece or the color filter assembly. So do not as they are mentioned.) The objective cell is make extra work for yourself. adjustable along its axis, so you cat' remove The Marks 67 and 68 telescopes are rugged parallax; there is a retaining ring to secure instruments, built to withstand the shock of the adjustment. The two erectors are in separate gunfire. But that does not mean you can handle

155 / So OPTICALMAN 1 & C

ASSEMBLY POINTER CAP INDEX COLLAR screws from the strip on each side of the elevation prism window (fig.12-10). Lift off the strips. 4. Removing the window strips will expose DEFLECTION SHAFT the four bolts that secure the window wiper attachment. Remove these bolts and their nuts (fig. 12-11). Lift the entire window wiper attachment, and its flexible cable, off the telescope DEFLECTION GEAR window. HOUSING 5. Remove the 16 screws from the elevating gear cover (fig. 12-12), and remove the cover. We have already described the elevation gear assembly for the Mark 67. The Mark 68 is BEARING RETAINER the same, except that the parts face in the opposite direction. 6. Now release the tension in the anti- INSERT backlash drum. First tightly by rotating the drum with a screwdriver. This will free the adjusting pin so it can be removed (fig. 12-13). Release the tension a few notches at a time, STUFFING BOX holding the drum with the adjusting pin while you shiftthe screwdriver to a new notch. 7. Remove the two screws that hold the DEFLECTION INPUT SHAFT antibacklash strap on the gear segment. Remove the four screws from the antibacklash drum 148.143 shaft support. Remove the support, the drum, Figure 12-7.Deflection mechanism. and the strap. 8. Now remove the packing gland from the them carelessly.Gunfireis a special kind elevating input shaft. (You will need the special of shockthe instruments are not built to be tool shown in fig. 12-14). jolted and banged around. The complete telescope 9. Now remove the cap from the input weighs about 180 pounts, yet you must handle shaft with the special wrench shown in figure it as carefully as you would a watch. Moving 12-15. Use the special wrench shown in figure itfrom one spot to another is a job for at 12-16 to remove the nut from the end of the least three men. Do not take chancesget help elevationinputshaft. Remove thelocker when you need it. washer. We will give you complete instructions for 10. Now withdraw the elevation input shaft overhaulingandcollimatingthe Mark68 through the packing box opening. This step telescope. Our pictures are mostly close-ups, takes a lot of care. First: do not scrape the so refer back to figures 12-3, 12-4, and 12-5 threads of the worm gear over the segment if you have trouble locating the parts. teeth, and do not bang them against the sides of the gland housing. Second: support the seg- DISASSEMBLY ment with your free hand, so it will not fall against its stop when you free the input shaft. Do not forget to make an inspection before 11. Remove thesmalllock screwthat disassembly. Be sure to check for correct secures the retaining ring over the input shaft assembly marks; make them,if necessary. thrust bearing (fig. 12-17). Then follow these steps: 12. Use the special tool shown in figure 1. Loosen and remove the screw from the 12-18 to remove the retaining ring. Press the air outlet. When all the gas has escaped from two thrust bearings and their separator out the telescope, replace the screw. from the bottom using a block of wood. 2. Disconnect theflexiblewindow piper 13. Remove the counterbalance from the gear cable from the motor drive unit. segment by removing the two screws shown 3. Remove the four nuts from the motor infigure12-19. Remove the bottom screw drive unit plate (fig. 12-9). Remove the seven first, then the top one.

156 Chapter 12 TILTING -PRISM TELESCOPE GUNSIGHT REPAIR

DEFLECTION PRISM MOUNT PR ISM MOUNT BEARING

DEFLECTION POINTER WORMWHEEL SEGMENT

DEFLECTION WORM HELD PF.SM MOUNT S. AND SHAFT

148.1z:'L Fig .t.:{i 12-8. Deflection prism mount.

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148.145 Figure 12-9.Releasing the motor unit. 148.146 Figure 12-10.Unscrewing the window strips. 14. Pull the cotter pin from the nut on the end of the long elevating shaft. Remove the side with orangewood sticks, while the other nut and lock washer. Use a special gear puller IMF with a suction cup (fir. 12-21). setto remove the gear segment from the 18. Remove the two screws tiwt hold the shaft (fig.12-20). Screw part A on the shaft, shutterinplace on the prism mount (fig. insert the screws marked B in the threaded 12-22). Take off the shutter. holes in the gear segment, and pull the gear 17. Remove four screws each from the rig1,1 by turning the knob C clockwise. and left shutter guides !lig.12-23), and lift 15. The next step is to remove the objective out the guides. window.First, remove the 26 screws from 18. Loosen and remove the 15 screws that the window retainer, and lift off the retainer, hold the head prism cover in place. Remow, Since the window itself may be waxed into the cover. place, removing it may be a two-man job. 19. Loosen andremovethe18serews One man can move the window from side to thatsecurethedeflectionprimcover.

157 OPTICALMAN 1 & C

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148.149 Figure 12-13.Releasing tension from the anti- 148.147 backlash drum. Figure12-11.Releasing the window wiping attachment. rifg/7417,

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148.150 Figure 12-14.Packing gland tool.

toolshown infigure12-26 toremove 148.148 the retaining ring. Figure12-12.Releasing the elevating gear 22. Remove the twothrust bearings and cover. their separator. 23. Remove the small setscrew from the (Itisdirectlybehind the window.) Remove deflection prism worm shaft bearing lock the cover. ring (fig. 12-27). 20. Loosen and remove the eight screws 24. Remove the bearing lock ring with the from the head prism bearing bracket (fig. special tool provided for it. 12-24).Remove the bracket. Now carefully 25. Remove the four screws shown in figure pull the head prism and its shaft out through 12-28. There is a spring that will push out the opening in the body. Be careful not to the plunger and plunger arm when you loosen chip the edges of the prism. Pull in a straight the screws. Remove these parts. line, supporting the prism and shaft with both 26. With the stop block centered and the hands. deflection index and pointer aligned, scribe a line on the gear segment, to show the posi- 21. Remove the small setscrew that locks tion of thelast thread on the worm gear the retaining rings on the head prism shaft (fig.12 -29). You will need this mark when thrust bearing (fig.12-25). Use the special you reassemble.

158 el 3 Chapter 12TILTING-PRISM TELESCOPEGUNSIGHT REPAIR ...idiell.

148.151 Figure 12-15.Input shaft cap wrench. 148.153 Figure 12-17.Removingtheshaftthrust bearing retainer lock screw.

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148.152 Figure 12-16.Elevation input shaft nut wrench. 27. Now find the coupling on the deflection shaft between the stop block and the worm shaft. Remove the cotter pin from this coupling. 148.154 Slide the worm shaft and its bearing to the Figure 12-18.Thrust bearing retaining ring right,untilthe bearing is free. Then very wrench. lightly tap the bearing with a mallet, to free it from the shaft.(Note: This must be done this step, watch for three shim type, washer before the worm shaft will clear the access shaped spacers, one each around each screw hole.) Now withdraw the worm shaft through hole. These washers must be reassembled in the hole in the telescope body, sliding off the their original positions. Gage the washers for bearing as you withdraw the shaft. Be care- thickness, and store them in marked envelopes. ful not to damage the worm threads during (See figure 12 -31.) withdrawal. 30. Remove the stescrew that locks the optical 28. Remove the three screws (shown in fig. tuberetainingring(fig.12-32).This ring 12-30) from the deflection prism mount housing and the opticaltubesetscrew are located while supporting the mount with your hand. through the deflection prism flange. 29. Pullthe housing out of the telescope 31. With the special wrench shown in figure body verycarefully. (CAUTION: As you do 12-33, reach through the hole in the end of

159 OPTICALMAN 1 & C

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148.157 Figure 12-21.Removing the objective window. 148.155 Figure 12-19.Releasing the segment counterbalance.

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148.158 co, t Figure 12-22.Removing theshutter mount screws. 1

148.156 Figure 12-20.Pulling the gear segment. of the body, and loosen the optical tube re- 111e-40 41..m..4134%.% 414.- taining ring. Unscrew the ring, and remove it. 32. Remove the optical tube setscrew. It is just to the left of the retaining ring setscrew.) Carefully withdraw the optical tube through the opening in the end of the telescope body. Put it in a safe place. 33. Remove the 11 screws from the color filter mount.Lift the whole color filter assembly off the body. A 34. Remove the lock screw from the eye- Gt. piece mount (fig. 12-34). Unscrew the eyepiece 148.159 mount, and remove it. Figure 12-23.Removing the shutter guides.

160 Chapter 12 TILTING -PRISM TELESCOPE GUNSIGHT REPAIR

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148.160 148.161 Figure 12-24. Releasing the head prism bearing Figure 12-26.Thrust bearing retainer ring bracket. wrench.

148.163 148.161 Figure 12-27. R emoving the worm shaft bearing Figure 12-25.Removing the thrust bearing retainer screw. retainer lock screw. 38. Use the special spanner wrench shown 35. In the telescope body, under the eye- in figure 12-36 to loosen the lock nut on the piece mount, you will find a diaphragm ring. rear erecting lens mount. Reach in through Unscrew and remove it. That will expose the the color filter opening, back off the nut, and sealing glass retaining ring. Remove it. remove it. 36. With a small scriber, pry out the brass 39. Reach inthrough the eyepiece prism ring from the lead seal around the sealing opening, unscrew the rear erector mount, and glass. Then pry out the lead seal, being care- remove it. ful not to scratch the sealing glass. Lift out 40. Now go back to the prism end of the the glass with a suction cup. deflectionshaft.Remove thethree screws 37. Remove the 10 screws from the square (shown' infig.12-37) from the stop block cover over the roof prism mount. Lift off guide bracket.Lift off the bracket. the cover. The six screws shown in figure 41. Use a heavy screwdriver as a lever 12-35 secure the prism mount to the body. (asinfig.12-38)to move the stop block Remove these screws, and withdraw the prism coupling and collars along the shaft. As you mount. pull the stop block assembly off the shaft,

161 OPTICALMAN 1 & C

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148.164 Figure 12-28.Releasingtheplunger arm, 148.166 plunger, and spring. Figure 12-30.Deflection prism mount screws.

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148.165 Figure 12-29.Marking the gear segment. 148.167 Figure 12-31.Deflection prism housing shims. run the block up to the stop on the collar which is closest to the eyepiece,so it will clear the end of the shaft. (Tosee how the coupling works, refer to fig. 12-52.) 42. Remove 10 screws from the deflection gear cover (fig. 12-39), and remove the cover. Use the special wrench shown in figure 12-40 to remove the deflection input shaftcap. Re- move the packing gland(it is locked by a small setscrew). 43. The lock nut on the end of the deflection input shaft is secured by a lock washer, with one of its points bent up into a slot in the nut. Use a punch and hammer to knock down the washer point and free the nut. Remove the nut with the special wrench provided fora. it, and lift off the washer. 148.168 44. Remove two screws from the deflection Figure 12-32.Removing the optical tubere- index (fig. 12-41), and lift off the index. Remove tauter setscrew.

162 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR two screws from the pointer(fig.12-42). Note: Make sure that both pinion gears are marked (see fig. 12-49). 45. Drivethe tapered pin from the input 111 shaft pinion gear.(Fig.12-43.) Remove the small lock screw that secures the retaining ring on the input shaft bearing (fig.12-44). Remove the retaining ring. 46. Tap the shaft lightly with a mallet to remove the upper bearing and pointer (fig. 12-45). Pull out the shaft with its lower bear- ingstillinplace.Support the pinion gear with your other hand,soitwill not fall. 47. Remove the gear from the deflection (7 shaft, using the gear puller shown in figure 12-46. Fit the small cap over the end of the shaft. Insert the two screws in the threaded 148.171 Figure 12-35.Eyepiece prism mount screws.,

44,

148.169 Figure 12-33.Removing the optical tube re- rjr taining ring. 148.172 Figure 12-36.Erecting lens mount spanner wrench. holes on the gear. Pull the gear by turning the large knurled knob clockwise. 48. Pulling the gear will expose the retaining ring on the deflection shaft bearing. Re- move the ring with the special wrench provided forit.Now withdraw the shaft through the opening in the end of the body. 49. Now you are ready to start on the sub- assemblies. Begin with the inner optical tube. Remove the small lock screw from its retaining ring (fig.12-47). Back off the retaining ring with a fiber grip wrench. 50. Find thesmall lock screw near the middle of the optical tube,and remove it. 148.170 Now withdraw the inner optical tube, which Figure 12-34.Removing the eyepiece mount contains the crossline lens andthe front erecting lock screw. lens. 163 /6k OPTICALMAN 1 & C

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148.173 148.175 Figure12-37.Removing the stop block guide Figure 12-39.Removing the deflectiongear bracket. cover. Mak

148.174 Figure 12-38.Moving the coupling and collars. 148.176 Figure12-40.Deflection input cap wrench. 51. From the other end of the optical tube, remove the objective mount lock ring with a When youfindthetrouble,recorditon fiber grip wrench. Unscrew the objective mount, the casualty analysis sheet. and remove it.Protect the objective with a When checking optical parts there are three rubber washer, and remove its ring withan main defects to look for: adjustable slot wrench. Remove the objective, 1. Check the antireflection coating on the and mark it to show the path of light through surfaces of the lenses. it. 2. Inspect the condition of the cement be- 52. Disassemble theeyepiece, theinner tween the lenses. optical tube, and the rear erecting lens mount. 3. Check the lenses for chips and scratches. If necessary, disassemble the color filteras- Record your findings on the casualty analysis sembly and the eyepiece prism mount. sheet. Checking optical parts is only half of the CASUALTY ANALYSIS casualty analysis. Inspect the mechanical parts next. Some common discrepancies are: Inspect all parts after disassembly and analyze 1. Burrs, dents, distortion,damaged casualties; functional defects listed on the job threads, and wear. order should be included in this inspection. 2. Appearance and finish defects.

164

/6 1 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

t.t.. .4=0, OIL 148.177 148.179 Figure 12-41.Removing the deflection index. Figure 12-43.Removing the tapered pin from the pinion gear.

Sr 1111111:1 ' 148.180 Figure 12-44.Removing theretaining ring 148.178 lock screw. Figure 12-42.Removing the screws from the pointer. Repair parts only when the repairs are eco- nomically feasible, otherwise replace with new UPPER BEARING parts.

REASSEMBLY et In reassembly refer back to the illustrations used in the disassembly procedure when needed.(Note:Use new gaskets throughout when reassembling anyoptical instrument.) POINTER Follow these steps: 1. Reassemble the eyepiece by replacing I I I r the focusing key, the focusing ring, and the focusing retaining ring. Replace the two eye- 148.181 piece lenses and their spacer, and secure them Figure 12-45.Removing the upper bearing and with the retaining ring.Replace the eyepiece pointer.

111;so OPTICALMAN 1 & C

4. Insert the input shaft through the pinion gear.There are punch pricks on both the bevel and the pinion gear (fig. 12-49).Line them up as you insert the input shaft. 5. Slip the pointer onto the shaft.Notice the two small holeE into which the pointer setscrewswillfit.Now push the shaft on .., through. Lubricate the upper bearing, and slip it over the ena of the shaft. 6. Secure the pinion gear to the shaft by hammering in the tapered pin.Do NOT hit the gear teeth. 7. Align the setscrew holes of the pointer 148.182 with the two small holes spotted in the shaft. Figure 12-46.Gear puller. Replace the pointersetscrews, and tighten

148.183 148.184 Figure 12-47.Removingtheinneroptical Figure 12-48.Replacing the deflection gear. tube retainer lock screw. prism initsmount,if you have removed it.Replace the objective and the erectors in their mounts. 2. Insert the deflection shaft through the hole in the end of the body. Reach down through thecolor filter opening to guide the shaft through itscenter bearing. When the shaft isin place, screw in the bearing retaining ring. Tighten it with the special wrench, and secure it with its setscrew. 3. Push the deflection gear onto the shaft 11 (fig. 12-48). Use equal pressure on both sides of the gear. Fit the slot in the gear over the key on the shaft. Screw the lock washer and nut onto the end of the shaft. Secure the nut 148.185 by bending one of the points of the lock washer Figure 12-49.Aligning the bevel and pinion up into a slot on the nut. gears.

166 Chapter 12 TILTING -PRISM TELESCOPE GUNSIGHT REPAIR them. Replace the deflection index, and secure it with its two screws. 8. Replace the deflection bearing lock ring, and tighten it with its special wrench. Secure the bearing lock ring by replacing and tightening its lock screw. 9. Replace the lock nut and washer on the deflection input shaft, above the upper bearing.Secure the nut by bending a point of the washer up into one of the slots. 10. Disassemble the packing gland by removing the retaining ring. (The ring is locked by a small retainer lug. Remove the lug first.) Figure 12-50 shows the parts: the gland, the retainingring,a brass spacer,and three packing rings. I 11. Fita new Koroseal gasket, 1/32-inch thick,to the gland. Slip the gland over the 148.187 shaft,screwitin, and tightenit securely. Now cut out three new packing rings of "Hycar." Figure 12-51.The retainer lug. Do not use any substitutes. Fit the three new packing rings onto the shaft, and push them up into the gland. Put the brass spacer, then the retaining ring, on the shaft. Tighten the retaining ring until you can no longer turn the shaft easily with your fingers. Secure the retaining ringwith the brassretainer lug (fig. 12 -51). 12. Screw on the shaft cap, and tighten it with its special wrench. 13. Replace the stop block coupling. Fit the keys on the stop block coupling into the slots on the shaft. (The insert in fig. 12-52 shows a cross section.)

148.188 Figure 12-52.Replacing the stopblock. 14. Lubricate the bearing surface of the stop block guide bracket. Replace the bearing over the block, and secureit with three screws. 15. Replace the objective mount in the optical tube. Reassemble the inner optical tube (containing the cross line lens and the front erector). Now you will have to make the first of many collimation steps which are required throughout the reassembly of this instrument. This first step is the squaring of the cross line inthe inner tube. You will make the final small adjustment to square the cross line to the collimator while the instrument is being given the final collimation on the collimator. 148.186 a. Place the inner optical tube on V-blocks Figure 12-50.Packing gland, disassembled. that are setting on a flat surface such as a

167 /102,. OPTICALMAN 1 & C collimatortable, making sure that the cross the objective mount in or out. Secure the line is facing you. adjustment by tightening the objective mount b. Set a small machinist's square on the retaining ring. table and alignthe blade of the square in 20. Remove the four screws from the cross theilluminationslot,makingsurethat line illuminator housing(fig. 12-54), and lift the blade isflush againstthe bottom of off the housing. the slot. 21. Insert the optical tube through the open- c. Set the protractor head of a combination ing in the telescope body. Sight down through square, with the scale fully extended, at 125° the illuminator sealing window to line up the (vertical plane 90° plus 35° eyepiece offset). slotthrough which thecrosslinelens is d. With the protractor head setting on the illuminated (fig. 12-55). table, pass the scale in front of the optical 22. When you get the optical tube properly tube until the scale edge superimposes on the lined up, secure it by replacing and lightly center of the cross line. Now carefully take tightening its setscrew(fig.12-56). Replace a scribe and scribe two marks on the end edges of the inner optical tube at the point where the protractor scale meets this surface. (When you reassemble the cross line to previously scribedlines you may find that upon moving the protractor head so that the scale superimposes on the cross line center, the cross line is superimposed perfectly with the edge of the scale along its entire length. If thisis so you will NOT have to make any further adjustments of the cross line in the inner optical tube.) e. If the cross line does not line up with the scale, then it will be necessary to loosen the cross line retainer ring, and using the scribe marks on the edge of the tube as a reference, rotate the cross line carefully untilitisalignedwith the scribe marks; 148.189 then retighten the retainer ring. Figure 12-53.Collimating the inner optical (With the cross line facing you, the scale tube. of the protractor will point to your left for a Mark 67, and to your right for a Mark 68 telescope.) 16. Mount the inner optical tube on the collimator. Sight the cross lines through an auxiliary eyepiece (fig. 12-53). 17. You will see two sets of cross lines: those inthe optical tube and those in the collimator. Screw the front erector lens in or out until both cross lines are sharp. (They do not have to superimpose.) 18. Now line up the inner optical tube in the optical tube.Sight through the setscrew hole, and line up the small hole in the inner tube.Replace the setscrew, and tighten it. Replacethe inner tube retaining ring, and tightenit with a fiber wrench. Secure it with ;I. its lock screw. 19. Set up the complete optical tube on the 148.190 collimator, and sight through it with an auxi- Figure 12-54.Removing the illuminator liary telescope. Remove parallax by screwing housing.

168 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

-r

148.192 Figure 12-56.Replacing the optical tube setscrew.

148.191 Figure 12-55.Lining up the illuminating slot. the optical tube retaining ring, and tighten it IT lightly with its special wrench. Replace and =hf-XTr, tightentheretaining ringsetscrew lightly. It goes just to the right of the optical tube setscrew. (Note: The adjustments just described are made lightly so that the outer optical tube may be rotated to square the scope cross line to the collimator cross line later ti in the final collimation step.) / 0, 1 23. Now get out the three shims (washers) 148.193 for thedeflection prism housing. Put them Figure12-57.Replacing the elevating shaft in their proper positions. Carefully guide the bearing bracket. deflection prism housinginto place without disturbing the shims. Replace and tighten the 26. Slip the two thrust bearings, with their three screws that secure the housing to the separator between them, over the end of the telescope body.(Note: The deflection prism shaft.Replace the retaining ring, and tighten will have to be removed after the scope cross itwith the special cutaway wrench. Secure line is squared to the collimator to facilitate the ring with its lock screw. tightening the outer optical tube lock ring; 27. Replace the key in the slot of the elevat- thus the lock ring must be secured just tight ing shaft. Fit the elevation gear segment over enough to hold the cross line snugly in place.) theshaft,making sure to line up the key 24. Insert the elevating prism and its shaft and keyway. Secure the segment with its lock through the opening inthe telescope body. nut, and replace the cotter pin through the nut. 25. Replacetheelevatingshaftbearing 28. With the gear segment resting against bracket (fig. 12-57).Secure it with its eight its lower stop (fig. 12-58), insert the elevation screws. input shaft, ana push it into place.Replace

169 OPTICALMAN 1 & C

thetwo bearings,with their separator be- drum shaft support over the other end of the tween them, over the end of the shaft. Replace shaft, and secure it with four screws. the lock washer and nut on the shaft, and 32. Securethe free end of the strap, by secure the nut by bending one of the washer itspin, to the strap arm. Fasten the strap points up into one of the slots. arm to the gear segment with two screws. 29. Replace the thrust bearing retaining ring, 33. Wind up the drum with a screwdriver, tightenitwith its special tool,and secure holding the drum with the adjusting pin while it with its lock screw. Replace the cap, and you move thescrewdriver toa new slot. tighten it with its special wrench. Replace the adjusting pin when you think you 30. Run the gear segment down to its lower have the proper tension.If necessary, you stop, so you can fit the sector counterbalance canchange the tension duringcollimation. around the shaft(fig. 12-59). Secure the up- 34. Reach through the eyepiece prism open- per screw with an offset screwdriver. Then ing and screw the rear erecting lens mount replace and tighten the lower screw. into place. You will adjust it during collimation. 31. Now reassemble the antibacklash group. 35. Put agasketof Koroseal,1/32-inch First, hook the steel strap over a pin on the thick, under the eyepiece sealing window, and drum,and rollit up.Insert the drum and replace the window. Form a lead and brass its shaft by slipping one end of the shaft into gasket aroundit.(Refertochapter12 of thebearing holeinthe body. Mount the 0_pticalman 3 &2, NavPers 10205.) 36. Replace the retaining ring over the glass, and tightenit.Screw in the diaphragm, and tightenitwithitsspecialtool. Screw the eyepiece assembly into place, and secure it with its lock screw. 37. Insert the eyepiece prism mount through its opening in the telescope body, and secure it in place with six screws. 38. Now you are ready to collimate. Figure 12-60 shows the Mark 6 collimator, with the fixture for the Mark 67-68 telescopes in place. Figure 12-61isa closeup of the checking telescope Mark 16 and its support fixture, ak which you will use to line up the telescopes ofthe collimator.(Note: OP 1417 may be 148.194 referred to for greater detail on these fixtures.) Figure12-58.Replacing the elevation input 39. Set the collimator base vernier index shaft. at zero. Use the checking telescope to align thehorizontal collimator telescope with the fixture (fig.12-62). Now align the 90°collimator tube (fig. 12-63). 40. Clean the bearing surfaces of the telescope and the collimator fixture. Mount the telescope on the fixture, and bolt it securely into place. 41. Set the eyepiece diopter scale at zero. Sight through the eyepiece with an auxiliary telescope, which is set to the repairman's individual eye correction, and check the focus of the crosslines. U they are not sharp, reachinthroughthecolorfilter opening and adjust the rear erecting lens mount until they are. (Be sure the eyepiece diopter scale 148.195 stays at zero.) Then, with the special spanner Figure 12-59.Replacing the segment counter- wrench, tighten the lock ringin the rear balance. erector lens mount.

170 /75 Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

148.196 Figure 12-60.The Mark 6 collimator. 42. Now sightthrough theeyepiece,and the worm gear segment (fig.12-65). When superimpose the telescope cross lines on the the stop block is centered, the first thread 0° elevation collimator telescope by operating of the worm gear must line up with the scribe the elevation input shaft and moving the de- mark. Insert a cotter pin to link the worm flection prism by hand. (Remember that the shaft to the coupling. deflection worm shaft HAS NOT been reas- 44. Insertthe plungerinthe eye of the sembled in the scope yet.) The vertical cross segment (fig.12-66). Fasten the plunger arm lineof the telescope must not be off the to the stop block with its four screws. vertical cross line of the collimator by more 45. Insert the deflection worm bearing lock than 1 minute. If the cross line is NOT square, ring, and tighten it,secure it with its set- rotate the outer optical tube until the cross screw. lineisexactlysquare with the collimator 46. Checkfor backlash inthe deflection cross line. Then secure the outer optical tube mechanism. First, rotate the deflection shaft setscrew, remove the lightly secured deflection to bring the pointer to the left of the index prism mount and tightenthe outer optical (fig. 12-67). tube lock ring and its setscrew. Replace the 47. Now bring the pointer back on the index, deflection prism and recheck cross line square- using an eye loupe to check the alignment. ness. Sight the vertical cross lines again. The vert- 43. Lubricate the deflection worm shaftbear- ical cross line of the telescope must not have ing, and slip it into place (fig. 12-64). Insert moved more than 30 seconds from its original

171 OPTICALMAN 1 & C

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148.197 148.199 Figure 12-61.The Mark 16 checking telescope. Figure 12-63.Aligning the 90° collimator tube.

4. .1

148.198 Figure 12-62.Aligning the horizontal colli- mater telescope. 148.200 Figure 12-64.Insertingthe wormshaft. position.Displace thepointer to the right, bring it bank to the index, and check again. 49. Sightthrough the eyepiece,and turn The vertical. cross line must still be within the drum until the two horizontal cross lines 30 seconds of its original position.Ifitis coincide, utilizing the 0° elevation collimator off by more than 30 seconds on either test, telescope. Loosen the drum lock screw. Turn there is too much backlash in the deflection the drum (without turning the input shaft) to mechanism.Either theplunger springhas align the mark on the drum with the index insufficient tension, or't.hethrust bearings mark on the pointer. Retighten the drum set- have been improperly replaced. screw. Check the cross to be sure you did 48. Slip a special collar with an indicat- not turn the input shaft. ing pointer over the end of the elevation,input 50. Elevate the line of sight 90° by turn- shaft gland (fig.12-68). Mount the revolu- ing the drum through exactly 13 1/2 revolution-cotuitt:g drum on theinput shaft, and tions. Sight through the telescope. The cross secureitwithits lock screw (rig.12-69) lines mustcoincidewith those of the P0° Chapter 12TILTING-PRISM TELESCOPE GUNSIGHT REPAIR

148.201 Figure 12-65.Inserting the worm shaft. 148.204 Figure 12-68.Special collar with index mark.

1111111.- 101162111Eitmt,..\-1,

I. *. 'a

tw 148.202 Figure 12-66.Securing the plunger arm.

148.205 Figure 12-69.Revolution counting drum. 52. Lower to 0°elevation, and line up the marks on the drum and pointer. Sight through the telescope. The horizontal cross line must not be more than 30 seconds off the horizontal cross line of the collimator.Ifitis off by more than that, there is too much backlash I in the elevation mechanism. Increase the tension 148.203 inthe antibacklash drum, and check again. Figure 12-67.Checking deflection backlash. 53. Lower the line of sight as far asit willgo. This must take not less than nine collimator telescope, with an error of not more turns, and not more than ten turns of the input than 2 minutes vertical or 3 minutes horizontal. shaft. Raise the line of sight to 0°. 51. Now elevateall the way to the stop,. 54. By rotating the input shafts, bring both This must take not more than one full ad- thehorizontaland the vertical cross lines ditional turn. The horizontal cross line of the of the scope and collimator into coincidence. telescope must clear the graduations on the Transfer your revolution counter to the de- vertical cross line of the collimator. flection input shaft, and turn the shaft through

173 OPTICALMAN 1 & C

exactly 3 1/3 turns counterclockwise. Remove 60. Replace the illuminator housing, over a the vernier adjustment screw block from the gasket of Koroseal. collimator, and rotate the telescope 20° to the 61. Replace the color filter assembly, over left.(Check the aligment on the collimator a gasket of Coroprene. (Each screw has its scale with an eye loupe.) own Koroseal gasket.) 55. Sight through the telescope. The horizontal 62. Insert an illuminator, and checkthe cross cross lines must coincide, with an error of line illumination. If it is satisfactory, replace not more than + 2 minutes. all the sealing plates.(Read the section on 56. Turn the deflection back to zero, and sealing, in chapter 8 of Opticalman 3 & 2, then turn the shaft exactly 3 1/3 turns clock- NavPers 10205.) wise. Swing the telescope back to zero deflection, and then 20° to the right. (Check the align- SEALING, DRYING AND CHARGING ment of the collimator scale with your eye loupe.) 1. Charge the telescope with dry nitrogen, 57. Repeat step 55. If the alignment is within to a pressure of 8 pounds. This is the maxi- tolerance, the telescope is properly collimated. mum safe limit to test this telescope. (Read 58. Complete your reassembly. Replace the the section on charging, in chapter 8 of Optical- two shutter guides, and secure them with four man 3 & 2, NavPers 10205.) screws each. Place the shutter in the guide, 2. Test thetelescope for leaks by sub- and fasten it with the two screws, using an mergingitin water.If no bubbles appear, offset screwdriver. remove the telescope, dry it,and bleed the 59. Replace the front window, over a gasket pressure to 4 pounds. of Koroseal. Fit a gasket of Coroprene over 3. Replace the window wiper attachment, and the window, and replace the window retainer. its side strips. Replace and tighten the window retainer screws. 4. Replace the motor unit, and bolt it into IMPORTANT: Each screw in each retainer and place. sealing plate must be fitted with its own gasket 5. Connect the flexible cable from the wiper of Koroseal. attachment to the motor.

174 7 791., APPENDIX 1

TRAINING FILM LIST Certain training films that are directly related tothe information presented in this training course are listed below underappropriate chapter numbers and titles. Unless otherwise specified,all films listed are black and white with sound, and areunclassified. For a description of these and other training films that may be ofinterested, see the United States Navy Film Catalog, NavWeps 10-1-777.

Chapter 1

ADVANCEMENT

MN-06798D Your Job in the NavyPart 4. (31 min.-1950.) Chapter 3

METALS

ME-07313A Heat Treatment of AluminumPart 1. (19 min.-1945.)

ME-07313C Heat Treatment of AluminumPart 1. (24 min.-1945.)

ME-06885A Heat Treatment of SteelElements of Hardening. (15 min.-1949.)

ME-06885B Heat Treatment of SteelElements of Tempering, Normalizing, and Annealing. (22 min.-1949.)

ME-06885C Heat Treatment of SteelElements of surface Hardening. (14 min.-1949.) INDEX

Advancement in rating, 1-6 Drying and charing the rangefinder, 77-79 Opticalman rating, 3 Drying equipmen,periscope, 119 requirements, for, 2 rewards and responsibilities, 1 Einstein's theory of relativity, 40 training, 3 Emergency flax packing, 126-128 courses, 3-6 Equipment Identification Code Manual, 24 films, 6 Equipment log, 7 information sources, 3 Erlenmeyer flasks, 119 publications, 4-6 Exception Time Accounting \Codes, 29 Altiperiscope, 107 Annealing, 36 Ferrous metals, 35 Auxiliary optical systems, 59-61 Films, training, 6, 175 Auxiliary telescopes, 113 Flooded periscope, care of, 123 Fogging of optical surfaces, 117-123 Binocular, ship-mounted, 129-137 Fresnel's lightwave experiment, 41 description of, 129 maintenance, 131-133 Galilean telescope, 113 operation of, 130 Garlock chevron packing, 126-128 overhaul, 133-136 sealing, drying, and charging, 136, 137 Hardening and tempering metal, 37-39 Brewster's law, 42 Heat treating processes, 36 Bronze, 36 Helium, 79 BuPers publications, 4 Inspection of rangefinder, 79-83 Calibration, rangefinder, 73-75 Instrument dryer for periscope use, 119 Casualty analysis, periscope, 126 Inventory of tools and equipment, 8 Charging gas for submarine periscopes, 118 Iron, 35 Circular measure, 45 Coincidence rangefinder, 50-57, 65 Knowledge factors, 3 operation, 65 Collimating telescopes aligned on binocular, Lead, 35 134-136 Light, 40-43 Color filters, submarine periscope, 113 Brewster's law, 42 Coordinated Shipboard Allowance List, 9 double refraction, 42, 43 Copper, 35 interference of light waves, 40 Courses, training for advancement in Fresnel's experiment, 41 rating, 3-6 Huygen's theory, 40 Cycling equipment, periscope, 120-123 Young's experiment, 40 polarization, 41 Daily Exception Card, 32, 33 Davey, Marie, 106 Maintenance Deferred Action Form, 26 and material management, 16-33 Dewpoint test, periscope, 119 quarterly schedule, 22 Double refraction, 42, 43 records of, 24-33 Double-slit interference, 40 schedules, 18-24 Doughty, Thomas H., 106

176 Opticalman I & C

Maintenancecontinued Periscopes, maintenance and repair and repair of periscopes, 117-128 ofcontinued casualty analysis and repairs, 126 drying equipment, 119 flooded periscope, 123 internal, 118 installation, 126-128 handling of, 117 removal, 123-126 installation, 126-128 safety precautions, 123 removal, 123-126 storage, 117 safety precautions, 123 and repair of ship-mounted binocular, storage, 117 131-133 Periscopes, submarine, 106-116 Maintenance Data Collection System, 24 auxiliary telescopes, 113 Maintenance Index Page, 18 color filters, 113 Planned Maintenance System, 17-24 components of, 114 rangefinder, 76 data, 106 ship mounted binocular, 131-133 definitions, 106 Manhour Accounting System, 29 design, 107-113 Man-hour report, 7 designation, 107 Mark 6 collimator, 170, 171 optical, 109-113 Mark 16 checking telescope, 170, 172 theory and, 107-109 Mark 20 Mod 6 periscope, 138 8B periscope, components of, 114-116 Mark 42 stereoscopic rangefinder, 84-105 telemeter lens, 113 Mark 68 and Mark 67 telescopes, 151-155 Periscope, turret, 138-150 Master Roster Listing, 29, 30 description of, 138-142 Material expended record, 7 Mark 20 Mod 6 periscope, 138 Metals, 34-43 overhaul, 142-150 annealing, 36 casualty analysis, 145 ferrous metals, 35 disassembly, 142-145 hardening and tempering, 37-39 reassembly and collimation, 145-149 heat treating processes, 36 sealing, drying, andcharging, 149, 150 nonferrous metals, 35 Plain carbon steels, 38 normalizing, 37 Planned Maintenance System Feedback properties of, 34 Report, 24, 25 stress relieving, 39 Planned Maintenance System operation, 17-24 types of, 35 Polarization, 41 Monel, 36 Polaroid films, 41 Practical factors, 3 Navy training courses, 5 Publications, training for advancement in Nitrogen, 118 rating, 4-6 Nonferrous metals, 35 Normalizing, 37 Quals Manual, 4 Objective lenses, 56 Radian, 45 Optical Instrument Dryer, 78 Rangefinder calibration and maintenance, 68-83 Opticalman rating, 3 accuracy, 68-73 Overhaul of ship-mounted binocular, 133-136 calibration, 73-76 drying and charging, 77-79 Packing, submarine, 126 errors, 68 Periscopes, maintenance and repair of, inspection of, 79-83 117-128 maintenance of, 76 casualty analysis and repairs, 126 record keeping, 75 flooded periscope, 123 setting the regulator valve, 78 fogging of optical surfaces, 117-123 - testing for leaks, 78 charging gas, 118 Rangefinder, stereoscopic, 84-105 cycling equipment, 120-123 description of, 84-90 dewpoint test, 119 Mark 42, 84-90

177 INDEX

Rangefinder, stereoscopiccontinued Safety precautionscontinued change-of-range input, 86 periscopes, 123 compensator unit, 86 responsibilities of supervisor, 9 correction wedge, 89 Scheduling of work, 12-15 end reflectors, 84 Sealing, drying, and charging ship-mounted end windows, 89 binocular, 136, 137 erecting lens system, 85 Sealing, drying, and charging telesoopes, 174 eyepiece assembly, 85 Shipboard Maintenance Action Form, 26 eyepiece prisms, 85 Ship-mounted binocular, 129-137 objectives, 85 description of, 129 range transmission, 87-89 maintenance, 131-133 reticles, 85 operation of, 130 overhaul, 90-105 overhaul, 133-136 disassembly, 90-98 sealing, drying, and charging, 136, 137 final checking, 102 Shop housekeeping, 8 internal adjustments, 103-105 Steel, 35 reassembly and collimation, 98-102 Stereoscopic rangefinder, 57-59, 79, 84-105 Rangefinder, theory and construction, 44-67 description of, 84-90 auxiliary optical systems, 59-61 inspection, 79 coincidence rangefinder, 49-57, 65 operation, 61 operation, 65 Mark 42, 84-90 construction of, 65-67 change-of-range input, 86 degree, 44 compensator unit, 86 measurement, 44-48 correction wedge, 89 operation, 61-65 end reflectors, 84 optical construction of, 48 end windows, 89 stereoscopic rangefinder, 57-59, 61 erecting lens system, 85 construction of, 65 eyepiece assembly, 85 field of view in, 49, 65 eyepiece prisms, 85 operation, 61 objectives, 85 telescopic system of, 48, 49 range transmission, 87-89 theory, 44 reticles, 85 triangulation, 45-48 overhaul, 90-105 types of, 49 disassembly, 90-98 Rating, advancement in, 1-6 final checking, 102 Opticalman rating, 3 internal adjustments, 103-105 requirements for, 2 reassembly and collimation, 98-102 rewards and responsibilities, 1 Storage of periscopes, 117 training, 3-6 Submarine periscopes, 106-116 films, 6,175 auxiliary telescopes, 113 information sources, 3 components of, 114 publications, 4-6 color filters, 113 Recording of maintenance actions, 24-33 data, 106 Record keeping, rangefinder, 74-76 definitions, 106 Record of Practical Factors, 4 design, 107-113 Records and reports, optical shop, 7 designation, 107 Repair work, 11-15 optical, 109-113 determination of repairs, 11 theory and, 107-109 periscope, 126 8B periscope, components of, 114-116 ship-mounted binocular, 136, 137 telemeter lens, 113 Rhemboid prisms, 59 Supervision, 7-33 incoming jobs, 11 Safety precautions inventory of tools and equipment, 8 cycling, 123 laying-out and assigning work, 11 in the shop, 9 maintenance and material management, 16

178 Opticalman I & C

Supervisioncontinued Tilting-prism, telescope gunsight Maintenance Data Collection System, 24 repaircontinued Planned Maintenance System operation, reassembly, 165-174 17-24 sealing, drying, and charging, 174 recording of maintenance actions, 24-33 Tools and equipment, care of, 8 order in the shop, 8 Training films, 6, 175 planning the work, 9 Training for advancement in rating, 3-6 priority of jobs, 11 films, 6,175 records and reports, 7 information sources, 3 repairs, 11-15 publications, 4-6 safety precautions, 9 Training on the job, responsibilities of petty scheduling of work, 12-15 officer, 15 supplies, 16 Triangulation, 45-48 training shop personnel, 15 Turret periscope, 138-150 Supplies, 16 description of, 138-142 Mark 20 Mod 6 periscope, 138 Telemeter lens, 113 overhaul, 142-150 Telescopes, Mark 68 and Mark 67, repair casualty analysis, 145 of, 151-174 disassembly, 142-145 casualty analysis, 164 reassembly and collimation, 145-149 disassembly, 156-164 sealing, drying, and charging, 149-150 reassembly, 165-174 sealing, drying, and charging, 174 Wave theory of light, 40, 41 Tempering metals, 37 Work Request Form, 27 Tilting-prism, telescope gunsight repair, 151-174 Work Supplement Cards, 27-31 Mark 68 and Mark 67 telescopes, 151-155 overhaul, 155-174 Young's light wave experiment, 40 casualty analysis, 164 disassembly, 156-164 Zinc, 36

{,U.S. GOVERNMENT PRINTING OFFICE: 1970-394061/5.15

179