The Locomotive Designer and Design

340 JOURNAL OF THE INST. OF LOCO. ENGINEERS. THE LOCOMOTIVEDESIGNER AND DESIGN. Paper read before the Iytitution by Mr. J. RODGERS, Member of Council, Brighton, Afiril 28th, Mlf. PAPER No. 53. It is an unfortunate circumstance, but one which cannot be avoided, that many men pass through the drawing office an,d others remain therein without getting an opportunity of participating in the preliminary calculations and design of a new locomotive, their work being the detailing of the design after its principal dimensions have been fixed. There- fore it, is to the young members of our Institution who find themselves in this position that this paper is principally addressed. The evolutionary period of the locomotive produced a basis from which subsequent experiments could be carried out and designs evolved, thus enabling the laying down of fundamental principles for future development. The re- markable progress that the locomotive has made is ample proof that this steam prime mover was founded on sound lines, for while we have extended, enlarged, and added to the initial designs, the principle of the locomotive still remains the same as' laid down in those early days, but at the same time one is forced to the conclusion that the engineers of that day had anticipated its capacity being reached long ere this, as it is the limitations created by them that the designet of the present day has to combat, because he has to meet the ever-increasing demands of the traffic department by placing more powerful machines on the same gauge of track, through practically the same loading restrictions, and over the same bridges, which were con- structed for the lighter types. To enable this to be done, much valuable information has been arrived at by experimental work, very much is waiting to be accomplished by experiment and research, and-it must be confessed that we in this country are far behind in this matter, in that we do not possess a public testing plant, such as is available at the University of Downloaded from jil.sagepub.com at The University of Melbourne Libraries on June 5, 2016 THE LOCOMOTIVE DESIGNER AND DESIGN-RODOERS. 24r Illinois, America, from which valuable information is not only obtained, but is issued for the benefit of all locomotive engineers, and it is mainly due to this cause that the most scientific publications on the locomotive are American. From the great amount ,of knowledge that is obtainable by the present-day designer, it is possible to produce types suitable for all classes of work, and to be certain that they will perform the duty for which they are intended. The aim of this paper is therefore to consider very briefly some of the problems with which the designer finds himself con- fronted, the fundamcntal principles in relation to these problems, abd to some extent the laying down of the first lines of the new design. It will perhaps sccm to some extent outside the scope of this paper to say anything about the designer (and by the designer is meant the person who works out the design to the instructions of the chief mechanical engineer, the consultirig engineer, or the chief draughtsman), but as the design is to a very large extent his production, it bears the mark of his capabilities, and these being very necessary for such a responsible position, a brief outline of the training desirable will be of some value. What should his capabilities be, then? Well, he should be a locomotive engincer, not merely a draughtsman, a man who has had a thoroughly good training in the practical as well as the scicntific, and is able to combine and produce such knowledge in the design. The practical training should be as extensive as possible, and if running- shed cxpericnce can be, obtained, it will prove of inestimable value, giving as it does an insight into wear, tear, and repairs, but as many draughtsmen do not obtain running- shed work, they can and,ought to overcome this want by the most careful consideration to design, embodying efficiency with simplicity, so that examination of all parts may be carried out with the slightest inconvenience, and repairs effected without difliculty and at the minimum of cost. He should have had a thorough training in the designing of details, keeping ever before him the advantages of standardisation, but at the same time never hesitating to propose what can be proved to be a decided advantage by adopting another form of design, for, while it may not be duplicate with existing stock, it may, and often does, pay to embody a new design instead of perpetuating that whlch has proved to be faulty for the sole reason.of duplication. Downloaded from jil.sagepub.com at The University of Melbourne Libraries on June 5, 2016 242 JOURNAL OF TEE INST. OF LOCO. ~:NGINEERS. He should also train himself into the most careful consideration of the convenience and accessibility of all parts that come under the control of the driver and fireman, and his imagination should be such that he can obtain from the drawing, quite as good as from the engine itself, a correct realisation of parts in juxtaposition, so that there need not be any alteration due to this cause after construction. Standardisation should not only -apply to the article itself, but also to shop tools, such as templates, jigs, drop- hammer dies, etc., as a small alteration of no importance often causes the making of new tools, and this being an expensive item, due consideration should be given to it in the designing of detail work. Then again, he should be aware of the most up-to-date methods of production, and n‘ot be one who hides himself behind the excuse that it is the business of the works to produce the article according to drawing, without giving consideratibn to the most efficient method of forging, moulding, machining, etc., and who is quite content to tabulate the articles as being made of *‘ steel,” “ brass,” etc., never troubling about the tensile strength of the steel, its suitability for welding or case- hardening, or whether the brass should have a high tensile strength or simply pe suitable for brazing. Such a one has a long road to travel ere he realises the importance of up-to-date designing. There should he no dividing line between the drawing office and shops, there should be entire unison between them, and it is the draughtsman’s duty, however difficult it may be, to keep in touch with the latest shop methods 0f production, thus enabling him to design to suit the ever- increasing improvements that take place in this direction. The drawing, as issued to the shops, should be so complete that it represents the article exactly as finished, with a definite statement of the material from which it is made, SO that there will be no doubt on this point when reference has to be made in cases of failure, and under no circumstances whatever should there be any deviation from the drawing without consultat,ion between the shops and drawing oflioe, as it is only by strict adherence to this rule that the drawing will correctly represent the article, and thus save an enormous amount of expense in duplicating parts. There is another point to which the author would draw attention. All parts should be designed as “ foolproof ” as possible, so as to prevent carelessness in assembling, and thus obviate failures under this head, which are the most annoying of all failures, as they are preventable. Downloaded from jil.sagepub.com at The University of Melbourne Libraries on June 5, 2016 THE LOCOMOTIVE DESIGNER AND DESIGN-RODOEBB. 143 In this very brief resum6 of the knowledge required by the designer perhaps enough has been said to emphasise the responsibility that attaches to him, and will allow us to proceed with the consideration of design as it appeals to a man having the foregoing training and qualifications. In laying down the first lines of a new design it is essential that sufficient information should be supplied by the authorities calling for the design of what may be termed the " controlling factors," and while it may seem, and is, unnecessary in some cases (as, for instance, we know the track in our own country is well laid, yet in some foreign countries this is far from true), it is of the greatest importance that the designer should know the exact conditions for which he is designing. These controlling factors are as follows :- Gauge of Track.--This varies from 2ft. to 5ft. 6in., the narrower gauges placing limita'tions on speeds, due to the greater tendency of the mass to overturn, owing to the centrifugal forces on curves, but it does not control the power of the locomotive that may be placed thereon. Permanent IYay.-This determines the maximum weight that is allowable per axle in tons, and is approxi- Weight of rail in lbs. per yard. mately equal to the - The 5 condition of the permanent way, how ballasted and sleepered, and the super-elevation of the rail on curves, are important when dealing with speeds. Bridges.-These structures limit the weight per foot run over total wheel base, fixed wheel base, or over buffers, which necessarily varies, owing to the strength of the structures, and is therefore of great importance. Construction Gauge.-A complete drawing of this is necessary, and should show distinctly the extreme dimensions which the locomotive may have, the designer taking care that these clearances obtain with the engine on a curve, and also with worn tyres, this affecting the clearances of the lower parts of the machine.

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