A T H OROUGH AND PR ACT I CAL PR ESENT AT I ON OF MODER N ST EAM ENGI NE PR ACT I CE

LLEWELLY DY N . I U M . E . V i

P O F S S O O F X P M L G G P U DU U V S Y R E R E ERI ENTA EN INEERIN , R E NI ER IT AM ERICAN S O CIETY O F M ECH ANI C A L EN G INEERS

I LL US T RA T ED

AM ER ICA N T ECH N ICA L SOCIET Y C H ICAGO 19 17 CO PY GH 19 12 19 17 B Y RI T , , , AM ER ICA N T ECH N ICAL SOCIET Y

CO PY RIG H TE D IN G REAT B RITAI N A L L RIGH TS RE S ERV E D

4 8 1 8 9 6 "GI. A INT RO DUCT IO N

n m n ne w e e b e the ma es o ss H E moder stea e gi , h th r it j tic C rli ,

which so silently o pe rates the m assive e le ctric generators in

f r mun a owe an s o r the an o o mo e w one o ou icip l p r pl t , gi t l c tiv hich

t m es an o u omman s our uns n e pulls the Limited a sixty il h r , c d ti t d

n And t e e m o emen is so f ee and e fe in admiratio . ye v ry v t r p r ct its a on e e un on is e fo me w su e s on and cti , v ry f cti p r r d ith ch pr ci i

e u a a we ose s of the won e u eo e a and r g l rity , th t l ight d rf l th r tic l me chanical development which w as ne cessary to bring these

f n ‘ machines to th eir present stat e of p er e ctio .

i T h n u of the fa e of the s eam en ne was so ll e ge i s Watt , th r t gi ,

his as on e on of h s his ea es n en on and great that b ic c c pti t i , gr t t i v ti ,

f n f hi no s o s in onne on w m a n o m a y o s mi r di c verie c cti ith it , re i

n Y h almost as he gave them to the world ove r a c e tury ago . et e was so far in advance of the me chanical development of his tim e that his workmen could not build e ngine cylind ers n eare r true

- n n M o n u s m n n than three eighths of a i ch . der b ilder de a d a accuracy of at least two-thousandths of an inch— almost two

hundred tim es greate r .

(11 But me chanical skill is not the only particular in which prog

ss h d n m M an m no b ut m o t n m m n s re a bee ade . y i r i p r a t i prove e t have been brought about by a careful study of the theory of heat

n n T h n n e es . e e u o of e o mous a oss s th u of u gi r d cti r he t l e , e se s pe r

e a e s eam the ea of om oun e ans on th e e o m n h t d t , id c p d xp i , e d v l p e t of the S e enson W l s h r nd o — ll t ph , a c ae t, a ther valve gears a have contributed tow ards m aking the s team engine well -nigh mechan icall f n n n n y p er ect a d as efficie t as is i here tly possible .

(11 T he story has been dev e loped from a historical st andpoint and a on soun n n I t f n l g d theoretical a d practical li es . will b e ou d absorbingly interesting and instru ctive to the stationary engine er as well as to all who wish to follow mod ern steam engineering

e o m n T i d vel p e t . he material s particularly ad apted to hom e s u f . I e e o e the oo s ou o e of ea a ue in t dy , th r f r , b k h ld pr v r l v l s timulating the interest of the trained man or the layman in the

e n a e e o men s of the da h u f t ch ic l d v l p t y , t e p blishers will eel th at its m ss on h n i i as be e accomplish ed .

CO NT ENT S

Deve lopment .

Early history

Parts of steam engine

T yp e s and c onstruction

n Classificatio .

Simple engines .

Co mpoun d engines

Stationary engines

Farm or traction engine

Lo co motive engines

Water pumps .

Special engines

M arine

T ypes of engines

n n s E gi e d etail .

Propulsion .

Propelle rs

M anagement of marine engines

M echanical and thermal effici ency

Low thermal efficien cy inheren t

n Losses i practical engine .

n R adiatio .

Cooling by expansion

m n n n n r - n Stea co de satio a d e evaporatio .

Exhaust w aste

Clearance

F n rictio .

Operation e conomie s

M ultiple expansion

Jacke ting

on ense s C d r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Anal ysis of engin e me chanisms Crank effort F w ly heel .

Go ernor v . CONTENTS

Ere ction of ste am engine s

f m e n n e s O p eration o ste a gi .

Engin e sp e cification s

Se le cting an

Drawing up

Contract

Engin e

R e lative cost of o pe ration

Annual o peration expenses

Engin e te sts

I mpo rt an ce of tests A M E S . . . o . c de

ST EAM ENGINES

PART I

DEVELO PMENT

Earl H ist r . of advis y o y In the study this subject , it is thought able to review the historical development of the steam engine in

of order that a broad conception it may be obtained . It is not

of intended , however , to give the history the steam engine in detail w w although it is an exceedingly interesting one , hich ould be bene

ficial one w— é é for any to revie but rather , a short r sum in order that the student may be prepared for a detailed study of the mod ern engine . The first steam engines of which we have any knowledge were

H w two described by ero of Alexandria , in a book ritten centuries f . S o w before Christ ome them ere very ingenious , but the best F H were little more than toys . rom the time of ero until the sev

h wa w enteent s . At century little progress made this time , ho ever , there was a great need of steam pumps to remove water from the 1615 S coal mines . In , alomon de Caus devised an arrangement , consisting of a vessel having a pipe leading from the bo ttom which was w w was filled ith ater and then closed . When heat applied to

was w w the vessel , steam formed , hich forced the ater through the discharge pipe . Later an engine was constructed in the form of a steam tur

was n was bine , but unsuccessful , and the attention of the i ventors

u again t rned to pumps .

S aver F . S 1693 y inally Thomas avery completed , in , the first

wa w f commercially successful steam engine . It s very asteful o w steam as compared ith engines of today but , as being the first ’ wa s . S engine to accomplish its task , it successful avery s , engine , Fi . 1 of two A A g , consisted oval vessels I and 2, placed side by side w B w and in communication ith a boiler 1 . The lo er parts Were con 2 STEAM ENGINES

nected w In by tubes fitted ith suitable valves . operation , steam

was to A from the boiler admitted , say, the vessel 2 and the air driven

w as o ut . The steam then condensed and a vacuum formed by let w ting ater play over the surface of the vessel . When valve 1 was w w w opened , this vacuum dre ater from belo until the vessel was

wa full . The valve s then closed and steam again admitted by valve 2 , so that on Opening valve 3 the water was forced out through

w o 0. t w the delivery pipe The vessels orked alternately . When

‘ one w as w w was filling ith ater , the other open to the boiler and was Of two B B one being emptied . the boilers 1 and 2 , supplied steam to the oval vessels and the other was used for feeding water

Fi m o m u m n 1 . ar o f S ea n ne g . E ly F r t P pi g E g i

to the first boiler . In operation the second boiler was filled while e cold , and after a fire had been lighted under it, acted like the vess l used by Salomon de Caus and forced a supply of feed water into the main boiler . ’ A modification of Savery s engine— the pulsometer shown in

i 2— w F g . is still found in use in places here an ordinary pump could not be used and where extreme simplicity is of especial advantage .

Its valves work automatically and it requires very little attention . A serious difficulty with Savery ’ s engine resulted from the fact that the height to which water could be raised was limited by the pressure which the vessels could sustain . Where the mine was STEAM ENGIN ES 3

very deep it was necessary to use several engines , each one raising

the water a part of the whole distance . The consumption of coal in proportion to the work done was about twenty times as great as

was that of a good modern steam engine . This largely , though not

of w was w entirely , due to the immense amount steam hich asted by condensation when it came in contact with the water in the oval

vessels .

N w me e co n . The next great step in the development of the

was N w wh steam engine taken by e comen , o in 1705 succeeded in developing a scheme which prevented contact between the steam w and the ater to be pumped , thus diminishing the amount of steam uselessly condensed H e intro duced the first successful engine which used a piston working in a

cylinder . ’ Fi 3 Newcomen s . In engine , g ,

wa A there s a horizontal lever ,

at pivoted at the center , carrying one end a long heavy rod B which connected with a pump in the mine below . A piston C was hung from the other end of the lever and worked up and down in a vertical

D w w as cylinder , hich open at the top . Steam acting on the lower Fi 2 u so me e g . . P l t r side of the piston , at atmospheric

was pressure , admitted from the boiler to the cylinder , and as the

was w w pressure the same both above and belo the piston , the eight of of w li the heavy pump rod raised the piston . A jet ater in the cy n der condensed the steam and formed a vacuum . This left the piston with atmospheric pressure above and very little pressure below

‘ was w (a partial vacuum) , so it forced do n and the pump rod raised again . Steam could again be admitted to the cylinder ; the w pump rod ould fall ; and the process could be continued indefinitely . In the days o f Newcomen it was very difficult to obtain good w For o orkmanship . this reason it was often necessary t make

of w w the cylinders ood . In order to prevent steam from blo ing 4 STEAM ENGINES

or w was around the piston , air from leaking in here steam being

was w condensed , it customary to keep a jet of ater playing on the top of the piston . One great trouble with all of these engines w as that some one was required to open and close the cocks , and boys were generally

w One employed to do this ork . boy , in order to get time to play , rigged a catch at the end of a cord which was attached to the beam

’ Fi . 3 N e w c om e n s S e am u m n n ne g . t P pi g E g i

f r B w o . overhead , and this did the ork him y making the valves in

wa w this y automatic, made it possible to dispense ith the services of the boy and at the same time greatly increase the speed of the engine . The Newcomen engine was improved slightly from time to time by different inventors and was very extensively used until the f o f f . time Watt , a very ew o them still being in existence today While this engine was a success and a great improvement over its STEAM ENGINES 5

it was w c o m predecessors , still very large , asteful , and heavy in

w w w o f parison ith the ork done , and the cylinders , hen made iron , w were simply cast and not bored , thus leaving a rough , inner all . 1763 w att. N W In the year , a small model of a e comen engine

a G w S w s taken to the shop of an instrument maker in lasgo , cot

. w was land , to be repaired This instrument maker , hose name

James Watt, had been studying steam engines for some time and

H e was of he became very interested in this model . a man great m genius , and before he died his inventions had made the stea engine so perfect a machine that there has been but one really great improve

ment in it since his time , namely, compounding . ‘ H e to was rst found that obtain the best results it necessary , fi , that the temperature of the cylinder should always be the same as

w second w that of the steam hich entered it ; and , that hen steam was

condensed it should be cooled to as low a temperature as possible . All improvements in steam-engine efficiency have been in the direc

’ tion of a more complete realization of these two conditions . In order to keep the cylinder nearly as hot as the entering steam , Watt no longer injected water into the cylinder to condense H or . e the steam , but used a separate vessel condenser made his

was piston tight by using greater care in construction , so that it H unnecessary to have a water seal at the top . e then covered the

’ top of the cylinder to prevent air from cooling the piston . When this was done he could use steam above the piston as well as below ; this made the engine double acting .

Al hot so , in the effort to keep the cylinder as as the entering steam, he enclosed the cylinder in a larger one and filled the space w . was w bet een with steam This not often done , ho ever , and only f o of . late years has the steam jacket been much advantage Also ,

was of was the steam used expansively , that is , the admission steam stopped when the piston had made a part of its stroke ; the rest of the stroke was completed by the expansion of the steam already admitted . This plan is now used in all engines that are built for economy . Other inventions made by Watt on his steam engines were : a

arallel motion p , that is , an arrangement of links connecting the end of the piston rod with the beam of the engine in such a way as to guide the rod almost exactly in a straight line ; a throttle valve for 6 STEAM ENGINES

of centrifu al overnor regulating the rate of admission steam ; and a g g , which controlled the speed of the engine shaft by acting on the ’ throttle valve . Watt s engine as finally developed is shown in

i 4 . F g . Watt saw that by using high-pressur e steam he could get more work from it ; but as it was not possible to make a very reliable

’ i 4 na o m o f W a s . te m m n n ne F g . . Fi l F r tt S a Pu pi g E g i boiler he never used a pressure of more than seven pounds per square A 1800 inch above the atmosphere . bout the year , comparatively high pressures came more into use and the non-condensing en gine ’ was introduced . In Watt s engine , and all those preceding hi s , a

was of vacuum produced in front the piston by condensing the steam , and either the atmosphere or steam at atmospheric pressure pushed STEAM ENGINES 7

- it through the stroke . In the non condensing engine , using high

pressure steam , the space in front of the piston could be opened to

s the atmosphere at exhaust and , although the atmospheric pre

sure resisted its motion , the pressure of the steam behind the piston w was still greater than that of the air . These engines ere much

more simple than the condensing engines , as they required no con

denser .

w wo Comp ound Pumping Engine. About this time hat uld now be called a compound engine was introduced by H ornblower

two and later by Woolf . It had cylinders of different size , steam being admitted into the smaller one and then passing over into the larger . Only a little expansion occurred in the small cylinder and

n much more in the larger o e . 1814 About the year , Woolf introduced a compound pumping

w was engine in the mines of Corn all , but a simpler engine later intro

’ duced and Woolf s engine fell into disuse . This later engine became known as the Cornis h p umping engine and was famous for many

was years because of its economy . It the first engine ever built that could compare at all with modern engines in the matter o f steam consumption . It consisted of a single cylinder placed under one end of a beam from the other end of which hung a heavy rod w S w as hich ope rated a pump at the foot of the shaft . team admitted to the upper side of the piston for a short portion of the stroke and w allo ed to expand for the remainder of the stroke . This forced

w r od the piston do n , lifted the heavy pump , and filled the pumps

w w a w with ater . Then communication s established bet een the upper and under side of the piston , exhaust occurred , and the heavy

t e w of pump rod fell , lifting the piston and forcing h ater out the

S - . was pumps team cut off at about three tenths stroke , and the pump made about seven or eight complete strokes per minute with a short pause at the end of each stroke to allow the valves to close easily and the pumps to fill with water . These engines needed great

w w w fre care and ere in charge of competent men , to hom prizes ere w quently given for the best efficiency , hich doubtless accounts for

e their wond rful performance .

Par s of te t S am Engine . Leaving the historical side of the steam engine let us now turn to the modern simple steam engine and study F w . 7 briefly its construction igs . 5, 6, and , ill serve to illustrate a 8 STEAM ENGINES

horizontal , center crank engine , all the more important parts being numbered . The function of the various parts will be considered in detail later in the work .

F 6 . R . 5 7 eferring to the numbers in igs , , and , the names of the parts are shown in the following list

LI ST o r PAR T S

Sub -b ase 1 Flywh e els 3 4 Frame 2 Valve pis to ns 3 5 M ain b e arin g caps 3 Valve rings 3 6 M ain be aring liners 4 Valve c ag es 3 7 Cylin de r 5 Valve r od 3 8 Cylin der he ad 6 Valve r od nuts (valve end) 3 9 F alse h e a d co ve r 7 Valve r o d n uts (r am en d) 40 Valve ches t he ad (h ead e n d) 8 Valve r o d glan d 41 Valve ch es t h ead (cran k en d) 9 R am b ox 42 Pisto n 1 0 R am b ox caps 43 Piston rings 1 1 R am 44 Pis to n r od 1 2 R am p in and nut 45 Pist on r o d nu t (pis ton e nd) 1 3 R am p in c ap 46 Pis to n r o d n ut (crosshe ad e n d) 1 4 E ccen tric r o d c onn e ction 47 Pis ton r od s tu ffin g b ox 1 5 E ccentric r od 48 Piston r od gl an d 1 6 E ccentric r o d nu t (r am e n d) 49 Crosshe ad 1 7 E ccen tric r od nut (e cc entric e nd) 50 Crossh e a d sh o e s 1 8 E cce ntric 5 1 Crosshe ad adj u stin g s crews 1 9 E cce ntric s trap 5 2 Crossh e ad p in 20 D ash plate 5 3 Crossh e ad p in n ut 21 D ash pl ate glan d 5 4 Cross p in w ashe r 22 D oo rs 5 5 Conn e ctin g r o d 23 Doo r h an dle 5 6 Conn e ctin g r o d b o lts 24 D o or cl amps 5 7 Conn e cting r od strap 25 Oil h oo d 5 8

‘ Crossh e a d p in b ox 26 Oil ho o d han dles 5 9 Crosshead p in b ox w e dge 27 E ccentric oil b o at 60 Adj us ting s cre w s 28 V alve r o d oil boat 6 1 Cran k p in b ox 29 Oil vent 6 2 Cran k p in b ox we dge 3 0 Sheet stee l laggin g 63 Adj us tin g s crews 3 1 Dra in co cks 64 Cran k disks 3 2 Shaft go vern o r 6 5 Cran k sh aft 3 3

b- Base - F of Su . 1 i . 6 The sub base , g , is made of a good grade cast iron and is usually heavily ribbed and made high enough to

- permit the wheels to clear the floor . The sub base is often omitted

of . with engines large size , the engine being set upon a concrete base

rame 2 w F . The frame is the element or link by hich all of the

f s parts o the engine are held in place , so that their relative position

10 STEAM ENGINES

w small sizes the cylinder is frequently cast integral ith the frame . Provision is always made for adjustmentsnecessitated by any wear

f . Fi o . 6 the frame or parts attached thereto It is to be noted in g , that the frame crank case 2 is connected with the crosshead guide .

- It frequently has an opening into the sub base , thus permitting the oil from the crosshead , guides , and crank to drain into a suitable

- receptacle in the sub base , from which it is taken by means of a drain cock conveniently located in the side or end . The crank is enclosed

i 7 E nd e a on an d a Se c o n f M m . o e n S e n ne F g . El v ti P rt ti o d r i pl E g i

S w oi by a neat , pressed , heet steel cover , hich prevents the l from w w f w being thro n out ard on the loor hile the engine is running .

"uite frequently the crank cover is made of cast iron . Fi linders . 5 . 5 Cy The cylinder , g , is one of the most impor

of tant parts the steam engine , for it is in the cylinder that the f energy o the steam is converted into useful work . The cylinder is circular in section and is attached to the bed by means of a number f f . o o bolts It is made close grain , gray cast iron . The casting of the cylinder should be done with great care , so as to insure a

of w- casting free blo holes or other defects . i 8 F g . illustrates the cylinder in cross section as well as show ing its contained parts . The cylinder barrel 1 is accurately bored STEAM ENGIN ES 1 1

2 and fitted . Inside of this barrel the piston is driven back and

w on one forth by the steam , hich is admitted alternately side and then on the other through the ports 13 . The piston is connected to the crosshead through the piston rod 3 . The continuous move ment back and forth of the piston causes the surface of the cylinder to wear away , and in order to avoid a shoulder being formed by this

action , the cylinder is counterbored at each end by an amount depending on the size of the cylinder . The diameter of the counter

i in F n m w n S c t . o n 8 . n n M e s S o e g . Cy li der a d V alve c h a i h

bore 22 is usually about one- quarter of an inch larger than that of w w the cylinder proper, depending , ho ever , some hat on the size of the cylinder . The stroke of the piston is such that the piston moves w beyond the earing surface at each stroke , thus preventing any w shoulder being developed in the cylinder all . The cylinder is attached to the bed of the engine by a number of bolts which are placed through the flanges 23 of the cylinder and E cylinder head . ach end of the cylinder is closed by means of the

6 9 6 c lin cylinder heads and . The cylinder head is called the back y 12 STEAM ENGINES

9 w der head (head end) , and is kno n as the front cylinder head

(crank end) . In the illustration the front head 9 is a portion of the frame , but in many constructions it is entirely independent of the

- frame . In order to have a steam tight cylinder , it is necessary to make a tight joint between the cylinder heads and the cylinder bar rel . This is accomplished by turning both surfaces true , then grind A ing the joints with emery and oil . fter the joints are well ground the heads are tightly drawn up against the cylinder by means of A bolts suitably arranged . Sheet iron jacket 19 is put around the 21 w cylinder, leaving an air space bet een the cylinder walls and the

. off w jacket This air space retards the cooling of the cylinder alls ,

of hence initial condensation the steam in the cylinder is reduced .

of In some types engines such as locomotives , this air space is filled

W i - m a a th some non conducting ateri l such s asbestos . This is also

Fi s on S o n s o n R n s for M ak n S e am-T J o n s g . 9 . Pi t , h wi g Pi t i g i g t ig ht i t

sometimes done by builders of stationary engines . It should be t noted also , tha the back cylinder head has an air space for the same reason as that given for the space surrounding the cylinder . Since

s condensation does take place in the cylinder , some mean must be w Fi 6 6 . provided for removing the ater , hence the drain cocks 4, g , are placed in the bottom of the cylinder at each end . The pipe connection for these cocks enters the cylinder in the counterbore

An w near the wearing surface . y ater that may be in the cylinder will be forced out through these cocks if they are open . Care must

of w not be taken that the cylinder is freed ater , for if it is , on account of of the incompressibility water , the cylinder head may be forced ff r o or other damage result therefrom . Some cylinde s are provided STEAM ENGINES 13

w with relief valves , which automatically open hen the pressure from any cause reaches a certain amount , thus preventing the bursting of a cylinder head .

B w 2 Fi o n Rin s . w f is to . 8 P g et een the piston , g , and the alls

- the cylinder there must be a steam tight joint , so that the live steam can not pass around the piston and be exhausted before expanded , i w w otherw se a great waste of po er ill be incurred . The require l Fi u w . 9 ment is f filled by having the piston grooved , as sho n in g , and fitted with packing rings . These packing rings , commonly

sna rin s i called p g , are turned up slightly larger in d ameter than the w i F . S cylinder and being cut , as sho n in g 9, they pring out into the w cylinder , al ays pressing against the walls and forming an almost perfect steam joint . The piston of every engine is made with two i or more of these pack ng rings . The cuts in the rings must not be placed directly in line with w each other , other ise the steam would have a better chance to w blo through . In order to pre vent this the joints are always placed on Opposite sides of the w piston . Packing rings are al ays

i t n n F . 10 a Se c o a a nd e t o n . a made of cast iron , and are usu g P rt i Pl El v i o f C o n i c a l Pis to n ally turned up to a uni form sec

two . tion . The outside portion and the sides are carefully machined Fi is tons . 2 . 8 P The piston , g , is usually made of cast iron , but sometimes is made of cast steel . It may be a solid disk grooved , i F . i o ut . F . 8 as in g 9, or the central portion may be cored , as in g Another type of piston that is largely used in marine and some i i 1 0. times locomotive service is illustrated n F g . This is a com

arativ el p y light cast steel piston , but at the same time a very strong w one , due to its conical construction . It ill be noted also that only 1 w the one packing ring is used . This packing ring is much ider than the ordinary snap ring and is pressed out against the cylinder wall by a number of single leaf springs being placed between the i of F . 1 2 body the piston and packing ring , as shown in g 0at . The 14 STEAM ENGINES

w L- 3 piston is made ith an shaped edge , a band 4 being bolted on the

S L open ide of the , thus forming a groove or opening for the recep f tion o the small springs and the packing ring . The connection of the piston rod to the piston is also clearly shown . The rod 5 has a tapered end which is forced by hydraulic pressure into a tapered hole in the piston ; the nut 7 is then tightened up and locked by placing the plate in position around the nut and fastening it with cap screws . This arrangement insures a lasting connection between the piston and the piston rod . It is essential that the piston be as light as possible in order to

a of w reduce the mount ork absorbed in pulling it to and fro , and

w on w of also to reduce the ear the lo er portion the cylinder . i 3 F . 9 The piston rod , g , is fitted into a tapered hole in the pis ton and secured by means of a lock nut and cotter pin placed o n the back end . Oftentimes the tapered fit is made very tight and the

An piston forced on by hydraulic pressure . older form of attaching i the piston rod to the piston is Shown in F g . 8 . In this instance the w rod has a tapered end , hich is driven into a tapered hole in the pis i w t . ton here is secured by a nut , no cotter pin being used The

of w other end the piston rod is threaded , scre ed into the crosshead , Fi w . 6 as sho n in g , and secured by means of a lock nut . In some constructions the crosshead end of the piston rod is tapered and M secured by a key . any schemes have been employed by different manufacturers for fastening the piston rod to the crosshead , all of which have their advantages and disadvantages . The piston rod ,

of although usually made a g ood quality of open hearth steel , is w frequently made of nickel steel , hich possesses great strength .

P As Stufiing Box and acking. the piston rod passes through the k front cylinder head , some provision must be made for ma ing a

- steam tight joint between the piston rod and the cylinder head . This

of f 5 is accomplished by means the stu fing box 4, and the gland , i f F . S o shown in g . 8 ome form packing is placed around the piston rod within the stuffing box 4 and the gland is forced in by means of w bolts or a secured cap as sho n , thus holding the packing in the box and at the same time crowding the packing tightly against the piston rod . The piston packing may be made of woven strands of hemp or

of ro cotton ; or asbestos may be used . To insure lubrication the d STEAM ENGIN ES 15

this fibrous packing is soaked in oil before being placed in position . In addition to this form of packing there are different compositions

Of rubber , graphite , cotton , etc . , also various kinds of metallic pack

ing in use . A metallic packing is made of material such as babbitt

w of metal , hich is a soft alloy copper, tin , and antimony . This and

n k other compositio s are used for metallic pac ing , and the metal , w w being comparatively soft , ears a ay much more rapidly than i 1 F . 1 h . one o f t at of the piston rod g illustrates form packing ,

w . . M kno n as the U S etallic packing . The principle of operation is

w : 2 as follo s The babbitt metal rings , consisting of three rings cut

in half, provide the packing and are the only parts which come in

contact with the rod . These rings are forced into the vib rat 6 ing cup against the rod , and are fed down as wear takes place by the pressure of the steam itself . The spring b e hind the follower 3 is merely intended to hold the rings and other parts in place when A steam is shut off . ground joint is made between the flat faces of the vibrating cup 6 and the ball joint 4. There is also

n w Fi 1 fin a grou d joint bet een the ball g 1 ° Stu f g o k ac k e d with M etallic ga c m g joint 4 and the gland r. The combination of the sliding face of the vibrating cup and the ball joint permits the packing to follow the rod freely without any increase in friction should it run out of line for any cause . This is an important w feature , since the ear of the crosshead , guides , piston head , and cyl w w inder produces an irregular alignment of the piston rod , hich ould

w a k s . injure the pac ing to a marked degree , if it not flexible The 7 w parts of the packing are held in place by the gland , hich is bolted

- w to the cylinder head . A steam tight joint is made bet een the gland

o f and the cylinder head by means a copper gasket . The purpose

w 5 a w w of the s ab cup is to hold in place s ab , hich is usually made of w w or oil aste , candle icking , a braided material , soaked in and oiled from time to time as a means of keeping the piston rod well 16 STEAM ENGINES

. to w lubricated In addition this service , the s ab catches and retains a considerable amount of dust and grit which would otherwise find w its way into the cylinder , here it might do harm . It is to be said in favor of the various so- called rubber

packings , that they give very good ser

vice . The four different styles of rubber Fi 12 packing illustrated in g . , are not

composed entirely of rubber , but contain

other material such as graphite , cotton , f etc . These di ferent styles of packing

on are used both piston and valve rods . It is to be borne in mind that all which has been said with reference to the piston rod is equally applicable to valve stem f packing . The general construction o the

valve stem glands , vibrating cups , etc . ,

w of is identical ith those the piston rod . The same materials are used for the packing medium and the same watchful care is required in order to obtain satis

an factory results . Packing is important subject and one which Should be care

fully looked after . It can not be said that any one particular kind or style of packing is the proper one to use in every

case , for a packing which may give very satisfactory results under one set of con

ditions may utterly fail under another .

For instance , a packing suitable for low steam pressures is not efficient where

high steam pressures are used , and a packing that may give satisfaction with high pressures may not in any measure Fi 1 2 T e s of R u bbe ac n g . . y p r P ki g meet the requirements imposed upon it by E the use of superheated steam . ach particular installation is , there

ff . fore , a different problem and must be solved in a di erent manner Fi V a s . w 1 1 w . lve . 8 In g , the valve is sho n in position It ill be noted that the valve rests upon the valve seat 14 and works between

18 STEAM ENGINES

surrounds it on all sides , hence there is no excessive pressure on any part of the valve . It is comparatively light and therefore easily m driven and lubricated . The general for of construction of piston 1 F . 2 an 22 valves is illustrated in plan in igs d .

Eccentric . The valve is driven by its connection to the shaft by means of the valve stem , eccentric rod , and the eccentric . The w Fi 1 relation of these parts is ell illustrated in g . 3 . The valve shown is an ordinary piston valve with flexible snap packing rings 4 similar to those previously described for the piston packing rings . In fact, the piston valve , as the name implies , behaves very much like the

two 1 2 steam engine piston . The piston ends and are held together by the valve rod 3 . The valve rod has nuts so placed that the pis tons are held the proper distance apart . The valve rods , or stems as they are often called , extend beyond the valve box some distance

of and connect with the eccentric rod 5 . The manner making the

w rod connection bet een the valve rod and the eccentric varies widely , this connection being governed largely by the type of engine and

Fi 1 w wo f the exigencies of the case . g . 3 sho s t methods o making

of this connection , one being accomplished by making use a rocker i arm and the other by using a ram . The way in wh ch the rocker 1 10 u . 0 arm is used , is obvious from the fig re The ram is a square w block , orking in a bearing and so constructed that the valve and eccentric rod can be attached to it . When the ram is used , the

i I S mi mot on trans tted to the valve in a straight line , hence there is less strain upon the connecting parts than if a rocker arm was employed .

rod 5 The eccentric , in both cases , is attached at one end to the eccentric strap 6 and at the other end to the ram or rocker arm . Nuts suitably arranged make the rod secure and at the same time provide a means for lengthening or shortemng the rod as needs demand . The valve and eccentric rod are usually made of mild steel turned true and polished . 6 w The eccentric strap is made of gray cast iron , lined ith good babbitt metal for a wearing surface upon the eccentric . The strap B is held on the eccentric by means of the bolts 7 . y removing liners

w two or shims from bet een the sections of the strap , adjustments for wear can be made . There are several patented straps on the m a arket th t possess particular features , but the essential elements STEAM ENGINES 19

P for of all eccentric straps are about the same . rovision is made lubrication by having an oil cup 1 1 east with the strap .

T he eccentric 8 is mounted o n the main shaft 9 and is held

Eccen secure in the position desired by means of the set screw 12 . tries for large engines are held by means of one or more set screws

For of of , and a key . a discussion the function the eccentric the “ " student is referred to the instruction book on Valve Gears .

15 Fi . 8 Steam Chest. The box , g , containing the valve and its 16 k w . parts , is no n as the steam chest The steam chest cover is held in place by studs which pass through the flanges 1 7 into the

box . The steam chest is connected to the steam supply by suitable pipe c o n n e c t i o n s , steam being turned on or off as desired by means of the throttle v a l v e . W h e n the t h r o t t l e v a l v e is opened , steam passes into the chest through the valve , into the w cylinder , here it is

4 a n in f r La e S z e n ne i . T c a oss e a d P o F g 1 . y pi l Cr h d rg i E gi

expanded and then ejected through the exhaust Opening . The energy of the steam is transmitted through the piston and piston 1 Fi 23 7 . 6 rod to the crosshead , g , thence to the connecting rod , 3 3 crank pin , to the main shaft . In order that these parts may properly perform the function of transmitting this energy , a correct design is highly essential ; therefore , a discussion of their construe tion is deemed necessary .

ross head and C Connecting Rod. The crosshead is usually made of steel which forms a connecting link between the piston rod and 20 STEAM ENGINES

rod . the connecting It is made in various shapes and patterns . i One F . 6 . type is illustrated in g In engines of larger size , the pre vailing form of the crosshead used is similar to that illustrated in 4 Fi . 1 . 1 two w g This crosshead consists of a steel casting and edges , or 2 w shoes , , hich fit over a projection on the outside surface of 1 . These wedges are either cast or forged and serve as a retainer for

on a layer of babbitt metal the outside . It will be noted that there are oil grooves cut on the surface of 2 in order to facilitate the oil ing of the crosshead guides . These wedges are provided with a nut for n and bolt 4, whereby adjustment wear can be made as e ces

I S sary . Usually there a slight amount of clearance between the crosshead and the guides , but it should not be in any case excessive . 3 The piston rod is fitted into the end , as already described . The d 6 w connecting rod is attache to the crosshead pin , hich fits into the hole 5 and is held in place by a nut . The crosshead pin 6 is made of a good grade of steel and has a portion B which fits into the

Fi . 1 5 So o e Ste e nn t n R g . lid F rg d l Co e c i g od

of back side the crosshead , as viewed , the other portion C fitting D into the outside part . When the pin is in place , the collar is E w A adjusted and the nut tightly dra n . The straight portion goes between the sides of the crosshead , and upon it the connecting rod brasses bear .

o of There are tw general types connecting rods in use , usually classified as marine and locomotive . Connecting rods of the marine

n of type are as a rule u sed o engines comparatively short stroke , while those of the locomotive type are employed on engines hav ing a long stroke . - W These rods are forged from open hearth steel , ith solid forged

n ends for the crosshead end , and a square end for the cra k end in c ase of the marine type ; and a solid forged or forked end for the crank end in case of the locomotive type . i 15 s rod F . The connecting rod , g , is a solid forged teel having 1 the ends machined out to receive the brasses . The crank end is STEAM ENGINES 21

fitted with a brass or bronze box lined with a good quality of babbitt 2 w metal . The crosshead end is usually , but not al ays , fitted in a A similar manner to that of the crank end . djustment for wear is

of w 3 . made by means wedges at each end , as sho n at These rods are usually of rectangular cross section , although round shapes some

' on times are used , especially small engine i of F 16 . The marine type connecting rod is illustrated in g .

rod The body of the is forged similar to the locomotive type , as is ff also the small , or crosshead , end , but the distinguishing di erence

wa w or . is in the y in hich the large , crank, end is formed The end of the rod is enlarged and finished square , and the box containing w w w the crank bearing hich is lined ith a good earing material , is

rod fastened to the proper by means of the bolts . Adjustment for wear is made by tightening up the nuts on the bolts .

w Fi 6 rod It ill be seen in g . that the connecting is the connecting w 33 link bet een the crosshead and the crank . The length of the

Fi 1 6 M a ne T e o f o n ne c n R o d g . . ri y p C ti g connecting rod bears a definite relation to the length of the crank

of of to radius . The ratio the length the connecting rod that of the crank radius varies in practice from four to eight . Occasionally

i conditions demand a greater ratio than e ght , but it is seldom less than four .

Fi 17 of g . illustrates the connection the piston , crosshead , con

ctin ne g rod , and crank shaft . The function and construction of the piston , crosshead , and connecting rod have been previously dis

H in w . w cussed o ever, the figure is valuable that it sho s quite clearly the relation of the various parts to each other . The crank shaft used on center-crank engines is frequently a solid steel forg

2 . ing , which includes the crank pin

Miscellaneous ar w P ts . In order to compensate for the eight of the connecting rod and brasses it is necessary to put counterweights n i w o w F . 1 the shaft as sho n at 4, g 7 . These counter eights are 22 STEAM ENGINES

usually heavy castings , machined to slip over projections on the

or crank shaft , and securely fastened thereto by bolts set screws .

of 1 F i . 17 The portion the shaft marked , g , fits into the bearings

for or provided the main shaft crank shaft , the length of this bear ing portion being the distance between the counterweights and the

w o collars 5 . It ill be noted that n one end of the shaft is located a 3 S disk . ometimes this disk is forged as a part of the shaft and at

other times it is made separate and forced on by hydraulic pressure . The purpose of disk is usually intended to provide a ready

Fi f sto n ss e n n n n . 1 7 . o nne c t on o o a o n e c R od a d a S a g C i Pi , Cr h d , C ti g , Cr k h ft means of attaching the Shaft of an electric generator when a direct connected plant is feasible or desired . It may be said here that a direct connected plant offers many advantages over a belt—driven system . It simplifies the plant , reduces friction , gives greater

w . reliability , and makes possible more po er in a given space The projection 6 on the other end of the shaft is the axis upon which the flywheel is forced and held secure by means of a key . The crank pin 2 should be of such ample proportions as to be safe against breakage and the heating of the pin or brasses placed upon it . STEAM ENGINES 23

ll - A engines are not of the center crank type , but many have a

o n side crank, the crank being a disk or a crank arm fastened the 3 end of the main shaft very much in the same manner as the disk , i i 17 . F g . In this k nd of construction the crank pin is usually a piece

or to separate from the crank arm crank disk , and is connected it by

on or on being forced and then riveted over , by nuts put and cot d r . te e In either the side crank or center crank construction , the distance from the center of the axle to the center of the crank pin

- is equal to one half the stroke of the engine , as for instance , an 1 24 12 w 8 X engine has a crank arm of inches in length , hich is just

- of f one half of the length the stroke . In speaking of the size o the

engine it is customary to mention the diameter of the cylinder first ,

of that is , in speaking an 18x 24 engine is meant a cylinder 18 inches in diam ’ eter and a stroke 24 inches . Fi The main bearing 4, g .

7 S w , hould be designed ith great care , having liberal proportions and lined with

- anti friction metal , ham mered in place and accu ratel y bored and scraped Fi 1 8 Se c o n o f abb t L ne u a e g , . ti B it i d , "rt r o e M a i n e arin g OI" B x d B to fit the Shaft . small engines the lower half of the main bearings are usually made

of . of a part the frame , the upper half being a removable cap B w w et een the upper and the lo er portion of the bearing , metal

neces liners are placed , which afford ready means for making any sary adjustments .

- Large engines have a babbitt lined , quarter boxed main bear

of Fi 1 ing ample size , g . 8 . To provide for both vertical and lateral adjustments it consists of four parts carefully machined on all sides and scraped to fit accurately . This bearing is so constructed that the bottom piece can be removed by slightly raising the shaft . B The other three parts are removed after taking off the cap . y

of w 3 2 1 use the adjusting scre s , the side and the top may be properly adjusted by the sense of feeling when the engine is in

motion . 24 STEAM ENGINES

There are many other types of main bearings besides those f mentioned , but they di fer only from those already described in some of the minor details . The value of these details varies through w own ide limits , each builder contending for his particular design .

- one A side crank engine needs but heavy bearing , such as that

Fi 1 w of w . 8 sho n in g , as the fly heel end the shaft, being subjected to forces acting in but one direction only , requires a much smaller

Fi 1 - . 9 out bearing . This outer bearing , g , is called an board bear ing and is smaller and simpler in construction than the main bear t w w ing . It is suppor ed by a special casting , hich has a hollo recess into which lubricating oil is poured . The shaft carries one or more small chains or rings which fit loosely on the shaft and dip into the

i 1 - e ar n o f m e o ns u c o n ha n M a n e n 9 . Ou t oa S a F g . B rd B i g i p l r C tr ti t i B ri g

oil a t w . Thus it is seen th t oil is constantly brought in con act ith

i of the bear ng of the shaft . This same scheme lubrication is also

f n f used for the main bearing . As the di fere t types o engines are

w . considered , the several types of bearings ill be noted and discussed

3 Fi two- ur o h one w . 5 se The belt heels 4, g , serve a fold p p as a v wh w go erning device , the value of ich ill be discussed later , and the other as a means of storing up energy while the piston is in mid w f stroke , here the crank e fort is greater than the resistance to be w w overcome . The belt heels act as a fly heel and give up this energy at the ends of the stroke , thus enabling the engine to run over the dead centers . The design of the belt or flywheel is an important item in the proper proportioning of a steam engine . Its weight and dimensions must be very acurately d etermined . The

w or w e w belt heel , fly he l . hichever is employed , is made of cast iron

26 STEAM ENGINES

The same authority further classifies engines according to their

w : structure , as follo s

Simple I E ans on . xp i Co mp oun d Dire ct acting Beam Vertic al o s on of c n e I I . P iti yli d r I n verte d H orizon tal I n clined

lCon densing I I Ste m I ' a l Non -con densin g

P s on V . i t

e am ur nes V I . St t bi I I R o a V . t ry

c onne cmd I I I onnec tio V . C

I X on ens a . C d ti

e They are frequently designated by the name of the inv ntor , designer, or or constructor , as the Watt , the Corliss , the Porter engine . From the last two groupings it is evident there is no sharp line of

of c demarcation , for in many instances engines one lass have essen

of tial parts similar to those another type . In this work the classi

fication outlined in the last group will be taken as a basis for study .

Simpl e Engines . The simplest type of engine is the single

one of expansion . It has cylinder and admits steam for a part the stroke , expands it during the remainder , and exhausts either into

or . S F . 5 6 the atmosphere into a condenser imple engines , igs and , are w 200 h now used only for comparatively small po ers , say p or less , and although more extravagant in the use of fuel than the others ,

l ow may still be the most economical financially , if first cost is an important item ; if they are not run continuously ; or if the load

fluctuates widely . n n in r Compou d E g es . Compound engines have two cylinde s F 2 2 l ow . 0 1 known as the high pressure and pressure , igs and . It will

o be noted that tw different types of compounds are represented , the

Fi 20 - two s ne . o in g being known as a cross compound , the cylinder STEAM ENGINES 27

Fi 2 1 - being parallel , and the one in g . , a tandem compound engine , w the cylinders being in line ith each other .

S or team enters the smaller high pressure cylinder , and the n w expands until release , hen it is exhausted into the larger cylinder,

where it expands further . The cylinders should be so proportioned

of that approximately the same amount work can be done in each , which may be accomplished by making the high pressure cylinder enough smaller than the low so that when the steam leaves the high w at a lower pressure than hen it entered it , the increased volume of the steam may be taken care of and at the same time the increased area of the low pressure piston may compensate for the drop in steam pressure .

i - 20. F g . T y pi c al Cross Co mp ou nd E ng ine

B - esides being economical , the cross compound has a distinct mechanical advantage . The two cranks may be set at right angles

w o ne of so that hen is on dead center , the other is at a position nearly its greatest effort . This makes a dead center impossible , and gives a more uniform turning moment . Then the individual parts may be made lighter and are thus more easily handled . When the cranks of the cross- compound engine are at 90degrees with each other the low pressure piston is not ready to receive the w steam hen the high pressure exhausts ; therefore , there must be a

l ow S receiver to hold the steam until admission occurs in the . uch

- engines are called cross compound , because steam crosses over from 28 STEAM ENGINES

one to side the other . Sometimes instead of having the cranks at 90 degrees , they are placed together or opposite . Then the strokes begin and end together , and the high can exhaust directly into the low w ithout a receiver . A - Fi 21 tandem compound engine , g . , has both pistons on one rod r , the high pressu e piston rod forming the low pressure tail rod .

Such engines are less expensive because there is but one set of recip rocatin a two g p rts instead of , but like simple engines they have the d isadvantage of dead points .

T ri le Ex ansion En ines p p g . Triple expansion engines expand

s s two the team in three stages in tead of . There are usually three

- Fi . 2 1 Se c on of n e an d a es of a T an e m m g . ti Cy li d r V lv d Co poun d E ng ine

V iz and low cylinders , , the high, the intermediate , the , arranged 12 hi with cranks 0degrees apart . T s gives a more uniform turning

S on moment than a compound . ometimes there are four cylinders

v iz one i one the triple expansion engine, , h gh , intermediate, and two low . This arrangement gives better balance and is often used in marine work . For triple engines there must be a rece iver between each two

i r of c F . 22 w e ylinders . g sho s the ess ntial featu es a triple expansion e ngine .

u "adruple Engines . "uadruple engines expand their steam in

of M e four stages instead three . ultiple xpansion engines are nearly w al ays condensing. STEAM ENGINES 29

Cylinder Ratios . There are several considerations to be remem bered when p rop orti omng the cylinders of the multiple expansion

engines . The ratio of the cylinders should be such that each devel w w ops nearly the same po er , and the drop in pressure bet een the cylinders and receivers should be as small as possible .

There are many formulas in use , some simple , others more com A for plex involving mathematical calculation . common rule com pound engines is to make the ratio of the cylinders equal to the square ex an root of the total ratio of expansion . Thus , if the steam has an p

Fi 22 c n of sen a e a ures o f T e ans on n ine g . . Se tio E s ti l F t ripl Exp i E g

9 3 sion ratio of , the ratio of the cylinder volumes will be or ; that

l ow w t is , the pressure cylinder ill have a volume hree times as great as the high pressur e cylinder . If the cylinder ratio is 3 and the

of of l ow length the stroke is the same for both , the diameter the pressure cylinder will be times that of the high pressure cylinder . Another rule is to make the cylinder ratio equal to the total ratio of expansion multiplied by the fractional part of the stroke com

l - p eted when cut off occurs in the high pressure cylinder .

S of 9 - uppose the ratio expansion is , as above , and that cut off

on - o f occurs at e third the stroke in the high pressure cylinder , the

of - ratio cylinder volumes will be or 3 . If cut off occurs at one- w or half of the stroke , the ratio ill be 3 0 STEAM ENGIN ES

For triple expansion engines the low pressure cylinder is made large enough to develop the full power if steam at boiler pressure is used . The intermediate cylinder is made approximately a mean between the high and low . The area of the intermediate piston is found by dividing the area of the l ow by one and one-tenth times the square root of the ratio of the l ow to the high . The above may be written thus °

Area of high pressure Area of l ow pressure cylinder

—off of cylinder Cut of high pressure X ratio exp .

Area of l ow pre ssure cvlinder of i Area nter . cyl .

In general , for triple expansion the ratios of the volume of the three cylinders are about as follows

V I : V 2 : V 3 : : 1 : to 5 to 8

For quadruple expansion engines , the ratios are as follows

V I : V 2 : V 3 : V 4 : : to to 5 : 7 to 12

It is self-evident that the compound engines illustrated are of the multiple cylinder class . They also have fixed cylinders and are f . o double and direct acting That is , steam acts on both sides the w piston , and the po er is delivered directly from the piston to the shaft or flywheel without the intervention of a walking beam or i F . some other transm tting medium . The engines illustrated in igs i 22 21 n w one w F . 2 . 0and , are horizo tal , hereas the sho n in g is vertical w A horizontal engine is , therefore , an engine hose cylinder is parallel

w or to the ground , and a vertical engine is one hich has its cylinder cylinders perpendicular to the ground . These engines may also be

- operated either condensing or non condensing . From the foregoing it must be obvious that it is not possible to w w classify an engine ithin narro limits , so it appears to be more logical to classify them according to the service for which they are to be used as in the second grouping .

l i n Se ect o of Type . In the selection and design of an engine there are a great many factors to be considered . The engine must w be as light as possible , and yet must be strong enough to do the ork STEAM ENGINES 3 1

likely to be imposed upon it . The bearings should be large and ample in number . Lubrication must be given especial attention if

n of w high speeds are to be used . Light ess design tends to ards small w f first cost , hich is important , but durability and e ficiency should

of not be entirely sacrificed for l ow first cost . In the course time the more expensive engine may prove to be the cheaper as maintenance and repairs may amount to considerable on a poorly designed and

For of w built engine . some classes service , ho ever , the cheap engine

For a one . s w is the best adapted instance , in mills , cotton mills ,

l ow and for similar class of service , a first cost simple engine is the one for w best suited the ork , because the labor employed to operate it is often inexperienced and ignorant . In such cases the protection w and care that can be given the engine is poor , hence the lo er the w value of the property exposed , the less ill be the loss resulting from

On the depreciation . the other hand , if one is selecting an engine

n for a lighting plant in a city , he would more than likely select o e of the most improved types of high speed , condensing machines . In the latter case the first cost would be considerably more than the

saw f one selected for the mill , but the increased e ficiency of Operation , w the slight depreciation , and the reduction in maintenance ould more than compensate for this . From the foregoing it is evident that there are many factors to be taken into consideration when selecting a steam engine for any given service . In the further study of the several different types the class of service for which each is best suited will be indicated in

so . w so far as it is possible to do There are , ho ever , some general

of features every engine should possess independent its class . It should be simple in construction , having compactness combined with great strength and durability . It should be well balanced and free A from severe vibration . ccessibility of parts is also an important consideration .

S T AT IONAR Y ENGINES

im l e i =Cr n T S S p S de a k ype . tationary engines for ordinary mill w service , such as machine shops , small po er plants , and various manufacturing concerns , are generally simple engines operating at

r moderate speed , having either plain slide valves o piston valves . w w There are , ho ever , some cases here compound engines of moder 32 STEAM ENGINES

ate size have been installed in similar plants in more recent years . The demand for electric generators has also largely affected the design of steam engines for small electric power plants . In speak ing of small plants , in this connection , it may be taken as meaning from 25 to 500horsepower .

of - w A simple slide valve engine the side crank type , hich has

w f was been largely used in plants here a cheap , e ficient engine the i 2 F . 3 . requirement , is illustrated in g This engine has one slide

S w w valve , an automatic or haft governor , and a heavy fly heel hich

u 9 is used as a belt pulley . It is b ilt in sizes varying from inches X 14 22 28 w inches to inches X inches , and develops a horsepo er of

Fi 2 m n - 3 . S e e a ne o f S e an T g . i pl Slid V lve E g i id Cr k y pe

o 45 300 i Si i r about to accord ng to ze of cyl nders , steam pressu e used , and the speed at which the engine is operated . Lubrication of the cylinders is secured by the use of a sight feed lubrication attached to the steam pipe . The main and crosshead

oil bearings are lubricated by cups . This type of engine has been extensively used in cotton gins and saw mills and in small machine shops throughout the country .

w on There are , ho ever , several grades the market , and it may be purchased for a comparatively l ow figure where the work to be done f does not demand a machine o high grade . This engine has a con

c w . rete foundation , is ell proportioned , and makes a neat appearance

34 STEAM ENGINES

anta es o Vertical over H ori nta T Adv g f z o l yp e . While the discus sion given above has had to do with a vertical engine of rather small w dimensions and po er , yet it must be borne in mind that vertical engines in very large units are built and successfully operated . This leads to a discussion of the relative merits of horizontal and vertical engines . At the present time the most common type of engine is the

- w horizontal direct acting , that is , an engine hose cylinder is horizon tal and whose piston acts on the crank through a piston rod and a

. w on one connecting rod In small engines the hole is often bed plate .

- Such engines are said to be self contained . The cylinder is either

of or bolted to the back the bed plate rests directly on it .

w on In marine ork vertical engines are used in almost every case ,

of savin o oor s ace w account the g f fl p , hich is so important in a vessel .

of This saving space is also a very important factor in many other cases ,

a w w such s in cro ded engine rooms in cities here land is expensive . A second advantage of the vertical over the horizontal engine is the reduction of the cylinder friction and unequal wear in the cylinder of the latter . In the horizontal engine the piston is generally sup

on w w ported by resting the cylinder , hich is gradually orn until it is no longer round , causing leakage of steam from one side to the other .

This is entirely avoided in the vertical engine . Still another advantage of the vertical engine is the greater ease of balancing the moving p arts so that there shall be no jarring or shak

of one ing . It is impossible to perfectly balance a steam engine or tw o cylinders . If it is balanced so there is no tendency to shake side wise it will shake endwise ; and if it is balanced endwise it will Shake w side ise . The jarring is due to the back and forth motion of the reciprocating parts and the centrifugal force of the crank and the connecting rod . The crank can be readily balanced by making it

e one of ext nd as far on side the shaft as it does on the other , but the piston and the connecting rod are more difficul t to balance . The effect of jarring can be greatly reduced, if the crank be balanced and w w w w the end ise thro made to come in line ith the foundation , hich v should be heavy enough to absorb the ibration transmitted . In a horizontal engine this endwise throw not being in line with the

foundation will cause vibration in the engine itself .

In machines that can be anchored down to a massive foundation , a state of defective balance only results in straining the parts and STEAM ENGINES 35

causing needless wear and friction at the crank- shaft bearings and

to elsewhere , and in communicating some tremor the ground . The problem of balancing is much more of consequence in locomotive and

marine engines . To sum up the general advantages of the vertical engines : they

Fi 2 - m . uc e e e oss o o u n n ne g 5 . B k y V rti c al Cr C p d E g i

w have less cylinder ear , they take up less floor space , and they can

be better balanced . In addition to these there are certain advantages

for which vertical engines have certain kinds of work .

Dis advanta es o V erti a T ressu re o the crank in g f c l yp e . The p n p i w is greater dur ng the do n stroke than during the up stroke , because 36 STEAM ENGINES . during the down stroke the weight of the reciprocating parts is added w to the steam pressure , and during the up stroke this eight is sub tracted . Another difficulty is that in large engines the various parts are on f such di ferent levels that they require considerable climbing .

This requires more attendants and is ' sometimes the cause for neglect

ations of the engine . The found for vertical engines need to be deeper

not than those for horizontal engines , yet they do need to be as broad .

= Buck eye Vertical Cross Co mpound Type . The development of electrical machinery and the increased demand for power in con

2 r w n h n Fi 6 . m e s s n n o a M e c a s m . S o e S e g i pl C li E g i , h i g V lv i

w gested city locations , here land is very expensive and buildings costly

of u because their great height , has been the primary ca se of the devel n o ment of . p large vertical steam engi es of various types The engine ,

Fi 25 - g . , represents a vertical cross compound engine as built by the B E w w uckeye ngine Company , hich is especially ell adapted to elec

w w w . tric rail ay and po er and lighting plants , hen floor space is limited

The engine may be obtained either as a side or a center crank design . This engine and simple horizontal engines of the same make are typical

of representatives economical , high speed engines . They are high

h a em priced, but t e economy of operation nd maintenance make th STEAM ENGIN ES 37

very desirable . The vertical engine illustrated may be obtained in w sizes developing from 75 to horsepo er . A discussion of the valve gear used on Buckeye engines is to be found in the instruction “ "

V . paper on alve Gears It is a double valve , giving automatic

- - cut off as distinguished from throttling cut off regulation . T Corliss ype . A general utility engine of the highest type both from the standpoint of design and economy of operation and main

nance te is the Corliss engine . It is to be found in electric railway power stations ; in large and small pumping stations ; in blast furnaces and rolling mills ; in textile and flour mills ; in machine shops and office buildings ; in technical schools and colleges ; and in nearly all kinds of industrial plants in this country and abroad . The Corliss engine is built in various types , styles , and patterns of any designed capacity up to horsepower . 2 w Fig . 6 sho s the valve connection and manner of operation of w a simple Corliss engine . It ill be noted that the engine is governed by a fly-ball governor which is driven by a belt connection to the main shaft . This governor is connected to the steam valves by reach rods . The speed is automatically governed by variation of the point of cut

w of w off. This engine , as ell as most engines this type , has large ell w proportioned frames , cylinders , etc . Good orkmanship and mate

hence w rial enter into its construction , it is kno n as a high

e conom priced engine ; but , on the other hand , it is perhaps the most ical in the use of steam .

V alve M echanis m. The distinguishing feature of the Corliss

w of w engine is its valve mechanism , a good vie hich may be seen in i F . 2 tw o g 7 . The gear has four valves , the top ones being the admis sion or steam valves and the two lower ones the exhaust valves .

Fi 2 w ec cen 7 . 7 There is a connecting rod , g , hich is connected to the Fi 2 6 . tric through a rocker arm , and another rod , as may be seen in g .

rod 7 As the shaft revolves , the , due to its connection to the eccentric , moves back and forth , and , by reason of its connection through the

8 w 6 . clamp to the rist plate , the latter is made to oscillate The w rist plate 6 is attached to the frame by a pivot projection . The rods 9 have a right and left screw adjustment on each end and transmit motion from the pins 14 on the wrist plate 6 to the steam and exhaust

10 15 . valve bell cranks and , respectively These valves receive i l " motion in such a manner as to open and close the ports rap d . 38 STEAM ENGINES

T he steam valve bell crank 10is free to rotate on projections of the bonnet and carries at the end of the lever shown nearly horizontal 3 w w the brass hook hich engages ith the catch block . This catch

13 w the block is rigidly attached to the valve lever , hich is keyed to

of end the valve stem, the latter transmitting motion to the valve . A 13 r ttached to the valve lever is the dashpot piston od 4. The hook is so made that it may be automatically tripped when the back part of the hook comes in contact with a cam which is operated by the

Fi 2 o 7 . ss a n g . C rli V lve M e c h a ism in Detail

2 arm connected to the governor by the reach rod 1 . The operation of the mechanism is such that the hook may be disengaged at any point of its travel by means of the cam coming in Contact with the tripping leg of the hook 3 and causing it to rotate on the pin and move the steel catch out of engagement with the catch block . w w m The slo ing do n of the engine , in consequence of reduced stea

or t pressure an increased load , causes the catch to hold its contac the longer and the steam to be admitted longer . In the event that STEAM ENGINES 39 speed be increased in consequence of increased steam pressure or w i diminished load , the hook ould be tripped by the cam and the adm s sion valve would be quickly closed by the vacuum dashpot 5 . It must be evident from the foregoing that the regulation obtained by this device must be very sensitive to any change of speed or load . The dashpot 5 closes the steam valve when the hook is tripped by the cam . The cylinders have four cylindrical holes accurately bored at 1 1 1 i 2 r w 2 F . . the fou corners , as is sho n at and in g 7 Into these open ings the valves are placed with their stems and proper pack ing devices . f The seats of the valves are circular . The portion o the valve marked i 2 w 2 1 F . 8 and , g , is circular , hereas the remaining portion may have any shape , depending upon the requirements of the design . The valve stem 5 -6 is also irreg ular in shape . The portion 4 fits into the slot 3 of the valve and round portions 5 and 6 serve as bearings and as means for attaching the driving mechanism . Advantages and Disadvan

Per ta es o orliss T e . g f C yp F 2 o i . 8 s a e a n a e m g . C rlis V lv d V lv Ste haps one of the chief disad vantages oi the Corliss engine is the large amount of floor space

w . required , a factor hich often precludes its use It possesses w w many advantages , ho ever , chief among hich may be men tioned the rapid and wide opening of the steam and exhaust ports ; w shortness and directness of ports , hich results in small clearance ; the adaptation of the steam valve to the functions of cut-off valves ; and the location of the exhaust ports at the bottom side of the cylin

. E der , thus draining the cylinders perfectly ach of these various f factors contribute to good engine per ormance , and their combina tion has resulted in making the Corliss engine one of the most eco nomical engines manufactured . It will operate upon from sixteen to eighteen pounds of steam per indicated horsepower per hour .

An l = g e Compound Type . As an outgrowth of the demand for

of an engine high speed and one that will occupy a small space , but w w of hich , at the same time , ill be economical in the use steam , there

- i F 29 . has been developed the angle compound engine shown in g . 40 STEAM ENGINES

ci . n Bala n ng In an ordinary high speed steam engi e , the inertia

— n of the reciprocating parts amely , the crosshead , piston , and

— con piston rod and the crosshead end of the connecting rod , is

n f siderab le . If a steam engi e is to be installed in o fice buildings ,

or in w n apartment houses , other houses here freedom from vibratio is a prime requisite , it becomes almost a necessity for the engine to

n be perfectly balanced . O an ordi nary reciprocating engine it is almost impossible to obtain perfect balancing for two reasons “ First , because of the angularity f w o the connecting rod , hich causes the rate of acceleration of the recip rocating parts to be much faster at one end than the other , therefore , counterweight which exactly

i - 2 . Se c o n f n m n n n F g . 9 ti o A g le C o pou d E g i e balances the forces at one end would be either too light or too heavy at the other end .

Second w of , the counter eight at all positions in the revolution the shaft exerts a radial force and when the counterweight is above w or belo the center of the shaft , there are no reciprocating parts developing a counteracting force , hence the centrifugal force of the

42 STEAM ENGINES

fac ur Uniflow r L . . t ed . M . J in this country is the engine Todd , in

18 out E 86 , took patents in ngland covering the principle of the

n ifl S of G U ow engine , but Professor tumpf Charlottenburg, ermany , deserves credit for developing the engine and for making it a prae

E of tical success . In urope the high cost fuel makes even small

n fl economies in the use of steam of considerable value . The U i ow engine was designed to secure better economy in the use of steam

f w As than is possible with other steam engines o equal po er . used

of in Europe , the poppet type valve is almost universally employed , w because of the better results it gives ith superheated steam , f T he which is used practically to the exclusion o saturated steam .

3 Sect ona e f Unifl n n Fig . 0 i l Vi w o ow E gi e or d er M anu actu r in om a n M Courtesy of N b g f g C p y , ilwau k ee , Wisconsin

Uniflow engine is now manufactured in the United States by a few

N one of concerns, the ordberg Company being the first to develop f and build a successful engine o this type in this country .

A - Method of Action of Nordberg Engine . cross section View of the Uniflow engine as manufactured by the Nordberg Manufacturing

i . Company is shown in F g 30. Steam comes to the engine through the inlet S and is led through the passages shown to either admission

f n A . o ot valve These valves are the Corliss type , only to conform

w A ractice . b ut ith merican p , because , with saturated steam , they give

as good results as the poppet type and are less expensive to construct . The steam is exhausted through a ring of ports cast in the middle of w e h w the cylinder and is conducted a ay by the x aust pipe sho n below . STEAM ENGINES 43

Thus it is seen that the piston performs the duty of an exhaust valve D by uncovering and covering these exhaust ports . is a relief valve w B w of large size , communicating ith chamber , hich is separated by a bridge wall in the cylinder head from the live steam space above . This relief valve

two : rst serves purposes fi , it relieves the cylinder of any water that may get into it ;

second Fi . 3 1 . n c f r U n and , it opens auto g I dic ato r ard o ifl o w E ng i ne Ope rati ng c o nde n smg matically in case the vacuum is lost and prevents the engine from compressing above line A pressure . lso , if it is desired to run the engine non -condens

of ing instead condensing , the

D ma I ndic ato r ard fo r U nifl o w n ne 3 2 . relief valve y be backed Fig . E g i Op e r ating 1Go n c o n de n s in g of its i i off seat, thus g v ng the chambers BB as the additional clearance volume which is required for

- CC S non condensing operation . The drums on each side of relieve the cylinder and cylinder heads from the strains caused by the

of expansion the inlet pipe .

Pe r c en/oge of I/mf Lead P e r c e n tage of Um"L 00d

f r ni Fi . n c n m u e U fl w n n c m u e f ni Fi . 34 . o o o o g 33 . E o o y C rv o r U flo w E ngine g E y C rv E g i e Ope rati ng Co nde nsi ng Operating N o n - Co n de ns i ng

T ical I ndicator ards Uniflow yp C . Typical indicator cards for a engine with condensing and non-condensing operation are shown in F . 1 2 4 3 . w 3 . F 33 3 igs and , respectively igs and sho economy curves

- w non . S when operating , condensing and condensing The cards ho the effect o f the large exhaust area by the rapid falling off of the pres sure as soon as the piston has uncovered the exhaust ports and also the gradual and high compression which is obtained . The economy 44 STEAM ENGINES curves Show that an overload of 100per cent requires only 10per cent more steam than for full-load operation when the engine runs con

- densin 12 w . g, and but per cent more hen Operating non condensing

f acto i i co om Chie F r n H gh E n y. The chief factor in the high economy of the Uniflow engine is the great reduction of initial con densation . In the ordinary steam engine the piston head and the cylinder head in particular are exposed to the low temperature of w the exhaust steam , hich cools them considerably and leaves them w cooler than the incoming steam . This causes the great loss kno n

initial condensation n fl as . In the U i ow engine the exhaust steam does

ot out of n pass near the head the cylinder, and so does not leave the

Fig ’

Pl ac e T hro u g h Ce ntral Po rts c linder and y piston heads cool ; and in addition , the compression is a carried to line pressure, so that when a fresh supply of steam enters the cylinder it meets surfaces of practically the same temperature as F f own . o its urthermore , the walls the cylinder in the Uniflow engine are exposed at each successive point in the stroke to tem p eratures which are more nearly the same than they are in the usual

-flow counter engine ; this also helps the engine economy .

linder and V alve Arran ement in Skinner En ine Cy g g . The form of

Unaflow cylinder and valve arrangement used in the engine , built S E E by the kinner ngine Company, rie, Pennsylvania , is illustrated

6 . in Figs . 35 and 3 It will be noticed that the steam valves STEAM ENGINES 45

are of the poppet type and are located on the top of the cylinder . Exhaust takes place through central ports in the usual way and also through the auxiliary exhaust valves show n on the bottom side .

n - w Fig . 35 show s the piston o head end dead center ith the steam valve at admission and exhaust taking place through the central

i . w . F 36 x ports g sho s the central e haust ports closed , the steam

on h valve the head end closed , and ex aust taking place through the auxiliary exhaust valve o n the crank end .

W - hen the engine is Operating non condensing , the auxiliary exhaust valve for the end in question is Opened by the valve-gear mechanism at the point when the central exhaust ports are just

Se c on of U nafl w n n Fig . 3 6 . ti o E gi e Sho wi ng C entral Exh aust Po rt s Clo se d and Exhau st T a ki ng Pl a c e T hro ug h A u xi li a ry Exhau st V alve o n Cra nk E n d

35 of closing , and compression commences at about per cent the

- stroke . When operating condensing , the valve gear mechanism controlling the auxiliary exhaust is automatically disengaged when the vacuum reaches a predetermined amount . Under these c o n ditions the auxiliary exhaust valves remain clos ed and compression f begins at about 90per cent o the stroke . The construction is such w that if hen Operating condensing the vacuum should fail , the aux iliar w y exhaust valves are automatically thro n into Operation .

i m i Ame r can Loco ob le . The locomobile is already highly E developed in urope , particularly in Germany, but in this country f developments have just recently begun . On account o its high 46 STEAM ENGINES

eflicienc of y, a description its construction and operation seems desirable . This apparatus is really a complete power plant all contained

of in a single unit . It consists a steam boiler with furnace , super heater , and reheater ; a compound steam engine with condenser and

-w vacuum pump ; a feed ater heater ; and a boiler feed pump . It is now A being constructed by different merican manufacturers , but that B E w built by the uckeye ngine Company ill be taken as typical , since f they were the first builders o locomobiles in the United States . l t i R F . 7 etails o ower an . 3 f D f P P eferring to g , the path o the f gases and steam can be traced through the plant , and some o the mechanical features can be seen . Consider first the boiler , furnace ,

. fire superheater, and reheater The former is an internally fired , A tube boiler, the combustion chamber being at and the fire tubes

B . B at eyond these tubes is the circular pipe coil C, which is the

on D superheater , and still further is the reheater , consisting of loops f tw w o o . pipe expanded into headers , as sho n The furnace gases from

A B D out pass directly through , C, and , and then to the stack w th through the connection sho n in e floor . The boiler is supported on X the cradle blocks , and superheater and reheater piping i s hung

w . from horizontal beams, as sho n The steam is led from the dome E to the rear end of the super heater and leaves it at the front end , going straight up to the high

f - o . pressure cylinder the engine Leaving the high pressure cylinder ,

of the steam is carried to the front end the reheater and , leaving at

l ow- of the Opposite end , is conducted to the pressure cylinder the

l ow - engine . From the pressure cylinder the steam is conducted to a

-w to of w feed ater heater and then the condenser, neither hich are w sho n in the figure . In both superheater and reheater , the steam is made to flow against the direction of flow of the furnace gases so that the steam will enter the engine cylinder at a higher temperature .

n The engine, as can be seen , is mounted directly o the boiler . F w The saddle , bolted to the boiler shell , supports the engine bed , hich

1s securely fastened to it . The engine frame is permitted to slide on the saddle C so as to allow for unequal expansion between the boiler

At of l ow- shell and the engine frame . the head end the pressure Y Y cylinder the yoke supports the cylinder casting . i F g . 38 shows the relative temperatures of the steam and the STEAM ENGINES 47

5 0 STEAM ENGINES

work will permit , has been covered by the discussions given concern in S g the plain slide valve engine , the vertical engine of mall units , the vertical engines for large installations , the compound and tan

a dem engines which are being used more and more , and finally by f consideration o the most economical engine of all , the Corliss , whether operated simple or compound . In addition to the types mentioned

of w there are a large number other makes , hich have distinguishing

w enumer features and hich give good service , but yet the principles ated in the types already discussed fulfill all the requirements likely to be made upon stationary plants . Hence a discussion of other makes is not thought necessary .

FA RM OR T RACT ION ENGI NE

The advancement of scientific and progressive farming has made the farm engine of more interest and importance than ever before ; in in fact , the demands of the active farmers recent years have taxed

of to of the builders such equipment the limit their output . The steam engine is used for a large variety of purposes upon the mod

of o- ern large farm , and appears most commonly in the form the s called

for w traction engine . It is used plo ing , digging ditches , building of w road ays, logging purposes , running threshers , and numerous other

of of w purposes . Various types stationary engines small po er are

the also to be found in use on the farm , small gas engines now hav ing been perfected to such a degree that they are rapidly replacing the steam engine .

Ge neral De scription. The traction engine is really more than - w simply an engine ; in fact, it is a self contained po er plant . It con

of or sists a simple compound engine , a boiler for supplying the steam

transmissmn required by the engine , and the mechanism, together A with all the auxiliaries necessary for a complete power plant . good f Fi o w . on type a general utility traction engine is sho n in g 40. It c

of sists of a boiler the locomotive type , carried by four wheels , the two o front ones serving as a means for guiding , and the tw rear being the ones which receive the power and known as the driving w i f heels . In order to prevent the slipp ng o the rear Wheels when doing heavy hauling , they are made with heavy projecting lugs or

w of cleats which are forced into the ground by the eight the machine .

on h s th The engine , which is mounted t e ide of e boiler, as may be STEAM ENGINES 5 1 5 2 STEAM ENGINES

of - seen in the illustration , is a plain slide valve engine the side crank

fl - type . The speed is regulated by an ordinary y ball , centrifugal

of governor . The construction of the various parts the engine are similar to those previously described in this work . The same

’ watchful care should be given to the lubrication , operation , and w u maintenance of this engine as to any other , hen economy , d rability , l - and reliability are desired . It shou d be noted that both cross com pound and tandem - compound engines are used as well as Simple

of engines in this class service , and that various types of valves find application . In order to make clear the construction and operation ‘ of the w w traction engine , a view sho ing the rear heels, platform , and side Fi 4 1 . tanks removed is shown in g . The means provided for guid ing , reversing , and driving this engine is clearly illustrated . It is , evident that the type of boiler used is similar to that of the l ocomo 1 w . tive boiler, having a narro fire box It has an extended front end and stack 2 for carrying away the gases of combustion . The boiler is mounted upon the front wheels through the pivoted pedestal con

i 3 w the rear ne ct on . It is supported on the rear heels , by having j

or axle extend beneath the fire box , by having the supporting ele 41 Fi . ments riveted to the side sheets as in g .

ra i n m of O e of Plant. Re ersin Mechanis p t o v g . The operation the plant is about as follows : If the engineer desires to go forward the mechanism is placed in forward gear by means of the reversing 29 i lever , the reversing being accomplished by means of a sw nging w w eccentric , hich can be thro n across the shaft at the discretion of

On the operator . ( some types of traction engines , a reversing link mechanism is used . )

T rans mission H . aving adjusted the reversing gear in accord w hr of ith the desired direction , the t ottle valve the engine is opened by

3 0 of moving the lever . The opening the throttle valve starts the

12 w 1 1 On the engine shaft , which carries the fly heel . the engine shaft behind the flywheel is keyed a small spur gear which is in mesh

As w 13 w w 1 . ith the larger gear , hich in turn meshes ith the gear 4 the engine shaft revolves , the small gear in the shaft revolves , which

13 on 15 w transmits its motion to and to the small gear , hich is

w w 15 F . keyed to the shaft driven by the heel 14. The gear heel , igs

40 4 1 w 1 Fi . and , is in mesh with an annular gear on the drive heel . g STEAM ENGIN ES 53 54 STEAM ENGINES

of to 40; hence , by reason this connection , the large wheel is made w 15 revolve . The shaft carrying gear heel extends beneath the boiler to the opposite side and drives a set of gear wheels which causes the other driving wheel to revolve with the one just considered . 16 w 1 7 Running Gear . The axle of the heel has a sliding head w attached to it . This head is free to move up and do n in guides

S s securely fastened to the fire box . This liding head works again t

b ox 18 . a spring , which is contained in the This spring reduces the w shocks to which the machine is subjected hen on the road , hence , the engine is much easier to ride than it otherwise would

be . In addition to the easy

re riding qualities , it also lieves the parts of the ma chine of stresses and strains w due to sudden jolts , hich would be detri mental to the durability of the machine as

a whole .

Steering Gear . The engine is guided by the hand wheel t 10. It will be noted hat a chain is connected to the front axle on either side of

the pivotal point . This

i 42 c t o n e a D e ce for S ee in F g . . r G r t r g F i i vi chain wraps around a cam T rac tio n E ng ine arrangement on the shaft

which carries the small gear wheel 8 . The wheel 8 is in mesh with

w 9 w w 10. the orm , hich may be turned by the hand heel If the

w w to driver when moving for ard should ish to turn the right, for w 8 w instance , he would turn the hand wheel so the heel ould be

- w driven counter clock ise , and in so doing the chain 6 would be 7 w 5 b shortened , the chain lengthened , the heel would e cut in , and

the machine would turn to the right . If it was desired to go in the

opposite direction , the reverse operation would be carried out, that is ,

gear 8 would be revolved clockwise .

f to It is sometimes di ficult operate the steering gear by hand , especially in large traction engines and in places where a heavy load STEAM ENGINES 5 5

is being driven over rough ground ; hence , some engines are provided 2 Fi . 4 with a friction gear device . This attachment , g , is exceedingly

n w . simple , and whe it is used the engine furnishes po er to guide itself It consists of a shaft 2 extending from the worm gear 1 to a bracket on the side of the boiler in front of the main shaft . On top of this vertical shaft is a horiz ontal miter gear 3 arranged to engage alter

one 5 mately with two vertical gears , at the right and the other at the left 4. These vertical gears are on a shaft run by a chain of small

. out gearing 6 from the engine shaft They are thrown in or , at the w pleasure of the operator , by means of a shifting yoke which is orked by a straight rod extending back to the right-hand side of the engi f A o . neer . lever at the end this rod is within easy reach all the time w By moving it forward or back ard , the engine is guided to the right

o r . left , as desired If the lever remains at the center , the engine guides straight . An extension rod is placed on the rear end connecting with

’ a hand lever at the left side of the platform , so that the engine may be guided equally well from either side . To operate this steering

of lever requires no appreciable exertion on the part the engineer .

rict l tc A F ion u h. w C friction clutch is provided in the fly heel , which permits the engine to be operated without driving the machine

on . forward the road With the engine running at full speed , the w w clutch can be gradually thro n into action , and the machine ill start forward on the road without any sudden shocks . The clutch i 3 1 F . 1 . B is operated by the lever , g 4 y disconnecting the engine w from the flywheel , a high speed can be obtained , so that by thro ing the clutch in gear quickly the engine is often able to pull the ut machine o of difficult places . Oftentimes it is desired to oper ate the engine independently of the traction wheels for the purpose of running the thresher, saw mill , electric generator , or for other pur poses , hence some form of clutch is necessary . B A rake . friction brake is operated by a system of levers and 1 a 0 1 Fi . s 9 2 2 41 . rods , , and g The operator can apply the brake by pushing downward upon the foot piece on the lever 19 . The amount of air admitted to the fire box is controlled by the two dam

22 26 b y 2 27 pers and , which may be manipulated the levers 4 and

Water Tan s 2 S wn . Fi . 3 k . 40 In g , large tanks , , and 4, are ho These tanks are water reservoirs from which the supply pumps take w O 2 for ater and deliver it to the boiler . pposite the tank is a bin 56 STEAM ENGINES

w w holding the fuel , hich may be ood , coal , or straw, depending upon the location and character of work to be done . If the traction engine w is used for threshing purposes , it ould have a fire box arranged for burning straw ; whereas if it was being used in a logging camp or a

aw w w w s mill , the available fuel ould be ood , hence the fire box ould be constructed accordingly .

oi S - B ler . an ince it is necessary to have a high grade , durable , d f economical boiler in order to have an e ficient and reliable machine , it is thought advisable to call especial attention to the type of boil ers used in this connection and point out some of their good and bad features . It was mentioned in the description of the traction engine ,

'

Fi . 40 t of w was g , that a locomotive ype boiler ith some modifications

Fi . f . 4 o used g 3 illustrates such a boiler . It is the fire tube horizon

4 3 T ac o n o e o f the Lo c o m o t e T e Fig . . r ti B il r iv y p

1 n tal type . The fire box is of a horizontal rectangular constructio

2 3 w . w with open grate bars and ash pit , belo The fuel , either ood 5 or coal , is fed through the fire door , and the ash is removed through the door 4. The products of combustion , such as smoke , hot gases , 10 12 w etc . , pass through the tubes into the front end , from hence they are exhausted through the opening 13 and the smoke stack into w the atmosphere . If stra is to be used as fuel , a brick arch is placed in the fire box which deflects the gases toward the fire door so that ,

w out after passing over the arch , they are dra n through the tubes f in the usual manner . It is also necessary to put in di ferent grate w the bars here straw is used , as the bars must be closer together so fuel will not drop through into the ash pan .

58 STEAM ENGINES which take the hot gases from the rear end 8 of the boiler to the smoke stack . The path of these gases is indicated by the arrows . To

of protect the rear sheet from the heat the gases , a protection plate

As 9 . is riveted or bolted to the plate steam is generated it rises ,

m 12 the 13 enters the stea dome , passes into steam pipe , and on to the engine . It should be noted that this boiler contains no stayed portions

c and that all the surfaces are cir ular in form and securely riveted . There being no stayed sur faces the circul ation of the water is not interfered with — which is an important con sideration— and the Opp or tunity for scale and sediment

to collect is greatly reduced , hence there is less likelihood of portions of the b oiler ‘ b e coming heated to the point of injuring the boiler or im

S an pairing its safety . till other feature of interest in the boiler is that the gases are made to traverse the en tire length of the boiler twice before being ejected at the

stack . This being the case an Opportunity is given for a greater portion of the heat contained in the gases to be

“ f difie °h Fi 44 ° d S°°t g : w 142mgofiz absorbed by the ater , thus securing a higher thermal H efficiency than obtained from boilers of the locomotive type . aving no stayed surfaces and a small number of flues results in a small

i of maintenance cost of th s type boiler . Traction engines run in sizes from about 74 inches X 10 inches 12 12 to inches X inches for single engines , and for compound engines the common sizes are 5% inches 8é— inches x 10inches to 1 1 w 9% inches X 13 inches x inches . The corresponding horsepo er STEAM ENGINES 59 60 STEAM ENGINES

w 1 1 developed ill run between 5 and 00. The speed attained on the i road n miles per hour is about 25 to 5 .

Road Roll er T ype . The traction engine just considered as an agricultural engine may also be considered as a portable engine or a A road locomotive . portable engine is , therefore , one that can be

of easily moved about from place to place , or as in the case the trac

l - tion engine it may be mounted upon wheels and se f propelled .

F m - o r a e ne n o e i 4 6 . Se b n a d g . i P t l E g i B il r

A of or nother illustration a similar type is the ordinary road roller,

of road locomotive as it is sometimes called . The principle its con struction and operation is similar to the traction engine , the chief

f w or di ference bet een the road roller , road locomotive , and the ordi nary traction engine being that the two front wheels of the traction

or i w engine are replaced by a large smooth roller , cyl ndrical eight, w hich revolves as the engine moves . The drive wheels of the road roller are also made large , heavy , and contain no cleats or lugs . These r s of s oller are used in the making macadamized or other forms of road . STEAM ENGIN ES 61

= l e e - S e mi p ortab Typ . The semi portable engine is usually connected with a small boiler and the two together may be moved

not w from place to place as required . It is mounted upon heels but

on w rather large ood skids , and is moved by being placed either in a wagon or on rollers . It is largely used for hoisting purposes in connection with the construction of large buildings , bridges , etc . Since the portable and semi -portable engines have no transmis sion mechanism , they are lighter and considerably cheaper to con struct than traction engines .

A of - very neat , compact , and serviceable type semi portable Fi . 4 engine is illustrated in g 6 . It is mounted upon skids so that it

o may be easily moved about . The engine is mounted n top of a S cotch marine boiler, similar to the boiler last described , and is of

- w the plain slide valve , center crank type , ith a centrifugal governor . w w The boiler is equipped ith a pressure gauge , ater glass , and such other appliances as are usually found in a boiler room of moderate

of size . The boiler used is sometimes the locomotive type and ,

i of oftentimes , both eng ne and boiler are the vertical type . The f smaller units are usually of the vertical type , the larger ones o the

- horizontal type . The semi portable plant is built in sizes ranging

2 e - 0 70 w . Fi from about to horsepo er If the s mi portable plant , g . 46 w w , be mounted on heels and dra n by horses or some other means , then it is usually classed as a portable engine as distinguished from

- a semi portable or traction engine .

LOCOM OT I VE ENG I NES It is not within the province of this work to fully discuss the

w suflice t modern rail ay locomotive , but it to say tha no other power developing unit has been so rapidly developed with such economical

. results Considering the exacting demands made upon a locomotive , its performance is remarkable . The locomotive consists of two pri w mary elements , namely, the boiler hich generates the steam and the engines which convert the energy of this steam into useful work by

n ni givi g motion to the transmission mecha sm .

B iler . Fi . 47 o g illustrates a modern locomotive boiler . It con sists of a cylindrical barrel and an enlarged rear end which contains the fire box . The fire box is securely fastened in the boiler shell by s di A few w tay bolts and ra al stays . ro s of sling stays are sometimes n M E ES ( STEA NGIN STEAM ENGINES 63 used at the front end of the fire box to allow for expansion and con

T he traction of the sheets . boiler is divided into three distinct

b ox A B departments , as the fire , the water space , and the smoke 5 w box C . The sheets 4 and , hich separate these departments , are known as the back and front flue sheets , respectively . The flue sheets are drilled with holes to receive the flues . 400 2- Flues . In the particular boiler illustrated about inch

flues flues are used . These extend from flue sheet to flue sheet and form a passage for the gases to travel from the fire box to the smoke

flues B box . Surrounding the in the space and surrounding the fire w w box is ater, hich is vaporized into steam due to the combustion o f fuel in the fire box . The total amount of heating surface will vary from to over square feet, according to the type and f size of the locomotive . O this total amount of heating surface only a very small per cent is furnished by the fire box, there being usually only about 200 square feet of heating surface contained in the fire fl b ox . ues a It is evident, therefore , that the are very important part of the locomotive boiler .

r f Grate A ea . The amount o grate area varies from about 40 to 60 square feet . It must be obvious that in order for so small a grate area to supply sufficient heat to such a large amount of heating surface there must be a very high rate of coal consumption per square f A f t o o S . foot grate area . series tests made at Louis during the Exposition in 1904 demonstrated that the amount of dry coal fired per square foot of grate area per hour varied from 20to as high as 13 w 0 pounds . These results ere obtained from several different types of locomotives Operated under widely different speeds and loads , hence the above figures may be taken as approximating the maximum and minimum consumption under ordinary running con

i ion d t s . Under these very widely different operating conditions it w as found that the equivalent evaporation per pound of dry coal 6 12 varied from % to pounds , which compares very favorably with stationary boiler performance which gives an average evaporation of f about 8 pounds o water per pound of coal .

Mechani l i ca Effic ency. The mechanical efficiency of a locomo tive is also very good . Through a long series of tests conducted on

w - v f of a ell equipped locomoti e testing plant , a mechanical e ficiency 65 f to 85 per cent was obtained . The same degree o efficiency has 64 STEAM ENGINES been obtained in various other tests and under more adverse condi

. ffi i tions The locomotive is also very e c ent in the use of steam . L The St . ouis tests showed that simple freight locomotives gave an average minimum water consumption per indicated horsepower per hour of pounds . The water consumption per indicated horse

w w as po er per hour under maximum load pounds , whereas the

w as r maximum rate pounds . Fo compound freight l ocomo tiv es the average steam consumption w as : minimum load i pounds , maximum load pounds , and max mum consumption

pounds . The average steam consumption for simple passen

was : ger locomotives minimum load pounds , maximum load

pounds , and maximum consumption pounds . When

w of these figures are compared ith those the best stationary engines ,

of i some idea of the economy the locomot ve can be obtained . The

- steam consumption of an automatic , tandem compound , condensing stationary engine with piston valves under full load is about 18 w w pounds per indicated horsepo er per hour , hereas the c ompound

- non condensing locomotive is about 21 pounds . A Corliss engine or

- w m a medium speed , four valve simple engine ill give a minimu steam consumption of about 22 pounds per indicated horsepower per hour under full load . A simple freight engine under full load will use about

pounds of steam per indicated horsepower per hour . The fore

w in going figures speak ell favor of the economy of a steam locomotive , which is operated under conditions unfavorable to the securing of good economy .

i h r i i Eng ne C a acte r st cs . The engines used on locomotives may

or be simple compound ; in fact , both are used extensively, although the simple type predominates . It is to be noted that the steam locomotive is equipped with two separate and distinct engines— one

attached ‘ to i being each side of the bo ler , and both attached to the i f w o . driving heels through the med um the frames , etc The mechanical construction oi these engines is quite similar to that of the type already described in this work . Certain features are made necessaryin order to properly tie together the engine , boiler , and transmission mechanism . Perhaps the most noticeable change in detail is in the construction of the cylinders and valve seats , other ) ise there is little variation from the well -established principles of engine design . The valves , rods , crossheads , guides , etc . , are

66 STEAM ENGINES STEAM ENGINES 6 7

w capacity . This engine is a compound type ith piston valves , is well designed , is neatly proportioned , and admirably fulfills every requirement .

m o w Co p und Typ e. In connection ith the subject of compound ing just mentioned it may be said that in recent years the compound locomotive has been found in increased numbers on American rail

A f and roads . type o compound that has given especial good service which is being adopted by many roads for heavy hill climbing duty is the Mallett Articulated Compound . The adoption of the com pound locomotive has been due to a general opinion among railroad officials that the findings of a committee of the American Master

M A w . echanics ssociation ere true , as demonstrated by practice This Committee says of compounding a I a n th fue u n e a a n 1 ( ) t h s a chie ve d a saving i e l b r d , ver gi g 8 p er cent at e as n a e s es r o ble b o ile r pr s ur .

I t ha sse e h am n f a t b an e (b) s le n d t e o u t o w te r o e h dl d . T h n in s n d w e e e c an e e fo e b e e u e e a e . (c) t d r , th r r , r d c d iz ight

I t has n e ase the oss es of s e e e o n s m e r (d) i cr d p ibiliti p d b y d ixty il s p e hour ,

without un d uly s traini ng the e ngine .

(e ) I t has in cre ase d the h au lage p o we r at full s p e e d . f I n so me asses of e n n es has n e ase the s a n ( ) cl gi it i cr d t rti g p o we r .

I t has e ssene the a e f on er o s e o w e e e o e (g) l d v lv ricti p h r p r d v l p d .

A of number other reasons are given in their report . Notwith w standing these facts , ho ever , the compound locomotive has not i come into very general use on ra lroads .

W AT ER P UM PS

The subject of pumping engines is a very broad one , and one which has received the thought and study of the most eminent engi neers F for many decades . rom the earliest history o f man there is gleaned the fact that human ingenuity and skill had been devoted in

of of w those early times to the perfection some kind po er pump . It would be a difficult matter to mention an industry of any char acter or description but what a pump was needed Somewhere in the

a enterprise . It w s first used in a large way in the mining industries

w of for pumping ater out the mines . Today it is found in all power B houses , mines, and factories of various kinds . oth the large and s w mall cities depend upon it for their ater supply . The heating and ventilating systems of modern apartment houses and office 68 STEAM ENGINES

of buildings use the pump , and mention might be made many other instances where the water pump is indispensable .

or fl There are tw o general classes of pumps , namely, crank y wheel type and direct acting pumps .

Crank or Flywhe el Type . The crank or flywheel type was the

first form to be developed . These pumps vary greatly both in their design and in the details of their construction . They are of vary

of ing sizes , including some the largest and most expensive in the

As world . a general thing they are used in heavy hydraulic enter

for ni w prises , fur shing ater supply for cities , and in various other w enterprises where a large and constant supply of ater is demanded . In this class of pumps or engines the application of the power in the steam cylinders in driving the pump plunger or piston varies greatly

or both in design and detail of construction . Long short beams or bell cranks may be used and sometimes gearing may be employed , but in all cases the limit of the stroke of the steam piston and of the pump plunger is governed by the crank of a revolving shaft . In pumping engines it is not absolutely necessary to have a revolving

c lin shaft , the only requirement being that the piston in the pump y der shall be driven back and forth with a plain reciprocating motion F w . or hich may be exactly like that of the steam piston this reason ,

reci rocat in early pumping engines and also in modern engines , the p

of ing motion the steam piston is applied directly , or through a beam , to produce the reciprocating motion of the pump piston or plunger

of F w . w ithout the use any revolving part requently, ho ever, it is w desirable to use a fly heel so that the steam may be used expansively , and in these cases , of course , a revolving shaft must be used .

- m Cameron Belt Driven Pu p . The power pump used as an illus

- tration Fi . 49 one . on , g , is a belt driven The belt is placed the pulley

1 o t 2 w . and can be shifted a loose pulley by the shifter , hen desired h The shaft 4, w ich is driven by the belt pulley , extends across the w 5 w frame and has attached to it a fly heel and a small gear heel , w w 3 hich meshes ith the large gear wheel 3 . The gear wheel is keyed 6 w to the crank shaft , hence , hen it is driven , the crank shaft is made to revolve , which in turn gives a back and forth movement to the

as w 5 piston in the ordinary steam engine . The fly heel , attached

of w to the revolving shaft , may be greater or less diameter and eight ,

c d depending on the on ition under which the pump is to be operated. STEAM ENGINES 69

In addition to assisting the crank to pass the dead center at each end

of of the stroke the piston , it can be employed as a reservoir in which any excess energy may be stored at the beginning of each stroke and

w out of w of dra n during the latter part the stroke , here the force B the water column is greater than that of the steam . y this means it is possible to use shorter cut-offs in the cylinder than could other M wise be permitted ; hence , a resulting saving in steam . any means h may be used to drive the power pump . W ile the illustration shows

B e lt-Drive n Po wer Pu mp o ne belt driven , yet they are frequently electrically driven , and sometimes the revolving shaft is attached to the shaft of a gas or steam engine .

Dee - r i F - Well o M ne u m . or w p P p deep ell or mine pumping , the cylinders are often set in a vertical position directly over the pump m di cylinder . The piston rod extends from the stea cylinder rectly below to the pump plunger . Sometimes it is possible to use steam expansively in these pumps by reason of the weight of the recip ro cating parts . When the weight is sufficient , the steam can be cut off before the end of the stroke and the momentum of the parts will 70 STEAM ENGINES

be enough to just finish the stroke , consequently these pumps are m sometimes compounded . They are used only in pu ping from very deep wells .

= - Dir ect Acting Type . A direct acting steam pump is one in fl which there are no revolving parts , such as shafts , cranks , and y

w of wheels , the po er the steam in the steam cylinder being transferred to the piston or plunger in the pump in a direct line thr ough the use of a continuous rod or connection . In pumps of this construction w there are no eights in the moving parts , other than those required to produce sufficient strength in such parts for the work they are

o required to perform and , as there is consequently n Opportunity

w One of to store up po er in part the stroke to be given out at another , it is impossible to cut off the steam in the steam cylinder during any

- - 5 0. n e n Le e Fig . D ire c t A cting D upl e x Pum p with R o c ker a d B ll Cra k v r

- part of its stroke . The uniform and steady action of the direct act ing steam pump is dependent alone on the use of a steady uniform

of pressure of steam through the entire stroke the piston , against a

of steady , uniform resistance water pressure in the pump ; the differ ence between the power exerted in the steam cylinders and the resist ance in the pump governs the rate of speed at which the piston or

of plunger of the pump will move . The length of the stroke the steam

w of piston ithin the steam cylinders this class of pumps is limited , and is controlled alone by the admission , compression , and release of the steam used in the cylinders .

Du lex um with Rocker and Be - a p P p ll Cr nk Lever . The direct i 50 F . w acting steam pump , g , is kno n as a duplex pump and con

of two - sists simply direct acting steam pumps placed side by side . w The steam pistons are at one end and the ater pistons at the other . STEAM ENGINES 71

The steam pressure acts directly on the pistons ; no flywheel is used ; and since the reciprocating parts are comparatively light and there i is no revolving mass to carry by the dead points , it is ev dent that

of in the ordinary form there can be no expansion steam . The i pump is inexpensive and g ves a positive action . It uses a relatively

of for large quantity steam , but small work the absolute amount is not very great . On the piston r od of each pump is a bell -crank lever which operates the valve of the other pump . There must be a rocker on

on of one side and a bell crank lever the other , because the relative motion of the valves and pistons . The first piston , as it goes for

d w . ward , must use a rocker , because it ra s the second valve back

- The second piston , as it goes back , must use a bell crank lever because it must push the first valve back i n the same direction as its own

w - motion . The two pistons are made to ork a half stroke apart ,

i i n t hus one begins its stroke when the other s the middle . In this w way a steady flow of ater is obtained , as both pumps discharge

of into the same delivery pipe . In large pumps this kind , and even in some small ones , the motion described above merely admits steam

x to a small au iliary piston on each steam cylinder, which then moves the main steam valve by steam pressure . m Duplex Pu p with Tapp et. Some pumps operate the steam valve by means of a tappet instead of a rocker and a bell- crank

Fi . 1 w lever , g 5 . Its construction and Operation is as follo s A F is the steam cylinder ; C, the piston ; L , the steam chest ; ,

- of w the chest plunger , the right hand end which is sho n in section ;

G H of w - , the slide valve ; , a lever , by means hich the steam chest plunger F may be reversed by hand when expedient ; I I are reversing valves ; K K are the reversing valve chamber bonnets ; and E E are exhaust ports leading from the ends of the steam chest direct to the main exhaust and closed by the reversing valves I I The piston C is driven by steam admitted under the slide valve G w , hich , as it is shifted backward and forward , alternately connects opposite ends of the cylinder A with the live steam pipe and exhaust . G’ F This slide valve is shifted by the auxiliary plunger , the latter w having hollow ends which are filled ith steam , and this , issuing u w thro gh a hole in each end , fills the spaces bet een it and the heads of the steam chest in which it works . Pressure being equal at each 72 STEAM ENGINES

F end , this plunger , under ordinary conditions , is balanced and motionless ; but when the main piston C has traveled far enough to I strike and open the reverse valve , the steam exhausts through the F w port E from behind that end of the plunger , hich immediately

w S G shifts accordingly and carries ith it the lide valve , thus revers

No it ing the pump . matter how fast the piston may be traveling ,

Sect o n of Pum n e S o n a e e ate T a et F . 5 1 g ig . i p Cy li d r h wi V lv Op r d with pp

must instantly reverse on touching the valve I . In its movement the plunger F acts as a slide valve to close the port E and is cushioned

- o n the confined steam between the ports and steam chest cover . The reverse valves I I are closed as soon as the piston C leaves them by a constant pressure of steam behind them conveyed direct from

the steam chest through the ports shown by dotted lines .

Fi . 52 The motion of the piston C , g , is transmitted through the

rod M to the water piston in the cylinder B . As the piston moves

74 STEAM ENGINES

w of of the engines already discussed , as ell as an untold number others of more or less merit , may be properly classed . The special engines referred to above were not mentioned for the purpose of studying them , but rather to indicate that outside and distinct from the steam engines classified and considered , there are a large number of special types that should not be entirely ignored .

MARINE ENGINES

The subject of Marine Steam Engines is a broad and important one to one or two , and treat it properly would require volumes the

n H w to s the s z f e . si e o this o o ever , it seems desirable discus ubject in a very general way in connection with the still broader subject of

T h E of e Steam ngine , and thus give the student a general idea marine engine parts .

Definition of T erms . B efore taking up the subject , it is thought advisable to present a brief statement of nautical terms used in

' f sse ho n Difl r n Fi 5 3 . an o e S e e t ts g . Pl V l wi g Par

f i . w o F 53 . describing a vessel . g sho s a plan a vessel The front part

A r An is c alled the bow; the extremity B is called the s te n . object

laced near b ow s forward p the i said to be ; if near the center C, it is ‘

mids hi a a n t. An so p ; and if ear the stern , it is f article , if placed that m d A B its ajor imension is parallel to the line , is said to be placed

or nd a t f of f e a f . Thus the crankshaft o a triple expansion engine a vessel is located along the line A B and is sometimes spoken of as a

- - An f . w fore and aft engine article located cross ise o the vessel , that

B n at r t a to A s athwarts hi . o e is, igh ngles , is aid to be placed p To

on b ow s tarboard o n standing the deck facing the , the side is his right and larboard or ort on the , p side , his left .

T he of a v FE is beam width essel its , and the perpendicular STEAM ENGINES 75

distance from its lowest part to the surface of the water is called the

f of w dra t. The length a vessel is the horizontal distance bet een f perpendiculars drawn at its extreme ends . The displacement o a vessel is equal to the weight of water it displaces and is usually

expressed in long tons .

s eed of knots The p a vessel is usually expressed in per hour , but A is sometimes given in miles per hour . knot is equal to about

1% miles .

Me th ds of Pr uls i n. S wa o op o peaking in a general y, the pro p ulsion of a steam vessel is accomplished by causing a mass o f water adjacent to the ship to move in a direction opposite to that of the

o w w ship . Motion is imparted t the ater in one of the follo ing three ways : (1) by paddle wheels ; (2) by screw propellers ; and (3) by jets

of water or hydraulic propulsion .

f of w The oldest of these three orms propulsion , the paddle heel , is still much used in lake and river steamers and ferry boats ; b ut for

- on w w ocean going vessels and in many boats inland ater ays , the

J et or screw propeller has supplanted it . hydraulic propulsion has not proved to be practical and for this reason has never been used in

commercial work .

T Y PES O F ENG INES

Beam T ype . The first steam vessels were fitted with paddle W heels , and as beam engines were the most common , this form of

. w engine was used Its construction , ho ever , was somewhat modi fied for this service . This arrangement of beam engine and paddle w heel was used for many years and was applied to ocean vessels as

well as to small river boats . It is still used , especially in this coun

try, on river steamers and some coast steamers . The beam is sup

a A- ported by large frame on the deck , and the engines are about on a level with the shaft .

Engines of this type take up rather more room than those now

of in common use , partly because of great size , and also because the A shaft and paddle wheels . nother disadvantage is that in heavy weather when one paddle wheel is thrown out of the water the other is deeply immersed and takes all the strain , so that there is a tendency to rack the boat . Then again if the boat is loaded heavily , the pad dle blades are very deeply immersed ; while if light, they barely 76 STEAM ENGINES

touch the water . It is difficult to handle the engines satisfactorily under either condition .

Inclined T ype . The introduction of the screw propeller over came these difficulties very largely and at the same time required a At . the high speed engine first , the increased speed was supplied by

- use of spur wheel gearing , but gradually higher speed engines were

was built and connected directly to the propeller shaft . It , of course , difficult with small width at each Side of the shaft to use horizontal

of w engines , therefore various arrangements inclined engines ere used before the vertical engine was finally chosen by all as the stand ard form for marine work . It is only in recent years that the verti cal engine has become general in naval work and in merchant steamers . V i T ert cal ype . In merchant ocean steamers the common form

s has three cylinders set in line , fore and aft , above the shaft , the crank being set 120 degrees apart in order to give a more even turning

the moment . The three cylinders are worked triple expansion , valves being usually of the piston type on the high and intermediate

- n s and double ported slide type on the l ow . Sometimes pisto valve

not are used on all the cylinders . Plain slide valves are suitable

- w of for high pressure ork any kind . While steam turbines are used

o - t e to some extent in cean going vessels , h majority of ships in this w — service are equipped ith high speed , vertical , multicylinder engines direct connected to the propeller shaft .

C lin r r n y de A ra ge me nt. The different arrangement of marine S w . 4 engine cylinders commonly found in ervice is sho n in Figs 5 to 57 .

Tandem and ross - T 4 om ou nd Fi . 5 A es . C C p yp In g , is the tandem- compound arrangement with its single crank ; B i s the cross ° compound with cranks set 90 apart ; and C is the three-cylinder 2 ° w 1 0 . C compound ith cranks set apart In arrangement , the high pressure cylinder is sometimes placed between the two l ow-pressure cylinders.

T ri le-Ex a i T e i ns on F . 5 p p yp . The cylinder arrangement, g 5 ,

on is found only the larger vessels , and is spoken of as the triple expansion type . In this type there are three cylinders to each engine, and they are called the high intermediate and low-pressure cylinders, each succeeding one being of larger volume than the one

i f of preceding . F g . 55 illustrates two arrangements o the cylinders

- l triple expansion engines . In arrangement A the cylinders fo low STEAM ENGINES 77

H B C‘

i 4 D a am s o f T an em an d ro ss- o m o un n e an e me n s 5 . g F g . i gr d C C p d Cy li d r Arr t

D ams h w n T e - ans on n e an em e n s 5 5 . a S o Fig . i gr i g ripl Exp i Cy li d r Arr g t

win T e- ans n n e an e ment . a a o e o Fig. 56 Di gr ms Sh g Oth r ripl Exp i Cyli d r Arr g s 78 STEAM ENGINES each other in natural sequence ; this requires the least length of B piping . Arrangement is frequently used , but requires more piping A A than arrangement . nother common arrangement is to put the

- of high pressure cylinder in the center the group . In any of these systems the cranks would be set at giving a more nearly uniform turning movement to the shaft, since each cylinder will develop

one- w of approximately third the total horsepo er the engine . Still other arrangements of the cylinders of triple-expansion A engines are found in Fig . 56 . rrangement A gives the effect of a tandem-compound between the high and the intermediate-pressure cylinder and a cross- compound between these two and the low pressure cylinder— ah arrangement which results in cranks being

D a a n u a ru e - ans o n n e r an e me n Fig . 5 7 i gr m Sho wi g "d pl Exp i Cy li d Arr g t

90° w set at ith the consequent uneven turning effect , but it is some times resorted to because of lack of space for all three cylinders in

B - . A c lin line rrangement is a triple expansion engine , having six y

H of one - ders . ere the volume intermediate pressure cylinder

two of one low- is divided among cylinders, and the volume pressure cylinder among three cylinders . This form is very expensive and is w not often used . The arrangement requires less floor area than ould

f - be required or the same power in a three cylinder engine .

l -Ex a i e "uadrup e p ns on Typ . The last cylinder arrangement to be

- considered is found on the quadruple expansion engine . In this type the steam goes from the high- pressure cylinder to the first inter

l ow mediate , then to the second intermediate , and finally to the pressure cylinder . The volume of each cylinder is larger than that of STEAM ENGINES 79

ff s o f the preceding cylinder . There are many di erent arrangement

- i cylinders possible with quadruple expansion engines . F g . 57 shows the arrangement of cylinders in their natural sequence with the four 90° cranks set apart, which gives a slightly more even turning effort

Fi . 58 . Se g ction o f T ypi ca l V ertic al M arin e E ng ine than is obtained with cranks at as in the triple-expansion engine .

The idea in the design of a quadruple-expansion engine is to produce an engine more economical in the use of steam than is 80 STEAM ENGINES

h - . 2 obtained in any other type With igh pressure steam , say 00 pounds and over , it gives a better economy in the use of steam than

- x H w ff does the triple e pansion engine . o ever, the saving e ected in

o f the use less steam is , to a very large extent , offset by an increase in first cost , operating cost , and general upkeep .

m i n M a in i h a i na 2 Co a s f w S e s . i 2 o e F . 2 p r o r t t t o ry Typ g , page 9,

w - w f Fi . S o and g 58 ho cross sectional vie s marine engines . In marine w of t ork many different designs engines are used . These w o Views are intended to present merely the general features and charac teristic f w s o the marine engine . In comparison ith stationary engines attention is called to the different form of frame used , lighter

f of n rod frames , di ferent details the connecti g , and in the latter figure the separate crankshaft for each cylinder and the singl e crosshead

A of guide . lso the cylinders are complicated form and have double

w of . w alls , and the pistons are a cup shape These points ill be brought out more in detail in what follows .

ENG INE DET A I LS

li T he of Cy nde r . general type steam cylinder for a marine engine

of consists three distinct parts , namely, the shell , the liner, and the cover .

hell i . S . F 59 In g , the shell is the outer casting forming the out

w w . side cylinder all , the lo er cylinder head , and the steam ports As its complicated form makes the casting of the shell a difficult S matter , an iron is used that runs freely in the mould . ometimes the w w lo er cylinder head is not cast integral ith the shell , but is fitted to it separately like the cover .

i r r ne . o L The liner is the plain cylindrical casting bushing , which forms the inner cylinder wall . Its use is made necessary because the metal in the shell is of such composition that it will not wear well

n of if the piston is permitted to work directly o it . The material the

- liner is usually hard , close grained cast iron . In some cases forged steel is used . It is secured to the shell by bolts through a flanged end , or Bu n . t o e by stud bolts end is fastened to the shell , the other end being left free to expand under the influence of the higher tempera tures to which the liner is exposed .

r Cove . The cover forms the upper end of the cylinder . Usually t of th i is made steel to comb ine lightness and strength . Sometimes e

82 STEAM ENGINES

more , each cylinder of an engine has a separate crankshaft . These w Fi 1 . separate shafts are bolted together by flanges , as sho n in g . 6

fi S w how a he The dotted lines in this gure ho , in large sh fts , t center is sometimes made hollow . This is done to make a saving in weight

in erfect and to remove p portions usually found in the center . The

6 1 o r o n o f M ar ne n ne r n w n M e h o f o t n Sect o n s T et e Fi . a S o t o o g . P ti i E g i C k h i g d B l i g i g h r center of the shaft is the least effective of any part of it in resisting w i f B t ist ng forces , and the outside is the most e fective . y using a l ittle larger shaft , therefore, and removing considerable metal from

of one around its center, a shaft the same strength as a solid is

w . obtained , ith a material saving in weight The crankshafts are

i 2 a M a ne T r ust e ar n 6 . T c F g . y pi l ri h B i g

of usually all made the same size , so as to be interchangeable , and thus require fewer parts to be kept in stock .

in 2 w not of n Be a s . Fi . 6 r g The bearing , g , hile part the e gine , h w ill nevertheless be discussed at this point . T is is called the thrust

u of bearing , and is sed to relieve the engine the thrust caused by the

- revolving propeller in screw propelled vessels . The propeller shaft STEAM ENGIN ES 83

f - R is turned with the collars C as a part o it . The cast iron box

of is secured to the frame of the vessel just aft the main engines , and

w . s s the cap 0 is bolted to it , as sho n The collars C pre s against ring

B of gun metal or brass and transmit the propeller thrust to them , and

R B S thence to the vessel . ings are plit and are prevented from turn H A ing by the tongue piece F . oles P are for lubrication and holes

i 3 T e o f T hr u s B e a n in W c o s o n I s M a e fo r T a ng Up W e a F g . 6 . y p t ri g hi h Pr vi i d ki r

are provided for water cooling when needed . Water may also be circulated through the base . 62 w r of Fig . sho s the p inciple the thrust bearing , but it is not much used because no provision is made for taking up unequal wear i 63 w of w F . between the brasses . g sho s a type bearing in hich pro m of vision is made for this feature , the wear being taken up by eans the nuts fitted to the long screw s at either side of the thrust bearing . 84 STEAM ENGINES

Thrus t Bearin Calcu latio g ns . The number of collars required in any given thrust bearing depends primarily on the total thrust w h that ill come on t em . There may be a large number of collars of r small diameter or a small number of large diamete . The experience of the designer is usually the determining factor as to the number used . K w no ing the number of collars required , their diameter may be

w wh n e of computed from the follo ing formulas , in ich is numb r collars ; D is diameter of collars ; d is diameter of shaft ; P is total

w of w thrust ; and p is safe allo able pressure per square inch area , hich 60 is usually taken as pounds per square inch .

F w e irst taking the formula expressing the total thrust , have

the 60 . in . and substituting for p value of pounds per sq , there results the formula

— (D2 — d2) n

— 47 (D2 — d2) n

s the D Transposing in the la t formula and solving for value of , there results the equation

which gives the diameter of collars required for the conditions assumed . AUX I LIA RY APPA RAT US The auxiliary apparatus aboard a ship is far more numerous than w ould be suspected by o ne not acquainted with it or even by one familiar with the apparatus in stationary power plants . The

of general features some of the more important pieces of apparatus ,

w . only , ill be described

s in M e chani m s Reve r g s . The rever ing mechanism of large marine engines is so large and heavy and , at times , has to be moved so quickly that it cannot be done by hand . Consequently, in some instances a small steam pow er cylinder is attached to the reversing

- gears to move them . This apparatus is called the steam starting gear and is under the control of the engineer . STEAM ENGINES 85

4 w : of Fi . 6 The action this gear , g , is as follo s When the revers in or - A B g lever , handle , is moved from the mid position to , the rod

CE m s rod H wh is moved to the left . This ovement raise the , ich is c T As H o . nnected to the lever fulcrumed at the rod raises , the rod

i 4 a r am a n 6 . De s o S e S e a F g . t il t t rti g G r

0 w w M w w moves do n ard , thus causing the arm to move do n ard and N the arm N to move to the right . This movement of the arm and pin I causes a corresponding movement to the right of the reach rod w and link, to hich it is connected . Thus it is readily seen that the movement of the reversing lever A moves the link slightly and at the 86 STEAM ENGINES

w same time causes steam to be admitted to the po er cylinder, which

of acts on the piston and aids in the movement the links .

C nde nsers . Su r ace T e o f yp . In marine work the surface con d w enser is used almost exclusively, because ith this type the cooling w not w water (sea ater) does come in contact ith the steam , and the

latter can then be used over and over in the boilers . Jet condensers on ocean vessels w ould prevent the continued use of the condensed steam because of the deposit the salt of the water would leave on the

S boiler tubes and hell .

K eel T e . I n yp small boats , such as steam launches , the surface condenser would occupy much valuable room and add considerable w eight , so a substitute , called the keel condenser , is frequently used . This consists of several row s of copper tubes placed outside the hull along the keel of the boat . The engine exhaust enters at one end of

is w these tubes , condensed by the sea ater in contact with the outside o f w of the tubes , and is then dra n out the condenser by the air pump and pumped back to the boiler . This form of surface condenser req uires no circulating pump .

Pum s . entrifu al T e n p C g yp . The pump most often used o shipboard to circulate condenser cooling water is of the centrifugal

or of type , driven by an independent engine motor . The absence

of of valves in this kind pump is advantage , as is also the fact that it

of can be run through a greater range speed and , consequently, give greater volumes of water when occasion demands . Oftentimes the piping is so arranged that these pumps can draw from the engine room bilge and discharge without passing the sludge through the condenser .

ir and acuu T es Of A V m yp . the many kinds of air or vacuum

w Fi . 65 pumps used , the one sho n in g has been chosen for description as being a good example and one easy to understand . The operation of the pump is as follows : The inlet E is piped to the outlet of the

On u - . of condenser the p stroke the piston P, a partial vacuum is

ow air E formed bel it , enabling the condensed steam and in to rush through the foot valves F and into the pump cylinder B below the

. A U f piston fter reaching the pper limit o its stroke, P descends , producing a slight pressure o n the air and water entrained in the

w c lin cylinder , hich closes the foot valves against the escape of the y

As s H der contents . the piston continues , the bucket valve in the STEAM ENGIN ES 87

f of w a to piston are orced open , permitting the escape air and ter the

n - air w a are space ab o ve . O the next up stroke this and ter forced o ut of the an pump through the delivery valves A and the outlet N .

A or - w fi is small check valve , pet cock (not sho n in the gure) , usually located in the cylinder wall B just below the delivery valves . When insuflicient air comes through with the conden sed steam to

on u — to properly cushion the piston the p stroke , this valve is Opened provide the required air for cushioning . This air does not affect the degree of vacuum , because it is on the discharge side o f w the pump , here pressure on the piston is imma terial as regards vacuum in the condenser . Vacuum is measured by gages similar to those used for measuring high pressures , but calibrated to read in inches of mer cury instead of pounds A per square inch . col umn of mercury under atmospheric pressure will stand about 30 inches

high . C o n s e q u e n t l y ,

30 of since inches mer Fi Se c o n f Ai o r . t o r a c u g 65 . i V u m P u mp cury is equal to about 15

o ne w 1 pounds per square inch , inch of mercury ill be equal to 5

30 or one- a divided by , nearly half pound per square inch , the ex ct

a value being pounds per square inch . Suppose the vacuum g ge 2 f of a condenser reads 6 . This means there has been a reduction o pressure corresponding to 26 inches of mercury . or o r pounds per square inch . If the atmospheric pressure is pounds i per square nch , then there remains in the condenser or

pounds per square inch absolute pressure . B d esi es the auxiliary apparatus already mentioned , there are 88 STEAM ENGINES many more o n large and small vessels which cannot be discussed

here , such as machines used for ventilation , forced draft , steering , w eighing anchor, operating hoists and capstans , compressed air and refrigeration machines, and electric lighting .

PRO PULS IO N

Pr ce ss f artin o o St g . When the engines are started and the

w w of I S a rec ia scre s or paddle heels a ship begin turning , there no pp

m of f r D ble otion the ship o a short time . uring this short time the work done by the propellers is all used in overcoming the inertia o f

. As the vessel the inertia is overcome , the ship gradually begins to

. AS move and increase its speed the speed increases , the resistance

of w offered to the motion the ship through the ater also increases . When all the power of the screw s o r paddle wheels is used in over coming the resistance of the water to -the passage of the ship through w it , then the ship ill be moving along at an approximately constant speed .

i t n Fa t rs for Shi in M ti n. w Re s s a c e c o p o o In smooth , quiet ater the resistance offered to the ship ’ s motion may be divided into three

: 1 of 2 elements , namely ( ) frictional resistance the hull ; ( ) eddy

- making resistance ; (3) wave making resistance .

c or The most important of these is the frictional resistan e , skin

of on friction . The amount this resistance depends the area and the

of o f length o f the immersed surface the hull , the roughness this

w -w surface (whether covered ith barnacles , sea eed , and the speed of the ship .

- w S Eddy making resistance , hich is usually mall , is caused by eddy currents follow ing just astern of the ship and by the churn of the propellers . Wave-making resistance is caused by the waves made at the ship b ow . f to Winds and waves also o fer resistance a ship , but the amount of resistance due to these causes is difficult to estimate .

t eed o essel w V ariations of Resistance wi h Sp f V . It has been sho n by experiment that for a given ship , the resistances vary almost

of w directly as the square the speed , and that the po er required to overcome these resistances varies almost as the cube of the speed . 10 t n That is , if at a speed of knots an hour a ship encounters a cer ai

90 STEAM ENGINES

of f S economical speed , the amount coal used at di ferent peeds is w determined by trial . These amounts are then plotted , as sho n in A w i . 67 . S F g it stands , this curve sho s merely the coal consumed at w o 0 different speeds , but by dra ing a line fr m tangent to the curve ,

of or the most economical speed is found at the point tangency , in

N or 8 . this case at , about knots per hour If the coal used by the CX auxiliary machinery is to be considered , then , the amount of

w t w new this coal , is laid off as sho n , and the angent dra n from the

" 5 /0 /Z

’ w fifl afs p ef ‘ H OUI ‘

7 u e o e to S o w M s c no m c a S e e o f a S i . o o F g 6 . C rv Pl tt d h t E i l p d hip

X new origin at . This line , tangent at L , gives a higher speed for the most economical one than that given for the main engines only .

PRO PELLERS

A not of lthough propellers are , strictly speaking , a part marine

tw o engines , yet the are so closely related that a brief discussion S w w at this point seems desirable . cre propellers only ill be considered , because they are used more extensively than any other device for f propelling vessels o various kinds .

De tail s f e P e lle r. w o Scr w rop A scre propeller is a set of blades ,

of w usually constructed iron or bronze , hich are made to revolve in

w of the ater at the stern the ship , by being connected to an extension

i of the ma n engine shaft . STEAM ENGINES 9 1

Small propellers are usually cast with the hub and blades in

ne w o piece , but large ones have a central boss to hich the blades are

f of . o bolted Propellers are made a variety metals , including iron , steel , bronze , and gun metal . f Blades . The general appearance o a blade may be seen from

tw or a . Fi . 68 . o g Propellers may have , three , four bl des In merchant vessels the latter is most common .

itc f P h. The pitch o a screw propeller is the distance in the direction of the axis of the screw that would be traveled by a point on the blade during one revolution if there w of ere no slip . It is similar to the pitch an

w of ordinary lathe feed scre , but course is much larger . i m w D a eter . The diameter of a scre propeller is simply the diameter of a circle described by the extreme ends o f the blades . The ratio of the diameter to the pitch of a propeller is ordinarily from 1 to and up to 1 to Thus for a 14- foot diameter propeller the pitch would likely be from

feet to feet .

P e llin c i n of Sc e P ll rop g A t o r w rope er . When a screw propeller is revolving in a given direction (for go- ahead motion for

o n instance) , the blades press the water as the threads of an ordinary screw do upon the threads in the nut . The pressing of the blades o n the water causes the water to be

w . w driven back ard There is , ho ever , a reaction caused by projecting this mass of Fi 68 . T c a S g . y pi l ha pe o f water sternward which results in the ahead Pro pe ller Bl ad e

of motion the boat . The useful work done by the propeller is the w w f w w of ork hich orces the ater directly stern ard ; course , the movement of water in any other direction than sternw ard results w w in a aste po er . I w w w f the scre orked in an unyielding medium , it ould adva nce

. H a distance equal to its pitch at each revolution ence , the speed of 92 STEAM ENGINES the screw per minute is the product of the pitch and the number of revolutions per minute .

s s is f 1 -f EXAM PLE . Suppo e a crew o 8 oot pitch and m akes 72 re vo lutions a is the s ee of the s ew in fe e er m n p er minut e . Wh t p d cr t p i ut e and kno ts p er hour"

T SOLU ION . 1 8 X 72 fee t p er minute X 60 feet p er ho ur

kno ts p er hour

for Slip . Water is a yielding medium and this reason the pressure of the blades causes the water acted o n to be driven back instead of

r of w remaining fi m . Then the actual speed the ship ( hen referred to the undisturbed water at a slight distance from the ship) is less than ff li the speed of the screw . This di erence is called slip . S p is the di erence between the s eed o the screw and the s eed o the s hi fi p f p f p , relative to still water . It is expressed in feet per minute and as a per w cent of the speed of the scre .

i m o n at the a e of 1 6 no s er ou T A s s . h EXAM PLE . hip vi g r t k t p h r e n m a es 7 e o u on s er m n s crew has a pitch of 1 9 feet a d k 9 r v l ti p i ute . What is the slip"

SOLUT ION . 1 9 X 97 = feet p er minu te = sp ee d o f s crew 0 1 6 X 6 ,08 f ee t p er minute = sp eed of ship 60 Slip = = 222 fee t p er minu t e 222 4 er en . 1 20 p c t

This may be expressed algebraically as follows : Let S equal speed of screw ; s equal speed of ship ; and L equal slip in feet per minute . Then

L = S — s

X 100 slip expressed in per cent

The slip thus found is not the actual slip , but the apparent slip . w It is not the actual or real slip , because the scre does not act in still

94 STEAM ENGINES

ou o e e f om all um s s ou e tb ard d livery valv s r p p h ld r ceive e spe cial attention . T he v alves to j ackets an d the bulkh ead and regu lating v alves should b e o p ened and inspe cte d . T he valves in the main ste am pipe should not b e close d tightly or they w ill b e set fast wh en s team enters . T he oil cups an d lubricators Should b e e xamined and p ut in goo d w orking n order a d the n e cessary w o rsteds adj uste d .

T he various j oints Should b e inspe cte d and the glan ds packed . Pressure and vacuum gages Should b e conne cted and the Shut- off cocks

T he bright p arts of the machinery that ar e likely to b e come splashed with water should b e o iled .

Au n n s e m s n n a e es S ou b e e a o s e ot a . xili ry gi h ld tri d by t if p ibl ; if , by h d Su u a h n n n u a n en n s nd th e e ch a xili ries as t e steeri g e gi e , circ l ti g gi e , a e l ctric I n ll i n en n es S ou e e e efu en on . a ases th n l ghti g gi h ld r c iv car l att ti c , e reversi g en gin e Should b e tried before u sing the m ai n en gines and b efore entering port it should again b e trie d to m ake sure th at it w o rks properly . l n T he main engine should b e o ile d at a l the rubbi g and rotating parts . An importan t item is the e xamin ation of the crank pits and all the w orking

f r m n m n m n n n a s . I e e a s e n t e a e so e o s u o a the e e p rt th s p rt a o x i d , b tr cti y preve t gi f n n n n l rom starting . T he main e gi es Should b e tur e d through at l east o e r ev o u

on o a ea nd as e n an . ti , b th h d a t r , by h d

I n ase fo e af is u se w ose s o e o s the a a es s ou c rc d dr t d ith cl d t k h ld , dr ft g g h ld b e cle aned and fille d with w ater an d the air- tight doors should b e examine d and n rigged . T he fans Should b e carefully o ile d a d adj usted .

a n in T o St rt E g e . In starting an engine the engineer in charge w w must use the kno ledge gained from experience , as no set rules ill

- to . For apply all engines instance , a small single cylinder engine is

- not started in the same manner as a large triple expansion engine . In the following we will consider the types of machinery most used

- the triple expansion engine and surface condenser . w In general , to start an engine it is first necessary to arm the cylinders and form a vacuum in the condenser ; the engine can then be started b y admitting steam to the cylinders . m T 0 Form V acuu . It is usual to fit an independent circulating

so the K or - pump , ingston sea valve should be opened and the dis charge valve tested to see if it lifts readily . The circulating pump is then started so that the condenser will not become heated by the

- drains and exhaust steam . The auxiliary air pumps should then be started to keep the main and auxiliary condensers free from water and

- to form a partial vacuum . If the air pump for the main condenser is independent , it may be started so as to form a vacuum . h w To Warm t e En ines . g To arm the engines , all cylinder, w receiver, and steam chest drains are put in communication ith the STEAM ENGIN ES 95

o a w not w condenser . In order t ascert in hether or the drains are ork

- b is . ing properly , a y pass arrangement often fitted This arrangement connects the drains to the bilges . The jackets are usually trapped to h t w o to . the ell or feed tanks , but can be drained directly the bilges

all If all the drains are in order , open slightly the throttle valve and

the valves in the main steam pipe . This will admit a little steam to

- high pressure steam chest . Steam is also admitted to the jackets to

n assist in warmi g the cylinders . Now Open the by p ass valves a little to admit steam to the w receivers . The steam in the receivers finds its ay into the cylinders and helps in the warming up . To warm both ends of the cylinders move the valve gear back and forth slowly from full gear ahead to

m a now . w full gear astern The throttle y be opened a little ider, B i in . enough to set the eng ne motion y means of the reversing gear , the cranks can be made to move back and forth without making a complete revolution . i th Op en ng e T hrottle . We will assume that the engine is thor w w S oughly arm and (as the drains are open) free from ater . team is in the jackets and the starting engine and starting valves ready . The centrifugal pump is at work circulating water through the condenser and either the auxiliary air-pump or an independent air- pump is at work .

or To start the engines , run the links into full gear ahead astern and open the throttle valve . In case the engines do not start , use the b - y pass or auxiliary starting valves . The engines should be started w slo ly and the speed gradually increased by admitting more steam .

200 o r After the engines have made revolutions more , the drain cocks may be closed .

ause o Fail r to t rt M to C s f u e S a . arine engines may fail start from many causes , but if proper precautions are observed before trying to

n w start there should be no difliculty . Amo g the causes hich are not apparent from the exterior are

The throttle valve spindle may be broken . The high - pressure valve (if a slide valve) may be off its seat and t admit steam o both ends .

m a w The engine y be gagged ; that is , the throttle ill supply steam to o ne side of the high -pressure cylinder and the b y-pass valves w admit steam to the opposite side of the intermediate or l o . In this 96 STEAM ENGINES

w . case the engine ill not move , as the pressures are equalized In

b - or e w using the y pass valves , the valve valves should be us d hich will produce a turning moment on the shaft . Let us suppose that

low - both the high and pressure valves cover the ports , and the inter mediate slide valve is in such a position that steam can enter that

now w cylinder . If the throttle is Opened , the engine ill not start ,

b - because both ports are closed . If the y pass valves to both receivers

of are opened , steam will be admitted to the proper side the inter

A in l ow - w mediate piston . lso the steam the pressure receiver ill find its way through the exhaust cavity of the l ow -pressure slide valve to f w the other side o the intermediate cylinder . The result ill be that the engine will not start because the high and loware not available

n for starting and the pressures o the intermediate piston will balance . In this case steam should be admitted to the intermediate receiver

n - . to low o ly If steam is admitted the pressure receiver only , it tends to force the intermediate valve off its seat . The opening of the wrong starting valves will frequently produce a similar situation .

If the engine has become gagged , it should be freed from steam . This may be done by closing the throttle and moving the link

1 to the opposite extreme pos tion . The engine can then be started in this direction and then be quickly reversed ; or it may be started in the proper direction if the mistake is not repeated .

w one w In case the engine ill not start , of the follo ing conditions may be the cause : (a) The valve stem may have become broken inside the chest or the

valve may have become loose on the stem .

(b) One of the eccentrics may be broken or slipped on the shaft . (c) Bearings set up too tightly or too much compression on the

fli n packing in stu g boxes often prevent starting .

The propeller may be fouled by a rope or other obstruction .

nn w (e) The tur i g gear may not be disconnected ; that is , the orm

may still be in gear with the worm wheel . u tm n Adj s e ts Afte r Starting . After the engine has been running for w S ' a short time , the follo ing adjustments hould be made The speed of the feed pumps to maintain the proper water level in the boilers . f The supply o circulating water to the condensing equipment .

98 STEAM ENGINES

the link in or out and adjusting the expansion gear . It may even be

to necessary reduce the speed for a time , but this is not done unless n ecessary , as it causes delay . w d If the bearing is discovered to be hot , the ater service shoul not be applied , as the sudden cooling may cause fracture . In this case the engine should be Slowed down or stopped and the bearing

w il r o o w oil . cooled ith , sulphur , a mixture of soft soap , ater , and Bearings that are lined with white metal should receive special w attention , as the hite metal soon becomes plastic and melts at 4 ° about 00 F . The water douche should be used only in extreme cases and with caution , because it may cause fracture and is likely to corrode and w u destroy the bearings . If ater must be sed , the parts should be i cleaned and oiled as soon as the eng nes stop .

H ot Rods . Piston rods and valve rods are often kept lubricated f o w . F t by means a large brush , called a s ab requen ly in starting , a w w man ith a s ab is stationed to keep the rods cool . If these rods w become arm because of tight glands , they may be cooled by slacking back the gland and applying water and oil by means of a swab or

hot w one syringe . If the rod is and ater is applied , side may be

w of cooled and shortened ; the result ill be a bent rod . Instead using

h few w t e . ater , engines should be eased If the rod cannot be felt , a drops of oil or water syringed on the rod will Show whether or not it w is . w w hot If hot , the ater ill hiss or the oil ill burn and cause smoke . w w As ith bearings , piston rods that are packed ith metal packing should receive careful attention , as the packing may run and cut the rods . The principal causes for hot rods are glands too tight or not

ffi . properly packed , piston rod not in line , and insu cient lubrication w K nock s . Bearings should be adjusted hile the engines are

w of running . If a bearing is loose , it ill knock at both ends the

or . stroke . Usually knocks can be located by the sound by the feeling

K nocking in the cylinder may be due to a loose or broken piston ring ,

on rod or or . piston loose the , a nut bolt loose If knocking occurs , open the cylinder and jacket drains to be sure it is not due to an accumulation of water . If the noise continues at various speeds , it is probably due to looseness of the piston rings . If this is the case,

he - n t ring must b e re scraped a d fitted . STEAM ENGIN ES 99

k T h J ac ets . e pressures in the jackets should be maintained at

T he s the desired amount . jacket drains are led either to the conden er f or . o to the feed tank If led to the feed tank , the temperature the w w . feed ater is then raised The jackets should be ell drained , as m water causes a crackling noise at each stroke . The re edy is to open w wh w the drains ide and , en clear of ater , regulate the drain valves by increasing the opening .

il T he w w B ge s . bilge pumps should be at ork constantly hile the

so w w n ot or vessel is steaming , that ater ill accumulate in the bilges w crank pits . The crank pits should not be in communication ith

or o il w the bilges , the from the crank pits ill be spread over the bilges . If the stokehold bilges empty into the engine room bilges , the bilge water should be strained o n account of the fine coal in the S stokeholds . trainers should be carefully attended to , as fine coal ,

w . aste , and articles carelessly left in the bilges are likely to choke them It is considered good practice to pump from w ells formed in the bilges and covered with strainers . h i k i U . t e L n ng p When starting , links are placed in full gear .

When running at the required speed , the engine is linked up so that w i f the expansive ork ng o the steam may be utilized . The best

of for r position the links a given speed is determined by expe ience .

w S w w w Trial ill ho at hat position the engine ill run smoothly ,

w . economically , and ithout too much noise The throttle valve should

w - be ide open , so that steam will enter the high pressure chest at nearly boiler pressure . If the engine is running at reduced speed , it is a good plan to link up the high -pressure engine by the use of the block in the slot o f the arm o n the weight shaft . This will increase

o f w not of the total ratio expansion , but ill reduce the port opening the

l ow - intermediate and pressure cylinders . If there is any probability f o a change in speed , the engineer in charge should see that the start ing engine is warmed and drained from time to time and be sure that

of it is ready for use . Grunting the slide valves is sometimes stopped by running the links into full gear for a short time , then adjusting them in a slightly difl ere nt position .

a k in u M r g Off N ts . In order to have a record of adjustments w and to aid in adjusting bearings , the follo ing marks are made . At each corner of the hexagonal nut near the face that bears o n the

w w i . i 69. asher , a number is stamped , as sho n in Fg The washer s 1 00 STEAM ENGINES

A of prevented from moving by some device . part the circumference of w h off 10 one - the as er is marked in , say, divisions about half inch

- apart . These divisions are then sub divided and numbered . It is then easy to record the position of the nut by noting what number on the washer coincided with the corner

f 1 on 1 or 2 on 8 — o the nut . Thus 5 5

ut Refitting Be arings . To find o whether or not a bearing needs refit ting and to ascertain the amount of

play, a lead is taken . The cap is first

removed and a piece of lead. wire is laid along the journal parallel to the

two axis . Some engineers place pieces around the journals near the ends and

. F n W others place them diagonally The 9 . M ar N u a n h ig . 6 ki g ts d as ers cap is then replaced and screwed down

n hard o the liners . The cap is again removed and the leads taken out and examined . They should be flattened uniformly . The

w on w thickness sho s the clearance . If the marks the nuts at hich w w the leads ere taken are noted , they may be compared ith the marks and leads taken sometime afterward and the location and

of w w extent ear kno n .

S w fi If the leads ho that the bearing needs re tting , the caps are v w first remo ed and the journal , caps , and oil ays cleaned . The journal is then carefully calipered and , if found oval , cut, or rough , fi should be led all over until smooth and true . This process requires considerable care and skill for the new surface must be concentric w o il or ith the axis . The filed surfaces are smoothed by an stone emery . If emery is used , care must be taken to clean all surfaces .

After the journals are in proper condition , the brasses , if used ,

on are fitted by filing and scraping . A little red lead smeared the w w journal ill assist in the fitting . The brasses should be eased a ay at the sides , as the metal at those points is of no assistance; but increases the friction . w w If the bearings are lined ith hite metal , they must be relined w w hen the hite metal is worn through . To do this a mandrel of the same size as the journal is placed in po sition in the bearing and the molten metal poured in or the strips of white metal are hammered

102 STEAM ENGINES engines stop ; in this case put on a feed- pump to keep the condenser free from water . The circulating engines may be stopped soon after the engines stop .

As of w in case entering harbor , atch receiver and jacket pressures , f o w . and stop the supply ater to bearings , etc If there is any chance of s w w starting again soon , keep the rever ing engine arm and ell drained .

rt Precautions for Long Stay in Po . If the stay in port is to be

- w long , the main condensers and air pumps should be ell drained and

of T he several the boilers may be cleaned and repaired if necessary . w t r fires should be allo ed to burn themselves o u g adually . If the stop is for a short time , the fires should be banked . i Eme rge nc e s . What to do in emergencies depends upon the f f arrangement o the machinery . The kind and number o engines and their arrangement and capacities of the condensers and aux iliary machinery often determine what course to pursue in case any part

r f breaks o gets o ut o position .

' li d B roke n er H ead n . Cy If a cylinder head breaks , it should be

m . repaired if proper eans are at hand If it cannot be repaired , the steam port which admits steam to that end may be blocked up by

n - driving in plugs of soft pine and the engine ru single acting . This is comparatively simple if the valve is a plain slide , but with a piston

o f valve the many ports make it more difficult . If a cylinder head a

— one s - triple expansion engine breaks , and engine must run ingle acting , the ex pansion gear should be arranged so that the work will be properly divided .

ractu re in th ra ft F e C nks ha . What to do in this case depends upon

of many conditions . If the engine is the multicylinder type , and the crankshaft is made in interchangeable lengths, fit the spare length

ne in place of the disabled o . In case no spare length is carried and

- the crankshaft of the l ow pressure engine is damaged slightly , change the l ow -pressure length to the high-pressure engine and place the

- l w l ow- high pressure length in place of the o . The pressure length h transmits t emost power . If the damage is considerable , such as

of the breaking the crankpin , the length cannot be used and the

- w high pressure engine must be disconnected . If the pumps are orked

- from the high pressure crosshead , repair the broken shaft, place it

- in the high pressure engine, and block up the steam ports to the STEAM ENGINES 103

- w l in high pressure cylinder . The po er is then deve oped in the ter mediate and l ow-pressure cylinders ; the amount of power trans mitted to the high-pressure crankshaft being just sufficient to work w the pumps . Probably it will be necessary to run the engines slo ly

c s o f be au e the weak shaft .

Pis to r n B oken . or If the piston , piston rod , valve stem become

dis broken and cannot be repaired , the damaged engine must be

connected and the power furnished by the others .

Air- Pu m B rok - p en . In case the air pump breaks and cannot be

o repaired , the exhaust may be carried t the deck and the engines

n n- of run o condensing . This is a great disadvantage if the amount

fresh water carried is slight and the ship is far from port . In case no

h - separate ex aust is possible , the auxiliary air pumps may be con

nected w and the ship proceed . In most cases, ho ever , the auxiliary air-pumps are not of sufficient capacity to remove all of the c o n

densed no w exhaust steam and the air ; therefore , vacuum ill be

carried , but the condensation may be returned to the boilers .

Bent is t - f on Rod. o P In the case a small rod and a long , slight

bend , the rod may be straightened by placing it in a lathe and

w A ro d or o ne w applying a po erful lever . large , ith a quick bend ,

should be heated to a dull red in a wood fire . The rod is then placed

in a large lathe and straightened by an hydraulic jack . In doing this w rod hot ork care must be taken that the is not heated too , does not

t of . scale , and tha the points contact are protected by copper plates

Eccentric Broken o - or . If the g ahead eccentric eccentric rod

o— breaks and cannot be repaired , the g astern eccentric can be shifted

. w now . in its place The engine ill run ahead , but cannot be reversed The go - astern end of the links must be kept from dropping by some

r . flexible support , such as a rope o chain Another method is to disconnect the connecting rod from the

of crankpin and crosshead the disabled engine , and block up the steam ports so that the steam will flow to the other cylinders by the

n of shortest passage . The piston should be secured o the bottom the

. A cylinder The valve should be removed . fter removing the

broken valve gear, the engine is ready to start . This method may be used if the pumps are worked from the l ow -pressure crosshead and

l ow - w - the pressure engine is intact . If, ho ever , the high pressure

eccentric is broken and the pumps are worked from that crosshead , 1 04 STEAM ENGINES the same method may be pursued as described for a fractured crank

h . e s aft That is , the valve gear should be removed , the ports block d ,

rod and the piston , the piston rod , crosshead , and connecting left in - w place . The moving parts of the high pressure engine ill then work the pumps by means of the power transmitted to the high-pressure w crank . The engine must be run slo ly , but can be reversed .

ST EAM ENGINES

PART II

MECHANICAL AND TH ERMAL EFFICIENCY

The brief historical review and the study o f the various types o f engines have served to unfold the degree o f perfection that has been attained in the design and details o f construction o f the F modern steam engine . rom a mechanical standpoint , the mod ffi . A ern engine is highly efficient mechanical e ciency , that is , Brake horsepower of from 85 to 95 per cent is no t infrequently Indicated horsepower

An 12-in h 1 - inch 1 — obtained . actual test of a c X 9% X 5 inch tandem compound Corliss engine operating non - conden smg gave a mechan fi w o f 4 . as ical ef ciency 9 per cent That is to say, if the engine 120 w w developing horsepo er in the cylinders , that horsepo er

w w . w ould be delivered by the engine to the fly heel In other ords , the horsepower used in overcoming the friction o f the various moving parts w as only o r 6 per cent o f the total horsepower developed .

p o f Low The rmal Effic ie ncy Inhe re nt. From the stand oint w f thermal efficiency, ho ever, the modern engine is very inef icient , E i but it is much more efficient than the older types . ven the max 1 mum thermal efficiency obtained is only about 5 per cent , and ,

' this v er so under favorable conditions , y low figure may be reduced

no w that the engine is operated at a great economic loss . It is proposed to briefly point o ut some o f the causes for the very low thermal efficiency obtained and to indicate some o f the means that have been employed to increase the thermal output o f the steam

o engine . In order t make this study it becomes necessary to again w w refer to steam and its properties . It is ell kno n that steam

of contains a great deal heat , and that this heat can be converted into useful work by allowing the steam to pass from the high tem p erature o f the heat generator to the lower temperature o f the

u . refrigerator, during this change giving p heat There are several 106 STEAM ENGINES

of of w forms heat engines , all hich convert the heat contained in some substance into work . The theoretically perfect engine shall fi be considered first , and after that the modi cations that go to make f up the steam engine o today .

in e . I deal En Fi . 70 g The theoretical engine , g , is supposed to receive heat from the generator at constant temperature T 1 until B communication is interrupted at . The working substance expands to C without losing o r gaining any heat from external sources until the temperature o f the refrig

crator is reached . The engine now rejects heat at the constant

temperature T 2 of the refrigera tor and then compresses the working substance without loss o r gain in the q uantity o f heat until the temperature o f the

heat generator is reached . These

are ideal conditions and , if ful Fi 70 eo et c a n c a o r D a r am . T g . h r i l I di t i g f o f filled , the e ficiency the per feet engine will depend only on the difference between the tempera

o r w ture at which heat is received and rejected , in other ords , it depends only upon the difference in temperature between the gen crator and the refrigerator .

If T 1 equals the absolute temperature of the heat received

o f and T 2 equals the absolute temperature the heat rejected , then the thermal efficiency E o f the engine will be represented by the formula

Or w , in other ords , the efficiency equals the absolute temperature o f o f the heat rejected , subtracted from the absolute temperature the heat received , and the remainder divided by the absolute tem

r f p e ature o the heat received .

P E m at a 12 oun s a so u e essu e E . n n n n u n XAM L Give a e gi e si g stea 0p d b l t pr r , a is the e m a effi en " an d exh austing at atm osphe ric pressu re . Wh t th r l ci cy

T h u m u n to 120 oun SOLU T ION . e absol te t e perat re corresp o ding p ds pressure is or an d the absolu te temp erature of the ex haust is 2 12 + or T hen

108 STEAM ENGINES

full length of the cylinder , and the clearance space must be filled with

w w . steam , hich does very little ork The theoretical and actual

1 . cards are shown in Fig . 7

o w fi Mechanical L sses . It has been sho n that the ef ciency of the theoretical engine is purely a thermal consideration ; the efficiency

f w . o the actual engine , ho ever , is largely a mechanical matter The f w w unit o work is the horsepo er , hich corresponds to the develop A ment of foot pounds per minute . s 778 foot pounds are

o ne B U equivalent to ritish Thermal nit , foot pounds per

or on w or minute , e horsepo er , is equivalent to

Now British Thermal Units . if a certain engine uses British

Fi 7 1 Su e r o se ea and c ua n c a o D a am s g . . p p d Id l A t l I di t r i gr

w Thermal Units per horsepo er per minute , it is evident that its

f one - o r 0 e ficiency will only be half, 5 per cent , because is one

of H half ence , it may be said that the efficiency of the actual

British Thermal Units per horsepower per minute

e f w of This ficiency is al ays much less than that the perfect engine .

ANALY S IS O F LOSS ES

' The effect of some o f the losses in the steam engine and the

for methods decreasing them will now be considered .

adiati n. w o f R o In the first place , the metal alls the cylinder ,

of being good conductors heat , become heated by the steam within and transmit this heat by conduction and radiation to the air or

. w external bodies With the cylinder ell lagged , much less heat is lost by radiation . If the lagging were perfect and the temperature STEAM ENGIN ES 109

of the cylinder remained the same as the temperature o f the steam

w no b v throughout the stroke , there ould be loss radiation , but heat f would still be lost by conduction to the different parts o the engine .

l in b E ans i n. D Coo g y xp o uring expansion , the temperature and f pressure o the steam decrease as the volume increases , and the tem

p erature at exhaust is much less than the temperature at admission .

w co m In the perfect engine , the orking substance after exhaust is

pressed to the temperature at admission , but in the actual engine much of this steam is lost and the compression o f a part o f it is

incomplete , so that its temperature is less than the temperature at

admission .

i = r i Ste am Conde nsat o n and Re Evapo at on. Consider an engine operating with admission at 100 pounds absolute and exhaust at

18 pounds absolute . From steam tables the temperature at admis sion is found to be and at exhaust The metal walls

o f of the cylinder , being good conductors and radiators heat , are

l ow o f cooled by the temperature exhaust , so that the entering steam in passing through ports and into a cylinder is subjected to a tem f 1 ° p erature o more than 00 cooler than the steam . This means that heat must flow from the steam to the metal until both are o f the

o f same temperature . This causes the steam to give up part its

o f latent heat , and as saturated steam can not lose any its heat w w w ithout condensation , the cylinder alls become covered ith a film f m o f o . moisture , usually spoken as initial condensation This co den w sation in simple unjacketed engines , orking under fair conditions ,

2 r m may easily be 0per cent o ore o f the entering steam . The mois ture in the cylinder has , of course , the same temperature as the steam ; it has simply lost its heat o f vaporization .

A o f lthough metal is a good conductor heat , it can not give up or absorb heat instantly ; consequently during expansion , the tem

r f p eratu e o the steam falls more rapidly than that o f the cylinder . This allows heat to flow from the cylinder walls to the moisture o n

lin them . As fast as the steam expands so that the pressure in the cy A w . s der becomes less , this condensation ill begin to evaporate the pressure falls it requires less and less heat to form steam and , there f o w . A fore , more and more this moisture ill be evaporated t release w the pressure drops suddenly , more heat at once flo s from the cylinder

- re x . walls, and evaporation continues throughout the e haust Prob 1 1 0 STEAM ENGINES ably all o f the water remaining in the cylinder at release is n ow re- w o ut o f evaporated , blo s into the air the condenser , and is lost w as far as useful ork is concerned . The steam that is first condensed in the cylinder does no work ;

w w re - its heat is used to arm up the cylinder , and later , hen it is evap

w o f orated , it orks only during a part the expansion and at a reduced

ffi re- e ciency, because it is evaporated at a pressure and , consequently , w f at a temperature very much lo er than that o admission . If the

-off 20 of cut is short, perhaps per cent the steam condensed may be re - - 10 evaporated during expansion ; if the cut off is long , per cent

re - may be evaporated , the rest remaining in the cylinder at release ,

f o f still in the form o moisture . Thus some the entering steam passes

- through the cylinder as moisture until after cut off , and still more passes entirely through without doing any work . Suppose an engine is using 30pounds o f steam per horsep owe 1 per hour and admission is at 00pounds absolute . The latent heat of vaporization at this pressure is 884 British Thermal Units per

. 33 10 pound If the condensation amounts to % per cent , then pounds

10 884 o r B are condensed and there is lost times , ritish Thermal

o r B Units per hour , per minute ; and since ritish Thermal 1 Units represent horsepower , there is lost by condensation

r — - off divided by o 35 horsepower (nearly) . If the cut is short

50 . ened , the condensation increases and may amount to per cent

Of a -off w course , very much less ste m is used at a short cut than ith

- 50 o f a long cut off , and doubtless in many cases per cent the steam at short cut-off is not as great an absolute quantity as 30per cent at

n - a lo g cut off .

hau Wa e Ex st st . In addition to the actual loss from condensa

- the re . tion in cylinder , there is still another loss due to evaporation

S 10 of t are uppose , as before , that pounds s eam condensed in the

2 of r — ex an cylinder , and that 0per cent this is e evaporated during p

- i w r x . sion . Th s ill leave 8 pounds to be e evaporated during e haust . Suppose the exhaust is at 3 pounds above atmospheric pressure o r

1 of 8 pounds absolute (about) . Then the heat vaporization is

B o f w ui e 8 ritish Thermal Units per pound steam , and it ill req r times

B 8 . or ritish Thermal Units , to evaporate the pounds

All of this heat is taken from the cylinder , leaving the engine much

- cooler than it would b e were it not for this re evaporation . This

1 12 STEAM ENGINES

o f o f o r The application the idea multiple expansion , compound ing , has materially reduced the losses both by lessening the amount o f condensation and also by utilizing the re - evaporated steam and

w n the steam that leaks by the piston , hich in some cases mav be co siderab l e w , and this important improvement ill be discussed first . f In addition , other means have been employed for the purpose o

of increasing the economic performance the steam engine , as for

ack etin su erheatin us e o condens ers instance , j g, p g, and the f .

MULT IPLE EX PANS I ON

T w o o n engines may be used together the same shaft , partly expanding the steam l n one o f the cylinders and then passing it over

One to the other to finish the expansion . advantage from this

- arrangement is that the parts can be made lighter . The high pres sure cylinder can be of much less diameter than would be possible f w o ne . o if the entire expansion ere to take place in cylinder This,

on course , makes the pressure exerted the piston rod much less , and

r the piston od and connecting rod can thus be made much lighter . The l ow-pressure cylinder must be larger than it otherwise would be , but its parts need not be much heavier , because the pressure per square inch is always l ow .

of This arrangement gives not only the advantage lighter parts ,

- but a decided increase of economy over the single cylinder type .

of If attention is given to the matter, a loss economy would be expected , because the steam is exposed to a much larger surface w through hich to lose heat , but the gain comes from another source and is sufficient to entirely counterbalance the effect o f a larger cyl inder surface . i n Le s s Conde nsat o . When very high pressure steam and a large

of w ratio expansion is used , the difference bet een the temperature

f and of x . For o the entering the e haust steam is great instance , suppose steam at 160pounds (gauge) pressure enters the cylinders

’ and 2 the difference the exhaust pressure is pounds (gauge) , in tem p erature as taken from steam tables is or This difference becomes nearly 230degrees if the steam is condensed to about three pounds absolute pressure . The cylinder and ports of the engine are cooled to the low temperature o f the exhaust steam

of and , as we have seen , a considerable quantity the entering steam STEAM ENGINES 1 13 is condensed to give up heat enough to raise the temperature o f the

o f cylinder to that of the entering steam . As the ratio expansion increases , the difference in temperature increases , and consequently the amount of steam thus condensed also increases . To keep this

of initial condensation as small as possible , the range temperature w must be limited , that is , it must not have as great a difference bet een

x o f admission and e haust . To do this the expansion the steam must be divided between two or more cylinders . It will be remembered that the great trouble Watt found with ’ Newcomen s w as o f engine its great amount condensation , and he

l aw the stated as the which all engines should try to approach , that

linder hou e t o a h team hi h enters it cy s ld be k p as h t s t e s w c . This is to

o . o f avoid c ndensation when steam first enters If, instead expand

n o ne ing the steam in one cyli der , it be expanded partly in and then

w out of fir finished in another , it ill have passed the st cylinder before its temperature has dropped a great deal , and consequently the cylinder walls will be hotter than they would have been if the exp an

n sion had taken place entirely in o e cylinder . This would then

f of reduce the amount o steam condensed . The importance this may not be evident at first , but it makes a great difference in the

of n economy the e gine . If there is less condensation , there will be l re- w ess moisture to evaporate , and consequently less exhaust aste , w hence there will be a saving in two ays .

Me h ds of C m n in t o o pou d g. In a compound engine the steam

o r - is first admitted to the smaller , high pressure , cylinder and then

- o r l ow . exhausted into the larger , pressure , cylinder Suppose steam at 160pounds (gauge) pressure is admitted to a

o f cylinder , and the ratio expansion is such that the steam is exhausted at about 60pounds (gauge) pressure ; then the difference of tempera ture is o r If now the steam when exhausted from the first cylinder enters

w s a second and is allo ed to complete its expansion , so that the exhau t

two o f pressure is about pounds (gauge) pressure , the difference temp erature in the cylinder will be or

for two Then the simple engine , if the exhaust pressure is pounds f (gauge) , the difference o temperature is degrees , while in the

tw o compound engine this difference is divided into parts ,

for degrees and degrees . The cylinder condensation both 1 14 STEAM ENGINES cylinders of the compound engine will be much less than if the total expansion took place in a single cylinder . The cylinders should be

of so proportioned that the same quantity work may be done in each .

w of If there are t o stages expansion , the engine is called simply

l adr l com ound tri e u u e . p ; three stages , p ; and four , q p ili n n Exhaust Waste Ut z e d . Besides reducing the excessive co de sation , there is still another gain in using multiple expansion . It has

x hi been shown how much heat is lost by the e haust waste , w ch in

. the simple engine blows into the air or into the condenser and is

- h x entirely lost . In the multiple expansion engine t e e haust and re -evaporation from one cylinder passes into the next and does work

- there ; furthermore , any leakage from the high pressure cylinder is

w w - also allo ed to do ork in the low pressure cylinder .

J ACK ET ING

The most primitive method o f effecting steam economy is by w i jacketing , h ch principle Watt early recognized and adopted . This method reduces the loss due to cylinder condensation by supplying

to the s heat team while it is in the cylinder, that is , by surrounding the cylinder with an iron casting and allowing live steam to circulate h T h in t e annular space thus formed . e cylinder covers are also f A made hollow to permit a circulation o live steam . cylinder having i 2 A F . 7 s . the annular space , g , filled with team is said to be jacketed

A lining L is often used in jacketed cylinders . i Funct on of J ack e t. The function of the jacket is to supply heat to the cylinder walls to make up for that abstracted during expansion and exhaust , so that at admission the cylinder will be as T h f hot as possible . e result is, that the di ference in temperature between the cylinder walls and the entering steam is considerably less than in engines where no jacket is used . Condensation is there f w th fore reduced and , since heat lo s from the jacket to e cylinder

a of during expansion , much larger amount this condensation is re-evaporated before release and it thus has an opportunity to do s some work in the cylinder . This leaves a comparatively mall amount of exhaust waste and the heat thus abstracted is made up

of from the steam in the jacket . Since a large amount heat is given

of . up by the jacket steam , a good deal it must be condensed Thus “ the q uestion is asked : What is the advantage of this method over

1 1 6 STEAM ENGINES

in f Saving Due to J ack et g . It is evident that a large part o the heat of the steam jacket flow s to the cylinder during exhaust and is

how thus entirely lost in the simple engine . In the triple engine ,

l ow - c lin ever , this heat passes into the intermediate and pressure y ders ; consequently w e might expect a greater gain from using a

n a o n . jacket o a triple engine th n a large , simple engine The main

f o ut advantage o the jacket has been previously pointed , and as in all cases the gain is small , there is to be found a considerable

On diversity o f opinion as to its real advantages . some engines there is undoubtedly little if any gain , the largest gain being in the f 2 w o 00 . On smaller engines , say , horsepo er and under very small

5 —inch 10- w o n e engines , such as a X inch engine hen developing only

o ne - w and half horsepo er under light load , the gain is as much as

On 10- w 30 per cent . a horsepo er engine the gain might be as

25 w on o f 200 w much as per cent , hile engines about horsepo er the gain would probably be 5 to 10 per cent for simple condensing and 10 15 compound condensing , and from to per cent for triple

on l of w expansion . The saving arge engines , say , horsepo er is very small , the reason being that large engines offer less cylinder

of surface per unit volume than small ones , and hence have propor

tionatel . y less cylinder condensation The very small engines , in w w hich the gain ould be the greatest , are seldom jacketed , because they are built for inexpensive machines and the first cost is o f more f Ow consequence than the economy o operation . ing to the cost o f construction and the care necessary to keep jackets operative , the

o f . F use the jacket has gradually diminished urthermore , the intro

o f - w duction the high speed and compound engines , as ell as the use of o f superheated steam , has reduced the advantage jacketing to relative insignifican ce . S UPERH EAT ING

G e ne ral Practic e . The use o f superheated steam is rather a modern practice , although for many years previous to its adoption engineers had appreciated its value in producing steam engine econ

m for o y . The reason its delayed adoption in a practical way w as due to the mechanical difficulties met with in superheating the steam and also to the increased cost of maintenance produced by its use . In recent years both of the objectionable features above mentioned have been , in a large measure , overcome , so that today STEAM ENGINES 1 1 7

o f w superheat is being used in a large number po er plants , and also

in steam locomotives . B w efore describing a superheater , it may perhaps be ell to fi w w clearly de ne hat is meant by superheated steam . Water , hen fi w confined in a vessel and heated suf ciently , turns into steam , hich ,

o f S if some water still remains , is spoken as saturated steam . atur

ated steam when further heated becomes superheated steam , if it

w . is separated from the ater To bring about this separation , a S h superheater is necessary . uper eaters vary considerably in details

fo r w of construction according to the service hich they are designed ,

i - 3 . W f e Su e ea e F g . 7 Se ctio n o f ater T u be B o iler Sh o wi ng Appli c ation o Fo st r p rh t r

fo r w there being , instance , quite a difference bet een the superheater designed for a stationary plant and one designed for a locomotive .

F s er u he w o t S pe r ate r. A Foster superheater as applied to a ater

i 73 . tube boiler is illustrated in F g . The superheating element

w B w o f is sho n at , hich is connected to the steam space the boiler by the pipe A . The saturated steam from the boiler passes through A the pipe , through the superheater, and then is conveyed to the

throu h h engine g t e valve 0. In this installation the superheater is placed in the passage provided for the transmission gases to the

hi w s . c mney, hence it is heated by what would other i e be lost heat S The manner of installing superheaters varies a great deal . ome are 1 18 STEAM ENGINES

m - entirely separated fro the boiler , being self contained and supplied with a grate for separate firing . 4 F . 73 7 The Foster superheater , igs and , is made up of a num

of w ber of elements placed parallel to each other , each hich consists f one o . of two straight steel tubes , inside the other The elements

n o r are joined at o e end to manifolds connecting headers , and at the other end to return headers for which return bends are often sub sti B i 4 f u On of F . 7 o t ted . the outside the tubes , g , are fitted a series

- D l cast iron annular flanges , p aced close to each other and carefully i fitted to the tube so as to be practically integral w th it , at the same

o f t time exposing an external surface cas iron , which metal is best

o f adapted to resist the action the heated gases . The rings are care

o n O l n o 1 . s fully bored to gauge , and shrunk the tubes nce being p

tion , the rings and tubes act vir

tuall As c oeffi y as a unit . the cient of expansion of steel is a trifle

of greater than that cast iron , the rings grip the tubes even tighter f when in service . This form o construction is flexible and dur I f able . t provides a section o great strength and entire freedom

from internal strains . The mass o f metal in the tubes and covering

acts as a reservoir for heat , which

s is imparted to the team evenly, 4 c n f s e r Su e e ate r be Fi . e t o o o T u s g 7 . S i F t p rh tending to secure a constant tem

erature of f p steam , even though the temperature o the hot gases does

. w s s fluctuate The seamless dra n tube ecures great initial trength ,

' i i r o n of wh ch s einforced by the rings shrunk the outside . Inside

0 of w i the elements there are placed other tubes rought iron , wh ch are centrally supported by means o f knobs or buttons regularly

r spaced throughout their length . These inner tubes a e closed at the A ends . thin annular passage E from the steam is thus formed between the inner and the outer tubes . The steam clinging closely to the heating surface is quickly heated in the most efficient manner . The superheater must be as free as possible from the liability of burning out in case of a chance of overheating of the exposed

120 STEAM ENGINES

- similar to the Stirling water tube boiler . The saturated steam from

1 s the main boiler plant enters the rear superheater drum , passe

of 7 w 2 the through the rear bank tubes into the lo er drum , thence to

8 the upper drum , from which it passes into the pipe line through d opening 4 . The furnace is similar to that used in the standar f m design o Stirling boiler . To protect the superheater tubes fro

o f o f high temperatures the furnace , a sufficient amount boiler heat

’ 5 6 o f 9 ing surface , as drums and and bank tubes , is located in front ‘ o f the superheater proper in order to reduce the temperature o f the gases to about degrees by the time they reach the superheater . T he builders state that when the gas temperature reache s

19 o f n degrees in the standard boiler , per cent the boiler heati g sur

w 50 of face has been s ept over by the gases , per cent the steam pro duced by the boiler has been generated , and the boiler heating surface

' w o n se u ntl in per horsepo er is square feet . C q e y the independently

w i 0 o f F . 75 5 fired superheater sho n in g , per cent the heat absorbed

w a is used to generate the steam , hich is dded to steam furnished by the main boiler plant and hence increases the capacity of the plant in

of o f proportion . The remaining 50 per cent the heat, a portion w out hich passes the stack , is absorbed by the superheater and super heats both the steam from the main boiler plant and that from the

of w front bank ater tubes . The superheater , because of the front

w 12 o f o f generator set , ill produce about per cent the amount

As steam furnished by the main boiler plant . a further precaution against any possible overheating o f the superheater tubes near the 1 2 furnace , a flap valve is placed in the pipe conveying saturated

i of s 5 . w F . 7 steam to the superheater , as sho n in g The spindle thi 13 valve is connected by links to the superheater damper , so that the damper to the opening is regulated according to the quantity o f w flow steam flo ing into the superheater . If the steam stops, the

I nde end valve 1 2 drops to its seat and the damper 13 is closed . p ently fired superheaters are furnished in any desired capacity, suit ° able for any degree of superheat up to about 300 F . The upper water drum 5 and the lower superheater drum 2 are connected by piping , hence , if desired , the superheater sections may be flooded , converting the whole into a saturated steam boiler .

Pur se s of u e h of po S p r e ate rs . These two types superheat

now o ur illustrated and described will suffice, and we may direct STEAM ENGIN ES 1 2 1

attention to a study o f the purposes o f the superheater and to

some consideration of the economy secured by its use . The pur i poses o superheating steam , as practiced in the past and as recog

niz d w e at present , are , according to Thurston , the follo ing (1) Raising the temperature which constitutes the upper limit in the operation o f the heat- engine in such a manner as to increase i the thermodynamic efficiency o f the working flu d . (2) To so surcharge the steam with heat that it may surrender as much as may be required to prevent initial condensation at entrance i nto cylinder and still perform the w ork o f expansion with o ut condensation o r serious cooling of the surrounding walls o f the

cylinder . (3) T o make the weight o f the steam entering the condenser w w and its final heat charge a minimum , ith a vie to the reduction o f the volume of the condensing water and o f the magnitude and cost

f h i i o t e air pump and condenser system to a m n mum . (4) To reduce the back pressure and thus to increase the power

f n f f developed from a given charge o steam a d e ficiency o the engine . (5) To increase the efficiency of the boilers both by the reduc tion of the quantity o f the steam demanded from the original heat ing surface and by increasmg the area of the heating surface employ ed

o o f o t absorb the heat the furnace and flue gases , and als by evading w w the aste consequent upon the production of et steam . If the steam entering a cylinder is only superheated enough to

T 1 T 2 dry - off o f give saturated steam at cut , the range temperature T 1

o f C is the arnot cycle is interchanged and there , therefore , no increase 1 f o f economy from item . The other four sources o economy depend

o n — f upon e fundamental fact the poor conductivity o dry steam . To the property o f non- conductivity o f heat of superheated steam

On is due its great advantage . entering a cool cylinder it slowly

u o f ffi w gives p its heat , and if the degree superheat is su cient there ill

o r w be little no initial condensation . The degree to hich steam

e should be superheated is still a d bated point , some engineers con tending that only a very moderate degr e e o f superheat of about 100 d ffi w egrees is su cient , hereas others maintain that no real economy is

w l e ss 20 o r W obtained ith than 0degrees over . hen a high degree

of was w u superheat first used , difficulties ere encountered s ch as 122 STEAM ENGINES

of r the disintegration the valves , valve seats , packing rings , and othe

o f parts subjected to the action the superheated steam . Lubrication was o f n also interfered with , since many the oils used were ot suited for All of f such high temperatures . these di ficulties no doubt account for the o ne w h of time idespread objection to igh degrees superheat , in but recent years they have in a large measure been overcome . The author is familiar with the performance o f a simple slide valve locomotive which has been in operation for several years under degrees of 80 214 superheat ranging from degrees to degrees , during which time no trouble has been experienced with the valves or with the M E lubrication . any uropean locomotives have been satisfactorily

o f operated with high degrees superheat , which insures the passage

f w r o steam through the cylinder ith but little o no condensation . n mi d n f Eco o c A va tage s . The economy obtained by the use o superheat has been clearly demonstrated by a large number o f p rac tical tests both upon stationary engines and upon locomotives . It is to of be noted also , that about the same per cent economy has been

on o f obtained the various types engines tested , the stationary tests corroborating the results obtained upon the locomotive and vice

ersa o f 12 to 15 v . The various tests indicate a saving from per cent of the amount of steam used by the engine per indicated horsepower f 2 2 o 0 5 . A per hour , and a saving coal from to per cent nother very significant thing that has been determined is that the output of w 20 30 po er has been increased from to per cent , depending upon

h of t e conditions . These three items saving have hastened the

o f o f t installment a large number superheaters , so hat at the present time thousands o f locomotives in Europe are equipped with super

S l ocomo heaters , and in the United tates and Canada over tiv es are so equipped . It seems that the railroads have been quicker to take up the idea of installing superheaters than have other

so industries , so that not nearly many superheaters are found in stationary service . It is to be noted that the greatest gains from the use o f super

to a heaters are be expected in the more uneconomic l plants . That is , the per cent of saving by the use of superheated steam in a simple

for co m engine would be greater than a compound engine , and for a w - i pound engine as compared ith a triple expansion eng ne . Several prominent engineers have advised the reduction of steam pressure s

124 STEAM ENGINES

b e the exhaust steam could condensed instantly, the back pressure would be reduced almost to zero and the engine would exhaust into a vacuum . Unfortunately the mere condensation of the steam will not give w a perfect vacuum because of the air , al ays present in the water M w which comes over from the boiler . oreover , the condensed ater is hot , and the vapor rising from it in the condensing chamber , together with the air and some leakage would spoil the vacuum were

Sect o n o f Ste am o n e n se o f the Sur ace T e 76 . Fig . i C d r f yp

w the . it not for the air pump , hich removes air and condensed steam Even with the best air pump it would be impossible to maintain a 26 w to perfect vacuum , but a vacuum of inches , hich corresponds about 2 pounds absolute pressure , can readily be maintained in good practice . It is well known that a certain amount o f heat is required to change one pound o f water at a given temperature into steam at the same temperature ; this is called the latent heat of vaporization .

u . If the steam condenses , it must give pthis latent heat The easiest ways of doing this are either to let the steam come in contact with STEAM ENGINES 125

pipes through which cold water is circulated , as in a surface condenser ,

f w . s two or mingle with a spray o ater , as in a jet condenser The e types will now be discussed . two T ype s of Co nde nse rs . Condensers may be divided into general classes as follows : (1) Surface condensers in which the cooling water is separated o f from the steam , usually by metallic surfaces in the form tubes , the cooling water circulating o n o ne side o f this surface and the steam coming in contact with the metal on the other side .

(2) Jet condensers , including barometric condensers , siphon

D a r a m Sho w n R e a o n o f Su r a c e o n e ns e to the u m s N e c e s sa r fo r 7 7 . y Fig . i g i g l ti f C d r P p P r o pe r Ope ra tio n

w w condensers , ejector condensers , etc . , in hich the cooling ater mingles with the steam to be condensed .

i 6 o ne f e w F . 7 Su r ace Typ . The condenser sho n in section in g is f w form o the surface type , in hich the air pump and the circulating pump are both direct acting and both operated by the same steam w w cylinder . The cool condensing ater is dra n from the supply into the circulating o r water pump and is forced up through the valves w and water inlet to the condenser . It flo s , as indicated by the

w o f w c arro s , through the inner tubes the lo er se tion , then back w through the space bet een the inner and the outer tubes . The w w ater then passes up ard and through the upper section , as it did

w o ut s w in the lo er , then it passes of the conden er through the ater w outlet , taking ith it the heat it has received from the steam . 126 STEAM ENGINES

The exhaust steam from the engine enters at the exhaust inlet

i w w and comes in contact ith the perforated plate , hich causes it to spread . The steam expanding in the condenser comes in contact w w c on ith the tubes , through hich cool water is circulating , and w f denses . The air pump dra s the air and condensed steam out o the condenser and thus maintains a partial vacuum . This causes the exhaust steam in the engine cylinder to be drawn into the con

of w denser , at the bottom hich it collects as, it condenses and is drawn into the air pump cylinder and discharged while heated to

o f w w the hot well of the boiler . The use this hot ater as feed ater effects a considerable saving , but the great advantage of the con denser is the reduction of the back pressure . H ot water can not be used by an ordinary pump as easily as cold water because o f the pressure of the vapor which arl ses fro m w w the hot water . In the condenser sho n , the ater and air pumps are run by the piston in the steam cylinder . Sometimes these pumps are connected to the main engine and receive motion from the shaft o r crosshead . The general arrangement o f the surface condenser with the w i 1s F . w necessary pumps sho n in g 77 . The cooling ater enters K w R through the pipe and flo s to the circulating pump , which forces the water into the condenser through the pipe L . In case w the ater enters the condenser under pressure from city mains , no

A e w circulating pump is necessary . ft r flo ing through the tubes it

of M w w Ex leaves the condenser by means the exit and flo s a ay . haust steam enters at S and is condensed by coming in contact with the cold tubes ; the water (condensed steam) then falls to the bottom of

nd w B E the condenser a flo s to the air pump by the pipe . The air pump removes the air, vapor , and condensed steam from the con N w w denser and forces it through the pipe into the hot ell , from hich it goes to the boilers o r to the feed tank . i m w ircu lat n u . C g P p The circulating pump , hen separate from

of . co n the condenser , is usually the centrifugal type This pump sists of a fan o r wheel which is made up of a central web (or hub) and

the wn arms (or vanes) . The vanes are curved and as water is dra w ff o . in at the central part, the vanes thro it at the circumference

o f adv anta A suitable casing directs the flow . This typ e pump is

eou e et out of o e and as the t g s becaus there are no valves to g rd r , lif

‘ WAT ER Dnsr RrBua \ T RAY AIR PUMP S UCT IO N

EXHAUST INLET

TOP VIEW OF WATER DIST RIBUT K NG TRAY

Alb e r e r a o m e c J e t o n e n se r i 8 0. F g . g B r tri C d nd onde ns er Com a n N ew Y or k Cit Courtesy of A lb erger Pu mp a C p y , y 1 30 STEAM ENGINES

w flow w the arro s indicating the direction of the . Cold ater enters

w P o f the condenser through the pipe sho n . art the mixture of

- exhaust steam and condensed water goes to the feed water heater , w hich is kept nearly full ; the rest passes to the sewer . The heater w is placed a little above the feed pump , in order that the ater may enter the pump under a slight head . This is necessary because the pump can not raise water which has been warmed by exhaust steam as readily as cold water .

r A o f Barometric Condens e . type condenser much used with reciprocating engines , and to a limited extent with steam turbines , w i F . 80. is the barometric condenser , sho n in g This condenser is S one o f the jet type . team enters at the point marked exhaust " inlet in the left-hand figure and completely fills the exhaust steam w w chamber , hile the condensing ater enters through the injection w w pipe . The ater rises into a distributing tray here it is broken up into many finely divided streams as seen in the left-hand

figure . This spray condenses the steam in the exhaust chamber w w and passes do n the tail pipe , carrying the condensed steam ith

Air w it to the hot well . entering ith the exhaust steam is cooled and collected in the air collector inside of the condensing cham

of ber . A vacuum is maintained in the upper part the condenser so that any air which has been collected during the process of con “ den sing the steam is carried away through the pipe marked air " A o f pump suction . small amount the cooler injection water is allowed to mix with this air so as to cool it before it passes on to the air pumps .

e ond ns r W f Westinghous e L blanc C e e . ith the ordinary type o 26 27 reciprocating engine , a vacuum of to inches is usually all w that is desired . With modern steam turbines , ho ever , a vacuum 2 of 28 to 9 inches is common practice , and in many plants even w these figures are exceeded . These figures , ho ever , cannot be f attained unless a very e ficient air pump is used . The Leblanc condenser is considered o ne of the most efficient types of the many forms o f jet condensers .

i 8 1 w o f L F g . sho s a cross section the eblanc jet condenser , as M manufactured by the Westinghouse achine Company . This type is especially used in the larger steam turbine installations . In this E a the to condenser steam enters through the large opening t p ,

132 STEAM ENGINES

I w w is the separate ater supply for this air pump , sho n more in i 2 w F . 8 A A . detail by g , hich is a cross section on i 2 F . 8 w In g , the ater entering through the center of the pump J w is discharged through the orifice into a tapering pipe , the ater

o f G being emitted in a succession layers , as indicated at . These

o f w o f layers ater are sometimes spoken as being water pistons . The air coming through pipe L is caught between these layers of water and carried to the atmosphere through the long diffuser K pipe .

Fi 82 Se c t n f Le n n r A Fi . b a c o e n se r T a e n t u A . 8 1 . o o o g i l C d k h g h , g ou r tes o Westin hou s e M a c hin e o a n E a s t itts u r h P en n C y f g C mp y , P b g , s yl va nia

S w o f ince the cooling ater enters by virtue the vacuum , an

o f accidental stopping the pumps might cause serious trouble , due w f to the ater rising above the top o the condenser . To take care of such emergencies , a very simple form of vacuum breaker is pro w v ided . In case the ater rises in the condenser to an undesirable i 1 0 F . 8 N height , the float , g , opens the valve and admits air to

o enter through passage "directly int the condensing zone . This

o f w immediately stops the inflow ater by breaking the vacuum , and prevents damage to the turbine .

i n u n Re lat ve M e rits of J e t a d S rface Co nde s e rs . In the jet con th w denser e steam , as soon as condensed , becomes mixed ith the

for - cooling water, and if the latter should be unsuitable boiler feed

- of . because scale forming impurities , acids , salts , etc , the pure dis w tilled water represented by the condensed steam is asted , and if it

w - were necessary to purchase other ater for boiler feeding , this might

f . On represent a considerable waste o money the other hand , if the STEAM ENGINES 13 3 cooling water is suitable for boiler - feeding or if a fresh supply o f good

o f water is easily obtainable , the jet condenser , because its simplicity

low . S and cost , is unexcelled urface condensers are recommended where the cooling water is unfitted for boiler- feed and where no

of - w i suitable and cheap supply pure boiler feed ater is ava lable . Condensed steam from a surface condenser makes the best boiler w w feed ater , being in fact pure distilled ater entirely free from scale

of forming matter and containing a considerable amount heat , as w compared with cold feed ater . If the exhaust from reciprocating

- w engines is to be condensed and used as boiler feed ater , a suitable o il separator should be interposed in the exhaust pipe between the

of n engine and the condenser . Another advantage the surface co denser as compared with the jet condenser is that there is no dan

of of w ger , in case failure vacuum pumps , of the circulating ater w backing up into the engine cylinder and recking the engine .

nd n r Effect of Co e se on Effic ie ncy. It has already been stated that there is a gain in thermal efficiency by running an engine con

densin w few . g, but it ill be more clearly seen by considering a figures The thermal efficiency may be expressed by the previously men tioned formula

This efficiency may b e increased if T I can be made larger which would happen if the boiler pressure were increased— o r if T w w 2 can be made smaller , hich ould result from reducing the back

. s pressure by condensing If the boiler pressure is rai ed , both the

of w numerator and denominator the fraction ill increase , and the value

of w . w the fraction ill be but slightly greater If , ho ever , the back T T w w pressure is reduced , the numerator 1 2 ill be larger , hile w the denominator T I ill remain the same . It is apparent that this will cause a much greater increase in efficiency than raising the boiler pressure a like amount . Suppose an engine is supplied with steam at pounds (gauge)

ab so pressure and it exhausts at pounds (gauge) pressure . The lute temperature corresponding to or 100pounds pres sure , is or degrees , and the absolute temperature

or 18 corresponding to pounds pressure , is or 134 STEAM ENGINES

T ABLE 1

I nc r e a s e in Ef f ic ie nc y b y Us e o f Co nd e ns e r f o r V a r ious Eng ine s

F e e d W a te r p e r I n dic a te d H o r se p o we r

N o n - Co n de n s i n g C o n d e n s i ng P r C e n t aai n T y p e o f E ng i ne e d A ssu m e d f r C o m o C o n d e n s er p a r i s o n P o u n d s

Simple H igh Sp e e d 3 5 to 26 Simple Lo w Sp e ed 3 2 to 24 Co mpo un d H igh Sp e e d 3 0to 22 Co mp ound L ow Sp e e d H T riple E xp . igh Sp e e d 27 to 2 1 Lo T riple Exp . w Sp ee d

ffi degrees . Then the thermal e ciency determined from the formula becomes

T 1 T 2

T 1

134 o r , per cent

w 140 If the boiler pressure ere raised to pounds absolute , the efficiency would be

16 1 or , per cent

If instead of increasing the boiler pressure a condenser is used

4 s s and the exhaust pressure reduced to pound (ab olute) , the c ffi c iency becomes

222 o r , per cent

Thus it is seen that if the exhaust pressure is lowered 14 pounds absolute there will be a greater increase in efficiency than if the 4 boiler pressure is raised 0pounds . The per cent of efficiency that is obtained by the use of a con w denser is sho n in Table I .

Cost of Cooling Wate r Determines Co nde nse r Economy. While i the above figures are very encouraging , yet cond tions may arise

or where the per cent of gain may be materially lessened entirely lost,

13 6 STEAM ENGINES

w of w within the to er , or a large number mats of steel ire cloth gal w v aniz ed after weaving . The to er may be supported upon a proper foundation or upon legs , instead of being situated on the top of a

w . building , as the one sho n in the illustration

i of w To ass st in the cooling the ater , the air is often made to

o f w circulate rapidly by means a fan , hich forces the air into the

D a am f Sta t o n a n ne w t o n n e t o n s to W ate o o n T o e o n Fi 83 . o c g . i gr i ry E g i i h C i r C li g w r R o o f o f B u ildi n g

lower part of the tower and upward through the mats . This fan ma y be driven by an electric motor , by a line of shafting , or by a small independent engine .

In case the fan is not used , the mats are arranged so that they are of exposed to the atmosphere . This course necessitates the

fanless w b e removal of the steel casing . Usually the to er must STEAM ENGINES 13 7 placed at the top of a high building or in some position where the currents of air can readily circulate through the mats .

W of w w ith an efficient type cooling to er, the ater may be reduced

30 50 wi of 22 26 from to degrees , thus allo ng a vacuum from to

w a f inches . This ill , of course , gre tly increase the economy o the w w plant and allo the heated feed ater to be returned to the boiler . The water table is usually made of wooden slats placed in the A ground near the plant . fter trickling over the slats and becoming

of cooled by the air , it collects in the bottom the reservoir and is then pumped into the condenser . B Amount of Cooling Wate r Per Pound of Ste am. esides con densin w g the steam , the injection ater cools it still further , so that more than merely the latent heat is removed from it . If exhaust t steam enters the condenser at a temperature 1 , it contains a certain

f k w tota heat at tem erat r o l u e t . amount heat , no n as p l If it is con densed t w and cooled to a temperature z , at hich it leaves the con

it w total denser , then contains a certain amount of heat , kno n as

at a m ra r he t te p e tu e t2 .

If A represents the total heat at t1 and B represents the heat of t one the liquid at 2, then the heat given up by pound of condensed s A — B B ni team is equal to ( ) ritish Thermal U ts , provided the exhaust that enters the condenser is dry saturated steam . If C is the temperature of the injection or cooling water and D is the tem

eratur e w of w p of the discharge ater, then every pound cooling ater absorbs approximately one British Thermal Unit for every degree

or we rise in the temperature , may say that the heat absorbed is D— B equal to ( C) ritish Thermal Units per pound of cooling water . Then it will take as many pounds of water W to absorb (A — B) D heat units as ( C) is contained in (A B) . This may be expressed thus

W w Therefore , represents the number of pounds of ater required per pound of steam condensed .

E P 1 Su o s e s e am is e an e in an e n ne to 4 o u n s ab s o XAM LE . pp t xp d d gi p d u e e s I f th n i s s u e . e a e m e ra tu f the n a e s 4 e e e l t pr r i iti l t p re o c o oli g w t r 5 d gr , and the o n ense is o f the s u fa e t e s a n w a e at 1 20 e e e s c d r r c yp , di ch rgi g t r d gr , 1 38 STEAM ENGINES

f h n en e m i 1 0 e ee s how man oun s an d the temperature o t e co d s d ste a s 3 d gr , y p d of cooling w ate r are re qu ir e d p er p oun d of s te am" B nsu n the e am a es w e fin d the o a e a of U T . o s SOL ION y c lti g t t bl , t t l h t T e e a ste am at 4 p oun ds pre ssure to b e British T herm al Un its . h h t of the liquid in the condense d ste am at 130 d egrees is British T herm al T n Units . he

Su o se s e am at 6 oun s a so u e essu e e aus s EXAM PLE 2 . pp t p d b l t pr r xh t n T he em e a u e of the n e on w a e is 50 e ees in to a je t co den ser . t p r t r i j cti t r d gr o m an oun s of w a e are ne e ssa and the disch arge is 120 de gre es . H w y p d t r c ry to condense 8 poun ds of st e am"

n the e t on en se the em e atu e of the on ense s e am SOLU T ION . I j c d r t p r r c d d t e fin d f om the s e am a es a the an d the discharge w ater is the s am e . W r t t bl th t B s T e m a n s and to t al he at of st e am at 6 pou nds ab so lute is riti h h r l U it , the he at of the liquid in the con den sed ste am at 120 degrees is British

en as efo e . T hermal Un its . T h b r

120— 50

T e e o e 8 oun s of wa e w e ui e X 8 or oun s h r f r , p d t r ill r q r , p d .

The above calculation can not be relied upon to any great

we w an extent for seldom kno the true condition in the condenser , d

of we w . it would be little value to us if did kno , as the exact condi tion will change considerably . In practice it is customary to allow w w w for about t ice as much ater as the above calculation ould require . These figures give us a fair idea of the necessary sizes of the pipes and passages leading to the condenser , and give a basis for estimating the dimensions of the air pump .

Cool ing Surface in S urface Conde nse rs . The amount of sur face required to condense the steam in surface condensers depends

of of upon the conductivity the metal , the condition the tubes and

ff w two their thickness , and the di erence in temperature bet een the

. of sides The tubes a condenser are much thinner than boiler tubes , hence we might expect them to be more efficient in condensing the w steam than the boiler tubes are in evaporating ater . It has been found in actual practice , that a surface condenser receiving cooling water at 60degrees and discharging it at 120degrees will condense from 10to 20pounds of steam per square foot of the tube surface per 13 hour . An average of pounds per square foot of surface per hour

1 40 STEAM ENGINES

Variab le T hrus t. In the actual engine the thrust along the rod is constantly varying even though the pressure on the piston r i emains the same . This s due to the angularity of the connecting r o d . The turning moment is always equal to the thrust along the connecting rod multiplied by the perpendicular distance from the

of connecting rod to the center the shaft . If the steam pressure on the piston remains constant, the maximum turning moment occurs w hen the connecting rod is at right angles to the crank, for in this position the perpendicular distance from the rod to the center of the

i of shaft is a max mum and equal to the length the crank ; and , as the rod makes its greatest angle with the line connecting the dead center at this point , the thrust along it will also be a maximum . If

-off one- the cut is very early , quarter stroke for instance , the maxi mum thrust along the rod will occur earlier than at the point pre v iousl w y mentioned , but the leverage of the force ill be less, so that really there will be little change in the point of maximum turning

- moment no matter where the cut off may occur .

ia rams . r D g To rep esent this turning moment , diagrams of

w i co- crank effort may be dra n , w th rectangular ordinates , having the crank angles represented as abscissas and the turning moments corresponding to these angles as ordinates .

FLY W H EEL

Besides the thrust of the connecting rod there must be taken c into account friction and the inertia of the recipro ating parts . At first this may be thought of small consequence but with a fairly heavy piston and connecting rod it is obvious that at high speed the

w . momentum ould be great In the case of a vertical engine , on the up stroke the steam must lift this heavy mass and impart a very w w considerable velocity to it, hile on the do n stroke the acceleration f o f the mass is added to the steam pressure . This makes the e fective force on the up stroke less than that due to the actual steam pres

w . sure , and greater on the do n stroke f Function . In the case o a horizontal engine it is evident that while the piston can push the crank around during part of the stroke ,

of e and pull it along during another part , yet at the end the strok

how the pressure on the piston , no matter great , can exert no turn

ro ing moment on the shaft . Therefore , if some means is not p STEAM ENGINES 14 1 v ided for making the shaft turn past these points without the assist

of . ance the piston , it may stop This means is provided in the w flywheel which is merely a heavy heel placed on the main shaft . On account of the momentum of the flywheel it can not be stopped quickly and therefore carries the shaft around until the piston can again either push or pull . Wh l ff i e of e e . S z If a long period be considered , the mean e ort and the mean resistance must be equal ; but during this period there

of ff are temporary changes e ort , the excesses causing increase of speed . To moderate these fluctuations several methods are employed . The turning moment on the shaft of a single cylinder engine

rst of second varies , fi , because the change in steam pressure , and , on account of the angularity of the connecting rod . Before the piston

- i x m w reaches mid stroke the turn ng moment is a ma imu , as sho n by

i l R e e se n a t o n o f T u n n M o m e n t o f n f n e F . 84 a c a a S a o a S g . Gr phi pr t i r i g Cr k h ft i g l Cy li n der E ng ine for O n e Stro ke

4 f Fi . 8 . N o the curve , g ear the ends the stroke the turning moment diminishes and finally becomes zero . This , of course , tends to cause a corresponding change in the speed of rotati on of the shaft . In order to have this speed as nearly constant as possible and to give

w ma a greater uniformity of driving po er , the engine y be run at high B f . hi o speed y t s means the inertia the revolving parts , such as w the connecting rod and crank , causes less variation . When the ork

e w fl to be done is st ady and al ays in the same direction , a heavy y w ~ . w w heel may be used The heavier the fly heel , the steadier ill

. h be the motion It is desirable , of course , in all engines to ave steady

For motion , but in some cases it is more important than in others . instance , in electric lighting plants it is necessary that the machinery w shall move ith almost perfect steadiness . It is undesirable to use w larger heels than are absolutely necessary , because of the cost of h t e w e . metal , the eight on the b arings , and the danger from bursting 142 STEAM ENGINES

M t z e hods of Reducing Si e . If the turning moment which is exerted on the shaft from the piston could be made more regular w and if dead points could be avoided , it ould be possible to get a steadier motion with a much smaller flywheel .

or If the engine must be stopped and reversed frequently , two h more cylinders are used , being connected to the same shaft . T e cranks are placed at such angles that when one is exerting its mini

ef or w one mum rotative fort , the other is exerting its maximum , hen ff ‘ is at a dead center , the other is exerting its greatest e ort . These cylinders may be identically the same in dimension as is the case with most hoisting engines and with many locomotives ; or the engine

x may be compound or triple e pansion . This arrangement is also

of used on engines for mines , collieries , and for hoisting any sort w here ease of stopping , starting , and reversing are prerequisites . Simple expansion engines with their cranks at right angles are usually spoken of as being coupled . The governor adjusts the power of the engine to any large varia w l tion of the resistance . The fly hee has a duty to perform which is similar to that of the governor . It is designed to adjust the effort of the engine to sudden changes of the load which may occur during f a single stroke . It also equalizes the variation in rotative e fort on w w th the crank pin . The fly heel absorbs energy hile e turning

of w moment is in excess the resistance , and restores it hile the crank is at or near the dead points . During these periods the resistance is in excess of the power .

c i n of Fl he l o f w re r A t o yw e . The action the fly heel may be p e 4 Fi . F . 4 w 8 sented as in igs 8 and 85 . It ill be noticed that in g , the curve of the crank effort runs below the axis toward the end o f the

u stroke . This is because the compression is greater than the press re

of o n near the end expansion , and produces a resultant pressure the i . f f . piston In F g . 85 the e fect o compression has been neglected L i e F . 4 t o r . 8 us suppose that the resistance , load , is uniform In g ,

A B - o f the line is the length of the semi circumference the crank pin . o r the circumferential distance the crank pin moves during o ne f stroke . The curve A M D O B is the curve o turning moment for o n N e A E F B e . M stroke is the mean ordinate and , therefor , represents the constant resistance . The effort and resistance must be equal if the speed is uniform ; hence the area A E F B equals

144 STEAM ENGINES

for that the variation is much less than a single cylinder, hence a lighter wheel may be used .

at M as s w Calcu l ions of . The eight of the flywheel depends upon

For the character of the work done . pumping engines and ordinary machine work the effort need not be as constant as for electric light

w of w ing . In determining the proper eight a fly heel the diameter

of w w . w the heel must be kno n If the heel is too large , the high linear velocity of the rim will cause too great a centrifugal force and the

w w . heel ill not be safe In practice , about feet per minute is

f - taken as the maximum linear velocity o cast iron wheels . When made of wood and carefully put together the velocity may be taken as to feet per minute . The linear velocity of a wheel is expressed in feet per minute

V = 2 rt R N 71' D N w V by the formula , or , in hich is velocity in feet

R of w D of w per second , is radius heel in feet , is diameter heel in N feet, and is revolutions per minute . 1 Then if a whe el runs at 00revolutions per minute, the allow able diameter would be obtained from the equation 6000 X D Therefore 6000

X 100 feet If a wheel is 12 feet in diameter the allowable speed is found to be V N 7: D

6000

3 . 1416 X 12 159 revolutions per minute

to It is usual make the diameter less than the calculated diameter . H w aving determined the diameter, the eight may be calculated by several methods . There are many formulas to obtain this result

on given by various authorities , e formula being 2 G X Cl X b D2 >< N2 in which W is weight of rim in pounds ; d is diameter of cylinder in inches ; b is length of stroke in inches ; D is diameter of flywheel in STEAM ENGINES 145 feet ; N is number of revolutions per minute ; and C is a constant having a value which varies for different types of engines and for different conditions as follows

S e a e e n nes or dinarv w o C lid v lv gi , rk

o ss en nes o n a w o . C C rli gi , rdi ry rk S e- a e e n nes e le n C lid v lv gi , ctric lighti g Au tom atic high sp e ed e ngines C

l ri li t n o ss e n nes e e c t c h i . C C rli gi , _ g g

1 F n th w e o f a w ee rim for an au m t EXAM P LE . i d e ight fly h l to a ic high t n T he n er is 24 n es in a m sp ee d e n gine use d for e le ctric ligh i g . cyli d i ch di e te r ; I t uns at 3 00 e o u o ns er m n u e an d th the s o e is 2 fe e . e w e e tr k t r r v l ti p i t , fly h l f e n me e is to b e 6 e t i dia t r . T SOLU ION . 1000000X X 24

36 X 90000 4266 p ounds

P E A a n s e a e e n ne for e e n is 2 n EXAM L 2 . pl i lid v lv gi l ctric lighti g 0 i ches 1 2 n es . I t uns at e o u ons er m nu e T X 4 i ch r 50 r v l ti p i t . he flywh ee l is to b e

W a t is the w e f its rim 8 feet in di amete r . h ight o "

S T . OLU ION 700000X 400x 24

6 4 X 22500 — 4666 pounds

w w The eight of a fly heel is considered as being in the rim . The

of w weight the hub and arms is simply extra eight . Then , if the w w w eight of the rim and its diameter be kno n , the idth of the face A and thickness of the rim can be found . ssume the given diameter

of to be the mean of the diameter the inside and outside of the rim . Let b equal width of face in inches ; t equal thickness of rim in inches ; 2 d equal diameter of flywheel in inches ; and . 607 equal weight of 1

of cubic inch cast iron . Then

h rim f n s is E P 3 . Su ose t e o a w ee w e s ou 9 XAM LE pp fly h l igh p d , f e in am e e an d the w o f the f is 2 i th ness e a e 4 n es . W a s e t di t r , idth c i ch h t thick of the rim"

SOLUT ION . W 1 d b . 8 9 6000

. 8 19 X 108 X 24

in ch es T h I n this c ase the rim w o uld prob ably b e ma d e 2 1 i nch es thick . e

w e n u n ub an d a ms w u o a b a u o un s . ight , i cl di g h r , o ld pr b bly e b o t p d 1 46 STEAM ENGINES

GOV ER NO R

v The load on an engine is ne er constant , although there are

i cases where it is nearly uniform . While the eng ne I S running at w constant speed , the resistance at the fly heel rim is equal to the work done by the steam , disregarding friction . If the load on the engine is wholly or partially removed and the supply of steam con

inu w t es undiminished , the force exerted by the steam ill be in excess

c of the resistance . Work is equal to force multiplied by distan e ; w hence , ith constant effort , if the resistance is diminished , the dis w tance must be increased . In other ords , the speed of the engine “ A w e w . ill be Increased , and the ngine ill race lso , if the load w increases and the steam supply remains constant , the engine ill “ Slow down .

It is evident , then , that if the speed is to be kept constant some means must be provided so that the steam supply shall at all times be exactly proportional to the load . This is accomplished by means of a governor .

- two M ethods of Action. Steam engine governors act in one of ways (1) they may regulate the pressure of steam admitted to the 2 steam chest , or ( ) they may adjust the speed by altering the amount

w wa of steam admitted . Those hich act in the first y are called throttlin overnors g g , because they throttle the steam in the main

of a tomatic cut- o steam pipe . Those the latter class are called u ff

- overnors . g , since they automatically regulate the point of cut off

Theoretically , the method of governing by throttling the steam

u ff ca ses a loss in e iciency , but the throttling superheats the steam , B thus reducing cylinder condensation . y the second method the f loss in e ficiency is very slight , unless the ratio of expansion is already

w S - great , in hich case hortening the cut off causes an increasing cylinder condensation .

f throt Control by Centri ugal Force . In most governors of the tling type and those applied to Corliss engines , centrifugal force A counteracted by some other fOrce is employed . pair of heavy masses (usually iron balls or weights) are made to revolve about a

S w . pindle , hich is driven by the engine When the speed increases , w the centrifugal force increases and the balls tend to fly out ard , w that is , they revolve in a larger circle . The controlling force , hich is usually gravity or springs , is no longer able to keep the balls in

148 STEAM ENGINES in which F is force in pounds ; W is weight of one ball in pounds v is velocity in feet per second ; g is acceleration due to gravity ; and r is F radius in feet . rom the above equation it is seen that force varies inversely as the radius .

While the pendulum is revolving , centrifugal force acts hori z ontally outward and tends to make the balls fly from the center ; f w and the action o gravity tends to make the balls drop down ard . In order that the balls shall revolve at a certain height , the moments

' of thes two e forces about the point of suspension must be equal , or

Fi 86 D a r am s S o n Ac t o n of e n u um o e n or g . . i g h wi g i P d l G v r the weight of the balls multiplied by their distance from the center

or must equal the centrifugal force multiplied by the height,

WX r = F >< h from which

S of F we ubstituting value just given , have

Therefore ,

of Now since v, the linear velocity a point revolving in the circum ’ ’ 2 7: r N w N ference of a circle , is expressed as feet per second , here STEAM ENGINES 149

is revolutions per second , this value may be substituted in the above formula , giving

F w and since the values of g and are kno n , the formula may be written

14 . 8 6 (N 9 2

i nches (N ’ ) 2

N N ’ If it is desired to use , the instead of , the the former may be substituted in the formula by multiplying the fraction 2 or 3600 by 60, , giving

inches

From the above formula it is evident that the height is inde

oi w pendent the eight of the balls or the length of the rod , depending entirely upon the number of revolutions . The height varies inversely f as the square of the number o revolutions .

not The ordinary pendulum governor is isochronous , that is , it does not revolve at a uniform speed in all positions , the speed changing as the angle between the arms and spindle changes .

= B n r two Fly all Gove r o . The early form consisted of heavy balls suspended by links from a pin connection in a vertical spindle ,

S w F S as ho n in igs . 87 and 88 . The pindle is caused to revolve by

or S belting gearing from the main haft , so that as the speed increases , centrifugal force causes the balls to revolve in a circle of larger and 1 50 STEAM ENGINES

larger diameter . The change of position of these balls can be made to affect the controlling valves so that the admission or throttling w ill vary with their position . With this governor it I S evident that for a given speed of the engine there is but one possible position for

one of one the governor , consequently definite amount throttling or

- h of point of cut off, as the case may be . If the load varies , t e speed

e the engine will change . This causes the position of th governor balls

But to be changed slightly , thus altering the pressure . in order that

-off the pressure or cut shall remain changed , the governor balls must

new . stay in their position That is to say , the speed of the engine

Simpl e T y p e o f Fl y L ate r T y pe o f Fly B all G o v ern o r B all G o v ern o r

S old must be lightly changed . Thus Wi th the ball governors there

S l was a light y different speed for each load . This condition has been greatly improved by various modifications until now such governors

n give excelle t regulation .

i Wi While the engine is runn ng th a light load , the valve con trolled by the governor will be open just enough to admit steam at

w ow a pressure that ill keep the engine running at a given speed . N w if the engine is heavily loaded , the throttle valve must be ide open . The change of Opening is obtained by a variation inthe height of the

w . governor , hich is caused by a change of speed Thus it is seen that the governor can control the speed only within certain limits which are not far apart . The difference in the extreme heights of the gov cruor must be sufficient to open the throttle its entire range . In

1 52 STEAM ENGINES

w ioned governor became sluggish . The balls had to turn slo ly because they were so heavy ; this was especially troublesome in high

Speed engines .

m d T e T o Porter I p rove yp . remedy these defects the weighted

wa . Fi 89 . s or Porter governor , g . designed It has a greater height for a given speed , and the variation in height for a given variation B i . n creas of speed is greater and , consequently , more sensitive y ing this variation in height , the sensitiveness is increased . Thus , if

0 o 57 a governor running at 5 revolutions has a variation in height f .

of 1 for inch , it is not as sensitive as one having a variation inch the same speed . w In the weighted governor , the eight is formed so that the center

on S of gravity is in the axis . It is placed the pindle and is free to w revolve . The eight adds to the weight

of the balls , and thus increases the mo

of w . ho w ment the eight It does not,

ever , add to the centrifugal force , and hence the moment of this force is un I t changed . may then be said that the weight adds effect to the weight of the governor balls but not to the centrifugal

force, and as a consequence the height of the governor for a given speed is in I i creased . W eq ual s the weight of the

8 1 0 T e ’ 9 y p W one- 2gFfiggfi50539324 ball as before , and equals half the w added eight , the equated moments are

r = Fh

S F ubstituting for its value obtained from the formula , p . 147, we have

W ’ ( + W ) r (

WX N ’) 2

X STEAM ENGINES 153

Since it is known that

g 8 146

2 ’ 2 ’ 2 472 (N ) (N ) W + W h (

H ence the height of a weighted governor is equal to the height o f W+ W, W a simple pendulum governor multiplied by ( +

For S instance , if the height of a imple pendulum is 10inches and

W te s a r G o vern o r with Fig 9 1 W aters Sp ri n g T y p e of Fly Sa e S o f ty t p B all G o ve rn or

of the weight of the balls equal to the added weight , the height the weighted governor will be

Thus it is evident that if a weight equal to the combined weight

of w . the balls is added , the height of the governor ill be doubled

off wi If the belt driving the governor slips or breaks , the balls ll 1 54 STEAM ENGINES

w w drop , ith the result that the engine ill run away . To diminish this danger many governors are provided with some kind of safety stop which closes the valve when the governor loses its normal U action . sually a trip is provided which the governor does not w touch in its normal positions , but hich will be released if the balls w w drop do n belo a certain point .

S rin T e p g yp . In many cases a spring is used in place of th weight . This type of governor is frequently used on throttling

engines , and it consists of a pen dulum governor with springs added to counteract the centrif

of ugal force the balls . Thus the height and sensitiveness are in Fi w creased . g . 90 sho s the ex terior view of a Waters governor Fi 1 and g . 9 Shows the same

governor having the safety stop . In this governor the weights are w al ays in the same plane , the variation in height being due to the action of the bell - crank levers

S connecting the balls and pindle . w When the balls move out ard , the Spindle moves downward and

tends to close the valve . The governor balls are caused to re

Se f a e e a F 92 ° ° f ig ' t v lv s of wgse g volve by means a belt and bevel

gears . The valve and seat are

S w Fi 2 w w ho n in section in g . 9 . The valve is a hollo cylinder ith three ports through which steam enters . The seat is made in four parts , that is , there are four edges that the steam passes as it enters the valve . The valve , being cylindrical and having steam on both sides , is balanced , and because of the many openings only a small travel is necessary .

Shaf G n t over or. Usually some form of pendulum governor

For is used for throttling engines . governing an engine by varying

of - S d the point cut off, haft governors are generally use , although the Corliss and some other engines use pendulum governors for this pur

156 STEAM ENGINES

T wo w A A ernor is keyed to the Shaft . arms , having eights at the b ends are pivoted to the arms of the wheel b . The ends having the , weights are connected to the collar on the loose eccentric C by means of rods B B . t When the weig hts move to the position indicated by the dot ed on f of lines , the eccentric is turned the sha t about a quarter a revo I S the lution l n the direction m which the engine runs , that , eccentric - ff is advanced or the angular advance I S increased this makes cut o , " S e G . occur earlier , as hown by the table presented in Valv ears If

S on of the the engine had a Single plain lide valve , the variati angular

Diagram Show ing Action o f Straig ht-Line T y p e o f Sh aft G overno r advance woul d produce too great a variation of lead ; but as this

r -off engine has , a sep a ate valve for cut , admission is not altered by

- the cut off valve . The Springs F F balance the centrifugal force of the weights ; the weights AA are varied to suit the speed ; and the tension on

of w c A the springs is altered by means the scre s c . uxiliary springs are added in order to obtain the exactness of regulation necessary for electric lighting . These springs tend to throw the arms outward ,

of but act only during the inner half this movement .

Strai ht- ine T e i 4 w o f . S g L yp . F g 9 Sho s the governor the traight

. B w S . on line engine It has but e ball , hich is linked to the spring STEAM ENGINES 1 5 7

DE and to the plate , on which is the eccentric C. When the ball w F flies outward in the direction indicated by the arro , the eccentric 0 is shifted about the pivot , the links moving in the direction of the H arrow . The ball is heavy and at a considerable distance from

the center , hence it has a great centrifugal force and the spring must

B - be stiff . The governor of the uckeye engine alters the cut off by

w - changing the angular advance , hile the Straight line engine gov ernor changes the travel of the valve . The latter type of valve is

very common .

a F w - i I nerti orm. w R F 5 The ell kno n ites inertia governor , g . 9 , is a form of shaft governor largely used for certain types of engines . This governor regulates the Speed of the engine by Shifting the eccentric , thus changing the valve travel and incre as ing or decreasing the angular

on advance , depending the

Speed conditions . It differs in its operation from the centrif ugal Shaft governor previous l y considered , in that it makes use of the inertia of tw o large weights instead of centrifugal force . To understand this action, it first becomes nec

95 ' “s e f fi a T "° f essary to know something eepsgggzg y p about its construction . The governor consists essentially of a heavy arm A pivoted at

two B E to the flywheel . This arm carries heavy weights at . The D w eccentric is fastened to the arm by three countersunk scre s , as

S w w S w ho n , and moves ith reference to the engine haft henever the F weights B cause the arm A to move about its pivot point . as

w A S tened to the fly heel arm and the governor arm is the pring C, which brings the arm A back to its normal position when the engine

S is not Operating . This pring also has certain other functions to

of perform in the operation the governor . The action of the governor is such that the valve experiences A very much the same movement as in the centrifugal governor . S 1 58 STEAM ENGINES

of A i the engine speeds up , the tendency the heavy arm s to lag behind i the flywheel . Th s lagging action controls the position of the cecen

a i tric SO that the v lve travel is reduced , thus lim ting the amount of steam that enters the cylinders . If , after the engine is operating at

S of a a uniform rate of peed , an increase lo d suddenly occurs , the motion of the engine Shaft and flywheel will be Slightly retarded and “ " n the engine will commence to Slow down . O account of the energy w BB w stored up in the governor arm and the eights , they ill not be

O f w S S quickly a fected , hence the governor ill be moving lightly faster than the Shaft . As a result the eccentric position with reference to

S w t the haft ill be changed , and the valve ravel increased , thus per d mitting more steam to enter the cylin er , increasing the power com mensurate with the added load . If for any reason the engine takes

of a sudden spurt in speed , the tendency the governor is to fall back w so S w w ard , to speak ; and if the engine is suddenly lo ed do n for any

e of w cause , the t ndency the governor is to plunge for ard ; hence the valve travel is Shortened or lengthened according to which action

of takes place . This type governor gives very close regulation when properly constructed .

ERECTION AND O PERATION OF STEAM ENGINES

(The limited scope of this work will not permit of an exhaustive study of these tw o important details— the erection and operation of steam engines ; only the general principles governing each will be pointed out .

ERECT ION

n Foundatio s . When about to erect an engine the first requisite

of w w is the foundation , the character hich ill , of course , depend upon

S l the type and the Size of the engine . It hou d be built according to

ui c on plans submitted by the engine b lders , no changes of material w sequence being made ithout the approval of the builders . It Should be neither connected with nor in close proximity to any sup porting column or columns of the building, as vibrations of the engine will be transmitted to the building which might prove to be disas

S ul trous . The foundation ho d be built upon a solid bottom , but if

t this is not obtainable at the dep h required by the foundation plans , the base of the foundation should be extended in all directions in

1 60 STEAM ENGINES

' order to is placed thereon in insure a proper setting of the cement .

fi S When the concrete has set suf ciently , it hould be inspected to see w that no omissions or errors have been made , after hich the engine may be unpacked and prepared for setting . If the foundation is a

one S on large , an inspector hould be hand at all times to follow the work and see that no errors are made . n in S etting the E g e . Upon the accuracy and thoroughness of

of r the setting the engine , in a large measu e depends its successful

f of operation as to smoothness and e ficiency running . In this proc

to F ess there are a great many things be considered . irst , the base

- . N and sub base must be carefully cleaned and set in position ext ,

S i the crank haft , cylinders, piston , crosshead valves , and other deta ls must be carefully placed in position and alignment made according

to of . the plans the builders As all of these details require skill , an inexperienced person should not attempt the setting up of an engine . w w It is al ays preferable , hen possible , to obtain an experienced man from the engine builders . hm n Installation of Attac e ts . In addition to the erection and setting of the engine proper there are various attachments and aux iliaries S that require care and kill in their proper installation . The steam and exhaust piping as well as the cylinder drainage Should be

f . S care ully attended to The piping hould be of ample size , all bends

S w should be easy , and gate valves hould be used henever possible . m The piping should have a gradual fall fro the boiler to the engine ,

or whi S at near ch hould be placed a separator . f Se arator . S o p The separator hould be approved design , and care must be taken to carefully provide for drainage in order to insur e

of w w the removal the ater , other ise the separator might form a reservoir for water and thus endanger the engine more with its use w than without . In addition to being a safeguard against ater ham mer , when properly attached , the separator also improves the steam

S of economy of the engine , ince it removes the most the entrained moisture which is carried from the boiler through the steam pipes .

Ex a t e h S of h us Pip s . The ex aust pipes hould be ample area to

of take care all exhaust steam , and safeguards should be used to insure no backing up of the condensed exhaust into the cylinders . To this

nd S S o d a o d a s sh uld b e sed e , harp bends h ul be v i ed and gate v lve o u STEAM ‘ ENGINES 1 6 1

if valves are necessary , as by their use the area of the pipe is less

S reduced than by other forms of valves . Check valves hould be avoided whenever possible .

of Cylinder Drains . The cylinder drains should be sufficient area to care for all condensed steam in the cylinders and so attached to the cylinders and the exhaust pipe or receiver that no pockets

of com~ will be formed for the accumulation of water . In the case pound engines the cylinder drains of the high and the l ow pressure

S se ar atel v cylinders hould not be connected together , but p connected

i to the exhaust or other main drain . In condensing eng nes the cyl inder drains Should always go into the exhaust drain if it is l ow enough to admit of proper drainage .

O P ERAT ION

Let us now turn our attention to the operation and manage

of S ment an engine . It hould be borne in mind that many sug gestions as to the proper alignment and adjustment of bearings , the w adjustment of valves , and the consideration given lubrication ill be applicable both to the first setting up of the engine and also to the daily operation afterwards .

C m ete n En in r o p t g ee a Req uisite . The operation of an engine should be committed to a careful , skillful , and reliable man . This is especially true in the case of modern well-equipped plants which t represent quite an ou lay of capital . In many of the smaller plants , w ho ever , not much attention is given to the matter and we find , as l h a resu t, men holding positions as operators w o know very little about their business . Under such conditions the plants are seldom f operated e ficiently . As a suggestion of some of the duties of a man in charge of a w modern plant , hich also suggest the amount of judgment and exp e u w ric ce required , the follo ing general instructions are presented .

Ca e of Bea in Ca s r r g p . The caps on the main bearings Should always have sufficient liners underneath to enable the nuts on the bearing studs to draw the cap down tightly upon them and not pinch

S the haft, which should be free to revolve in its bearings without u nnecessary play . The caps Should be removed occasionally as conditions demand in order to clean out the oil grooves which are chipped in the babbitt 1 62 STEAM ENGINES

w metal , as the passages may become clogged ith dirt or other for i e gn matter .

m f nne in x Adjust e nt o Co ct g Rod Bo . In adjusting the connect

b ox ing rod at the crank pin end , the same general rules Should be observed regarding the liners under the cap— the large nuts drawn solidly upon it , the small nuts firmly jammed and the cotter pins

of placed in position . The adjustment the box Should then be w 12 tested ith a lever about inches in length , the adjustment being so made that w' ith a lever of this length the operator can easily move the end of the connecting rod sufficiently to take up the side play w k bet een the flanges on the cran pin and the end of the box . The adjustment should never be made so close that this side movement can not be observed . The adjustment of the connecting rod box at the crosshead pin Should be made by placing the crank on the center nearest the cyl

w w for ofl inder ; then ith a rench provided that purpose , slack both w w w S edge scre s at the upper and lo er ides of the connecting rod , and draw the wedge up until it is solid against the box ; then slack

ff w of O one scre about a sixth a turn , and draw up the other so as to w firmly lock the edge .

S w Lining Up Crosshead . The crosshead hould be lined up bet een

i whi . W the gu des , le disconnected from the connecting rod hen in this condition the crosshead should be so lined that it can be easily pulled from one end of the guides to the other with a Short lever .

S ul w The crosshead shoul d never be run very close , and ho d al ays be free enough to allow long and continuous runs without heating the guides to the degree that they woul d be uncomfortably warm t o the touch .

When making any adjustments of the crosshead , the operator should assure himself that the lock nut which prevents the piston rod turning in the boss of the crosshead is securely placed .

Adjusting Ecce ntric Strap . The eccentric strap adjustment is made by liners placed between the halves of the strap and double

of nutted bolts . When adjustment is necessary , the other end the wi eccentric rod Should be disconnected and , after dra ng up the strap bolts , it should be tested by giving the strap a half revolution about w the eccentric . If it is found that the friction bet een the strap and

rod t the eccentric is suflicient to support the weight of the , the bol s

1 64 STEAM ENGINES

So id Lubrica t l n s . S everal solid lubricants are used , such as graphite , metalline , soapstone , and fiber graphite Grap hite when mixed with certain oils is well adapted for heavy pressures . It is especially good for heavy pressures and l ow veloci

. w a oil ties Under conditions hich require large amount of cylinder , a small amount of crystal or flake graphite may be used with good

w x results . Care must be exercised , ho ever , if the e haust steam is w i used for feed ater , as the graph te may get into the boilers and cause inconvenience and perhaps serious trouble .

Metalline is a solid compound containing graphite . It is made

of whi to in the form solid cylinders , ch are fitted the holes drilled h . W into the surface of the bearing en a bearing is thus fitted, no other lubricant is necessary . Soap stone in the form of powder and mixed with oil or fat is sometimes used as a lubricant . Soap mixed with graphite or soap-stone is often used where wood is in contact with wood or iron . A preparation called fiber grap hite is used for self-lubricating

of bearings . It is made finely divided graphite mixed with fibers of w w ood . It is pressed in molds and after ards fitted to bearings .

For S w w great pressure at lo speed , graphite , lard , tallo , and other solid lubricants are suitable . If the pressure is great and the

S and peed high , castor , sperm , heavy mineral oils are used .

For l ow n pressure and high speed , olive , sperm , rape , and refi ed petroleum give very satisfactory results .

In ordinary machinery , heavy mineral and vegetable Oils and

of lard oil are good . The relative value various lubricants depends Oil upon the prevailing conditions . that is suitable for one place

not fl ow might freely enough for another .

oil e The quality of is of great importance . In many branch s of industry it is imperative that the machinery run as perfectly as

. On a possible this account and bec use of the high cost of machinery,

oil only first class oil should be used . The cylinder especially Should be high grade , because the valves , piston , and piston rods are the most delicate parts of the engine .

i a d F "ual ties of Goo Lubricant. rom the foregoing brief discus sion of lubricants it will be evident that they must possess certain qualities which may be enumerated as follows : STEAM ENGINES 1 65

w The lubricant must be sufficiently fluid , so that it ill not in

itself make the bearing run hard . It must not be too fluid or it will be squeezed out from between w i the bearing surfaces . If this happens , the bearing ill immed ately w heat and begin to cut . The heating ill tighten the bearing and increase the pressure and the cutting .

It must not gum or dry when exposed to the air .

It must not be easily decomposed by the heat generated . If it w w should be decomposed , it might form substances hich ould be injurious to the bearings .

It must not take fire easily . S It must contain no acid and hould form no acid in decomposing , as acids corrode the bearings . Both mineral and animal oils are used as F w lubricants . ormerly animal oils ere used entirely , but they were likely to decompose at high temperatures and form acids . It is impor “ tant in using high pressure steam to have high " w w test oils , that is , oils hich ill not decompose or volatilize at the temperature of the steam . It was the difficulty of getting such oils which made great trouble when superheated steam was Mi w first used . neral oils ill stand high tempera tures very readily , and even if they do decompose , they form no acids .

ommon Oilers E C . ngines are lubricated by means of oil cups and wipers placed on the Fi 96 . t n g . S a d a r d T y p e ° f Sim pl e 0“C up bearings wherever required . They are made in

F a many forms . ormerly, the oil cup w s made with a tube extend ing through the oil . A piece of lamp wick or worsted leads from

oil the in the cup to the tube . Capillary attraction causes the o il to fl ow w continuously and drip do n the tube . When not in use ,

w S w w the lamp ick hould be ithdra n . This type of oil cup is now seldom used . i S w F . 96 The oil cup ho n in g is simple and economical . The

of il opening the valve is regulated by an adjustable stop . The o ~ w may be seen as it flo s drop by drop . The cylindrical portion is

of h made glass , so that the operator can see ow much oil there is in w the cup ithout opening it . 166 STEAM ENGINES

w Fi 97 . A form of wiper crank pin oiler is sho n in g . The oil

oil cup is attached to a bracket . The drops from the cup into the Sheet of wicking or wire cloth and is removed at each rev olution of the crank pin by means of the cup which is attached to the end of the

connecting rod . This form of oiler works very satisfactorily

at Slow speeds . Fi 98 ntrif a i rs . Ce ug l O le g .

S w Fi W in e r ho s a centrifugal oiling de . 9 o m o f e r an P g 7 . F r ip r C k Oil vice which operates very sat isfactoril S w y at all peeds . The oil flo s from the oil cup through the tube to the small hole in the crank pin by centrifugal force . It reaches the bearing surface by

me h ans of anot er small hole .

er L b r Cylind u ication . In oiling

the valve chest and the cylinder , the lubricant must be introduced

of against the pressure the steam . i w Th s may be done in several ays , in each of which it is introduced into the steam before it reaches the valve chest and is carried by the steam to the surfaces to

be lubricated .

um s T he oil By Oil P p . may be forced into the steam pipe by

or a small hand pump , in large

engines , by an attachment from

the engine itself . The supply of 8 e ntr u a er 9 . C if g l Oil oil of is , course , intermittent if the i pump is dr ven by hand , but continuous and economical if driven

by the engine .

B Si ht-Feed u bricators y g L . The most common device for feed ing oil to the cylinder is that which introduces the oil drop by drop w into the steam hen it is in the steam pipe or steam chest . The oil

1 68 STEAM ENGINES

is o engines run so fast that it impossible to examine the vari us parts ,

for and special means must be provided lubrication . It is especially

S important in high speed engines that there hould be no heating . In order to avoid the danger of neglecting to oil a bearing of a high speed engine , it is customary to have all the bearings oiled from

ll oil on one central source . A the is supplied to e reservoir, from

w . oil hich pipes lead to all bearings If this is not done , large cups are used , as a rule , so that oiling need not be attended to as frequently . In some high speed engines the moving parts are enclosed and

f oil the crank runs in a bath o . This secures certain oiling and is l f . A l very e fective the bearings may be inside this crank case , so that all are oiled in this way . It is thus impossible for a careless

one w operator to overlook point and so endanger the hole engine .

ar in the En ine . B St t g g efore starting an engine , the oil cups w w Should be started feeding , grease cups scre ed do n , and the gov e rnor and other parts of the valve gear oiled . The cylinder l ub ri cator Should be started before the engine so that the oil passages

S will contain oil . The cylinder drain cocks hould be open so that any condensed steam in the cylinder will b e removed without injury to the cylinder . These precautions having been observed , the throttle may be opened slowly and the engine started and gradually brought to the required speed .

S of After starting the engine , notice hould be taken the governor and all the lubricating apparatus to see that each is properly per forming its function .

When the engine is to operate condensing , the condenser Should w be started first , if it is in such a position that the ater in the exhaust can drain into it . If the condenser is above the engine and

for w no means are provided removing the ater , the engine should be

- non . started condensing When a jet condenser is used , the quan tity of injection water Should be increased as the load is increased ; the amount being determined by the conditions of the vacuum and ° of w w S 100 temperature the discharge ater , hich hould be from to ° F w w d 1 10 . If the ater is colder than this , it ould enote that more injected water is being used than is required . The foregoing suggestions and indicated precautions are only a few of the more important things that will arise in the course of the

of erection , setting , and operation an engine . The one performing STEAM ENGINES 1 69 these various duties must at all times exercise good judgment and act according to what his past experiences and that o f others have taught under Similar circumstances .

ENGINE S PECIFICATIONS

n who Se lec ting an Engi e . The engineer has the responsibility of selecting an engine for a given class of service has no small task to perform , if he carefully analyzes all the factors entering into the problem . If the installation contemplated is to be an extensive or

S . S expensive one , expert advice hould be solicited ince this is not

w few w how al ays to be had , a suggestions ill be given as to best to

n proceed when o e has to specify an engine for a given service . Con sider for the time being that an expert consulting engineer is not avail

or non- ni who able and a rather inexperienced person , tech cal man , knows little about the theoretical questions that Should be given consideration , has to select the engine . In this case the most satis factory procedure to follow would be to go to some reliable engine builder and ask him to build or specify an engine that would per

H one form the service required . aving only builder intrusted , the item of expense would not be chief in his consideration since there w ould be no competition , therefore the builder would build or specify

for the best engine possible the service . If the funds available

or are limited must be closely conserved , the intended purchaser may state the limits of cost and then require the builder to come within

of those limits . It would also be wise on the part the purchaser to require a guarantee as to the performance of the engine and its maintenance cost for a given period of one year or more .

D awin U e ifi r g p Sp c cations . If the purchaser is a competent

or of engineer he has in his employ such a person , a complete set S pecifications may be drawn up and submitted to several engine

fi S builders for competitive bids . The speci cations submitted hould

for cover in detail the service which the engine is to be used , the

w O of speed at hich it is to perate , the type valves and valve gear

of its desired , the per cent variation permissible in governing , and M many other items as to the design and detail of construction . ost w specifications also specify ithin what limits the engine must operate , w as to the amount of steam used per indicated horsepo er per hour ,

ro and the range of mechanical efficiency that must be attained . A p 1 70 STEAM ENGINES vision should be made in the contract as to the conditions under which the acceptance test will be made and by whom . The form of specification usually submitted by the builders and which in general will be like those written by an engineer when

w . requesting bids , is submitted here ith This may be taken as a typical specification , the items being changed to meet different con ditions of service as the particular case demands .

PE CI FI CA T I ONS OF A E R T I CA L CROSS - OM P O D S I DE S V C UN ,

E E D - E C A K GI E A RA G FO 1 000 K . DI T R N N N R N R W . R C , , O E T E D E E A T 6 Y LE A L T E A T C NN C G N R OR , 0 C C RN OR

S Z P W R D S S I E , O E , AND IMEN ION D ame e of essu e n e 2 n e i t r high pr r cyli d r , 7 i ch s .

D ame e f l o e ss n 4 o w u e e n es . i t r pr r cyli d r , 5 i ch o 42 n e es . Str k , i ch m n e o u ons er u e 120. R v l ti p i t ,

I n a s e am e ssu e 125 oun s 26 n es v a uum on ens n iti l t pr r , p d , i ch c , c d i g . R a e o a in n a e o se o w e c ut- off t d l d i dic t d h r p r , ,

At cut- off n a e o se ow e m a mum cut- off , i dic t d h r p r , xi ,

Es m a e o a w e of en n e o un s ti t d t t l ight gi , p d .

u D am e e 1 f e . F e We of w e e o n s . 6 e a n ight h l , p d i t r , t c , i ch es .

D m e e of e a n s 19 n es Len n es a 3 5 . i t r b ri g , i ch . gth , i ch

D f af e n am e o s w e e e a n s 22 n es . i et r h t b t b ri g , i ch D f n in n me e a n es Le t n e . a o 9 . 8 s i t r cr k p , i ch g h , i ch D s a n n me e of os e in n e s . Le 8 es a 8 . i t r cr h d p , i ch gth , i ch f e f s 1 n e B e a n su a o o s e a n es 20 s . ri g r c cr h d , 7 i ch by i ch

D am f s on r n es e e o od 5 . i t r pi t , i ch

D am e e f o a e 12 n es i t r o thr ttle v lv , i ch .

D am f n 22 n s e e o e aus en e . i t r xh t Op i g , i ch

WO R K MANS H I P AND M AT E R IALS T he w o m an s n s n an d ma e a s w b e fir st- ass in e e rk hip , fi i h , fitti g , t ri l ill cl v ry a u a All fo n s w b e of o en - e a s ee or amm e e on as p rtic l r . rgi g ill p h rth t l h r d ir ,

f fi a su a n s e e a e S e e . All as n s su e to w e s e u es h r t r p ci d c ti g bj ct r , ch cyli d r , g id ,

tc f o n n a oa n a s ons e . w b e ou e o m m u e s n a o e pi t , , ill p r d r ixt r c t i i g ch rc l ir , gr d d a cco rding to the Siz e of castin g in order to se c ure the pro pe r h ardn e ss an d osenes f a n cl s o gr i . T n n n a e T s fea u e he e gine will b e made to gauge and i t e rch a ge bl . hi t r

w u a ill b e th oro ghly c rri e d ou t .

F a su fa es b e s a to su fa e a e s an d su fa e an d c lindri l t r c will cr p ed r c pl t , r c y c al n n an a ous gri di g w ill b e u se d w here adv t ge .

GUAR ANT EE We gu aran te e the w o rkm anship an d m at eri als in the en gine to b e first class an d in fulfillmen t of o ur gu ar an t e e w e will giv e a d uplicat e to take the a e of an a a m a o e efe e in m a e a w o mans or pl c y p rt th t y pr v d ctiv t ri l , rk hip ,

design within one y e ar after the en gin e is st arte d .

1 72 STEAM ENGINES

T he a e ea is os e om ose of S m e e e s and n s an d th v lv g r p itiv , c p d i pl l v r li k , e c u t- off c an a e a e at an o n e w e en e o and the m a mum cut-off t k pl c y p i t b t z r xi .

T he cut- off e e at oa s o u s w en the m a n an d c ut- off a , xc pt light l d , cc r h i v lves n in s e e on s and the cut-o ff is as s a ar e mo vi g o pp o it dir cti , h rp as with a r el eas f e a no w s an n the S o s o u se ing typ e o v alv e g r t ith t di g h rt tr ke d . T he cu t- off is v arie d simu lt an eously upon all the cylin d ers in su ch a man

ner a the w o o ne in e a is a o m a e e u a as is a so th o th t rk d ch ppr xi t ly q l , l e dr p T s a s to s m oo u n n n in temp eratu re of st e am in e a ch . hi dd th r i g and gives on of s e am for e onom at all cut- off s u n e a a b es t dis tributi t c y d r v ri ble loa ds . T he v alv e gear w ill b e constru cte d in the m ost su b st an ti al an d durable

nn n d in su a w a as to e ua e the c ut-off at o en s of the c lin ma er, a ch y q liz b th d y - ff R o - S af s ns an d n s w b e m a f r all cu t o s . e of n ders o ck h t , pi , li k ill d o p e o nn e n n s w b e fi e w on e en s a n h e arth steel . C cti g li k ill tt d ith br z d h vi g qu ick n T he e en s a s w b e n e w t ap e r k ey adj u stm e t . cc tric tr p ill li d ith babbitt T - a n h ammere d in an d bore d o ut . he ro ck s h aft be ri g will b e b abbitt e d

an d adj ustable . GO V E R NO R S e S u a e on the ma n s af of the en n T he go v ern or w ill b it t d i h t gi e . A ch an ge in p osition of the c en trifu gal w eights r e vo lv es the e cc en tric co n tro lling the p osition an d mo ti on of the cu t- off valves aroun d the Sh aft an d varies the

- p oint of c ut o ff . All the b e arin g pins in the go v ernor will b e made of to o l ste el h arden e d

u n n in e a n s u s e w os o on n oun e . T h n a d gr d , t r i g b ri g b h d ith ph ph r br z e c e trifugal fo rc e of e a ch go v ern o r w eigh t is r esist e d by a pl ate Spring thro ugh in a n a en e s e e o n s es n in os ho on e u s n t a p h vi g h rd d t l p i t r ti g ph p r br z c p , o e a the end of the spring an d the o th er at the c en t er of gravity of the go v ernor T he en fu a fo e of the o e no w e s is us o o s e in w eigh t. c tri g l rc g v r r ight th pp d a dire ct an d fricti o nl e ss m ann er w ithou t c au sing pressure or fricti on o n the n T pins up on which the go v ern or w eights swi g . his go v erno r will re gu late the Sp ee d of the en gin e with a clos en ess an d cert ain ty imp ossible with a

- o e n o an d its a on is u n affe e w e and su en fl u fl y b all g v r r , cti ct d by id dd ctua T he o e no w o n o o cut- off e en s tions of l o a d . g v r r ill c tr l b th cc tric .

P S T S P S T R S ST F F G B S I ON , I ON OD , AND U IN OXE T he s on s w b e o e out an d o e w n e n a n mak pi t ill c r d pr vid d ith i t r l ribbi g , n T e w b ing the m very light an d s tro g . h y ill e se cu re d to the pis ton r o d by n fo e u on a a e w S ou e e on an d a nut w a S m e b ei g rc d p t p r , ith h ld r b y d , by , ith i pl e e T he s ons w b e o - b ut e fficien t lo cking d vic . pi t ill pr vide d with cast iron s p ackin g ring . T he piston ro ds w ill b e of o pen-hearth s teel ru nn in g throu gh dee p stuff T he o s n t u — in g b o xes an d b abbitt e d gl an ds . r d will o to ch the h ea ds which will b e bo re d large — bron z e rings fitting the rods in the bo tt om of e a ch

ffin b ox an d e en n es a e of a n to the n e o of the n stu g pr v ti g c p p cki g i t ri r cyli der . on e f s L ow pressure pist will b o t eel . FR AMIN G ns s for e a n e f a ee T his w ill co i t , ch cyli d r , o d p and massive b ase con t ain s On the a of e ing the main b earing . b ck ach b ase will st an d a ve ry h eavy n u a o u mn as S own in the u e n se u e re ct a g l r c l , h bl pri t , c r ly bo lte d to a h e avy I n f on the f am e ea s w frame he ad . r t r h d ill b e conn e cted to the b ases by

e s mns o te an es o e w u T he forg d teel colu b l d by fl g f rg d solid ith the col mn s . STEAM ENGINES 1 73

rear c ol umn w ill supp or t the cylind ers w he n the fo rge d c olumns in fron t a ar e re mo ve d fa cilitatin the pl acin o f Shaft an d o the r p rts . , g g

U S R S S H S C R S S H P S G IDE , C O EAD , AND O EAD IN T he gu ides will b e se p arate fro m the fram e an d adj us table for w e ar with o e e w a n ass f n e u on the an o il dish at the b o tto m which , t g th r ith thi br ri g p

- f he ss e a fo ms an e ffi en s e f o n e e . bo tto m o t cro h d , r ci t l ili g d vic T he crossh e ads will b e o f o p e n-he arth s tee l fitt e d with b abbitted cas t

n S es ir o ho . T he crossh ea d pins w ill b e of o p en-he arth s teel fl att en ed on two sides to

a pre ven t w e aring o v l . CONNE CT IN G R OD S AND B OXE S n r d of fo e s e e o e w ib an d k e T he co nn e cti g o will b e rg d t l , pr vid d ith g y

T s a s w b e o e w n n o s w w e en en ds . he tr p ill pr vid d ith pi chi g b lt hich ill pr v t

S a n B o an an d oss ea in o es w b e ne w a pre di g . th cr k cr h d p b x ill li d ith b bbitt

h amm er e d in and b o re d o ut . T he b o dy o f the co nn e ctin g r od w ill b e m a de o f l arge r s e cti o n th an the

o r o d e n es n e o e for the a e s a n d ue to its en pis t n , b i g d ig d pr p rly dd d tr i l gth

an d an gul ar mo ti on . SH F T R K PI N D S K A , C AN , AND I f an d a e amm e n fo n T he s h a t w ill b e pile d f gg o t d h e r d iro rgi g . T he an s w b e m a e w o u n e a an e o f a m u e on a n cr k di k ill d ith c t rb l c , ixt r c t i T n in w b e m a e o f f e s e T S aft he a o e . he ing charc o al iron . cr k p ill d rg d t l h an d cran k p in w ill b e fo rc e d i nto the disk by hydraulic press ure an d the disk

will also b e key e d s e cu rely to the S h aft . M AIN BEAR IN GS AND R EMOV A B LE SH ELLS T h a e a n s e n a S e s ne e m in b ri g will b e fitt d with cyli dric l h ll , li d with b abbitt ,

amme e in a n d o e ut T es e S e s c an e as b e a en o u t em o v h r d b r d o . h h ll ily t k by r ing the c ap an d simply j a ckin g up the S h aft su ffici ently to t ak e the w e ight off the e a n s w en e c an b e e o e a oun the S af an d a en out b ri g , h th y r v lv d r d h t t k w u s tu n an o a f t n n T he S e s ar e m a e l itho t di rbi g y th er p rts o he e gi e . h ll d ho

f r u a o n T i l o w o w a e . s s not n en e to b e u se o na b ut t r circ l ti hi i t d d d rdi rily , in ase or o e u nu sua on ons S o u ause the e a n to ea c dirt th r l c diti h ld c b ri g h t , it of en en a es the e n ne to o m e e its r un w o u s o n t bl gi c pl t ith t t ppi g . T he main b e arin gs w ill b e pro vided with a se lf- o iling de vic e which will ee e m oo e w il k p th fl d d ith o . OI L FEED S Y S T EM T he fe e w b e os e and a us a e an d the s s em w b e ose d ill p itiv dj t bl y t ill cl d , so a e e w b e e w as e and e e o a n f l n s at th n s th t th r ill littl t d t ri r tio o o i . R i g e e d o f the b e arings w ill thro w off es c apin g oil i n to cl ose-fitting Shi elds with su it

a e a n es ea n to a a e s e n es e o en a m bl dr i pip l di g l rg ttli g r rv ir b e th . A s all p ump driven fro m the v alve ge ar w ill d elive r the oil to a fe e d t ank at e a ch b ear n T n i g . his ta k will b e pro vide d w ith an adj us table fee d o u tle t pipe leadi ng to the e a n s and w a a u e - ass and b - ass o e ow and c n b ri g , ith g g gl y p v rfl , a b e filled by h an d and use d as an o rdinary oil cup if it is d esire d to c ut o ff the au o ma su w e the en ne is run n t tic pply hil gi ni g . FL Y W H EEL T he wh eel will b e cas t in h alves an d will b e b olted to ge th er at the hub w eame o s a e fu e in o es f m th an th ith r d b lt c r lly fitt d h l drilled ro e so lid , d e a ts Wi b e an er e o n p r ll p l ed Wh e th y j i , Steel arrow head links will b e used 1 74 STEAM ENGINES

T he w ee w b e a efu es ne rou ou in or e at the rim . h l ill c r lly d ig d th gh t d r to

e f f s afe an d o e es an d fa e f rim hav e a l arg actor o ty , b th dg c o will b e turn e d

tru e . PL AT F OR MS Platfo rm s convenien t for h an dling an d o p e rating the engin e will b e p r o n in n t T es e c an b e a an e t s u he v ided as S how pri . h rr g d o it t lo c ati on of the

ff t a a n T he an f a n en gin e an d will b e m ade s ti o void vibr tio . h d ili gs w ill b e m u n fi e n ass a s or on os s T h s e a ess ass o . e a f of l br t bi g , tt d i t br c p ir p t pl t orm

e am on fi u e an e w e e e o n o e e an n plat es will b di d g r d , pl d h r th y j i t g th r d e atly ma e f anne on w eas - n S a s w b e o o am n a s . fitte d . t ir ill d ch l ir , ith t ir di o d thre d FIXT U R E S T he foll owing fixt ures will b e pro vide d : thro ttl e v alve ; indic at o r mo ti on ; co mple t e ou tfit of s ight-fee d cylin d er lubric ato rs ; glass bo dy oil pu mp s ; gre as e c ups for v alve g e ar ; cen trifu gal cran k p in o ilers ; rese rvo irs with Sight fe e d ou tl et s ; o il pip es and wip e rs for o ilin g the m ain p arts of the e n gin e con v en ientl y an d co ntinu o usly ; re lief valves for e a ch en d of the cylin ders ; drip d f un a n s w en es foun a on o s an o o ans . co ck ; r ch , d ti b lt ; d ti pl A Contract. fter the engine has been selected and the builders w determined , a ritten contract should be entered into in order to B make it a legal document . A contract , according to lackstone , is an agreement upon sufficient consideration to do or not to do a par f i l ar h . o t cu t ing In the case of the purchasing an engine , the builder agrees to build , erect , and put into operation an engine in accord w ance with the specifications and drawings submitted , hich items become a legal portion of the contract . The purchaser may also require that the engine be ready for operation in a given time and that it must also come up to certain requirements in its performance ,

of as previously mentioned . In consideration the foregoing , the

of purchaser agrees to pay the builders a specified sum money , either w in one payment or more as determined by them . The ording and statement of the contract should be carefully prepared , in order to

of avoid any possible misinterpretation any of its provisions .

COST OF ENGINES AND OF T H EIR OPERATION

The question of the cost of an engine and of its erection and operation is indeed a very vital one . This cost can not be classified

S in a brief way , ince there are so many contributing factors that differ

' ifl n For w - defined w d ere t . idely in localities example , no ell indica

of of of tion the cost Operation can be given , and the cost labor and material are fluctuating items of expense ; therefore , the cost of the engine can not be stated definitely , since in a brief interval of M time it may be considerably more or less . any articles appear

176 STEAM ENGINES

T ABLE V

Cos t o f I ns ta l l a tio n a nd Op e r a tio n f o r One Y e ar

K i nd of E ng ine

Simple Slide alve N on - c on V o 75 $4 03 $23 5 5 d ensing T Co mpoun d Sl I de Valve 1\ on 1 4 3 8 3 0 50 2 1 45 ‘ condensmg Co mp Ound Slide Valve Condens ing Simpl e Co rliss N on-con densin g Co mp oun d Co rliss Con den sin g T riple Co rliss Con densing

on on interest real estate ; interest investment ; maintenance , etc . , w of equipment ; fuel ; ater ; supplies ; and attendance . The relative value of these various items for a large central sta

was En ineerin M a az ine Ma tion lighting plant given in the g g g , y, of 100 1905 . Taking the total cost maintaining the station as per

w w of : cent, the follo ing ere the average costs the various items Fuel wages water oil and waste rent station repairs steam repairs electric repairs

Annual Operation Expe nse s . Professor Carpenter in the Economist summarizes the cost of installation and the operation of

n of an entire plant for o e year hours as given in Table V . A coal consumption of pounds per boiler horsepower per hour is assumed and the cost given per engine horsepower is for a horse

power engine . An illustration involvingthe items given in Table V will serve

S S - to make it clearer . The case of a imple lide valve non condensing

plant will be considered .

Co st of en gin es an d b o ilers at p er

n es at er h . Annu al cos t of de pre ci ation an d i ter t p p . An nu al cost of co al at p er ton = 6750>< 2 An nu al cos t of lubrican t s at p er Annual cost of lab or at p er horsepow er

Annual cost for the l as t four items or p er h . p . STEAM ENGINES 1 77

The foregoing tables will serve to give some idea of the cost of

s of i o f it engines , al o of the cost operat on a steam plant , but must be remembered that the figures given w ill not be exact for all localities

or . for all times , due to the changing influences previously mentioned

ENGINE TESTS

m an e f w as w the I port c o Te sts . It mentioned in connection ith discussion of specifications and contracts that often a guarantee is given by the builder as to the economical performance of a steam

ascer engine , hence it is required that the engine be tested in order to f W tain whether or not it meets the provisions o the guarantee . hile this is one reason that may be assigned for testing an engine , yet there are several others of importance . The user from time to time may want to ascertain the condition of the engine as a whole and

Fo r o f . also the condition particular features such as the valves , etc purely theoretical reasons an engine is often tested in order that an analytical study may be made of its performance under various f i conditions and in compa rison with other engines o d fferent classes . M w any such tests have resulted in obtaining data , the facts of hich have demonstrated to both the builder and the user possible e c ono B mies . ecause of the information thus obtained , the builder has been enabled to design a better engine , and the user to operate his w ffi engine more advantageously . The remarks given ill su ce to indicate that the ultimate object of an engine test is the determina tion of the economy with which the engine produces a given amount

f w r o o e . p In steam engines the economy , as usually ascertained ,

w of i relates to the eight steam consumed , to the quant ty of coal required to make the steam , or to the number of heat units supplied . The elementary quantities concerned are accordingly tw o in num .

or ber , viz , the amount of steam , fuel , heat (as the case may be) f o w . H ow consumed , and the amount po er developed to determine these quantities is the problem .

. . M . . d of M A S E Co e . The American Society echanical Engineers deemed the testing o f engines according to some definite and standard method of such importance that a com mittee w as appointed to devise a standard code . This , after much

w as . labor and diligent study , presented to the Society and adopted V 24 713 The full report appears in olume page , of the Trans 1 78 STEAM ENGINES

actions . This code indicates the method of obtaining the required

of data and also g ives a recommended form report . In so far as the w d w conditions ill permit, this co e should be follo ed . The several items of the code are summarized as follows

MET H OD OF CONDU CT I NG ST EAM EN GI N E TE ST S — CODE OF 1902

1 b t t ( ) O jec of Tes . Ascertain at the outset the specific object of w of the test, hether it is to determine the fulfillment a contract to guarantee , ascertain the highest economy obtainable , to ascertain ff the performance under special conditions , to determine the e ect of n changes in the conditio s , or to find the p erformance of the entire boiler and engine plant , and prepare for th e test accordingly . N0 specific rules can be given for the preparations for the test as conditions surrounding each test will req uire a more or less differ w on e . one ent solution , hich must be solved by the in charge The particular thing to be emphasized at all times is , that in order to r w obtain data that is absolutely reliable for the pu pose in vie , the c m a one in harge ust be vigilant , conscientious , and , bove all , honest .

2 n ra it E ( ) Ge e l Cond ion of the Plant. xamine the engine and the entire plant concerned in the test ; note its general condition and

of or w on any points design , construction , operation hich bear the

M of objects in view . ake a special examination the valve and pis tons for leakage by applying the working pressure w ith the engine

of w at rest and observe the quantity steam , if any, blo ing through per hour .

of f If the test is for the purpose ascertaining the highest e ficiency,

an - the valves d pistons must be made steam and water tight . To test the valves and piston block the flywheel so the piston

w of r . ill be near one end the stroke , and tu n on the steam The leak age will escape to the exhaust port and will be observable . Another approximate method is to block the en gine as before and having an i ind cator on the cylinder , observe the drop in pressure after an inter of w w val time . In a tight engine the fall of pressure ill be slo , s on l O of wherea in a leaky e it wil be fast . ther methods determining the amount of leakage may suggest themselves to the engineer in charge of the test .

3 Dimens ions tc or of e . M ( ) , easure check the dimensions the

w . cylinders in every case , this being done hen they are hot If they M w . are much orn , the average diameter Should be determined eas w ure also the clearance , hich should b e done , if possible , as described

1 80 STEAM ENGINES

to of and it become thoroughly heated in all its parts , in the mean time all of the measuring apparatus should be properly adjusted . H i a t aving made the prel minary arrangements mentioned , a given i w Signal the he ght of ater in the gauge glasses of boilers is observed , the depth of water in the reservoir from which the feed water is supplied is noted , the exact time of day is observed , and the test is

the m held to commence . Thereafter measurements deter ined upon for the test are begun and carried forward until its close . It is con v enient or to begin the test at some even hour minute , but the impor tant thing is to begin the test when accurate readings can be obtained i irrespective of the t me . When the time for closing the test arrives , the water in the glasses Should be brought to the same height as it was not at the beginning ; if this is possible , corrections must be made in the report . l (9) I I eas u rements of H eat Units Consumed by the Engine . The measurement of the heat consumed requires the measurement of all w i w the ater supplied to the bo ler , by hatever means ; the tempera ture of the w ater supplied from each source ; together with the pres w to sure and quality of the steam , hich are be taken at some point of near the throttle valve . The quantity steam used by the steam calorimeter must also be accounted for .

~ The heat to be determined is that used by the entire engine equipment , embracing the cylinders and all auxiliary cylinders and mechanisms concerned in the Operation of the engine , including air pumps , feed pumps , reheaters , etc .

10 Measu rement o Feed Water or Steam onsum tion o ( ) f , C p f En ine etc . of g , The method determining the steam consumption applicable to all plants is to measure all the feed w ater supplied to the boilers and deduct therefrom the water discharged by separa w w tors and drips , as also the ater and steam hich escapes on account of leakage of the boiler and its pipe connections and leakage of the main and branches connecting the boiler and engine . In plants where the engine exhausts into a surface condenser the steam con sumption can be measured by determining the quantity of w ater of discharged by the air pump , corrected for any leakage the con denser and adding this to the steam used by jackets , reheaters , and i i aux liaries as determined ndependently . In measuring the water it is best to carry it through a tank or tanks resting upon platform weighing scales suitably arranged for w w the purpose , the ater being after ards emptied into a reservoir w beneath , from hich the pump is supplied . STEAM ENGINES 1 8 1

s (1 1) Measuremen t of Steam Used by Au xiliarie . Although the steam used by the auxiliaries was measured as mentioned in item yet it is very desirable to ascertain the steam consumption of each of n auxiliary independently , in order that a close analysis the engi e S performance can be made . everal means may be employed for

m x i i determining the stea consumption of the various au il ar es , and Since they will be apparent to the operator no dis cussion of them w s ill be given , but they are only mentioned in order to empha ize the desirability of obtaining such data .

Meas ure ent (12) Coal m . In commercial tests of the combined

' or engine and boiler equipment , those made under ordinary cond

of tions commercial service , the test should extend over the entire

w - period of the day , that is , t enty four hours , or a number of days C S b e f . o that duration onsequently , the coal consumption hould n determined for the e tire time . If the engine runs but a part of the fire time and during the remaining portions the is banked , the meas w urement of coal Should include that used for banking . It is ell , w a ho ever , in such c ses to determine separately the amount consumed during the time the engine is in operation and that consumed dur w ing the period hile the fires are banked , so as to have complete

rec au data for purposes of analysis and comparison , using suitable p tions to obtain reliable measurements . The measurement of coal w fi begins ith the rst firing , after cleaning the furnaces and burning w of w do n at the beginning the test , and ends ith the last firing , at the expiration of the allotted time . w w In connection ith coal measu rements , hatever the class of tests , it is important to ascertain the percentage of moisture in the c w of a roxi oal , the eight ashes and refuse, and , where possible , the pp

Fo r mate and ultimate analysis of the coal . ( discussion of this item

2 M . . f o l 2 4 o f . . E o V . P . 3 S coal the student is referred to , , the A

Transactions . )

1 I ndicated H orse ower w S ( 3 ) p . The indicated horsepo er hould be determined from the average mean effective pressure of diagrams o f w taken at intervals t enty minutes , and at more frequent intervals if the nature of the test makes this necessary for each end of each cylinder . The indicator diagrams Should be taken at regular intervals but not necessarily simultaneously at the two ends of the cylinder . d If the diagrams vary so much as not to give fair results , the iagrams t Shou ld be aken more frequently . of The method attaching , operating , and adjusting the indicator 1 82 STEAM ENGINES and also the method to follow in obtaining the mean effective pres “ " sure are described in Steam Engine Indicators .

1 15 T estin I ndicator S rin s and Brake H ors e ower ( 4) and ( ) g p g p . These items are fully discussed and explained in “Steam Engine " Indicators . 1 6 ualit o Steam. ( ) " y f When ordinary saturated steam is used , its quality Should be obtained by the use of a throttling calorimeter attached to the main steam pipe near the throttle valve . When the

S steam is superheated , the amount of superheating hould be found by the use of a thermometer placed in a mercury well Inserted in the pipe . 1 ( 7) Sp eed. There are several means for obtaining the num ber of revolutions the engine makes per minute . They may be of counted during one minute or some other division time , a tach ometer may be used , but the most reliable results are obtained by was using a revolution counter , such as illustrated and described in “ "

S E . team ngine Indicators In using the counter , the total reading

Should be taken each time the general test data is recorded . These revolutions per minute corresponding to the difference in reading of w the instrument can then be computed , kno ing the time interval .

din ata w (18) Recor g D . Take note of every event connected ith of the progress the trial , whether it seems at the time to be impor R of tant or unimportant . ecord the time every event , and time of O the w . taking every eight , and every observation bserve pressures ,

w or u w S . temperat res , ater heights , peeds , etc , every t enty thirty w minutes hen the conditions are practically uniform , and at much O w more frequent intervals if the conditions vary . bservations hich concern the feed water measurements Should be made with special care at the expiration of each hour of the trial , so as to divide the tests into hourly periods and Show the uniformity of the conditions w and tests as the test goes forward . Where the ater discharged w from the surface condenser is eighed , it may be advisable to divide n the test by these means into periods of less than o e hour . The data and observations of the test should be kept on properly prepared blanks or in notebooks containing columns suitably arranged for a clear record . 1 if ( 9) Un ormity of Conditions . In a test having for an object the determination of the maximum economy obtainable from an w w engine , or here it is desired to ascertain ith special accuracy the

f o f e fect predetermined conditions of Operation , it is important that all the conditions under which the engine is operated Should be main

184 STEAM ENGINES

w taken and reported upon . This report ill serve to give the order and manner in which data should be tabulated and also the method in which the report should be worked up .

DET ER M I NAT I ON OF EFFICI ENCY OF A B UCK EY E ENG I NE UNDER DI FFER ENT LOADS

P u r p o s e

T he pu rpose of this se rie s of te s ts o n the B u cke ye e n gin e lo cate d in the En gin ee rin g Lab o rato ry of Purdue Un ive rsity w as to d e termin e the b e s t e ffi en un e Six ff e en oa s an n f o m e o to oa 4 lo ad ci cy d r di r t l d , r gi g r z r l d , by s e s the en ne u nn n n on- on e ns n an d u s n 160 oun s of s e am es t p , gi r i g c d i g i g p d t pr u e a so u e s r , b l t .

Pl a n

T he e o oa w as e m n 00 emov e e e w the n a e I Fi . 1 z r l d d t r i d ith frictio br k , g , r d

nd the en ne unn n f T he fu oa w as e e m ne the a e o a a gi r i g ree . ll l d d t r i d by br k l d

Fi . 100 B uc e e n ne te o n a e and I n c ato s g . k y E g i Fit d with Pr y Br k di r

’ w the en n e a e w 25 er en cut-o ff s e n the u e s a n hich gi c rri d ith p c t , thi b i g b ild r r ti g r f en n e T he 1 n d 1 - o a s e a en as fo e o . a w e this typ gi 4, , 1 l d r t k s f the f a nd e e e o u o . a r p ctiv ly , ll l d Steam pressu re w as m ain t ain e d c ons t an t at the pressure in dic at e d fo r the es Ea es w as of o ne ou u a on the en n e a n e en r un t t . ch t t h r d r ti , gi h vi g b un de r c on diti on s of the t est a l en gth of time s uffici en t to p e rmit the condi

t o e ons an tions o b e c m c t t . STEAM ENGINES 1 85

Me thod o f Co nd uc ting T e s t

Constant steam pressure was obtaine d by thro ttling the 5 -in ch ste am f n a e T s n line leadin g to the e ngin e by m ean s o the pipe li e v lv . hi thro ttli g n t aus e the s e am to e o me s u e ea e action was n o t s u ffici e t o c t b c p rh t d . T he re volutions p er minute w e re obtain e d by means of a revolution coun ter . a a ms e e a en e e fiv e m nu es 13 s e s of a a ms I n dicato r di gr w r t k v ry i t , t di gr ’ S un b eI ng o bt ain e d for e a ch ho ur r . n 1 m nu e s B aro m e te r re adings w ere t ak e e very 5 i t . T he amo un t of w ater was d e te rmined by conde nsing theexh aust steam e ess e at atmosph ric pr ur .

P r e li mina r y W o r k

B efore commencing the work the en gine w as plac ed in as goo d condition a oss e T he o e no was a us e in o e to e u e o n a as w s p ibl . g v r r dj t d rd r r d c fricti ; pl y was t ak en u p in the v alve gear and the v alves w ere carefully se t to give e qu al cut-off o n bo th en ds at full lo ad ; all s tuffin g b ox es were re p a cke d ; the brake e w as u n e u and a e r e a a e whe l t r d p br k c libr t d . -2 T he pressure in the en gin e s upply line w as obt aine d by tapping a i-in ch

th m a n a u f e f o m th a - a c on e n o e o 3 e e e . T s n e s pip i t i , b t t r v lv hi i i ch pip w c d t a a s e a au f the a f th n a n e te o l rge t m g ge which ac ed o p er to r o e throttli g v lve , thus en ablin g him to watch the gau ge all the time and maintain a const an t ress u e p r .

Ob s e rv e d Da ta

I n ea ch tes t the follo wing o bs ervatio ns were taken S eam essu e ons an ou ou t pr r , c t t thr gh t Brake lo ad R evo lutions p er minute Weight of con d ense d s te am B aro me ter I ndic ato r diagrams

R e s ul ts

H aving the abo ve dat a it b e co mes p ossible to c alculate the follow in g 1 P r en of c u - ff ea end an d an end e t o . ( ) c t , h d cr k 2 ean ffe e essu e e a e n d an d an end ( ) M e ctiv pr r h d cr k . I n a e o s e owe ea end an d ank end n d o a (3 ) dic t d h r p r , h d cr a t t l . (4) Brake horse po we r (5 ) Fricti on horsepo w er

6 M e an a e ffi en ( ) ch ic l ci cy .

7 Po un s s e am er n a e o se o wer er o r and er rak e o se ( ) d t , p i dic t d h r p p h u p b h r owe er ou p r p h r .

8 B s T e ma n s er our er n a e o se o wer nd r a e o se ( ) riti h h r l U it p h , p i dic t d h r p a b k h r owe er ou p r p h r .

9 T e ma e ff en ( ) h r l ici cy .

Constants and For T he ons an f n n nd o mu as mulas . c t ts o the e gi e a f r l e m o e in o a n n the a u a e e ms in th of esu s are as pl y d bt i i g c lc l t d it e s ummary r lt , follows 186 STEAM ENGINES

188 STEAM ENGINES

T ABLE V I

Indic ator Diag ram Da ta f or Buc k e y e Eng ine T e st STEAM ENGINES 1 89

T ABLE V II

Indic ator Diag ra m Da ta for B uc k e y e Eng ine T e s t 190 STEAM ENGINES

T ABLE V I II

PER F O R M A NC E OF

’ - FF UNDER DI F F ERENT C U T O S . S U MMA RY

L GA D

M"L OA D

14 L OAD

Fi 4 I nd ca or D a rams T ak en Du n T est of Buck e e n ne g. 7 . i t i g ri g y E gi

192 STEAM ENGINES

Cooling w ater for the brake e nters throu gh a h ose no t sh own in the illus trati n T he e on of o . dir cti rotation of the br ake w he e l I S I n dica te d by the D B n f t a ow ne a . mea s o he an w ee E the a e o a rr r y h d h l , br k l d is applie d an d

e u a e . T he a e was a efu a a e efo e e nn n the e r g l t d br k c r lly c libr t d b r b gi i g t st .

Calibration of Consta nts

E . s n s m H . o a e en 4 1 cu f pi t di pl c t . t .

E . s on s m n C . a e e . 3 96 cu pi t di pl c t . ft .

E ea an e H . . cl r c

E . ea an e C . cl r c

n n 1 E . . . . o s a 00 H . i h p C t t 787

1 5 5

E . . n an 1 o s . 0 2 C . . i h p . C t t 0 7 6 12 5532650

n 000 06 H P ons a . 6 B . . . C t t 95

3 3000 T h ermal Efficien cy Constan t 42 42 778

T a es V I an d V I I on a n n o ma on o m the n a o a ams bl c t i i f r ti fr i dic t r di gr , and T able VI I I is a general summ ary of the ob s erve d an d c alculate d results of s s the te t . i 04 m F . 1 ow sa n m g Sh s ple i dic ator diagra s t aken during the test .

INDEX P AGE En ne me an sms ana s s of on nu gi ch i , ly i (c ti ed)

flywhe el . go ve rno r Engine Spe cifications n co tract . drawing u p spe cifications sele cting an engine Engin e

A M . E . C S . o e . d importan ce of m o of on u n eth d c d cti g .

Farm or traction engine o peration of plant

ro ad roller type . semi-po rtable type Fly-ball go vernor Flywheel fun ction S ize of wheel action of Foster superheater

Gove rnor

m ethods o f action pendulum

Jacke ting a e fun on of j ck t , cti saving due to j acke ting

Lo como tive engines

o e b il r . engine characte ristics m e chanical e fficien cy

s f type o .

oss s ana s s of L e , ly i a n cle ra ce . coo ling b y e xpansion exhaust friction radiation s team condensation and re- evaporatio n INDEX PAGE

M arine engines auxiliary apparatus n conde sers . pumps re versin g m e ch anis m defini tion of te rms

s engine d etail . n beari gs . cranks crosshead guides

n . cyli der . marine det ails resemble st ationary management o f adj ustments after starting before starting bilges

e mergen cies . hot bearings hot rods

j ackets .

knocks . link ing up lubrication m arking off nuts refitting bearin gs s tartin g engine stopping vesse l methods of pro pulsion

prope lle rs . s crew pro pe lling action of n propulsio . e cono mical spe ed indicated thrust resistan c e facto rs fo r Ship in motio n startin g types o f

co mparison o f marine with sta tionary types cylinder in clined ve rtic al M e chanical and therm al e fficie n cy analysis of lo sses

osses in n n l practical e gi e .

l o w e ma e ffi e n n n th r l ci cy i here t . . M ultiple expansion

e aus w a u xh t ste tiliz ed . INDEX PAGE M ultiple expansion (continue d)

ess on ensa on l c d ti . methods of compounding

Newcomen steam en gme Nordberg engine

Pendulum gove rno r Piston rings Pistons

"uadruple engines

Savery steam en gine Separately-fired su perheat er

Shaft governo r . Snap rin gs Stationary engines

n - un a gle compo d typ e . B uckeye vertic al cross- compound typ e Corliss type Nordberg engine Simple side- crank type Simple vertical type advan tages of vertical o ve r ho riz on tal type n s of disadva tage vertical type . stationary U niflow ste am en gin e

Steam chest . Steam engines annual o peratio n exp en ses compound pu mping engine f cost o . n developm e t . early

en n e me an sm s an a s s of gi ch i , ly i engine spe cifications e re ction o f fou ndations installations of attachm ents n n setting the e gi e . n n n mari e e gi e . m e chanic al and therm al efficien cy N

INDEX P AGE T ypes and constru ction of st eam en gines (continued) station ary en gines w ate r pumps

Uniflow ste am en gme typical indicato r cards

Water pu mps cran k or flyw heel typ e dire ct -acting type Watt steam engine