· pre fa c e say , bo— de kko th is bi rd "a real hunky bunch of practical shop stunts for...

A Few

Useful Shop Hints

on Locomotiv e

V a lv e S etting

By

J A CK BR I T T O N

MasterMechqnic

HONORARY RETIRED MEMBER 0? rm:

Foam y APPRENTI CE 1m mLocouorrvn ERECTING SHOP Dm onsru rox

AND VALVE SE r-

rmc SPEc usr

FIRST EDITION

T E E F E DE RAT E D PRE S S Lun t nD

MONTREAL. CANADA

1 9 20

COPYR IGHT, CANADA, 1920

BYJACK BRITTON

Pre face

SAY , BO— DEKKO TH I S BI RD "

A real hunky bunch of practica l shop stunts FOR a shop

man ,pu t up BY a shop man , rai sed AMONG shop men on the

erecting shop pi ts .

Be a valve se tter as wel l as a sl edge hammer arti st on frames ,cy l inders , etc .

You don’ t have to be a designer to understand these kinks .

Take what you want and forget the technical i ti es you don’

t

need on the shop end of the game .

Certa in unn ecessary dope which Often occurs in shop

treati se i s cu t out from this l i ttle shot at a —boomer’

s”shop

dream .

The au thor real izes what a green hand on the pi ts i s up

agains t in order to gain a l iving , l et alone a thorough know ledgeof the game ready for a show down .

This book i s the fi rst of a se r ies in the endeavou r to showhow to crack many of the apparently hard nuts met wi th

during the erec tion Of a locomotive , from the preparation O f

the pit for main frames , to the fin ished engine ready for de

l ivery to the round house , includ ing tr ial tr i p .

The authOrj being a shop man , makes no apology for grammatical errors or shop slang .

I f you l ikeit , tel l the other boys .

I f you don'

t l ike i t , tel l me why . Shoot .

JACK BRITTON .

Montreal , November , 1920.

Introductory .

DES IGNER of Locomotive Valves and Valve Gears

A aims at the real th ing in distribu tion of steam by way of

the valves to the cyl inders at each and every reverselever posi t ion , wi th due regard to obtaini ng a smar t engine , tothe general construction of engine , to the serv ice i t is in tended

for and to the economy of fuel consumption .

There are , however , cer tain’ difficul ties for the designer tocontend wi th which compels h im to make certain sacrifices in

the lay ou t of the valve gear from his Standpo in t , which aremore or l ess pronounced and in evidence when the engine i sbu i l t and pu t in to service , dependent on the ski l l O f the design er

to a grea t exten t .

A valve setter , particu larly one whose exper ience has beensomewhat l imi ted , i s apt to get puzzled when , after squaringan engi ne to two given reverse lever posi t ions , that sameshows " ou t of square ” in others .

The Object O f th is work i s to show clearly how to get the

best resu l ts in valve setting wi th due respect to the designer ,yet in such a way as to prevent any possible chance Of therespons ib i l ity of a weakness in des ign to be passed on to the

shoulders Of a valve setter , to el iminate the tendency on the

part of a certain few who would monopol ize th is class of work ,and to present to the person who i s seeking the information ,

an Oppor tuni ty to get in on the game more rapid ly .

Fol low in detai l the practice herein,apply same as case

requira , l eave the errors O f motion , etc . ,to the designer , and

you wi l l be playing safe as a shop man .

You wil l a lso be gai ning that know ledge which wi l l enab leyou to go after any ,

ki nd Of valve rigging and se t the valvessatisfactor i ly wi th a degree Of confidence worth whi le .

The au thor real izes that other methods Of valve setting areemployed , yet , i f the green hand

“works back"the dope

herein he wi l l find himse lf i n a posi t ion to grasp and fol lowmost of the stunts he may poss ibly run into .

The sketches are pu t up in skeleton form , more or less,particularly wi th a view to al low Of '

an'

easy understand ing to

the beginner .

A designer could pick out many errors from same . We

should worry . They sui t the purpose for the shop man’

s

benefi t .

A beginner shou ld Get in " quickly on the proper way tokeep and use smal l tools such as cal i pers , scale , scribers , etc .

This should be unnecessary at this time , however , for theBohunk

"who doesn

’

t “know how when he “blows"i nto

the Erecting S hOp , shou ld get al l that's coming to h im .

The very elementary de tai ls are especial ly intended for thegreen hand .

The author gratefu l ly acknowledges the courteous treatmen t

received from “The Pil liod Company , and the privi l ege

extended , gran ting the use of certain data and sketches of

the “ Baker Valve Gear . "

Chapter I .

A CRUDE ENGINE

S a rule one has to walk before catching on to the runningstunt , l ikewise , le t us get in

"on a crude one way engine .

Get famil iar wi th the names of the parts . Figure 1shows them .

A Piston Val ve is represented at D and when operating ,d istr ibu tes l ive bo i ler steam to bo th sides of the Piston “

K”

at the proper time . The valve al so al lows exhaust steam to

escape from the cyl inder from ei ther side Of the Pi ston , at theproper time .

INSIDE ADMI S S ION VALVE

When l ive steam passes the inner edge s Of the valve on i tsway to the cyl inder , the valve is cal led an

“ Inside AdmissionValve .

" See Figure 1 .

OUTSIDE ADMI S S ION VALVEWhen l ive steam passe s the ou ter edges Of the va lve on i ts

way to the cyl inder , the valve i s ca l led an“Outside Admi ss ion

Valve .

"See Figure 10.

Figure 1 Shows a valve placed cen tral ly wi th the steam por tsand arranged to j ust cover them in th is posi tion . Note theposi tion of Eccentri c Sheave “A" wi th respec t to the Main Pin4 l B .

I NDIRECT MOTI ON

The arrows in Figure 1 i nd ica te the d irection in which th isengine must operate . The Eccentri c Rod “

C”mov es i n an

Opposi te d irec tion to the valve “D’

and the valve rod “E” atal l times . For th is reason the valve rigging is said to haveIndirec t Motion .

"

This “ Indirec t Motion is se t up because an IndirectRocker i s used .

“H

’ represen ts the Rocker Shaft ,“HF .

" theUppe r

‘

Arm , the Lower Arm .

D I RECT MOTIONWhen the Eccentric Rod and the Valve moves i n the same

direc tion at al l times the Valve Rigging is said to have “D i rec tMotion .

" A D i rect Rocker i s used to effec t same as Showni n Figu re 9 .

Shop H ints on Locomotive Valve S etting 9

THE D IRECT ION IN WH ICH AN ENGINE WILL OPERATELive steam adm i t ted to Valve Chamber as in the case

sho‘

wn in Figure 1 would not start the engine by reason of theposi tion of the Valve “D and the M ain P in “B .

”

Pul l the fly wheel around a shor t d istance in the d irectionindicated by arrow “

J’

and the movement of the Valve al lowssteam to pass to Piston K ’

to favor the movement . I f ,however the fly wheel was pul led around in a direction opposi teto that Indicated by arrow “

J , the engine would not operate .

Hence a On e Way Engine .

The d irection in which an engine wi l l Operate depends onth ree th ings

( l ) The Main Valve being Inside or Outside admisS lO Il .

(2) The motion of Rocker being D i rec t or Indi rect .

(3) The relative posi tion of Eccentri c S heave to Main Pin .

Live steam passing by Valve “D” th rough steam ports , actson Piston “K

’

du r ing Operation , which th rough the medium of

the Pis ton Rod , C rosshead and Main Rod acts upon Main Pin“B . In th is way the reciproca ting motion of the Piston isconverted in to the rotary motion of the Crank Pin . TheCrank Pin tu rns the fly wheel , the shaft of which actuates theEccentric Sheave . The Eccentric S heave in turn causes themovement Of the Main Valve th rough the medium of

‘

Eccen tric

Rod, Rocker , Valve Rod and Valve S tem . isTo fol low the passage of l ive steam , take the case shown in

Figure 1 and tu rn the fly wheel wi th Main Pin to posi tionshown in Figure 2 . The Valve has moved , which al lows steamto pas s to and act upon the Piston . Move the engine aroundunti l the steam por t i s fu l ly open as shown in Figu re 3 .

Note how the centre l ine of Main C rank stands wi th respectto centre l ine of Eccentric Sheave . They form an angle of

i .e . , they are at r igh t angles . I f the engine is movedaround sti l l further

,the Valve continues to move bu t retu rns

and closes the Back S team Port .Figure 4 shows the Back S team Port j u st closed as the

Piston arrives at the fu l l extent of i ts travel forwards , whichmeans that when the Piston i s at ei ther end O f i ts stroke , thevalve is j ust in the middle of i ts stroke , and again when thevalve is at ei ther end of i ts travel , the Piston i s j ust in themiddle of i ts stroke . Figu re 5 shows a posi tion where l ivebo i ler steam is being admitted to the fron t side of Pi ston , and

12 Shop H ints on Locomotive Valve S etting

ow ing to the Valve being made to j ust cover the steam portswhen Valve i s on the centre Of i ts seat , the steam from theback side of Piston can now escape along through the exhaustpassages . Figu re 6 shows front steam port ful ly Open to al lowl ive boi ler steam to pass to front side of Piston , al so a ful lport opening to al low steam to escape to the exhaust passagesfrom the back side of Piston . I f we continue to tu rn the eng ineanother quarter of a tu rn , we reach the posi tion shown inFigure 1 , thus making one complete revolu tion . From thedescription i t i s seen that l ive bo i ler steam is admi tted to thePiston during the en ti re stroke and direc tly the Piston i s on

i ts retu rn stroke , th i s l ive steam commences to escape andcontinues to do so du ri ng ' the enti re retu rn stroke . This constitutes a wastefu l engine in the major i ty of ca ses , al thoughth is same arrangement i s used to advantage once in a whi le .

Figure 7 shows an eccen tric sheave placed diametr ical lyopposi te to . the case we have already considered . The enginemust move in the opposi te d irection accordingly .

Figure 8 shows the path of l ive al so exhaust steam afterhaving moved engine around sl igh tly .

I f i t was seen fi t to retain the relative posi tion of Eccen tri cSheave to Main Pin as i n the case of that shown in Figu re 1and to sti l l use an “ Inside Admission Valve , yet a movementof engine was requ i red in the Opposi te d irection to that shownin Figu re 1 then a D irect Motion ” Rocker wou ld have to beused , as shown in Figure 9 . Again i f the relative posi tion of

Eccentri c to the Main Pin was decided upon , as in the caseshown in Figu re 1 , al so an Indirect Rocker had to be used ,and yet the engine was requ ired to operate in the d irectionshown in Figure 9 then an Ou tside Admiss ion"V alve wou ldhave to be used , see Figure 10.

S TEAM LAP

Whilst i t was known that steam had the power Of doingwork owing to i ts expansive properties , a means whereby samecould be u ti l ized had to be arranged . In order to do this .the Valve i s extended beyond the edges of the ports on thel ive steam side , when valve is placed on the centre of i ts sea t ,and a longer valve travel i s arranged by increasing the throwof the .Eccentric in order to ensure a fu l l steam por t openingat each end of cyl inder , during operation . Figure 1 1 showseveryth ing arranged as in the case shown in Figure 1 except

Shop H ints on Locomotive Valve Setting 15

that S team Lap has been added to the valve , and the throwOf the Eccen tri c increased .

S team Lap" i s the amount that a Valve overlaps the

steam ports on the l ive steam sides Of the Valve when Va lvei s in central posi tion .

“Steam Lap” canno t be aff ected by any changes in the

Valve Ri gging , other than mach ining the Valve .

In order to place the valve on the po int Of Opening to admi tthe l ive steam to Piston when steam lap i s in troduced , theEccentri c S heave has to be moved around the fly

“

whee l Shaft ,wi th respect to the Main Pin as shown in Figure 12 and keyedthere .

Note the posi tion Of Valve , Eccen tri c S heave and Main Pin .

The relative posi t ion of Eccentri c S heave to the Mai n Pin ,when set properly , becomes fixed .

“ A posi tion i s shown inFigure 13 , with a fu l l port open ing under the new condi tions .The Piston has not yet reached the centre of i ts s troke .

THE POINT OF CUT OFF

Move the engine round unti l the va lve i s ju st closing theback port , i .e . , j u st cu tting OH the entry Of l ive boi ler steamto the back end of Piston as shown in Fi gure 14 . This i scal l ed the “ Poin t Of Cu t Off .

A CU T OFF

A Cut'

Of’f i s the d is tance the Pi ston has travel l ed fromthe beginning of i ts stroke to where i t has arrived when thevalve j ust shuts the steam port ( the back port in th is casetaken for example) see D i stance A" Figure 14 . Before steamlap was in troduced , l ive steam was admi tted du ri ng ful l s troke .

I t is now seen that the supply i s cu t OH before Piston hasrea ched the end of i ts stroke , the Cu t Ofl

‘depending to acer tain ex tent , on the steam l ap given to the val ve . Therebeing two steam ports leading to both Sides Of Piston , respectiv ely , al so steam lap being arranged on bo th Sides of Valve ,natural ly the “Cu t Ofi

'

s"as wel l as a l l other events wil l occu r

a t both ends of cyl inder . Fo r the time being let one end Ofcyl inder be considered .

EXPANSIONFigure 14 shows a po

'

si tion where l ive steam is trappedthe back end Of the cyl inder .Expansion in a Locomoti ve Cylinder i s a property of the

volume Of steam under pressu re , which is trapped in the

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Shop H ints on Locomotive Valve Setting

the exhaust sides of the valve We now have , see Figure 18 ,

what i s known as Exhaust Clearance ,"i .e . , the d istance

between t he edge of valve on the exhaus t side and the nearestedge of steam port when valve i s placed on the centre Of i tsseat . When exhaust clearance is arranged i t has the opposi teeff ect to exhaust lap , i .e . , release occurs earl ier duri ng thestroke of the piston and “ Pre - release ” i s l engthened .

Figure'

19 shows the valve on the po int of Release , at backport wi th a va lve having Exhaust Clearance . I t al soshows the piston farther from the end of i ts stroke as compa redwi th Figure 17 where Exhaust Lap i s present on the valve .

THE POINT OF ADM I SSION

Le t us continue wi th a valve having Exhaust Clearance .

Turn engine around unti l pi ston reaches the fron t end Of i tsstroke , see Figure 20. The valve i s here seen ori the Pointof Admission for l ive steam at the fron t por t . Note thatthe back port i s open to release steam from the back end O f

cyl inder to the exhaust passages .

Figure 2 1 shows a fu l l front port opening for l ive steam tofront end of cyl inder . Figure 22 shows valve on the “Pointof Cut O ff , when l ive steam is trapped at the front end ofcyl inder .

ADM I SSI ON

Admission occurs du r ing the period be tween the Poin tof Admi ssion and the Point of Cu t Off .

“Admission i s aport opening to admi t l ive steam from the valve chamber tothe cyl inder by way of the steam ports . No te in Figure 22that the back port i s not yet closed to release .

THE POINT OF EXHAUST CUT OFF

Figu re 23 S hows the valve j ust on the Point of ExhaustCut O ff , at

“

the back por t .

EXHAUST

Exhaustion occu rs dur i ng the per iod between the Poin t ofRelease " and the “ Point of Exhaust Cu t Off . Exhaustionor release i s a port opening to al low steam which has donee ff ective work to escape from the cyl inder to passages leadingto the atmosphere or condenser i f used .

22 Shop H ints on Locomotive Valve Setting

COMPRESSION

The exhaust steam which i s trapped in the cyl inder whenthe Poin t of Exhaust Cu t Off ” i s reached , i s now forced in toa smal ler volume as p i ston continues to move towards the endOfgits stroke .

“Compression occurs during the period be tween thePo int Of Exhaust Cut Off and the “Point OfAdmi ssion atthe same port .

TO be clearly understood on the eff ects of Exhaust Lapand “Exhaust Clearance ,

” take the case shown in Fi gure 15 .

I f Exhau st Lap" i s added , the Poin t Of Release " wou ld

occur later and the “Poin t of Exhaust Cu t Off ” would occu rearl ier . I f on the o ther hand “Exhaust Clearance " i s giventhe “ Point of Release " would occur earl ier and the Point OfExhaust Cut Off” wou ld occur l ater .

LEAD

As far as we have gone , the valve has been shown on the

point of Admission , when the piston is abou t to commence itss troke . A port Opening at th i s particular moment seems tobe favored by the majori ty , i f one can be gu ided by presentday Locomotive S hop Practice . This amount Of port Opening ,when piston is abou t to commence i ts stroke i s cal led the“Lead of the valve , see Figure 24 .

ANGULAR ADVANCE

Figure 24 ,as compared with Figure 12 , shows the Eccentric

S heave moved around the axle a l i ttle fur ther to Obtain theport opening cal led “

Lead .

”

The angle the centre l ine of Eccentr ic Sheave was movedthrough to overcome the Steam Lap of the Valve , in Fi gure12 , added to the angle i t i s moved through to give Lead , i sknown as the “Angular Advance ” of the Eccentric S heave ,see Angl e E , Figure 24 .

I f the length of rocker arms A a nd B , Figure 24 , areequal

,then the Eccentric S heave has to be moved around

from the posi tion shown in Figure 12 to that Shown in Figure24 , so that the d istance

“C " i s equal to the “Lead

” “D",

Figure 24 .


PRE -ADM I S SION

Wi th the last change made , move engine around‘

unti l thevalve i s on the Point of Admi ss ion ” at the back steam port ,see Figu re 25 . I t wi l l be noticed that the Piston has not yetcompleted i ts stroke . The distance the piston travel s fromthis poin t to the end of i ts travel i s cal led Pre -Admi ss ion .

”

LEAD EFFECTS

I ncrease the Lead of the valve and Pre -Admissionoccurs earl ier du ri ng the piston stroke .

Compare Figu re 25 with Fi gu re 12 where no Lead is givenand the resu l t Shows that when Lead

”i s given to the valve ,

the “ Poin t of Admission " occurs earl ier during the p i stonstroke .

Figure 26 shows the valve on the po in t of Cu t Off at theback port , and when compared wi th Figure 14 , proves a muchShorter “ Cut Off i n Figu re 26, where

“Lead ” i s gi ven to the

valve . This means that when “Lead i s given -

t he Cut Offoccurs ea rl ier in the stroke of the piston , o ther condi tionsremaining the same .

I f you compare Figu re 27 wi th Figu re 19 , i t wi l l be seenthat the valve Opens to

“ Exhaust i n Figure 27 , before thePi ston has travel led as far as in the case shown in Figure 19 .

I t fo l lows when “Lead

”i s given to valve , or

“Lead ” i s in

creased that rel ease occurs earl ier .

Again , if we fol low the engi ne around as see n in Figure 28 tothe “ Poin t of Exhaust Cu t Off ,

” we find that i t occurs earl ieras compared wi th the case in Figure 23 .

To sum up we find when “Lead ” i s given or increased that

al l valve events are hastened as compared wi th before thechange . When “

Lead ” i s decreased i n any way the va lveevents are delayed as when compared wi th before the change .

LEAD ON

Lead On”i s an expression u sed when more l ead is requi red .

LEAD OFFLead Off

" i s an expression used when a reduction in leadi s requ ired .


The length Of a valve travel i n th is case , depends on thethrow

‘

Of the Eccentric Sheaves and th e lengths Of th e RockerArms .Where a Valve travel shal l occur depends on the lengths Of

Eccentric Rods , Va lve Rod and Va lve Stem .

Bear in mind , whi lst the length of the valve trave l may beO .K . and the Eccentric Rod , etc . , may be se t O .K . , to Obtai nequal travel to the valve on ei ther side of the

"

centre Of va lveseat , yet i t i s possible for the l ead to be incorrec t owi ng toincorrec t setti ng Of Eccentric Sheave .

The “Travel of a Valve " i s the ful l d istance through whichany part Of i t travels i n one direction during one s troke .

OVE RTRAVEL

The Overtravel O f a va lve i s the dis tance the l ive steamedge Of va lve moves beyond a ful l port Opening , see Figure 31 .

SEAL OF A VALVE

The Seal of a Valve i s the area or surface on the va lveseat which the valve covers at the end Of i ts travel to preventl ive steam from escaping into the Exhaust Passages . S ee Fig .

3 1 .

TRAC ING THE POSIT ION OF ECCENTRI C SHEAVE APPROX IMATELY

When th e Valve is known to be Inside or Ou tsideAdmission and the Rocker known to be D i rec t or Indirec t ,Figu res 32, 33 , 34 and 35 wi l l Show how same are laid out for

each of the four cases.

Note the posi tion Of Eccentric Sheave , i n Fi gure 32 . I t i sthe same as in Figu re 35 , i t l eads the Main Pin , and in Figu re33 , the same as the case in Figure 34 . i t fol lows the M ain Pin .

PI STON VALVE

Inside Admission Pi ston Valves have been represented upto th is time .

Piston Va lves may be arranged for Outside Admi ssion int ch case “Steam Lap

"would occu r on the ou ter sides of

Valve and “Exhaust Clearances on the insides , see Figure 36 .


D VALVE

A D Valve i s an Outside Admission Va lve , see Figure

VALVE MOVEMENT

In the case of Inside Admission the valve moves in anOpposi te direc tion to that of the Pi ston when the latter i scommencing i ts stroke , see Figure 32 .

In the case of Outside Admission , the valve moves in thesame direction to that Of the Piston , when the latter i s commencmg i ts s troke , see Figure 33 .

LOST MOTION

When an engine has been in service for a considerablepe riod , the parts wear and cause what i s known as

“Lost

Motion .

Turn an engine in one d irection un ti l the valve moves , thenstop . Turn the engine the other way and the valve remainss tationary for a short period whi lst the Main Pin i s movingto take up the slack , cal led Lost Motion

” in al l the parts .”Lost Motion deve lopment is more pronounced in rever

S ible than In one way engInes.

CENTRE LINE OF MOTION

When a rod during operation ri ses and fal ls an equal d istance above and below a given l ine , that l ine i s cal led theCentre l ine of Motion " of the rod .

The Centre Line of Motion Of a Main Rod i s shown inFigure 35 , of an Eccen tric Rod i n Figure 38 . When same ishorizontal no set i s requ ired in Rocker Arms .

Figure 39 shows the Centre Line of Motion Of EccentricRod when depressed . Note the se t necessary to the LowerRocker Arm (exaggerated ) . The Centre Li ne Of LowerRocker Arm stands at righ t angles to the “Centre Line OfMotion

”of Eccentric Rod , when valve occurs in the centre of

Valve Seat .

Figure 40 shows a case Of the Centre Line Of Motion Ofan Eccentric Rod, when same i s elevated .

Shop H ints on Locomotive V alve Setti ng

LAYING OFF ANGULAR ADVANCE OF ECCENTRI CThe

“Angular Advance of an Eccentric i s always laid O ff

from a straigh t l ine d rawn at righ t angles to the Eccen tricR

d“Centre l ine of Motion

"and passing through the cen tre

0 axle .

S ee Figures 38 , 39 and 40. Whil st the cen tre l ines of

Eccentric Sheaves l ie at various angles , to cen tre l ine of maincrank , note that the “Angu lar Advance ,

”i .e . , the Angle

“E "

remains the same .

ALLEN PORTED VALVE

I f lead is given to the valve , Pre -Admission occurs . Thegreater the lead the better , i f Pre -Admission can be kept .

smal l . Figure 4 1 shows the Al len Ported Valve which servesadvantageously in th is respect .When this valve i s open to the extent of the lead given to

an ord inary “ D "Valve , the

“Al len ” Port i s also open the

Same amount . With th is arrangement p racti cal ly double theamount of l ead i s Obtained w i th the same amount of ”PreAdmission ” which would occu r w i th the ord inary “D Valve .

When setting for lead wi th an “Al len” Ported Valve , forgetthe “Al len" Por t , work to specifications and do the same asyou would in the case of an ordinary D Valve .

’

(See ValveS etting later) .

FROM BOILER To ATMOSPHERE OR CONDENSER

When steam throttl e valve is opened , steam passes along thesteam pipes to the valve chamber .

The valve when properly se t , distri bu tes and exhausts steamat the proper time .

S team passes th rough the steam ports a t each end respective ly as fol lowsAdmission occurs during the per iod from the poin t Of

Admission un ti l the poin t of Cut Off i s reached . The steamnow being trapped and separated from the supply chamberexerts i ts power of expansion unti l the poin t of Release isreached .

The steam now escapes along the exhaust passages to theatmosphere or condenser as the case may be .

Exhaustion of steam con tinues dur ing the period betweenthe point of Release and the poin t of Exhaust Cu t Off . Theexhaust steam which remains in the cyl inder is trapped and


the further movement Of the piston compresses same unti l thepo int of Admiss ion i s reached , which again al lows Of the entryO f l ive boi ler steam . This Operation occurs at both ends ofcyl inder and is conti nuous whi l st engine remains in Service .

THROW OF ECCENTRIC SHEAVE

Figure 4 2 shows an Eccentr ic Sheave . The distance Ai s often cal led the “Throw "

of the Eccentr ic and twice th isamount the “

Ful l Throw .

" The “ Ful l Throw of an Eccentri c Sheave whether keyed to an axle or not, i s quickly foundby measuring radial ly wi th a scale the Shortest dis tance “ B ,

al so the longest di stance “ C ” and subtracting B ” from “C ,

i .e . , i f“ C " equals 636" and B equals then l ess

‘

gives 5"“ Fu ll Th row .

THROW OF MAIN PIN

The Throw Of the Crank Pin sometimes cal led the MainPin i s shown at “A Figure 4 3 .

“The Fu l l Throw Of MainPin wi l l be tw ice the di stance A . To measure up qu ickly ,

scale the d istance “ B ” from centre of Shaft , to Main Pin ,

mul tilpy by 2 and add to same the diameter Of Main Pin , i . e . ,

i f “ B equals 12" and “ C"equals then 12” mul tipl ied

by 2 and added to 6” gives 30"“ Ful l Throw "

of Main Pin .

The travel of a Piston during operation practical ly equal sthe Ful l Throw "

of Main Pin in al l cases .

DEAD CENTRES

Figure 44 shows the posi tions Of a Main Pin which areknown as Dead Cen tres , Front and Back .

A Main Pin i s sa id to be on a Dead Centre when the cen trel ines Of the Main Rod and Main Crank are in the same straightl ine when viewed from the side as seen in F igure 4 4 , dottedl ines .

The quarters and eigh ths are al so shown in Figu re 4 4 .

WORKING QUARTERS

Note the posi tion of piston, i .e .

, exactly in the centre Of itsstroke and the main p in , i .e . , ahead of the top quarter . Thi sposi tion i s known as the top wo rking quarter . The posi tionof the main pin when on the bottom working quarter i s al so

‘

shown .

Chapter I I .

STEVENSON LI NK MOT ION .

A REVERSIBLE ENGINE .

HE valve movements , etc . , explained in the previouschapter are appl icable more or l ess to reversible valvegears .

Ono

a locomotive there are two reversible engines , one on

ei ther Side , both be ing control led wi th the same reversinggear and same steam throttle valve .

INS IDE AND OUTSIDE VALVE MOTI ON .

A locomotive is said to carry Inside Valve Motion , whenthe source of motion to the valve is set up from that part Of thedriving axle which l i es be tween the Main Frames , also anOuts ide Valve Motion ,

"when the source Of motion is se t up

on the outside of the Main Frames .

S TEVENSON LINK MOTION .

There are various reversible valve gears in service on Locomotives . Let us consider the S tevenson Link Motion .

Figure 4 5 shows a sketch of same wi th the parts named .

Figure 4 6 is a dupl icate sketch of Figu re 4 5 .

Both sides Of a locomot ive are equipped similarly , exceptthe reach rod and reverse lever wh ich serves for both . Demonstration wi l l be made from one side only for the time be ing .

Al though one side only of locomotive is considered inFigure 4 6 , l ook closely and you wil l note that there are pract ical ly two one - way engines , one eccentric sheave and eccentricrod for each , connected to the same common l ink , and thesame valve , valve stem , valve rod and rocker is used in bothcases .An Inside Admission Valve and an Indirect Rockeris used in the example chosen .

I t is easi ly seen in figure 4 6 , i f eccentr ic sheave A wasconnected by i ts Eccentr ic Rod to the Lower Rocker Arm Pinat “E ” and the Eccentr ic Sheave “ B disregarded , that theengine would have to move in the direction “C ,

”i .e . , a for

ward engine would resul t , the same as shown in figure 24 .

Shop H i nts on Locomotive Valve S etting 39

Again , if eccentri c sheave B was connected by i ts eccentri c rod to the pin at “E and eccentric sheave “A wasd isregarded , the engine would have to move in the d irec tionD ,

”i .s . , a backward engine would be the resul t .

In order to swing'

the eccentri c sheave “A ” or B in tose rv ice at wi l l , a l ink block was attached by means of a l inkblock pin in a sui table manner to the lower rocker arm at E .

The l ink block 13 fi tted to a sh ifting l ink at ei ther end Of whichis connected the forked ends of the two eccentric rods respectively , see F " and “G . The forward or go- ahead eccentricrod is general ly connected at the top end of l ink . A meanswhereby to raise or lower the l ink is used . A reverse lever“H" wi th i ts fulcrum pin “

J at i ts lower end al lows of aconnection with the reach rod at “N .

" The other end of

reach rod is connected to upper end of reverse shaft upper armat the po int “

L . The reverse shaft occurs at “K "and

carries two lower or l i fting arms , one for each side of l ocomotive . One reverse shaft l i ft ing arm is shown making aconnection at the upper end of the l ink l i fter at

“M .

The lower end of l ink l i fter connects wi th the l ink saddlepin shown at point The l ink saddle is a means by

t li

K

Ch the l ink l i fter is connected in a practical way wi th theIn

FORWARD FULL GEAR .

In the case of a one way engine , the eccentric rod is connected directly to the end of rocker arm .

This reversible gear having a l ink and l ink block , the nearest approach to Obtain ing the events dur ing operation as before is tolowert he l ink in the case of driving the engine forward , unti l theforked end or clevis of the forward eccentri c rod is in l ine wi ththe l ink block pin , see

“A ” Figure 4 7 . The engine in th isreverse lever posi tion is said to be in Fo rward Ful l Gear .

FRONT CORNER NOTCH .

The reverse lever is said to be in the Front Corner Notchwhen reverse lever is in forward ful l gear .

BACK UP FULL GEAR .

I f the reverse lever is pul led backwards unti l the forkedend of back up eccentr ic rod is in l ine wi th the l ink block pin ,

then the engine is sa id to be in “ Back Up Ful l Gear ."

4 2 S hop H ints on Locomotive Valve Setting

The appl ication O f Figures 39 and 40 can be made also to

th Is reversible gear respecting the back se t of lower rockerarms .

LINK RADIUS .

Figure 4 9 shows a l ink in which the arc A .B .C . is knownas the “

Link Rad ius .

"

LINK PIN ARC .

The arc D .E .F see Figure 4 9 ,which passes through

the centres of the two l ink pins wh ich connect the forked endof eccen tric rods to the l ink Is known as the “Link Pin Arc .

’

S L IP OF THE LINK .

When an engine , fi tted w i th S tevenson Link Motion , i smoved around , the li nk moves over the l ink block Sl igh tlywhen the reverse lever i s near to the M id Gear Notch , andbecomes most pronounced in fu l l gear . This movement Ofthe l ink w i th respect to the l ink block i s cal led the “Sl i p ofthe Link .

OVER - REACHING .

When an engine of thi s kind i s in operation the l ink movesth rough various angles . The eccentric rod pushes the l inkand the latter pushes the l ink block in order to move the valve .

I f the valve runs dry ow ing to neglected lubrication , etc . , thevalve is hard to move . The Eccentr ic Rod forces the l ink ,

especial ly at and near the end of the ful l gear valve travels; toS l i p a l i ttle more than when the valve moves easi ly . Thisextra sl i p of the l ink is cal l ed “Over - Reach ing .

”

OUT OF SQUARE .

When a valve r igging is not S et properly , i t i s said to beOut of S quare .

"

LAME ENGINE .

When an uneven beat i s heard as steam is exhausted fromthe smoke stack

,one often hears the expression , she Is Lame .

"

FULL GEAR VALVE TRAVEL , OR LONG VALVE TRAVEL .

The distance the valve travels during operation wi th thereverse l ever in ful l gear notch is cal led the “ Ful l Gear ValveTravel

,or “

Long Valve Travel .”


‘SHORT VALVE TRAVE L .

The . distance the valve travels wi th reverse lever in the‘

Mid Gear Notch " du ri ng Operation is cal led the “S hort

Valve Travel .”

VARIABLE VALVE TRAVELS .

The valve travels being greates t when reverse lever is placedin the “ Corner Notch , and least when placed in the “M idGear Notch ,

” the decrease in valve travels when Hooking Upis easily seen , al lowing of

“Va riable Valve Travels ."

LE NGTH OF VALVE TRAVEL DEPENDS ON

( 1) The Throw of the Eccentri c S heave .

(2) The Length of the Rocker Arms .(3) The posi t ion of Reverse Lever in rack , or the posi tion

of Link Block in Link .

LEAD INCREASE DURING HOOK UP.

Figu re 50 shows main pin on dead cen tre when lead occurs .To Show clearly why lead increases during Hook Up , see thefol low ingI f i t were possible to have the centres of both eccentri c

sheaves at“A ”

Figure 50, and then the reverse lever hookedup , from ful l gear forward to Mid Gear , the Link Pin B " of

Eccen tric Rod would sweep through the dotted Arc to thePoint C .

An Eccentr ic S heave Centre must necessa ri ly be out Of theCentre of Dr iving Axl e to render a source of motion to the valve .

When f everse lever is placed in ful l forward gear and then i ti s hooked up to mid gear , the point

“ B ,

" Figu re 50, sweepsthrough an Arc , the centre of wh ich is at “D " and arri vesat the po int “E .

Again the Link Pin Centre K having a rad ius , the cen treof which is at L ,

” sweeps through an arc and arrives atpoint “ J .

"The Link rad ius and the Link Pin Arc , see Figure

4 9 , are paral lel to each other and have a fixed relationsh ip .

except the S l igh t di ff erence caused by wear and tear of theparts during operation .

Hence i t fol lows that as the Li nk Pin Centre B , Figu re50, moves to

“ E " and Link Pin Centre K ” moves to “

J"

and the Link rad ius being advanced during the operation , unti lmid gear is reached , the l ink block pin is advanced an amount

Shop H ints on Locomotive Valve Setting 4 5

equal to that shown at F i .e . , th e di s tance be tween H

and B . The movement of the L ink B lock Pin aff ec ts thelead ‘

Of the valve through the med ium of the Rocker , ValveRod and Valve Stem .

Thu s i t i s that Lead i s increased as lever is hooked up fromei ther of the ful l gea r notches towards the centre of reverselever rack .

RI GHT AND LEFT LEAD ENGINES

When the main pin on the righ t hand Side leads the mainpin on the left hand Side of an engine nine ty degree s whenrunning forward the locomotive is cal led a Ri gh t LeadEngine .

When the left Side main pin leads the righ t when runningforward the same amount , i t i s said to be a

“Le f t Lead

Engine .

Do not confuse the aforemen tioned wi th the Lead of aValve .

"

How To QUICKLY DETERM INE WHI CH I S THE Go - AHEADECCENTRIC

The fol lowing appl i es at any time particularly i f abou t toconnec t the eccentr ic rods to the l inks in a dark round house .

One does not have to trace for “ Inside " or “Outs ide ” admission valves , whether rockers are

“ D i rect ” or “ Ind irec t " or

the relation of eccentri c sheaves- to the main pin .

Figure 5 1 shows the posi ti on of axle and eccentr ic Sheaveswhere by chance they have stopped .

A man going under an engine to pu t up a set of eccentr i crods knows in which d irec tion the front end of engine l ies bythe posi tion of fi rebox .

The centre l ines of the webs of the eccentr ic Sheaves conta ina smal ler angle on one side see “ BAC ”, Figu re 5 1 , than on

the other , i .e . , a man can reach the two webs on one Side inthe case of a heavy engine far easier i n the posi tion shown atD ”than when in the posi tion Shown at “E .

"

Just imagine yoursel f i n the posi tion “ D spann ing thesmal lest angle be tween the webs . In order to b ring C ”

towards “ B i t would have to be moved In the di rection F,

which , when con tinued as a rota ry motion , and appl ied to thed riving wheel , same would tu rn in a forward direc tion . Theforward eccentric sheave therefore i s that wh ich con ta ins thecen tre web l ine C .

4 6 Shop H ints on Locomotive Valve S etting

Again , i f Centre Line B is moved towards C samewou ld move i f continued as a rotary motion abou t the axle ina back up d irection . The eccentr ic sheave wi th the centrel ine “ B ” i s for the back up gear and is u sual ly connected to

the bottom of the l ink .

A lways pu t your hands on the centre webs of eccentr i csheaves so as to contain the smal l angle and br ing you r handstogether . Continue the motion wi th your hands and thed i rec tion in which they move indicate the way in which theengine wil l move for the two sheaves handl ed respectivelywhen brough t in gear . The forward eccen tr i c rod i s general lyconnected to the top end Of l ink .

The afo rementioned stun t often S aves expensive mistakesand leads one to a check up to see i f driving wheels have beenpu t in the righ t way in repai r shop .

TRAC ING APPROXIMATELY THE PO SIT ION S OF ECCENTRICSHEAVES

Figure 52 shows the posi tions of eccen tric sheaves approximately , wi th respect to Main Pin wi th an engine having“ Inside Admiss ion Va lves " and “ Indi rect Rockers ."

Figure 53 shows the posi tions to be the same wi th OutsideAdmission Valves ” and D i rect Motion .

"

Figure 54 with“ Inside Admission Valves and D irec t

Rockers " Shows the approximate posi tions Of eccentric sheavesto be the same as shown in Figure 55 where

“Outside Admission Valves " and Indi rec t Rockers ” are represented .

CYLINDER CENTRE LINE

The centre l ines of the cyl inders on some engines are horizontal and very Often l ie three or fou r i nches h igher than thecentres of dr iving wheel axles .There are other cyl inders incl ined at a smal l angle to thehorizontal .In any case the picking up O f dead centres prope rly for valve

setting see next chapter , takes care of same , no matter howthey occur from a valve setter

’

s standpoin t .

S ERVICE CUT OFFSThese are cu t off s taken when reverse lever is in the posi tion'

where most Of the regular work of the engine i s done ,the case Of a swi tch engine where most work Is done W I th

Shop H ints on Locomotive Valve Setting

reverse l ever in the Ful l Gear Notch the cu t offs occu rwhen the piston has travel led abou t seven - eigh ths O f i ts s troke .

I n the case of a fre igh t engine the se rv ice cu t off s occur whenpi ston has travel led abou t one - th i rd of i ts s troke , and in thecase of a passenger engine when abou t one- quarter O f thepi ston stroke i s reached .

These service cut Off s are only approximate . I t i s for theengineer to use hi s j udgment diIring operation as to how farhe can “ hook up

"the lever to get the best resul ts , compa tible

wi th speed and economy as the case warrants . I t i s worthnoting that i f an engine i s squared up to “

S ervice Cu t O ffsShe W i l l be practical ly O K . i f “

Hooked up” w i th in a notch

or two of same ei ther way .

50 S hop H ints on Locomotive Valve Setting

. Exper ience has taugh t the pol icy of leaving slackS Idewise a nd slack diametrical ly between the eccen tr i cstrap and eccentric sheave .

S ee thaf Eccentri c Sheaves are securely fastened to d rivingaxle .

ECCENTRIC ROD- S ETT ING

Try out each eccentric rod for twists and sets as fol lows

Bol t the back end of eccentric rod to i ts eccentr ic strap .

Don ’ t forget to tigh ten the nu t wi th a spanner and avoid beingfooled , see

“A" Figure 56 .

Li ft the forked end of eccen tric rod to touch the part of theli nk where same has to be connected . Work the forked endsidewise back and forth to se e i f same has equal side play on

both sides of l ink during the movement , i f not , measu re thedistances travel led by the fork as shown at “ B

”and

“C ,

Figure 56 . Take the short d i stance B ” from the long distance C and hal f the diff erence i s the amount the forkedend of eccentri c rod has to be brough t over by placing a setin the rod at the part marked “ D . Before making any

al teration , disconnect the eccen tric rod at the eccentric strapand connect up the forked end to the l ink as shown at

“A ,

Figure 57 . Don ’

t forget or neglect to pu t on Link Pin Nutand tigh ten i t up wi th a Spanner .

Now try out for S ide play as Shown at B , Figure 57 , i n asimi lar manner as before .

Note how far eccentr ic rod needs to be brought over . Thishas to be effec ted by putting a set in the eccentri c rod at thepoint shown at “ C , Figu re 57 .

Before pu tting a set in a rod , Chalk careful ly and scr ibethe ou tl ine of the rod on a plate or place ‘a straigh tedge on theflat portion of the fork as at “A , Figure 58 , and measure

“B"

Figu re 58 . After placing the set in at “ C ,

"check same by

applying the rod to the scribed ou tl ine or by the use of thestraigh tedge appl ication again to see i f O .K .

The other set can be made in a simi lar manner .

Get one set over the requ ired amount before tackl ing thesecond one .

When two sets have to be made in one rod , make an al lowance for the eff ect of one set on the other . This IS found by

52 S hop H i nts on Locomotive Valve Setting

experience only . A close approxima te se tting can be figuredfor exampleTake the Point D , Figure 56 , as 9 from the back end Of

eccentric rod , the poin t C ,

"9” from the centre Of fork end

pin , see figure 57 , and the length of eccentric rod from thecentre of the fork end pin to the back end of eccen tric rod as3' Upon trial i t i s found that the back erid of rod has tobe brough t over see Figu re 57 , and the front end See

Figure 56 .

Make the bend at C , Fi gu re 57 , to bring over the endB ,

" Figu re 57 , j ust the MThis se t made at C ,

" Figu re 57 has favored the fork end ,i .e . , C

"i s 36” from the back end B and 9" from the front

‘A .

Br inging over end B 34 means that end “A” has beenbrough t over favorably in this our case , when fork endis d isconnected and back end B is again connec ted .

The fron t end trial , see Figure 56 , proved that the fork hadto be brough t over bu t having been favored the se tpu t in at “ D ,

” Figu re 56 , has to be pu t in to b ri ng the forkover only .

I f a press i s used to pu t the sets into a rod and same isoperated by power , take a precau tionary measure to reduceguess work to a minimum by adjustment of packing careful lyunder the rod before applying pressure .

ECCENTRIC ROD TWI STED

When pu tting up an eccentric rod after the se ts are O .K. ,

bol t the back end on the eccen tric s trap fi rs t and tigh ten thenu ts .Place the fork end on the l ink wi th a view to pu tting in the

l ink pin .

A twist i n the rod i s easi ly noticed i f present , See Figure 59 ,

and the pin cannot be entered by hand easi ly .

Do not grind a fin ished l ink pin ra ther than remove a twistin a rod .

I f the holes appear as shown in Figure 60, depend on i t theset i s i ncorrec t .A pair of twisters are general ly suppl ied as a Shop tool , seeFigure 6 1 .

Do not twist a rod when connected bo th ends . D i sconnectthe fork end at least . Remove the twist and try again .


One Should be able to push a l ink pin in M of being homeready for tapping home with a hand hammer .Sometimes a long handled twister i s u sed wi th the rod i n a

strong vi ce,see Figure 62 .

Bear in mind a man seldom gets fi red for doing a good job .

I f in doub t , go to i t , take the rod down and do the job ri gh t .Se ts and twi sts in other rods can be handled in a Similarmann er to the foregoing .

Af ter al l Se ts are O .K . and twi sts removed , disconnec t bo thback up eccentri c rod fork ends and lower them out of theway Of the l inks .

BLOWING THROUGH S TEAM PASSAGE S

Before pu tting in main valves i t i s the general prac tice tofil l up the bo i ler wi th h igh pressu re ai r , give a warning to you rworkmates to keep clea r by blowing the whistle or by anycommonly understood practice Of the ShOp , then to open upthe throttl e val ve and blow th rough the d ry pipe , steam pipesand steam passages in cyl inders to clear same of any fo reignmatter , di rt , etc .

I t i s understood that the S team Pipes , etc . , are al l assembledon the locomotive to al low Of same .

Again pass your hand and arm after blowing through , intothe passages , using a piece of wire to find out i f any piece offoreign matter such as a bol t or stud , etc . , has become lodgedin such a way that blowing through could not rid the passageof same , yet at a later date , vibrati on might work same downin to the steam chest and wreck the valve .

Remove any such foreign materi al i f presen t from thecavi ti es .

Some workers think i t a better pol icy to pu t valves intovalve chamber , pu t on the steam ches t covers and then blowthrough , moving each valve be fore each Shot Of ai r to openeach steam port in turn .

The safes t practi ce i s to consider and use both , i .s . , blowingthrough be fore and after valves are pu t in .

In any case blowing through the cyl inders occurs beforepi stons are pu t in .

SHOP REPORTBefore valves are pu t in make sure al l inf ormation is ga ined

as requ ired by the shop you are working in .

Take the case of an “ Inside Admiss ion " Piston Valve .

5 4 Shop H ints on Locomotive Valve Setting

Take the d istance A , Figure 63 ,with amadjustable gauge

as Shown ,i . e .

, the distance between the i nside edges of the twosteam ports when bush ings are in thei r proper pos i t ion i nsteam chest . Thi s d istance must be 0. K . to blue printrequ irements .

Now measu re the d istance B , Figure 64 , subtract i t fromA" Figu re 63 , and divide the answer by twoThe steam lap of the valve is the answer

,provid ing that the

steam ports and valve d imensions are as cal l ed for by blueprIn t .

Measu re the d istance C , Figu re 63 ,‘and take from i t the

d istance D , Figu re 64 , and d ivide by twoThe resu l t i s the exhaust clearance of the valve .

I f the distance D , Figu re 64 , is greater than the d istanceC , Figu re 63 , take

“C"

- from “ D , divide by 2 and theresu l t is the exhaust lap of the valve . Exhaust lap is seldomused , general ly

“ Exhaust Clearance " or “ Exhaust Line andLine .

In the case of an Ou tside Admission Valve , A Figure63 , taken from B , Figu re 64 , and divided by 2 would g ivethe Exhaust Clearance , also

“C ,

’ Figu re 63 , taken from D ,

"

Figu re 64 , and d ivided by 2 would give the steam lap .

The steam lap and exhaust clearance O f a “D "Valve can

be measu red in the same way as a piston valve .

DO not O i l the valves at th is time , pu t the valves in , pu t onthe steam chest covers , and blow through before oi l ing . Dust ,etc . ,

during blowing through col lects on valve i f oil i s presen tsame being unnecessary and detrimental .In addi tion to steam lap and exhaust clearance being re

qu i red for shop report,the type .of valve , whether

“ Inside ” or

Outside ” Admission,Al len ” ported or i f a D Valve , the

th ickness of valve l i p a l so the th ickness of valve seat aregeneral ly cal led for , see Figu re 65 . These i tems can be readi lytaken and noted before valves are pu t in .

VALVE S TEM FITS

A piston valve stem is r igidly secured to i ts piston valve ,whereas a D ”

Valve stem is welded'

to a Buckle t ch fi tsover i ts valve . The latter fi t i s an easy one W I thout slackinasmuch that when the proj ecting piece “A , Figu re 65 , i smachined down to proper l ength to keep the valve stemal ignment du r ing Operation i t S hould be possible for the other


The fixed centre pop A , Figure 68 , is general ly placed in aplug which has been screwed tigh t into cyl inder to sui t thetrammel l ing of valve stem .

Take this tram , place properly in centre pop in plug andS cri be a smal l arc to cu t l ine on valve stem

,see “ D

,Figure

68 .

Push the valve ahead and lever backwards to the bumpingpo int again . Try out the tram again to see i f the fi rst arcscri bed i s not false . I f tram marks coincide on this secondtrial , pu t a smal l pop where the arc cuts the straigh t l ine andconsider same as an indication of danger dur ing valve se ttingi f ever th is pop comes w i th in of the tram poin t .Push the valve to the fron t end , levering same unti l a bump

is fel t . Proceed to take the bump mark for the fron t end inthe same way as j ust detai l ed for back end .

FULL GEAR VALVE TRAVEL

The approximate ful l gear valve travel can be found byadding twice the steam lap of the valve to twice the w id th of

the l ive steam port in valve Seat and to th i s add V8” for over

travel of the valve at each port .The last i tem is mentioned as a gu ide to the unin formed

when starting in to figure the distance a valve stem readingwi l l take up on a valve stem .

Another way to figu re ful l gear travel when the valves arein and covers are on , i s to measure the ful l throw of the eccentric in inches and divide same by the length of the inner ro

'

ckerarm in inches and mul tiply the resul t by the length O f theou ter rocker arm which connects wi th valve rod , in inches .

PI STON BUMP MARKS

Pu t in the pistons and put up the front cyl inder covers .

Connect piston rods to crossheads properly being sure thepiston glands

,etc .

,are on piston rods . Drive the pIston rod

cotters home .

Pul l back by levering the crossheads ‘

unti l a fairly goodback bump is fel t . Be sure crosshead i s not foul ing a bracke- I

etc . Scr i be a l ine on guide bar as shown at “A ,

"Figu re 69 ,

by means of a short straigh t edge and scri ber .

Pul l the crosshead ahead six inches and haul back W I th abar unti l you can feel the piston real ly bumping the backcyl inder head . Put up straigh tedge to see I f the first mark


taken i s not fal se . I f same coincides wi th straigh tedge at th issecond tri al , cen tre pop same and consider i t a danger markas far as crosshead travels are concerned .

Go ahead , pul l crosshead to the front end and obta in thefront bump mark “ B , Figu re 69 , i n the same way as desc ri bedfor the back end .

The distance be tween these two piston bump marks bo thscri bed from the same end of crosshead i s general ly abou tlonger than the ful l th row of main pin .

CLEARANCE

TO arrive at a clea r understanding on Clearance,suppose

the main rods are connected , also the valve riggi ng includ ingeccentr i c rods .

Move engine around in ful l gear and the long valve traveloccurs .

The distance be tween the v alv e at the extreme end of i tstravel and i ts bumping po int at that end is understood by theshop man as Clearance of the valve . Thi s occu rs and appl iesat each end of steam chest .The distance between the piston at the extreme end of i ts

travel and i ts bumping point at that end is understood by theshop man as the “ Clearance

"Of the piston . This occu rs and

appl i es at each end of the cyl inder .

This must not be mistaken for or confused w i th the ExhaustClearance ” of a valve previously explained .

Ag ain i t must not be confused wi th the in terpreta tion Ofclearance as understood by some ou tside the province of theshop va lve setting , i . e . ,

the volume of the cavi ti es lying be tweenthe face of the valve seat or the face of the bush ings wherevalve fi ts and the face O f the pis ton when the extreme end of

i ts travel is reached . This latter i tem in no way appl ies to

valve se tting , i t is Simply explained to prevent m isunderstanding .

Le t us get back to an assembled motion wi th the two backup eccen tric rods di sconnected and d ropped Clear Of the l inks .

PORT MARKSTo take po rt marks in the case O f a D Valve the steam

chest cover i s left O ff .

Peep hole plugs are provided in the case of piston valveswhich al low a di rect view of the steam por ts from the outside ,


when plugs are taken ou t and a flash l igh t or a piece of l igh tedcandle on the end of a piece of wire i s used .

I n any case j ar valve over careful ly unti l i t i s seen that i t i son the Point of Admission .

” Exerci se grea t care in th isrespec t and i f i n doubt move valve to open the port and comeagain as the saying goes to the “ Point O f Admi ssion ,

”edge to

e ge .

I f perchance an Ou tside Adm i ss ion D Valve is u sed andthere is a sl igh t angle be tween the edge of the valve and theedge of the port , say to noth ing in the fu l l length of theport , some workers spl i t the difference and set edge to edgein the centre of the transverse length O f the port .Once the valve i s se t O .K . to poin t of Admi ssion , say at

the front port , Scribe a smal l arc wi th the valve spind le tramto intersect the l ine “C , Figure 68 ,

and shown more clearlyat “A ,

" Figure 70.

Jar the valve over to the point Of Admission at the backport and scribe a smal l arc to in tersect th e straight l ine asshown at B , Fi gure 70.

Find the centre of the d istance between arcs A and “B”

on the l ine“ C

"at the po in t “D ”

with a pair of sharp need lepo inted d ividers .

Many valve setters would figu re on A and B , Figu re70, as being port marks and

“D as the centre of same . Thisi s not SO i n al l cases.

In the case Of a “D Valve wh ich is Ou tside Admissionor wi th an “Ou tside Admission Piston Valve ,

" the sl igh tincrease in the length Of Valve stem due to a d i fference inexpansions is compensated more or l ess by the volume the

piston rod occupies at the back end of cyl inder and the aforementioned poin ts “A” and “ B " are O .K . as port marks .In the case of an “ Inside Admiss ion Valve ," the smal l

amoun t of valve stem expansion over and above that of thecyl inder

,coupled wi th an al lowance to com

pensate for piston

rod volume warrants an al lowance Of bare in the caseof non - superheater engines , and in the case of superheater engines .This al lowance i s made only on engines having Inside

Admission Valves in the fol lowing way .,

Take Figu re 70. Consider a superheater engi ne for example .

Instead Of centre popping the centre Poin t “D ”make a fine

centre pop on the straight l ine“C ” ahead Of the po in t


D . See E , Figu re 70. S et d ividers to the lap of thevalve wh ich i s exactly hal f of the d istance be tween “A" and“B .

”With

“ E "as centre scribe two smal l arcs F " and

G and centre pop finely where the arcs cu t the straigh t l ineC . You may now forget al l eff ects of valve stem expansionand piston rod volume during the remainder of the valvesetting .

Consider F and G as Port Marks wh ich w i l l ind icatewhen the po ints of Admission and Points of Cut Off for bothsteam ports occu r respect ively , as they reach the valve spindletram later .To al low of a clear understand ing on Port Marks , take i t

for granted that the Inside Admission V alve " in ou r examplehas V8

” exhaust clearance .

With the d ividers set to exactly rad ius and w i th thepoin t E "

as centre scr i be two arcs “H

"and J .

"S ee

Figu re 7 1 . Centre pop where arcs cu t the straigh t l ine .

When centre popping , make a clean pop in the r igh t spotw i th one centre and not make a couple of stabs at i t , and geta resu l t wh ich cannot be rel ied on for accu racy . Be ca refu lwhen draw i ng a pop mark over and get one cen tre in a popmark , not two .

The centre pops at H. and J , Figu re 7 1 , are port marks

wh ich wi l l ind icate the points of release and the po ints Ofexhaust cu t off for both ports respectively as they reach thetram poin t .

I t i s wel l to remember that the release and exhau st cu t offport marks are not taken or used in Shop practice duringvalve sett ing unless a record of the pre - release and exhaustcu t offs are cal l ed for particu larly .

In order to make th is sti l l clearer , suppose the valve hasV3 exhaust lap

,then the pops on the arcs “

H”and “

J ,

"

Figu re 7 1 , scribed wi th the d ividers se t to a rad ius ofequal to the exhaust lap , would sti l l serve to ind icate as theyreach the tram point

,when the point of release and the poin t

O f exhaust cu t off s occu r respectively .

I f the valve has no exhaust clearance and no exhaust lapthen the centre pop “ E ,

" Figure 7 1 when i t j ust reaches thetram point would indicate the poin t Of release to one port andthe point of exhaust cu t off to the other or vice versa dependen tupon the d irection in which the valve is moving at the time .

S hop H ints on Locomotive Valve S etting 63

Care must be exerci sed when using port marks . To helpou t in th is respect , take i t for granted that the valve mot ion ,

etc . , is assembled w i th main rods u p and the eng ine i s be ingmoved around .

The fol lowing tables together w i th the sketches wi l l give anidea of that which occurs as the port marks reach the trampoin t respect ively .

l Occurs atUnder Tram Point Point of Admission orFront or Back

Point of Cut 03 Port

Inside Pt of Admission Back PortCut Off Front

1 AdmissionOutside

Cut Off

Admission

Exhaust ClearanceOl n

élc

ée

XEPoint Of Release Occurs atUnder Tram Point or Exhaust 11 eor Poin t Front or

Lap Moves of Cut Off Back Port

Pt . Mk Exhaust C learance Inside Ex. Cut Ofi Back PortRelease Front

U

BackClearance Outside Front

Back

Front

The beginner wi th a l i t tle concentration wi l l easi ly fol low thetables and Sketches relative to exhaust port marks . Havingdone SO , the case where a valve has no Exhaust Clearancenor Exhaust Lap ,

” j ust “Exhaust Line and L ine " wil l alsobe fol lowed easi ly .

PROTECT ION OF VALVE STEM READINGSWhen port marks have been taken , bend a piece of th in

Sheet Iron or t in around the valve stem and long enough tocover the read ings to protect them on both sides of engine .


When working on one valve stem have '

the other one covered .

Both readings to be covered during a temporary absence .

I t “gets your goat ” when a shop mate Sl ides down from Off arun board and wipes out your read ings with h is overal ls .S afety First Often saves a d ispute .

When taking port marks in the case of a D Valve , andthe buckle i s somewhat slack , take up the Slack whil st SOdoing by inserting a th in steel wedge between the buckle andthe valve as at “A ,

” Figure 78 , whilst taking the front portmar

l

l

iand as at “ B , Figure 79 , when taking the back port

marWhen port marks are obtained the steam chest covers , etc . ,

can be placed , and steam chest fini shed up properly in thecase of a “D ”

Valve .

VALVE ROD LENGTH .

To determine valve rod lengths . Place the valve practical ly on the centre of valve seat , i .e . , j ar the valve unti l cen tre

pop“E reaches the valve spindle tram poin t when placed

properly , see Figure 80.

I f the valve travels hor i zontal ly then a plumb l ine Shouldpass through the centre of the upper or outer rocker arm pin

A ,

” and the centre of the rocker shaft “ B ,

”Figure 80. A

plumb l ine i s quickly made up with a piece of fine twine anda nu t ti ed at one end of Same .

I f the valve rod is of such a length as to push the upperro cker arm ou t Of plumb , or in any case

“out of square ” tothecentre l ine of the travel of the valve stem , have valve "rod al teredin length to eff ect same , when the aforementioned centre pop“E

,

” Figu re 80,coincides w i th the tram point . Make th is

change righ t at th is time,and DO NOT ALTER IT LATER .

BOILER EXPANSI ON ALLOWANCE .

A locomotive boi ler increases in length.

as steam pressureis raised in i t

,when compared wi th the same boiler cold , the

amount depending upon the length of the barrel , firebox , etc .

A reach rod has a certain defini te length and once th is isarranged , Should never be al tered .

Take an example where two or three inches of air space atl east l ies between the reach rod and the side of the firebox ,also the reverse lever fulcrum pm and the reverse lever rack ,


being in no way connected to the side of the boi ler . The reverse lever in mid gear notch Should stand plumb

,when main

frames are level l ed , see“A , Figu re 81

When reverse lever i s placed in the mIddle notch of i ts rackand the reach rod i s connected

,i ts length

,

“ B ” Figure 81 ,should be such that i t wi l l hold the upper arm of r ocker shaftplumb as Shown at “C ” Figu re 81 .

Let us assume that boi lers are cold during valve settingoperations. In the case where the reverse lever rack , al so thereverse lever fulcrum pin , are both d irectly connected to SideOf firebox , the reverse lever when placed in mid gear notchShould stand plumb , see

“A " Figure 82 , but the centre of thereach rod pin connecting wi th the upper arm of reverse Shaftmust occur ahead Of the plumb l ine passing through the centreof reverse shaft a d istance equal to the amount aff ected byboi ler expansion, see

“ B " Figure 82 .

A ‘

th ird case shows where the reverse lever fulcrum pin isattached to main frame

‘

Of engine or to a bracket at tached tosame , see

“A " Figure 83 , and yet the reverse lever rack i sfastened to Side Of firebox or to the run board , which is in turnattached to Side of firebox and affected by boiler expansion ,see “ B Figure 83 .

In the cases shown in Figu res 8 1 and 82 the reverse lever i splumb when placed in the mid gear notch , Whereas in this casethe al lowance for boi ler

’

expansion is made at the rack , whenerected

,inasmuch that the mid gear notch is arranged ahead

of the plumb l ine which passes through the centre O f the'

ful

crum pin “A” Figure 83 , the d istance be ing equal to“C

Figure 83 ,which i s equal to boi ler expansion eff ect , and has

in turn a proportionate effect on reach rod as Shown at D "

Figure 83 .

The reach rod pin centre , see E Figure 83 , should occurahead of the plumb l ine

“F” Figure 83 , a d istance“G equal

to '“D” Figure 83 ,

when reverse lever is in mid gear notchand boi ler i s cold .

‘

One can almost hear the inqu iry . How much do you allowfor boi ler expansionThere is so much guesswork in th is respect that one i s forcedto reply that the only way to gain the proper informatIonowing to the various arrangements of reverse levers and connections i s to take one Of each class Of engine in turn andpursue the fol lowing course .


When boi ler i s cold take a sui table tram made up to su i tthe class of engine on which the check is to be made , and froma centre pop D "

Figu re 84 , made on a rigid portion of theengine , such as a main frame , which i s not affected by boi lerexpansion , scri be an arc on the reach rod as at

“A " Figure 84 ,

the reverse lever being i n the mid gear notch . Scribe a shortstraigh t l ine on reach rod see Figure 84 , paral lel tothe centre l ine of reach rod . This i s done when you knowthat there wi l l be no changes on an engine , i .e . , in the case of aboil er having a wash out , same would be a good t ime to commence as aforementi oned .

When boiler washout is completed and engine i s ready forthe road w i th maximum boi ler pressure raised , DO NOT attemptto complete your j ob . Wai t unti l the engine has shuntedaround or run say four or five mi les or more , and then put onepoin t of the aforementioned tram in pop “D and scri beanother arc , when reverse lever i s in mid gear notch .

The distance between the Arcs “A "and “E ” along the

straigh t l ine B.C"Figure 84 , i s the actual effec t on reach rod

ow ing to boi ler expansion .

I f ai r reservoirs , etc . , are in the 'way on certain engines ,find a r igid spot not aff ected by boi ler expansion , and fol lowingthe pr incip le of the aforementioned , any old shaped trammay be used i f su i tably r igid for the aforementioned purpose .

RECORDS OF BOILER EXPANSIONS .

S hop records wil l probably show the bo i ler expansions andthei r eff ects on reach rods , etc . , for al l classes of engines re

paired in that shop , for the ready reference of a valve setter .Do not try to , obtain bo iler expansion proper in a back

sh op , where a boi ler steam test , you may think , would servethe purpose

,you get unrel iable resul ts i f you try i t .

ADJUSTABLE REACH Roos.

Many reach rods to - day are adj ustable for length , i n whichcase proceed as fol lowsAdj ust the length of reach rod so that upper reverse shaft

a rm is plumb as shown at B.C” Figu re 85 , when reverse lever

i s in mid gear notch . I f boi ler expansion aff ects the reach rod ,

adj ust the length of the latter to al low for the former aftervalve setting , as shown at

“A " Figure 85 .


NON - ADJU STABLE REACH ROD.

In the case of a non - adj ustable reach rod take note of thefol low ingNo matter whether boi ler expansion aff ects the reach rod

or not , or whether the shop cond i tions at the time al low for

an actual reach rod length change before valve se tting or not ,one can go ahead with the valve se tting after measuring foractual reach rod length al teration , and the amount of al teration in length figurat ively speaking for valve setting purposes .

ACTUAL REACH ROD LENGTH CHANGE To BE AFFECTED .

Case . 1 . Where bo i ler expansion DOES NOT affec t reach rod .

Place reverse lever in mid gear notch . D rop a plumb l inethrough centre of end of reversing shaft and measure thed istance as shown at ”A ” or

“ B ” Figure 86 , as case requires .This is the actual change requi red .

Case 2 . Where boi ler expansion DOES aff ect reach rod .

D " Figure 86 , shows the al lowance made for th is boi lerexpansion efi‘ect and vari es wi th the length of boi lers used .

Place reverse lever in mid gear notch . D rop a plumb l inethrough the hentre of the end of reversing shaft and measurethe d istance as shown at “A "

or“B " Figure 86 , as case

requires .The actual change to be made in the length of the reach rod

by the blacksmi th equals the distance “A " less the distanceD shorten ing , or the d istance

“ B ” added to the distanceD lengthening . In th is case the fron t end reach rod pinhas to be brought to the posi tion shown at C

”Figure 86

by actual change .

FIGURAT IVE CHANGE TO REACH ROD LENGTH FOR VALVES ETT ING .

In al l cases whether reach rod is aff ected by bo il er expansionor not , measure the d istance

“A "or

“B ” Figure 86 , and usesame to guide you in making al lowances on lead and valvetravels during valve setting . S ee detai ls in later chapter.


S et wheels and rol lers Over i f necessary when the weigh t is offsame . Once set properly the wheel s seldom work over duringValve Se tting .

Again there must be no j amb of a wedge to hold an axlebox off i ts j ou rnal . A t th is time make sure that the binders orguard stays which brace the shoe and wedge horns together forthe main drivers , now set u p on the rol lers , have their bol tsand studs wi th nu ts properly tigh tened .

DRIVER WEDGES

S lack down the axle box wedges , see that axle boxes areproperly seated on their j ou rnal s , give the whee l s one revolutionwi th the ai r motor and i f they tu rn freely , set up both maindriver wedges , using a monkey wrench or spanner abou t 9"l ong to pul l up on the nu ts of wedge bol ts as tight as you canpu l l alone , then pu l l each wedge down %3

" and lock wedgebol t nu ts .

The S hoes and Wedges having already been fi tted beforeengine is wheeled al lows Of a fine adj ustment of wedges in th ismanner .

MAIN RODS

Pu t up main rods and see that brasses are a good fi t oncrank pin and crosshead pin respectively . Adj ust the wedgesor d r ive the cotters home properly as case may be in the mainrods .

MINOR DETAILS

S ee that valve rod cotters are properly d r iven home andminor detai .s such as rocker arm pins , etc . , are placed and nu tspul led up proper ly .

S ee that L ink Saddles are tigh t . O ther simi lar detai ls ofthe motion should be checked up and i f O .K . connect up thetwo back up eccentric rods to the two l inks respectively .

FINDING DEAD CENTRES WITH USE OF MAIN RODS

Dead Centres are taken in Valve S etting in order to obtainvalve stem readings which readi ly presen ts an idea of th e ful lgear lead on the engine .

Al l four dead centres are general ly laid off on the r igh t maindriving wheel tyre . This gives a benefi t to valve settersinasmuch that as a man is picking up dead centres , he has


a better opportuni ty to keep an eye on anybody attemptingto or actual ly moving reverse lever from the proper notch ini ts rack wi thout noti fying the valve se t ter . Movemen t of areverse lever wi l l often cau se a fal se reading to be taken . Theposi tion of a reverse lever in i ts rack does not matter whenfinding dead centres . I t i s , however , of great importance tohave the reverse lever in the corner notches when catchingdead centres to take l ead l ines .

To find a dead centre turn the d r ivers around to take upany possible slack in main rod . Con tinue to tu rn whe els unti la main pin reaches approximately 6" or 8" from a dead cen treas far as can be j udged by the eye . See Figure 88 . Stop the

'

rol lers and wi th a conveniently bent wheel tram see Figure 67 ,one po int of which i s placed i n a centre pop made on the sideof the frame or from any su i table fixed poin t , see P ,

” Figure88 , scribe an arc wi th other poin t of tram on the side of thetyre of the righ t main d r iving wheel as shown at “ B .

”Now

take a pai r of d ividers se t conven ien tly say to 4 " and from acentre pop placed in crosshead as shown at

“ C , scribe an arcon gu ide bar as shown at “D .

” I f there i s over sideplay in crosshead , insert packing to reduce same wh ilst takingdead centres .

Now continue to turn rol lers so that main pin approachesand passe s the dead centre . Whilst th is movement i s goingon in d irection “A" Figure 88 , keep one point of dividers inthe pop

“C ” in the same manner as before un ti l the otherpoin t of d ividers passes a coupl e of inches by the previouslyscribed arc D on the gu ide bar Reverse the rol lers to turnthe wheel s in the direction shown by arrow “F ,

”Figure 89

and stop when the free point of dividers j ust reaches “D ,

i .e . , an arc can be scribed to j ust coincide wi th are“D , see

Figu re 89 .

Place the wheel tram point in the fixed pop P and scr ibeanother are on the same side of the tyre see E , fi gure 89 .

With a pai r of oddleg cal ipers se t , say to scribe an arc“G .H . Figure 89 , paral lel to the outside ci rcumference ofrim and long enough to pass through both arcs

“ B and E ,

”

Figure 89 On the arc “G .H . find the central point“J"

be tween points of intersection of the arcs “ B”and E .

Centre pop the po in t“J ,” make a chalk mark around same

and mark i t for the dead centre i t represents to avoid anypossible mistakes . The Pops at “ B ” and

“ E ” are general ly

Shop H intson LocomotiveValve S etting‘

l

:"

77

hammered out at th is time . The other three dead centres canbe found in a similar manner on the righ t driving wheel . Theright ‘back dead centre i s chalked “

RB . and the righ t frontetc .

FIND ING DEAD CENTRES WITH USE OF TRAM

In the event of dead cen tres being requ ired to be found andthe main rod s are not del ivered , the former can be ob tainedwi th a tram of su i table length .

In Figu re 90, i s seen a crosshead pul led back unti l samei s at the back end of crosshead travel or actu ally at t he backbump mark . A fine straight l ine

“AB .

”i s scr ibed on cross

head so that same passes th rough the cen tre of crossheadwri s t pin and i f produced would pass through the cen tre of

driver ax l e when viewed from the‘side as shown in Figu re 90.

Turn main'

driv ers around un ti l the cen tre of main pinreaches a po in t approximately 6” or 8

" from the dead cen tresee Figu re 90. S top the whee l s .

Place one po in t of tram in the CENTRE of main pin and wi thother tram poin t scribe a l ine to cu t the l ine at “C .

Place one po in t of wheel t ram in a fixed centre pop as shownat “P ,

" Figu re 90, and wi th the other tram po in t scri be anare on the rim of the wheel as seen at “D .

”Turn the wheels

so that main pin approaches and passes the dead centre ,meanwhi l e hold ing the tram in the centre of main pin . Watchthe fro nt tram point carefu l ly and j ust as i t coincides wi ththe po int “C " stop wheel s .

From the pop“P " using the wheel tram scribe another are

on the rim of the whee l as seen at “E , Figure 90.

With a pai r of oddleg cal i pers se t to abou t 1% scri be al ine paral lel to the ou ter ci rcumference of the tyre to cu t thetwo arcs scr ibed wi th the whee l tram at “D and E .

Find the centre be tween “D and E at the po in t Fon the l ine paral lel to the rim and centre pop same . Hammerout the pops at D and E " and chalk 3 ring around pop F .

”

I f the wheel s are turned around unti l the pop“ F

”j u st co in

cides wi th one point of wheel tram , when other point i s placedin the fixed pop

“ P " and then are stopped , you have caughta dead centre . Exercise care in finding and catch ing a deadcen tre , i t pays

Shop H ints on Locomotive Valve S etting 79

Al l dead centres can be found wi th the use of a tram in th ismanner and can be rel ied u pon , provi ding the crosshead i smoved to the end of i ts travel , the posi t ion of which co rrespondswi th the dead centre being found and the l ine throughcen tre of crosshead wr i st pin be ing scri bed to su i t each deadcen tre as before de ta i led i n the example j us t given .

CRO SSHEAD TRAVELS AND CLEARANCE

I n the event of finding dead centres wi th main rods Up , thepiston travel and piston clearance at both ends of cyl inderscan be found at the same time by scribing a l ine wi th the useof a Shor t s traigh t - edge in a manner simi lar to that used whentaking piston bump marks and shown at “ C and “D ,

”

Figu re 9 1 , when crosshead i s on the ex treme end Of i ts travelat each end respe ctively .

MAIN ROD ADJUSTMENT

I f the crosshead travel marks l ie central ly between thebump marks , the length of

'

the main rod i s considered O .K .

S hould the main rods need adj ustment take them down ,

adju st for length and leave them down unti l you have takenal l the read ings necessary before taking cu t off s . Pu t u pmain rods later when ready to try cu t o ff s .

Se rious damage to cyl inders and thei r heads has Often beencaused by making mistakes when lengt hening or shorten ing amain rod w i th a view to equal iz ing the piston clearances a tfront and back end of a cyl inder . A l iner taken from the backend of the big end brasses and fi tted in the fron t of same ,lengthens the main rod . V ice versa , a l iner taken from thefront end of big end brasses and fi tted in the back end of

same next to the big end strap , shortens the main rod .

LEAD AND VALVE TRAVEL LINE SLead l ines are always taken in the case of Stevenson Gear

wi th reverse lever i n the fu l l gea r notch . Lead i s always se tto and figured from ful l gear read ings

,hence , when abou t to

catch a dead centre , see that reverse lever i s in the cornernotch .

Run the wheel s around in the d i rection indicated by reverselever . Be su re that valve stems are moving

,thus ind ica ting

al l possible slack motion is taken up . S l igh tly j amm ing the


valve stem gland wi th some packing and by tighten ing up oneside only of same is often done to ensure th is . With wheeltram po int placed in the fixed Centre pop

“P ,

” wai t for thenearest dead centre to come around and when i t arr ivesexactly under the other point of wheel tram , stop the rol lers .I f perchance the dead centre pop on the r im of the wheel

sl ips by a l i t tle , DO NOT back the wheel in the opposi te d irec tionsl igh tly to pick up the centre . Run back a matter of 8" or10” unti l the valve stems are moving , then come ahead again

and catch the dead centre properly without a Sl ip .

When a dead centre i s caugh t properly , take the valvespindle tram which was used to take port marks and bumpmarks of the valve and placing one po in t in the centre popi n cyl inder plug before mentioned scribe a l ine on valve s tem .

This l ine is cal led a “Lead Line , see

“A,Figure 92 .

Turn rol lers to con tinue the movement of driving wheels inthe same direction indica ted by reverse lever and wi th thepoin t of tram appl ied as when taking a lead l ine watch thevalve stem move to a ful l gear valve travel . When the valvestem has reached i ts fu l l exten t of travel and same is on thepo in t of return , scr ibe another l ine on valve stem , see

“ B ,

”

Figu re 93 . This l ine i s cal led a Ful l Gear Valve TravelLine .

"

The ful l gear lead l ines and valve travel l ines can be takenin th is manner for both sides of engine and for both forwardand back up gears . Hook up or Notch up valve travel l inescan be taken by simply placing the reverse lever in the notchrequired and then continue as in the case of ful l gear valvetravel l ines .

The forward gear lead and valve travel l ines are general lyscribed as shown in Figure 94 ,

mostly above and sl igh tlybelow the straigh t scr ibed l ine , whereas the back up lead andvalve travel l ines are general ly scribed mostly below and sl ightlyabove .

MEASURING SLIP OF THE LI NK AND LINK BLOCK CLEARANCE

After having scribed a lead l ine,the valve se tter sti l l holds

the valve spindle tram wai ting to take the ful l gear travel l ine .

The valve setter ’s helper , general ly an apprentice ; havi ngcaugh t the dead centre for the lead l ine taken ,

‘now planks the

wheel tram in a safe place and j umps down be low to thel inks . He scribes l ines or i f there i s no chance to do th is ,


lengthen or shorten same proceed as fol lowsWi th a pair of sharp pointed d ividers , find the centre of the

forward travel l ines which proves to be in the read ing‘ takenand shown in Figu re 94 , behind the central point be tweenthe two port marks . The centre of the back up travel l inesproves to be 54

" ahead of th is centre point .The ru le i s “Always br ing the centre poin t be tween the two

port marks to the centre of the travel l ines .

I n the case taken , the port marks wou ld have to be drawnbackwards towards the centre of forward gear valve travel

and having an indirec t motion , the eccentric rod has tobe lengthened thi s amount owing to engine being in ful l gearwhen reading was taken and the rocker arms be i ng the samelength . We also see that i f same procedure is fol lowed respecting the back up read ing , that the back up eccentr ic rod wi l lhave to be ShortenedI f the rocker arms had been of di ff erent lengths , i . e .

, theupper outer arm 18

" and the lower inner arm 12” long , then

the forward eccentr i c rod length change would be determinedby mul ti plying the 3/16

” referred to by the length of the innerlower rocker arm in inches , i .e . , then d ivide the resul t bythe length O f the ou ter or upper rocker arm in inches , i .e 18

and the answer would be to lengthen the forward eccentr icrod The change to back up rod in th i s case can befigured out in the same way .

Whether to lengthen or shorten an eccentric rod dependswhether motion is D i rect or Indirect . ”

A slotted hole in each eccentri c strap when one bol t only isused for setting valves al lows of temporary adj ustment at thi stIme .

I f bo th eccentr i c rods need to be adj usted exactly the sameamount in the same d irection make both adjustments andDO NOT change the length of a valve rod instead .

LINK LIFTER ADJUSTMENTE qual izing the length of forward and back up valve travelscan be eff ected by adj ustment of the l ink l i fters , providingthere i s su ffi cien t l ink block clearance in l ink in the fu l l gears .

I f when a l ink l i fter length i s changed the l ink block fou l s thel ink in fu l l gear

,a corner notch or notches in reverse lever

rack have to be plugged according to the corner in which thereverse lever i s found when the fou l ing occurs .


PLUGGING A NOTCH

Sometimes a corner notch is plugged to hold a given fu l lgear valve travel to i ts l imi ts and sometimes to prevent avalve from striking i ts bumping point or danger mark as wel las to be sure of l ink block clearance .

THE EFFECTS OF HOOKING UPWhen a reverse lever i s hooked up , towards the mid gear

notch i t has the eff ect of increasing the lead at both ends ofeach cyl inder and shortening valve travel on both sides oflocomotive dependent on the number O f notches hooked up .

EFFECTS OF SHORTENING A REACH RODWhen a reach rod i s Shortened , other condi tions remaining

the same , and new valve stem readings are compared wi ththose taken before the change is made , one finds the leadincreased and valve travel decreased in forward gear al so leaddecreased and valve travel i ncreased in back up gear on bothSides of locomotive . Lengthening a reach rod causes anopposi te eff ect .

EFFECTS OF BOILER EXPANSION

When a valve gear is affected by boi ler expansion the eff ecton the lead and valve travels is the same as in the case ofreach rod shorten ing when you compare the readings takenwhen boiler i s cold and those taken when boiler expansion hastaken place .

EFFECTS OF PLUGGING A CORNER NOTCHWhen a corner notch is plugged and a reading i s taken with

reverse lever i n the new com er notch one finds as comparedw i th reading taken w i th lever in the old co rner notch that thelead is increased and the valve travel decreased in the gearonly where the plugging is done .

EFFECTS OF SHORTENING A LINK L IFTERS horten a l i nk l i fter and you get the same eff ect as shortening a reach rod except that only one side of the locomotive isaff ected

,i . e . ,

the side on wh ich the l ink l i fter change is made .

Lengthening a l ink l i fter causes the opposi te eff ect , to Shortening same .


EFFECTS OF MOVEMENT OF ECCENTRIC SHEAVEAROUND AXLE

Move an eccentr ic Sheave around the axle , i .e ., change i ts

relation to the main pin and the lead i s increased or decreasedat bo th ends of cyl i nder according to the di rection in wh ichthe change is made . FULL GEAR VALVE TRAVEL REMAINSTHE SAME .

EFFECTS OF A CHANGE IN ECCENTRI C ROD LENGTH

Change the length of an eccentr ic rod and lead is i ncreasedat one end and decreased at other end of cyl inder dependenton which way the change i s made . This i s eff ective on theS i de of the locomotive and in the gear where the eccentr ic rodcontrols the valve . The ful l length of the valve travel remainsthe same bu t there is a d i ff erence in the distance the valvetravels on ei ther side of the centre of valve seat as comparedwi th that which occurred before the change . A change in thel ength of an eccentr i c rod in one gear does not affect the otherfu l l gear lead .

I t does affec t the lead in the other gear however , whenreverse lever i s placed in any other notch than the fu l l gear

,

the extent O f the eff ect being dependent upon the amount ofeccentr i c rod change . The e ff ect on the lead in the other geari s most pronounced , when the reverse lever i s nearest to themid gear notch .

The e ffects of a change in the amount of backset to a l inksaddle p in and the back set or fron t se t of a rocker arm wil l bedeal t w i th later in valve setting .

A PECULIARITY OF THE STEVENSON LINK MOTI ON

There are certain troubles wh ich a design er of valve gearsbu tts up against when he gets on to his j ob . H is resu l tsdepend on hi s ski l l and concentration the same as wi th youand you r game , hence one of the pecu l iar i ties of a gear i sl ikely to Show up du r ing valve setting ,

’

which to Show moreclearly what is meant a fu l l gear read ing similar to Figu re 94i s shown in Figure 95 , except that eccentr ic rods have beenadj usted for length and same being exaggerated sl igh tly inorder to demonstrate how to measure lead figu ratively for

valve setting and how to measu re lead for shOp report .


Note how valve travel l ines are equ id istant from cen tre ofport marks for each gear , also that lead l ines are unequald istances from centre of po rt marks in each gear .To measu re lead at each end for the purpose of shop repo rt

a t any time see the fol lowing

How To MEASURE LEAD FOR SHOP REPORT

Take the forward gear reading as an example by wh ich tomeasu re lead at front end . This d istance shown at “

Q ,

Figure 95 , be tween the front lead l ine and front port marind icative of that which occurs at the back steam port in th isour case of inside admission valves proves to be posi tivel ead , whereas at the other end the lead is negative

, i .e

bl ind , Shown at“R ,

” Figure 95 .

Take the back up reading and the lead S , Figure 95 ,measured in the same way from the fron t port mark to thefron t lead . l ine shows 19/ posi tive lead whereas the lead“ T ,

” Figure 95 , at the front steam port and shown at backe nd of valve steam reading shows posi t ive lead . I tfol lows that a sacrifice has to be made somewhere , and as inthe case shown i t is the general practice to square the eccentri crods to valve travel l ines at the expense of the lead . One canget as nearly r igh t as possible by measur ing lead when figur ingfor adj ustment in the fol lowing manner .

How TO MEASURE LEAD FOR VALVE S ETT ING PURPOSES

Se t a,

pair of d ividers to the'

distance between the two

forward gear lead l ines “ F ” and G ,

” Figure 95 . Withoutmoving d ividers to change the measurement , careful ly applyone poin t to the smal l are

“D where i t cuts the straigh t l ineand j ust mark the latter w i th the other point of d ividers asshown at Take the d istance between point “

0"

an d

smal l arc - E ,halve i t and the resul t is the lead change

requi red .

IN ALL CASES OF S TEVEN SON MOT IONWhen the d istance between the lead l ines , see F.G

Figure 95 ,is l ess than the distance between the two smal l arcs

D ” and “E,

” Figure 95 ,

“Lead On ” i s requ ired . When the

d istance between the l ead l ines see Figure 95 , i sgreater than the d i stance between the smal l arcs “D andE ” then “

Lead Off ” i s requ ired .


The forward gear reading at the valve stem shows in thi scase

,

that “.Lead On ” i s requ ired . I f measured in a

simi lar manner the back up read ing at the valve stem showsthat 13/

“Lead Off ” i s requ ired .

How To MEASURE VALVE TRAVE LS FOR VALVE SETT INGPURPOSES

In order to measure for example ful l gear valve travel s forl i fter adj ustment , se t the d ividers to the forward gear

'

travel

l ines on the S traigh t l ine , se e Figu re 95 . Withou tchanging th is measurement apply one po in t of d ividers to

point of intersect ion “M and scr ibe w i th the other po in t ofdividers a smal l mark as at P ,

"F igure 9 5 . Measure the

d istance between poin t “ P ” and point of Intersec ti on “N on

the other back up valve travel l ine . Halve th is d istance andthe resul t i s the amount the forward trave l in th is case has tobe lengthened and the ' back up to be shortened by l ifter adj ustment .

HOW To MEASURE THE EFFECTS ON LEAD AND VALVE TRAVELSBY A REACH ROD OR L IFTER LENGTH CHANGE

One can almost hear the ques tion : How much do you

leng then or shorten a l i fter to square up the valve travels andhow much does i t aff ec t the lead?

The answer i s , ow ing to the pecul iari ties of the various l ayouts of S tevenson Valve Gears , one has to take the eff ects of areach rod or l i fter change on lead and valve travels for EACHclass of engine ONCE and make a note of same for l ater referencedu r ing valve sett ing , on al l engines of each class respec tively .

Proceed as fol l owsHaving taken ful l gear lead and travel l ines in forward gear ,

i .e . , w i th reverse lever in the ful l gear forward notch , take atram (wheel tram w i l l do) , place one poin t in a centre pop , See“ P ,

”Figure 96 , made on someth ing ri gid ,

for instance theboi ler . With the other tram point scri be a l ine on reach rodas shown at “A ,

” Figu re 96 .

Scr ibe a l ine C .D Figu re 96 , with a pair of oddleg Cal ipersparal lel to the centre l ine of reach rod and extend ing a coupleof inches on ei ther side of are

“A .

Hook up reverse lever one notch from the corner .

90 Shop H i nts on Locomotive Valve Setting

rod length , i s in the same proportion as the length of thereversing shaft l i fting arm when compared to the length ofthe upper reverse shaft arm .

I t thus fol lows from the aforementioned that in the case ofa sw i tch engine where valves are always set from ful l gearread ings , and a reach rod has to be changed ,

but not unti lafter valve sett ing i s done , that the eff ect of the change on

lead and valve travels can be al lowed for when valve se tting .

After the reach rod al lowance has been made and yet onefinds the l i fter lengths need adjustment to square the valvetravel s one can also note down the e ff ect on lead which wi l l becaused by l i fter change , see later when fol low ing the train ofmoves when setting a sw i tch engine .

After having figured out changes to l i fters , i f any , and theeff ects on lead , etc . , i t i s found that certain changes to thelead in the forward and back gear is necessary to Obtain thelead requi red on both S ides of engine by movement of theeccentric sheaves , around the axle , proceed to figure ou t VERYCLOSELY the amount of ACTUAL movement of eccentric sheavewi th relation to the axle as fol lows

How FAR TO MOVE ECCENTRIC AROUND AXLE TO OBTAIN AREQUIRED CHANGE IN LEAD

Le t us take one forward fu l l gear reading showing lead linesfor example , see Figu re 98 , al lowing that the lead l ines Showexactly the Change requ i red . Assume for clear demonstrationthat l ead O ff i s requ ired , the length of . upper ou ter rockerarm is the inner lower rocker arm length i s theeccentr ic sheave fu l l throw is and diameter Of axle isMul ti ply by the length Of the inner lower rocker arm in

inches x 12” equalsD ivide the product by the length of the ou ter - upper

rocker arm length in inches , i .e .

,15” and the resu l t i s

3/Mul tiply the l ast resul t by the diameter Of the axle

in inches , i .e . , x 10” and the resu l t i sEfiDiv ide the last resu l t 3

" by the ful l throw of eccentricsheave in inches , i .e . , 3

— 6 and the final resu l t i s theamount APPROXIMATELY that the eccentr i c sheave has to bemoved around the axle , and measured around the surface ofsame where eccentric sheave touches i t .

Shop H ints onL ocomotive Valve Setting“

91

I f the aforementioned had been a case where lead on wasrequ ired the same approximate figur ing shou ld be made up tothis po in t as in the case of l ead off being requ i red . Figure 99wi l l Show why the figur ing is only approximate . Let uscompare bo th cases of Lead On and Lead Off . Takei t for example that Figure 99 , represents the centrel ine of the web of eccentric sheave , when the requ ired lead isO .K . Let

“O .B . represent the posi tion of

'

the cen tre l ine ofeccentr ic sheave when lead on i s requ ired . Let

“O .C .

represen t the posi tion of the centre l ine Of eccentric Sheavewhen lead off i s requ ired . By referring to Fi gu re 99 or

laying ou t to scale you rsel f i t wi l l be seen that the sheave hasto be

'

ac tual ly moved around the axle to Obtainl ead on and to obtain lead off . Thus i t fol lowsMake your calculation and i f a beginner (an old hand knows

by experi ence) make a smal l l ayou t to sca le on a flat brassplate as shown in Figu re 100 to ob ta in

,

the exact amount ofmovement of an eccentr i c Sheave around the axl e .

Don ’

t guess , boys , go r igh t to i t and be sure .

CU T OFF SWhilst an engine can be square as far as eccentric rods ,

valve rods , reach rod and l i fters are concerned , also the leadO .K . , yet i t i s possible for the Cu t Off s at each end of cyl inderfor each gear respectively on both sides of locomotive to beunequal .I f t he di ff erence in Cu t Offs at each end of cyl inder i s kept

wi thi n the forward and back up gear beingconsidered separately , the engine i s general ly accepted asbeing wel l se t .I t i s good practice after having adjusted the length of

eccentr ic rods , to t ry the cu t Off s . Pu t up main rods , samehaving been adjusted for length . The e ff ects and al lowanceson Cu t Off s wi l l be treated also in the next chapter bu t at thi stime let us fol low the taking and squaring Of cu t Off s in forwardful l

,

gear on one side of locomotive .

P lace reverse lever in forward corner notch .

Move engine around forward unti l valve stem moves .

Al l poss ible slack motion having been taken up in thi smann er , tu rn engine unti l the port mark which represents afron t cu t off , arrives exactly under the poin t of the valve stemtram when held in the same posi tion as when por t marks were

Shop H ints on Locomotive ValveSetti ng 93

taken , see Figure 101 . S top engine and measure the di s tancethat the crosshead has moved from it s fron t travel mark , see“A3" Figure 101 .

Make a note of th e len gth of thi s Cu t O ff .Conti nue to turn eng ine in the same directi on unti l the port

marks rep resen ting the poin t of Cut Off for the back po rtarrives exactly under the valve stem tram poin t when held asbe fore explained .

S top engine and measure the di s tance the crosshead hasmoved from i ts back travel mark , See Figu re 102 .

Compare th is back Cu t O ff wi th the Front Cu t Off and ifequal the Cu t O ffs are O .K .

I f C ut O ffs are not equal take the Shortest one from thelonges t and halve the di fference .

S uppose the back Cu t Off was 22 and the fron t Cu t Off23 1A

" take 22" from and l % remains . Hal f of th i sremainder equals Turn engine around to pick up theshortes t , i n th is case , the back , Cut 05 . Tack on bymoving engine around unti l crosshead runs by the 22

" and.stop

when i s reached , see“ B ,

” Figure 102 .

Apply one po int of valve stem tram in the cen tre pop i n theplug in cyl inder as before and wi th other po int of tram scri bea l ine on valve stem , see Figure 102 . The distance “A"

be tween this sc ri bed l ine and the po rt mark which has j ustS l i pped by is the amount Of al teration wh ich has to be effec tedby a . change made in the length of eccen tri c rod to ob tai nequal Cut Off s at front and back end of cyl inder in tha t gea r .

94 Shop H i nts on Locomotive Valve S etting

I f a movement is made to equal ize the Cu t OHS after havingsquared eccentr i c rods from valve travel s , by further adjustment of eccentric rods , there becomes a di ff erence in the leadat one end of the cyl inder as compared wi th the other .

Squaring the service Cu t Off s , i .e . , the Cu t Off s whereengine does most of i ts work , i s considered good practice atthe expense of the lead i f ncessary .

The effect on ful l gear Cu t Off s for a given reach rod or

l i fter change can be easi ly found i f you need same at any timewhen squar ing by the Cu t OHS , by taking the two fu l l gearCu t OHS i n inches as shown in Figu re 101 and 102 and addingthem together .

Hook up the reverse lever one notch out O f the corner ,having scr i bed the reach rod, etc . , as explained and shown inthe case given in Figu re 97 . Take

‘it for granted the amount

of Reach rod change i s as before . Take the Cu t OHS atboth ends of cyl inder again and add the two together . Takethe sum of the two last Cu t OHS from the sum Of the fi rst two

fu l l gear Cu t OHS , halve the remainder and the resu l t i s the .

eHect on a ful l gear Cu t OH for a given Reach Rod al teration ,

in th i s case .

An eHect on,Cut OHS owing to a l i fter length change can be

figured in proportion accord ing to the length of the upper andl i ft ing reverse shaft arms .

Chapter V .

IMPORTANT PO INTS TO REMEMBER W ITH S TEVENSON LINKMOTION .

HE nearer a des igner can get to an ideal lay out , thebroader the field of se rvice is extended in wh ich thelocomotive can work eHiciently and economical ly .

I t is not good shop practice or pol icy for a valve setter tofigure beyond the fol low ing , unless especial ly ordered to do so .

FOR A SWITCH ENGINE .

Square the lead from ful l gear read ings .

Square the l i fters from ful l gear valve travels .Square the eccentr i c rod lengths from ful l gear valve travels

and then try the Cut OHS .

Make the valve rod lengths and reach rod lengths r igh t ,and as there is only one righ t when O .K. , DON

’T CHANGE THEM .

Square the eccentric rod lengths final ly to the ful l gear Cu tOHS , i f after squari ng their length to the ful l gear valve travels ,the diHerence in the ful l gear Cut OHS , on each side of enginein each gear respectively , prove to be not more thanI f same shows a diHerence of 3” or 4

” depend on i t you wil lhave to change the back set of l ink sadd le pin . This is explain ed later in chapter .

FOR A FREIGHT ENGINE .

Sq ii are the lead from ful l gear read ings .

Adj ust eccentr ic rod lengths in the firs t place from ful l gearvalve travels .Square the l i fters from the hook up valve travels , i .e . , travel staken when reverse l ever i s placed in a notch which wi l l causethe valve to Cut OH l ive steam when

'

piston has travel l edapproximately one

- th ird of i ts s troke .

S quare the eccentr ic rod lengths in the second pl ace to thehook up valve travels .Make the valve rod and reach rod lengths r igh t in the first

place , and DO NOT ALTER THEM .

Square the eccentric rod lengths final ly to the hook up Cu tOHS , i f after sq uaring them to the hook up valve travels , thed ifference in Cut OHS on each side of engine in each gea r


respect ively prove to be not more than 2 I f same proves tobe 3" or more , figure on a change to the back set of l ink saddlepm , see later , in chapter .

FOR A PASSENGER ENGINE .

"

The same as in the case of a freigh t engine , with this oneexcept ion

When hooking up for service cu t oHs place the reverse leverin a notch to give approximately 25% Cut OHS , i .e . , to CutOH after piston has travel led approximately . one quarter ofi ts stroke .

One hears the remarks Why does an engineer duringOperations hook up the reverse lever beyond the notch wherevalves are se t The answer i s , the engineer uses h is ownj udgment when feel ing out h is engine for economical resul tscompatible wi th speed and often approaches very close tothe mid gear notch .

I f when valves are set on any engine as per the rul ing hereingiven and the engineer sees fi t to notch Up a l i ttle h igher , therewi l l be no appreciable diHerence in the equali ty of the CutOHS as compared to Cu t OHS by which engine was set .Present day reverse lever racks are general ly slotted regularly

the ful l length , and a double reverse lever catch is arrangedwhereby a hal f way posi tion be tween each rack tooth can beobtained .

The corner notcheséare general ly determined by ful l gear

valve travel SpecificatIOns.

I f in doubt where to place a reverse lever for a given Cut OH,

approximately , proceed as fol lows

REVERSE LEVE R ' POS I TION FOR A GIVEN CUT OFF .

For example,take a passenger engine required to be squared

at 25% Cut OHS and the piston stroke is 30

Place the reverse lever in a notch abou t 4” from mid gearnotch and in the forward gear .25% or M of a 30" stroke is

The sum of two Cu t OHS equal 15

Take'

the front and back Cut OHS in forward gear for onecyl inder . Assume the front Cut OH as 8 1 2

" and the‘ BackCut OH as

98 Shop H i nts on Locomoti ve Valve Setting

the reverse lever to the running notch before moving theengine around .

Now get undernea th the engine and measure the d istanceas shown at “A "

Figure 103 . Let us assume for example th isd istance is 12 Measure al so the d istance “B ” Figure 103 .

Let us assume th is d is tance as 3” Move reverse lever intothe back up running notch of rack wi thout moving enginearound . Measure the d istance “C .

"Le t us assume this

d istance as The d istances B and C " Figure 103 ,

general ly prove to be about equal . Take i t for granted therocker arms are of equal length and when the hook up valvetrave l l ines are taken the read ing demands a push ing ahead ofthe valve M" by adj ustment of the forward eccentric rod , seeFigure 104 , also a pul l ing back as i t were of the valveby the adj ustment of the back up eccentric rod .

Let us sti l l adhere to an engine wi th Indirect Motion . Byreferring to Figure 104 a valve stem read ing on the left side isShown above a skeleton sketch of a " l ink and eccentric rods .

Note that “A " and “B ” represent the posi tions of l inkb lock in l ink when the reverse lever i s hooked up respectivelyin forward and back up gear when main pin is on a dead centre .

To obtain the required cHect in forward gear j ust imagineyou can move the l ink so as to turn about the point “ B ”

without having any eHective movement on the back up gear ,yet to move the poin t “A " back to a new posi tion “C .

"

The rocker arms being of the same length , the required al terat ion at the valve stem is eHected . Take note the l ink has beenmoved to another posi tion ind icated by the dotted l ine , necessitating a shortening of the forward excentr ic rod V

", and a

lengthening of the back up eccentr ic rod which is easi lyseen from the proportionate distances shown . Note thesedown as first changes .In a simi lar manner imagine you can hold the poin t C

in the new posi tion and move the point “ B ” ahead topoin t “D .

" This means a further lengthening of the backup eccentr ic rod and a further shortening of the forwardeccentr ic rod Add the two changes for each rod t e

spectively and separately and the final actual change to bemade to the forward eccentric rod is to shorten same 27/64

”

and to lengthen the back up eccentric rod

Figuring out changes to eccentric rods from a hook upreading in th is manner can be depended upon , and needs only


a trial to confirm same . I t is espec ial ly useful when an engine18 needed on the ou tgoing track in a hurry

,etc .

EFFECTS ON LEAD AND HOOK UP VALVE TRAVELS FOR A

G IVEN REACH ROD OR LIFTER LENGTH CHANGE ON

FREIGHT OR PASSENGER ENGINE .

In the case of a freigh t orpassenger eng ine the eHect on ful lgear lead for a given reach rod or l i fter length change can befound in the same manner as explained for a sw i tch engine .

The cHect on hook up valve travel s - for a given reach rod or

l i fter length change can be found in the same manner as ex

pl ained in the case of ful l gear valve travels on a swi tch engine ,except that the reverse lever is placed in the running notchfor the first valve travels scr ibed and hooked up a notch nearermid gear when the second set of valve travels are taken .

KEEPING CHECK ON ACTUAL CHANGES .

Whenabout to make final changes in the lengths of rods , etc . ,

check same before and after the change is made . Don '

t trustanybody

Ask for what you want i f somebody else is making thechange . I t i s up to you to see that you get i t right .

POINTS WORTH WHILE IN CUT OFFS .

Bear in mind,an engine i s considered O .K . when squared

to the l ive steam Cut OHS . NO NEED TO WORRY ABOUTSQUARING THE EXHAUST CU T OFFS .

Hooking up a reverse lever towards the mid gear notchduring Operation shortens the Cut OHS at both ends of cyl inderson both sides of locomotive in the gear ind icated by the reverselever position .

Shorten ing a reach rod length shortens the cut OHS at bothends of cyl inders on both sides of locomotive in forward gear ,and lengthens the cut oHs at both ends of cyl inders on boths ides of l ocomot ive in back up gear , when comparedwith thatwh ich occurred before the changeLeng thening the reach rod has a opposi te cHect to Shorten ing .


In any case , scribe the l ink saddle wi th respect to the l inkbefore separating them .

The back set may h ave‘

to be increased or decreased . Theexact amount wil l have to be determined by tr ial . Figure105 Shows the back set Of l ink saddle pin .

Try out by increasing the back set wi th temporarybol ts wel l tigh tened through l ink and l ink saddle .

Replace same on engine and make the necessary connections .Square up the eccentric rods to another hook up read ingtaken on the aHec ted

‘

side or sides . Try the Cut OHS , and i fan improvement is shown the movement of l ink saddle pin hasfavored same . I f not make the change in an oppos i te d irection .

DO not expect to square the cu t oHs exactly .

I f the resul t Shows a diHerence in Cut OHS to be withinand the se t of the inner or lower rocker arm is in the righ td irect ion , smile and let her go.

After the new posi t ion of the l ink saddle , with respect to thel ink is found , the bol t holes w i l l have to be reamed out to su i tand new bol ts or rivets appl ied .

LAY ING OFF ECCENTRIC SHEAVE KE Y WAY S .

Eccentric sheave key ways are general ly marked OH andmachined , also eccentric sheaves fi tted and keyed to the axleof the main d r iving wheel s before being sh ipped to the ErectingS hop .

TO lay OH the eccen tric sheave keyways on the axle ready'

for

machin ing , no matter whether the wheels are pressed on theaxle or not , proceed as fol lows :Take a piece O f flat plate , preferably brass , and place a

sharp l igh t centre pop i n same as shown'

at“A Figure 106 .

S et you r sharp divider po in ts to hal f the diameter of the axlewhere the eccentric Sheaves have to be fi tted .

Place one po in t of dividers In centre pop A and scribe acircle wi th the other po in t of d ividers , S eeNow set your dividers to hal f the fu l l throw of eccentric

Sheaves . Place one po in t Of d ividers in centre pop“A ” and

scribe another ci rcle,see S cr ibe two straigh t

l ines “B C . and “

DE . at righ t angles to each other , bothof which pass th rough the centre of centre pop

“A .

I t has been previously explained that the centre l ine Of motionof eccentr i c rods occu r as per the design Of the motion . T hI S


centre l ine.

O i motion l ies at an angle general ly to the l inewh ich pa sses through the centre Of axle and the centre

of ma in pin .

S cribe a straigh t l ine F .H representing the centre l ineO f motion to pass through the centre Of centre pop

“A,and

at an angle to the straigh t l ine “A .K , according to the blue

prin t instructions .

NO matter i f the centre l ine O f motion of eccentric rod coincides wi th the straigh t l ine “

A K ,

”or i f i t i s elevated or de

pressed wi th respec t to same , the eccen tr i c sheave keyways arelaid Off on the plate from the centre l ine of motion .

Let the straigh t l ine F .H Figure 106 represent the cen trel ine Of motion of eccentri c rods for this our example . Thestraigh t l ine

“A .K

"passes through the centre Of the

‘

keywaywhich i s used to key the main dr iving wheel centre to the axle ,as shown at C .

Lay OH a straigh t l ine J .G at righ t angles , to straigh t l ineF.H and passing th rough the centre of cen tre pop A .

By tracing or by reference to blue prin t one can find on wh ichSide of the l ine J .G , the centre O f eccen tr ic sheave keywayswi l l occur .

Let us continue wi th a case Of inside admission valves andind irect motion . This mean s , the keyways wi l l occur on theother side Of the l ine “

J .G , when compared wi th the side onwhich the crank pin i s si tuated

Scribe a l ine L .M” accord ing ly , paral lel to J .G and on

the Side furthest from the main pin . The dis tance betweenthe two l ines measured along the l ine “

F .H must equal thelap of the valve , when rocker arms are of equal length .

I t may possibly occur that “ posi tive lead " i s specified forboth gears , or the valve to be Line and Line

”in bo th gears ,

or i t may be that Posi tive Lead" i s requ ired in one gear and

“Negative Lead ” i n the other . In any case mark OH froml ine “

L .M. Take for example that posi tive lead in bothgears i s required .

Lay OH a straigh t l ine N .O paral lel to L .M the distance be tween the two l ines measured along the straigh t l ineF.H being equal to the amount Of “ Posi tive Lead required .

Note in al l cases where Posi tive Lead is requ ired that thelead is laid OH from the l ine “L .M in a d irection away fromthe centre pop

“A,whereas Negative Lead ” i s lai d OH from


In the case where wheels are al ready pressed on the axle ,locate the centre l i ne Of whee l centre keyway . This usual lycu ts a straigh t l ine which passes through the centre of axl eand the cen tre of main pin . This must be found on the axlebetween the wheels . I t i s general ly found in a prac tical waywi th the use O f a j ig .

The j ig i s careful ly made wi th a tu rned pin as shown at EFigure 108 . The base Of the j ig i s machined to fi t the axlediameter Of the class Of engine the j ig i s in tended for. Whenthe j ig i s made , i t i s carefu l ly laid OH, inasmuch that the mark“D " l ies radial ly correc t on a straigh t l ine , i f same cou ld bescribed from the centre of the axle to the centre Of the tu rnedpin Of the j ig .

When applying the J Ig to an axle , as shown , see that the partsare c leaned and the poin t of the pin “ E ” fal l s in to the centreof the inside end of main pin . I f point of pin fal l s a l i ttlebe low the centre Of main pin , be sure that i t i s held O .K . on

a radial l ine scri bed from the centre Of inside end Of main pintowards the centre of axle .

Scribe a mark on axle at the end of the l ine D , which isal ready on the

'

j ig .

With the use Of a box square scribe a l ine lengthwise on theaxle from this mark . Consider th i s l ine as the continuationof the centre l ine of wheel centre keyway .

You can now proceed as before explained to lay out the centrel ines Of the eccentric keyways , etc .

The foregoing i s a good practice , and i f owing to a possibl ere - arrangement Of the parts Of an engine du ring constructi on ,

and an eHect on lead i s caused , then same can be adj ustedby stepping the eccentric key when valve setting .

To FIND APPROXIMATE LENGTH OF ECCENTRIC RODS .

To Obtain the approximate length Of eccentric rods :Leve l main frames .D i sconnect the l ink in order to be able to move rocker

arms , etc . , for convenience .

D rop a plumb l ine through the centre Of rocker shafts as atR ” Figure 4 6 .

0

D rop a l ine over main driving axle as at S Figure 4 6 .

Measure the distance between these two l ines as Seen atT " Figure 4 6 .


To the distance“

T add hal f the diameter of the maindriving ax le and obtain the dis tance “ U ” Figure . 4 6 .

From thi s distance U ”take away the amount of backse t

of the 1nner rocker arm as shown at “A ” Figure 109 , i f any i spresent or i f a case occurs as shown in Figure 1 10, add thedistance

“A Figure 1 10to the distance “U ” shown in Figure4 6 .

Now take away from the last resu l t the distance from thecentre Of l ink pin to the l ink rad ius , as Shown at C

” Figure 49 .

Again take away the distance from the centre of eccentri cstrap to the bu tt for the eccentr ic rod as shown at “A ” Figure1 1 1 .

Final ly deduct from last resu l t to a l low for eccentric rodadjustment , and you have the approximate length Of eccentricrod from centre of clev ice pin to the end Of eccentric rod wherei t bu tts eccentric strap .

Another method when rol lers are under main driving wheels ,by which each eccentr ic rod approximate length respec tive lycan be Obtained qu ickly is as fol lows

Take for example forward gear ri gh t side . Place reverselever in forward corner notch . S pot right main pin on frontdead centre . Se t main valve on r igh t side Of engine to specifiedfu l l gear lead at the fron t port .

Raise the r igh t forward eccentric strapwhich is properly appl i edto i ts sheave , i n a l ine wi th top l ink pin centre , and get you rhelper to hold t he l ink abou t square to the eccentri c rod centrel ine Of motion .

Measure from the centre O f top l ink pin hole , to the bu ttOf the eccentric strap and deduct from this d istance V4 for

eccentric rod adjustment and you have the requ ired approxi

mate length for blacksmi th .

Take each eccentric rod approximate length in a simi larmanner separately

,taking a dead centre for each Side Of loco

motive and having the reverse lever in the forway or backupcorner notch when measu ring the length of the respectiverods . I f a back dead centre i s u sed , set the valve to the Specified lead at the back port . I f a front dead centre , use thefront port .

Chapter V I .

VALVE SETTING ON A SWITCH ENGINE FITTED WITHSTEVENSON LINK MOTION

Assume for example that the steam lap of the valves is lThe specified fu l l gear lead in both gears i sThe spec ified fu l l gear valve travel i sThe fu l l throw of eccentr ic sheaves i s 6The d iameter O f axle where eccentr ic Sheaves are fi tted is:9

”.

The rockers are ind irect .The rocker arms are Of equal length .

The upper reverse Shaft arm is one and a hal f times as longas the reverse shaft l i fting arms .The reach rod 15 not aHected by boi ler expansion .

That fu l l gear lead i s aHected at each end of cyl inde rwhen the reach rod is l engthened or ShortenedThat fu l l gear valve travel i s aHected Vs at each

end when the reach rod i s lengthened or shortened

That motion i s assembled except eccentric straps and rods ,valves and valve rods .The pi tch O f the reverse lever rack teeth and lever catches

are such that wi l l al low the reach rod to be moved at eachnotch ing as lever i s being hooked up .

Obtain the information requ ired for valve setter ’ s shopreport

_

before main valves are pu t in steam chest , i .e .

Length and width Of steam ports .Type Of valve .

Inside or ou tside admission valves .Thickness O f valve l ip i f a D Valve .

Whether “A l len ". ported i f a D ”Valve .

Thickness of valve seat i f a D ” valve i s u sed .

The steam lap O f the valves .

The exhaust clearance , i f any , or the exhaust lap Of valves .Eccentric sheave fu l l throw , or any other i tems requ ired

which can be taken at this time .

B low out steam passages from boi ler to steam chests .

Pu t main valves in .

Pu t steam chest covers on in the case Of piston valves?

Shop H ints on Locomotive Valve Setting 1 1 1

Take valve bump marks or danger marks .

Take port marks al low ing . for valve stem expansion andpiston rod volume in - the case Of INS IDE ADM I SS ION VALVESONLY .

Scri be two smal l arcs equ idis tan t from the centre Of the twoport marks to indicate the specified fu l l gear lead .

Apply loose tin coverings to protect valve stem read ingsdu ring valve se tt ing .

Put on steam chest covers at th is time in the case of DV alves .

B low through and clea r steam ports from valve chests tocyl i nders

Pu t in pistons and connect to crossheads , see ing that pistonrod glands , etc . , are on piston rods p roperly .

D rive home the piston rod cotter in crosshead .

Put up fron t cyl inder heads and tighten th ree or four nu ts .

Take pi ston bump marks:Jack main frames level .Pu t up valve rods when valve stem glands , etc . , are on O .K .

See that valve rod cotters are d r iven home properly .

Check up valve rod lengths , and i f a change is necessa ry ,

MAKE IT NOW .

Check up reach rod length . I f same i s adjustable , plumbthe reverse shaft upper arm when reverse lever i s in mid - gearnotch Of rack at th i s t ime . I f reach rod i s not adj u stable andi t i s not convenien t to make the change at th i s t ime , make anote of the actual change to reach rod length requ ired . Thefigu rative change to reach rod length for valve setting pu rposesequals the actual change In th is our case , where reach rod I S

not aHected by boi ler expansion . Assume that reach rod

requ ires shorteningPu t rol lers under the main d r iving wheel s properly .

Se e that main d riv ing ho rn binders are tigh tened up .

Se t up main d r iving wedges .Pu t up main rods .Adjust main rod wedges or drive cotters as ca se may be .

GO over the motion and see that rocker and reverse shaftbrackets are bol ted properly and al l motion pin nu ts are tigh t .Check up fu l l throw Of eccen tri c sheaves and incidental ly

thei r approximate posi t ion wi th respect to the main pin . Now18 the t ime to correct errors .


Pu t up eccen tr ic straps and see that Same can be pu l l edaround one complete tu rn easi ly when bol ted tigh t .Take ou t al l unnecessary sets and twists from eccentr i c rods .Pu t up eccentric rods and bol t wi th one bol t on the strap

end in the slot hole .

Tigh ten l ink pin nu ts .Adj ust the reverse shaft balance spring and see that reverse

lever can be moved freely in bo th d i rections from one cornerto the other .Place reverse lever in fu l l gear forward notch and see that

same i s not moved unti l you are ready to take a back upreading .

Tu rn engine in forward gear and find a dead centreBack up the engine un ti l th is dead centre found passes the

poin t of wheel tram when held properly 8" or

Come ahead again’

and catch th is dead centre wi th wheeltram .

S cribe the lead l i ne on valve stem for th is dead cen tre .

Scribe the piston crosshead travel mark for th is dead centre .

S end apprentice underneath to measure the sl ip Of the l ink.and l ink block clearance whi lst you scribe the ful l gear travell ine as the helper moves engine around forward .

Keep an eye ou t to see i f valve rigging foul s anywhere .

I f eccentric straps fou l the ash pan door clear same immediately .

Keep an eye on disinterested individual s who may poss iblymove the reverse lever w i thou t your knowl edge , thus renderi nga false reading . This frequently happens and causes unnecessa ry extra labor .Find the next dead centre .

Back up the engine as in the case Of the finding of the firstdead centre

,come forward again and catch this second dead

centre .

Scribe the second lead l ine .

Scribe the piston crosshead travel l ine whi l st on th is deadcentre .

Continue in this manner and in one complete revolu tion Ofthe main d r iving wheel s forward Obtain the fol lowingThe four dead centres .The four pis ton crosshead travel l ines.

The forward ful l gear valve travel l ines .The forward fu l l gear lead l ines .

S hop H ints on Locomotive Valve Setting 1 15

Note down as the actual change to make in l inkl i fte r length , bu t not at th i s time .

Figu ri ng on th is l i fter change , the forward fu l l gear leadfiguratively speaking now at wi l l be increased toalso the back up fu l l gear lead now at bl ind wi l l become

bl ind .

The valve travels 6 14” are longer than spec ified . In order

to reduce same to 6 a corner notch in each gear has to beplugged , or i f a screw reversing gear , the co rner stops have tobe arranged acco rdingly .

Plugging a corner notch aHects the fu l l gear lead .

The forward fu l l gear lead figured at wi th reverselever in the notch which has to“

be plugged , becomes M" wi thlever in the new com er notch .

Similarly the back up fu l l gear lead figured up to th is timeas bl ind becomes bl ind . See eHect on lead andvalve travels by hooking lever u p one notch in the early partof chapter .Don 't forget a co rner notch may need plugging because Of

valve fou l ing a bumping poin t after making eccentric rodadjustment .

Now is the time to plug the co rner notch or clear the partwhich fou ls in steam chest i f a “D ”

Valve .

Compare the lead specified wi th the lead figu red out

up ti l l th is time and i t i s seen that in forward gear leadOH i s requ ired . Back up fu l l gear lead being bl indneeds lead on .

Figure ou t as per previou s explanation the amount to moveeach . eccentr i c sheave around the axle . In th is case theforward gear lead OH amounts to a figu rative movementOf and the back up %3

" l ead on , figures out asThe actual movement Of the forward gear eccen tr ic sheave

measu red where i t touches the axle i s and being a caseOf lead OH, the sheave i s moved around the axle

’

in a d irec tiontaken by the d r iving wheel when runn ing back up .

The actual movement of the back up eccentr ic sheavemeasu red at the axle i s bare and being a case Of lead on ,

the eccentric sheave i s moved around the axle in a di rectiontaken by the d riving wheel when running back up al so .

A green hand on valve setting should always make a smal llay ou t after figu r ing the amount of eccentric sheave movement requ i red in order to ge t the actual amoun t requi red .


Make a note Of actual amounts to move eccentri c sheaveson axle and In wh 1ch directIOn .

Pu t up main rods .

Take fu l l gear cu t OHS .

Equal ize the ful l gear cu t OHS by adj u stment O f eccentricrod lengths i f the diHerence in cu t oHs i s or less andsuHer the eHect on fu l l gear leads .

Equal ize the fu l l gear cu t OHS by adj ustment Of the l inksaddle pin , i f the diHerence in these cu t OHS i s over prov id

ing the se t of lower rocker arm is in the righ t d irection . Prev iously explained .

S end reach rod and l ink l i fters to blacksmi th to have changesmade .

Send eccentr ic rods to have changes made . S ame be ingequal to the distance as shown at “A” Figu re 1 13 , i n eachcase to al low of a tu rned bol t fi t when re - assembl ing .

Mark and scribe eccentric sheaves both ways as a checkbefore taking down and stepkeying same to Obtain the requ iredmovement around axle .

When par ts are retu rned to engine , check up to be sure thatthe changes have been made correctly . Watch out that rodsets and twists are as before .

Replace parts , finish OH by tigh tening nu ts and spl i t pinningwhere requ ired , etc .

I f what i s known as a fu l l card is requ ired , i .e . , the fu l l gearleads , valve travels , cut OHS , pre — admission , etc . , take thedesired information from the engine AFTE R al l rod changes ,e tc . , have been made including eccentric sheave movements .

NOTE , i f fu l l gear travels are correct and equal ized by l i fteradj ustmen t or by plugging a corner notch in rack in one orboth gears , one can figu re on equal iz ing the cu t OHS by adj ustmen t Of the eccentr ic rods respectively w i thou t worrying whatcHect on cu t OHS the movement O f an eccentr ic S heave aroundan axle wi l l have .

I MPORTANT POINTS TO REMEMBE R FOR A SWITCH ENGINE

When ful l gear readings have been taken in the case Of aSwi tch engine and there is a figu rative reach rod change present ,DON ’T FORGET to make al lowance for same on fu l l gear leadsand valve travels on both Sides O f engine in both gears .

1 18 Shop H i nts on Locomotive Valve S etting

The pitch Of the reverse lever rack teeth and lever catchesare such that wil l al low the reach rod to be moved ateach notch ing as the lever is being hooked up .

Obtain the necessary information for valve setter ’s reportbefore mam valves are put Into steam ches ts , i .e .

Length and w id th Of steam ports .Type Of valve .

Inside or Outside Admission Valves .

Thickness of valve l ip i f a “D ”Valve .

Whether “Al len ” Ported i f a “D ”Valve .

Thickness of valve seat i f a “ D Valve is used .

The steam lap Of the valves .The exhaust clearance , i f any , or exhaust lap Of valves .Eccentric S heave ful l th row , or any other i tems cal led for

wh ich can be taken at th is time .

Blow ou t steam passages from boiler to steam chest .Put main valves in .

Put steam chest covers on In the case Of p iston valves .Take valve bump marks or danger marks .Take port marks al low ing for valve stem expansion and

piston rod volume in the case of “ INSIDE ADM I S S ION VALVESONLY J

’

Scribe two Smal l arcs equ id istant from the centre of the twop ort marks to ind icate the specified ful l g ear lead .

0

Apply loose tin cover ings to protect valve stem read ingsdu r ing temporary absence dur ing valve setting .

Put on steam chest covers in the case Of D Valves at th is

between valve chests and cyl inders .Put in pistons and connect to crossheads when the p1ston

rod g l ands , etc . ,are .On the pi ston rod O .K .

Dr ive home the cotter through the piston rod and crosshead .

Put up front cyl ind er heads and nip tight wi th three or fournuts at least .Take pi ston bump marks .Level the mai n frames wi th j acks .

Put up valve rods when valve stem glands , etc . , are in pos it ion O .K.

Dr ive home valve rod cotters .Check U p lengths Of valve rods and I f a change IS requ i red ,

MAKE IT NOW .


Check up reach rod length .

I f reach rod i s adj ustable , plumb the upper reverse Shaftarm , when the reverse lever i s in mid gear notch , for valvese tti ng purposes and when finished i t i s a cinch to lengthen thereach rod by adj ustment , enough to OHse t the eHects, i f any ,

.

Of boil er expansion .

Assume that our case is shown in Figure 1 14 .

The figu rative change for val ve sett ing purposes is shown as34" at “ C .

”Make a note of same for reference later . The

actual change al low ing for boi ler expansion eHect on reachrod i s 3 4

” added to which ‘resul ts in lengthening bythe blacksmith after al l changes have been figured .

Make a note O f actual reach rod change .

Put rol lers under the main driving wheels properly .

Tighten main driving horn binder bol ts and studs .Se t up main dr iving wedges .Put up mai n rods .

Adj ust main rod wedges or drive cotters as case may be ,GO over the motion and see that al l rocker and reverse shaft

brackets are bol ted properly and al l motion pin nuts , etc . , aretight .Check up the ful l throw Of eccentri c sheaves and thei r

approximate position w i th respect to the main pin . Now isthe time to correct an error in this respect .Put up eccentr ic straps , tighten strap bol ts and see that a

complete turn‘can be made w i th each eas i ly .

Take out al l unnecessary sets and twists from eccentr ic rods .Put up eccentric rods and bO l t w i th one bol t in the strap

end in the Slot hole .

Tigh ten l ink pin nuts .Adj ust the reverse shaft, bal ance Spr ing and see that reverse

lever can be moved freely in both d irections to reach the cornernotches .

Place reverse lever in ful l gear forward notch and See thatsame is not moved unti l you see fi t or you are ready to take aback up read ing .

Turn engine fo rward and wi th one complete revolu tion Ofthe main driving wheels , proceed ing as detail ed in the case Ofthe switch engine .

Find the fou r dead centres on the ri gh t main driving wheels .Scribe the piston crosshead travels .Scribe forward ful l gear lead l ines .


Let Figure 94 represent a ful l gear reading taken to servefor th is example , al though both sides Of locomotive have to beconsidered .

Adj ust the eccentr ic rod lengths from the ful l gear read ingsas explained in the case of a sw i tch engine at th is t ime whichmeans in our example the forward eccentric rod has to belengthened and the back up shortenedNote down the fo rward and back up ful l gear l eads from the

read ings taken , keeping each Side Of locomot ive separate . Ou rexample shows bl ind in the forward and lead inback up gear .Note down the forward and back up ful l gear valve travels

for both Sides of locomotive keeping them separate .

Our example shows valve travel in the forward and6 7 8

” in the back up ful l gear .C lean OH the ful l gear lead and valve travel l ines from the

valve stems , renew .the marking and scr ibe the straight l ineonce again through the port marks .The reverse lever being in the forward hook up notch , move

engine ahead and scribe the hook up valve travel l ines duringone turn of the main

,drivers on both sides of locomot ive .

I f the eHect O f a reach rod length change on hook up valvetravels is not known , NOW i s the t ime to find i t as beforeexplained and make a note of same .

Place reverse lever in the back up hook up notch .

Move engine back up and scri be the hook up valve travell ines for back gear on both Sides O f engine dur ing one tu rn ofthe wheels .

Let Figure 1 16 represent the hook up read ing taken (exaggerated for demonstration) on the same locomotive on thesame side after adj ustment Of eccentr ic rods has been madefrom the ful l gear read ing Shown in Figure 94 .

Adj ust the eccentr ic rod lengths from this hook up reading .

Accord ing to Figure 1 16 , the forward eccentr ic rod requi resShorten ing and the back up eccentr ic rod is to be lengthened .

Figure 1 17 Shows more clearly the actual adj ustment Ofeccentric rods as before explained .

Al low for the cHect O f the figurative lengthening Of

reach rod on ful l " gear lead , ful l gear valve travels and hookup valve t ravels . See Fig . 1 14 .

Forward ful l gear valve travel taken from read ing asfigures out as 6

‘ Shop H ints on Locomotive Valve Setting 123

The back up ful l gear valve travel taken from reading asfigures down to 6M”.

The forward ful l gear l ead taken from reading asbl ind figures out as bl ind .

The back up ful l gear l ead taken from reading as

figures out to

The forward hook up valve travel taken from read ing at2 figures out to 2 1 2

”

The back up hook up valve travel taken from reading as2 figures ou t to

4+ 75

De termine the l ink l i fter length adj ustment requ ired toequal ize the hook up valve travels last figured .

The forward and the back up 2M” wil l both equali f the reach rod is lengthened M"

.

The reach rod has been taken care of however , therefore thel ink l ifter has to be lengthened Of M” which amounts to

ful l , owing to the proportionate length Of reverse shaftarms . Note

'

down'

the l ink l i fter change requi red .

Al low for the eHect O f ful l lengthening Of l ink l i fteron ful l gear lead and ful l gear valve travels .The forward ful l gear valve travel last figured at 6 is

brough t to GM".

The back up ful l gear valve t ravel figured at 6M; i s broughtor reduced to 6M".

The forward fu l l gear lead figured at bl ind now becomesbl ind .

124 Shop H i nts on Locomotive Valve S etting

'

/I‘

he back up ful l gear l ead figu red at now be comes1 1

I f you plug a corner notch in each gear to bring the ful lgear valve travels to 6”don

'

t forge t the eHect on ful l gear lead .

Plugging a notch In our example amoun ts to the movementOf M” as far as reach rod 1s concerned .

The forward ful l gear l ead wh ich was figured l ast asbl ind now is brough t to bl ind .

The back up ful l gear lead which’

was figured last asnow becomesLead specified in ful l gears i s therefore to Obtain

same , the forward eccentric sheave has to move around to giveM,” lead on and the back up eccentric sheave is moved aroundto take lead OH.

Figure ou t the d istance to move eccentr ic Sheaves aroundthe axle in a manner the same as explained in the case of aswitch engine .

Having adj usted the eccentric rods from the hook up readings , put up main rods and take the hook up cut OHS beforemaking any actual changes to rod lengths , etc .

Final ly adj ust eccentr ic rods to equal ize the hook up out

OHS i f less than 2” diHerence in same is present .I f the diHerence in hook up cu t OHS is more than 2 square

same by adj ustment Of l ink saddle pin .

Make al l rod length changes and move eccentric sheavesaround the axle the correct amount , stepkey ing same for bes tresul ts .Keep check on a l l changes before and after they are made

to see i f made O .K . , includ ing or iginal sets and absence Of

twists in rods .I f a record Of pre - release , pre - admission , etc . , i s required

make al l changes including movements O f eccentric sheavesbefore taking the necessary information known as a FULLCARD .

The specifications in one shop Often diHers considerablyfrom another , but i f the methods previously explained arestud ied careful ly no d iffi cul ty w i l l be exper ienced in complyingw i th shop demands .A valve setter may be cal led out to square Up the eccentri c

rods from the valve travels In a hurry wh ilst engine i s on theoutdoor track . As long as the port marks have been takenproperly the engine can be moved slowly g iv ing the valve

Chapter V I I .

WALSCHAERT VALVE GEAR

HERE i s a type of reversible va lve gear,largely used

tod ay , known as the“Walschaert Valve Gear . "

The “Walschaert Valve Gear ” i s an ou tside motion,

1 .e . the Source of the valve motion as wel l as the valve gear l ieson the ou tside of the main frames Of a locomotive .

A CRUDE ENGINETO obtain a clear idea of this motion , le t us revert to a crude

engine , Simi lar to figure 1 and shown in Figure 1 18 . I t i seasi ly seen that the engine is non f rev ersible ,

explained in

chapter 1 . A valve i s used having no steam lap,no lead , no

exhaust clearance nor exhaust lap.

An inside admi ssion valve i s represented at G and anInd i rect rocker shaft at “K .

"

The source Of valve motion i s se t up by an eccentri c crankpin “A” supported by an eccentri c crank arm which in tu rn issecu rely fastened to the end Of the main crank pin B ,

” samebeing represented in Figu re 1 18 .

The eccentri c rod “ C”connec ts wi th the lower rocker arm

at D .

"

The valve rod connects wi th the upper rocker arm at E .

The valve being Inside Admission and wi th due respect tothe posi tion of eccentr ic crank pin in relation to the main pin ,i t i s evident that this one way engine moves in the directionindicated by the arrow “

H .

" Note in this case , when thecentre l ine O f valve stem “

J" i s p roduced backwards , that i t

passes through the centre O f rocker shaft K .

”

I f the engine was requ i red to run in the d i rection indicatedby arrow “

L then same cou ld be eHec ted by connectIngthe valve rod F to the point “N ” instead of to “ E ” thusforming a direct rocker , see Figu re 1 19 .

When valve rod is connected to rocker arm at E , theengine wi l l Operate in one di rection and when connected toN Operates the Opposi te way .

128 Shop H ints on Locomotive Valve Setti ng

A CRUDE REVERSIBLE ENGINE

Egide Walschaert conceived an idea whereby -

a sui tablearrangement Of rods , etc . , was made so that the back end Ofvalve rod could be passed from point “ E " to point N atwil l wi thou t breaking a connecti on ,

thus arriving at a reversiblegear .The indirect rocker EKD, see Figure 1 18 ,

i s replaced bya _ l ink and the rocker Shaft now becomes known as the l inkfu lcrum . See Fig . 120.

The valve rod F , Figure 1 18 , i s arranged to carry a l inkblock which fi ts in the slo t Of the l ink . The valve rod nowbecomes known as the radius rod .

The radius of the l ink i s equal to the valve rod di s tancesee Figure 120.

The radius rod i s extended beyond the l ink , i n th is case ,and is moved up and down by a radius rod l i f ter as shown at

The reverse lever T is connected to the reverse shaftupper arm “

Q by the reach rod “S .

The lower or l i fting reverse shaft arm P connects wi ththe radius rod l i fter “ O .

”

The reverse lever i s shown in mid gear posi tion . In thi sposi tion the centre of l ink block coincides wi th the centre of

the l ink fu lcrum at the poin t “V ,

” Figure 120. I f the engineis moved around at th is time , there would be no movement Ofthe valve or radius rod .

D IRECT AND INDIRECT MOTIONWhen the reverse lever i s placed in forward gear , the radius

rod is dropped below the l ink fu lcrum and a direct motion is inevidence . When in back gear an indi rect motion is Ob ta ined .

The eccentri c rod connects wi th the l ink at“D .

" On cethe eccentri c crank pin i s set O .K . i ts fu l l th row remains thesame . When the eccentric rod length is adjusted and theengine i s operating

,the poin t “ D cal led the l ink foot has a

continuous unvarying osci l lating movement .

RADIU S ROD LENGTHAgain wi th these adj ustments O .K . and the main pin Spotted

on a dead centre , see Figu re 120, the valve remains dead whenthe reverse lever i s moved from the forward to the back upcorner notches

,i f the radius rod length i s Correct .


LONG VALVE TRAVEL

When the reverse lever i s placed in forward or back up fu l lgear posi t ions and the engine is operated the valve gets a fu l lgear travel known as the Long Travel Of the Valve .

”

VARIABLE VALVE TRAVEL

The valve travel i s var iable dependent on the posi tion ofthe reverse lever . The valve has no steam lap

,which

means that admission of l ive steam and exhaustion Of samerespectively occu rs du r ing the enti re stroke Of the piston .

Note in Figu re 120, the centre of the l ink foot pini

occurs ona l ine shown dotted which i s a tangent to the l ink radiu s fromthe centre “

V”Of the l ink fu lcrum .

LAY OUT CONSIDERATIONS

On some engines the radiu s rod in forward gear i s droppedbelow the l ink fu lcrum , see Figu re 12 1 . On others in forwardgear i t i s raised above , see ‘Figu re 122 .

On some engines the eccentric crank pin leads the main pinin forward gear , see Figures 120and 122 . On others i t fol lowsthe main pin in forward gear , see Figures 121 and 123 .

Again the poin t O f connection be tween the radiu s rod andthe radius rod l i fter often occu rs ahead O f the l ink fu lcruminstead Of behind same .

The aforementioned i tems , however , depend on the lay ou tof the valve gear and ow ing to the many designers Of Walschaert Valve Gear , there i s no common standard lay ou taccepted .

I f uncertain as to whether the eccentr i c crank pin fol lowsor leads the main pin

,work back from the valve , considering

i f same i s “ Inside ” or “ Ou tside ” Admission , al so notingwhether the motion i s D i rect ” or Indi rect ” in forward gear .Imagine the main pin on a dead centre and thu s arrive at theapproximate relative posi tion Of eccentr i c crank pin to themain pin .

BACK S ET OF L INK FOOT PIN

The back set of a l ink foot pin in the case of Walschaert

Gear i s determined by the designer and must not be tamperedwi th by a valve setter . An explanation why a l ink foot pinis back set i s ventured , al though same does not enter intoga


The valve i s on the centre of i ts seat .The main crosshead i s in the centre Of i ts stroke or travel .A l ever cal led a combination lever has three con

nections.

The end W of the radius rod , Figure 120, connects wi thcombination lever at “A ,

” Figure 126 .

The valve stem connection occurs at B and the crosshead union l ink connects at C .

"

The crosshead i s arranged to connect wi th Union l ink at D .

Al l these connections al low O f movemen t Of the parts .Figure 127 shows the main crosshead drawn backwards to

the extreme end O f i ts travel .The point “A" ac ts as a fu l crum poin t in th is posi tion when

main pin i s on a dead cen tre and the Inside ” admission valveis moved backwards to give lead to the valve becau se theproportions Of the combination lever together wi th the arrangemen t of the layou t al lows O f same .

I t i s read i ly seen that the same lead i s aHected at the fron tport when the crosshead arrives at the extreme front end Of

i ts travel .

How TO DETERM INE WHETHER I NSIDE O R OUTSIDEADM I S SION VALVES

The radius rod connecti on with the combination lever i sseen to occur above the valve stem connection in the case Ofinside admission valves .

In the case of “ ou tside admission valves th is radius rod

connection occurs below the valve stem connection , see Figure128. The propor tions and layou t are arranged, however , bythe designer to Obtain the lead requ ired .

COMB INATION LEVER BACK S E TS ometimes a designer arranges a back set to the lower part

Of the combination lever , see Figu re 129 . The reason in mostcases i s to su i t the construction Of the other parts Of the locomotive . One simply has to fol low the blue pr in t requiremen ts .

SHORT VALVE TRAVELThe main crosshead i s the direct sou rce Of the motion which

gives lead to the valve in Figures 127 and 128 . This i s sometimes cal led the “

S hort Travel ” Of the valve and i s equal tothe sum of twice the lap and twice the lead . The combination


of the short travel.

and the long travel of valve is madewhen

.

the comb1nat1on lever i s connected to the radius rod,

see FIgure 130.

CONSTANT LEADThi s means when main pin arrives at a dead centre and the

l ink i s in a central posi tion that the lead is obtained by reasonOf the travel given to the valve by the crosshead , independen tof the posi tion O f reverse lever . Sweep the reverse lever atthi s time the ful l l ength of i ts rack and no valve movementresul ts .

brave/ 1 J oh an / o”Va /re

The lead therefore remains the same for every reverse gearposi tion and is said to be constant .

When main piston and crosshead are in the centre O f thestroke , the valve would be central as Shown in Figure 126 , i f i twere not for the eccentri c crank pin which has acted upon thevalve to inS IIre a ful l port opening in ful l gear Operation .

The ful l gear posi tion seen in Figure 130 Shows the leadrequ ired and the l ink in i ts central posi tion .

S pot the main pin on a working quarter and move thereverse lever from one corner notch to the other and the longtravel of the valve i s the resul t approximately which general lyinsures a ful l port opening in the forward and back up ful lgears .

When hooking up a reverse lever wi th a S tevenson LinkMotion the valve travel s are shortened bu t the lead i s


increased , whereas in the case Of Walschaert Gear the valvetravel s are shortened bu t the lead remains the same .

The valve travels being var iable , the cu t OHS are vari ableal though the lead remains constan t .I f the l ay out O f a Walschaert Valve Gear i s good and the

valve setter sets the eccentr ic crank and adj usts the length Ofthe eccen tric rods and valve stems to Obtain equal and constan tlead one would natu ral ly expect the cu t OHS to be practi cal lyequal , i .e . , wi thin M” Of diHerence .

I t i s good pol icy however , to always try the cu t OHS wi ththe reverse lever in the working or running notch after havingsquared the lead by adj ustmen t aforementioned .

THE S LIP OF THE LI NK BLOCKThe sl i p Of the Link Block in the l ink i s greatest

'

in ful l gearand i s reduced as the reverse lever i s hooked up nearer to themid gear notch .

FULL GEAR VALVE TRAVELSOwing to the sl i p of the l ink block , one finds that the valve

travels on ei ther Side Of the centre Of the valve seat are Oftenwidely diHeren t . The diHerence i s most pronounced in fu l lgear . Ful l gear travels are taken however to see whether afu l l por t Opening i s Obtained , also .as a check wi th the valvebump marks to see i f valve properly clears the .valve chamber .

EXHAUST CLEARANCE , ETC .

Exhaust Clearance O f a valve , and Exhaust Line and Lineare used to advan tage w i th valves Operated by Walschaert

Valve Gear .A valve setter checks the amoun t Of exhaust clearance for

Shop reports only,unless a fu rther detai led repo rt Of pre

releases and exhaust cu t OHS are cal led for , i n which case hewould lay ou t the port marks for same in a manner simi lar tothat explained in the case Of Stevenson Link Motion andObtain the information requ i red .

VALVE EVENTS.The valve events such as Admission ,

”Cut OH,

"Expan

o o o H

S ion ,

” etc . , occu r on an engme W i th Walschaert Valve Geari n a manner simi lar to those explained in the case Of S tevensonL ink Motion .

The valve gears are widely diHeren t by comparison bu tsimilar valves are used for bo th .

14 2 Shop H i nts on Locomotive Valve Setting

REACH ROD ADJUSTMENT .

Reach rods nowadays in the case Of Walschaert Gears areadj ustable . The main frames are level led for valve sett ing ,in which case , when reverse lever is placed in mid gear notch ,the reach rod or rods as the case may be , can be adj usted unti lthe reverse shaft arms stand j ust as the blue pr int cal l s for .This is necessary ow ing to the var ious shapes and angles

Of reverse shaft arms on the various engines .

RADIUS ROD LIFTER LENGTH ADJUSTMENT .

TO check up rad ius rod l i fter l engths , adj ust reach rod

l ength as j ust detailed . Place reverse lever in the mid gearnotch . S et the combination lever plumb . I f the combinationl ever has a back set to i t , plumb the top end of same . Thiscan be done approximately by spotting crosshead in the centreO f i ts stroke w i th Union l ink connected . S et each l ink plumbas shown in Figure 13 1 , i f the l ine d rawn through l ink fulcrumcentre and the centre of poin t of connection between rad iusrod and combination lever is horizontal . I f th is l ine is not

hor i zontal , rather elevated instead , then set the l ink at r igh tangles to same as in Figure 132.

The distance between the inside top of l ink and the top of

l ink block shown at “C ” Figure 13 1 , al so the d istance betweenthe under side of l ink block and the inside bottom Of l inkShown at “D Figure 13 1 Should conform to the blue printrequirements . S ometimes these distances are equal andsometimes unequal .Again by sw inging the l ink back and forth there should

be no movement to the valve stem or rad ius rod at this time .

I f the d istances are not O .K . , i .e the l ink block centre doesnot coincide wi th the l ink fulcrum centre , get the rad ius rodl i fter adj usted , accord ingly , at th is time and replace same .Treat both sides of engine in the same manner .

PUTT ING ROLLERS UNDER .

When putting rol lers under the main dr ivers for settingthe valves Of an engine wi th Walschaert Gear , do so in exactlythe same manner as for Stevenson Gear , paying particularattention to the equal iz ing of side play be tween main driversand both main frames , the tighten ing of main driving hornbinder bol ts , and the S etting up of main driving wedges .


ECCENTRIC CRANK ARM APPROXIMATE S ETTING .

Eccentr ic crank arms are j arred around the main pins intotheir approximately correct posit ions and nipped tigh t wi thtemporary bol ts .These posi t ions can be determined by reference to the blue

prin t for same , or by tracing back from the val ve as beforeexplained in chapter 7 .

ECCENTRIC RODS .

Try eccentric rods for unnecessary sets or twis ts , and removeany i f present . The l ink . foot pin Should tap in nicely whenmaking th is connection , wi th the eccentric crank pin endproperly connected .

DEAD CENTRE S .Dead Centres are found in a similar manner to that ex

plained for Stevenson Link Motion .

MAIN ROD ADJUSTMENT .

Ow ing to the eHect of crossheads on the valve motion ,

adj ust the length Of main rOds as soon as the main crossheadtravel s are taken , and replace main rOds. This occurs beforeany valve readings are taken .

ECCENTRIC CRANK ARM S ETT ING PROPER .

Catch the dead centre shown at C Figure 133 .

The eccentric rod being up,place one point Of a tram Of

convenient length , in the centre Of l ink foot pin and scri be asmal l arc “A ” w i th the other poin t Of tram on a bar or bracket ,so as to cut a horizontal ly scr ibed l ine as shown at B Figure133 .

GO ahead and catch the other dead centre shown at Dby dotted l ines . Again place one point of tram in the centreOf l ink foot pin and wi th the other tram point scribe anothersmal l arc as shown at E .

”

I f the two arcs A and E coincide , i .e . , A occursexactly in the same place as E , then the eccentr ic crankarm is set O .K .

I f , however , the two arcs occur apart , j ar the eccentriccrank arm in direction to obtain the desired resul t , i .e , unti lthe Second tram point reaches a point nearly hal f way betweenthe two arcs .


GO ahead , catch the aforementioned dead centres again ,and scr i be wi th tram as before to be sure you have Obtainedthe desi red setting .

Always tigh ten up on temporary bol ts after j arring eccen triccrank arms with ‘ a copper hammer .

i t is pol icy to mark an eccentr ic crank arm with a fine sharpch isel wi th respect to the main pin as a check on any furtherrelative movement after setting same .

O thers mark off the eccentr ic crank arm dowel holes at th istime .

A METHOD OF SQUARING LENGTHS OF ECCENTRIC RODS ANDVALVE S TEMS .

The fol lowing method O f setting the lengths of eccentric rodsand valve stems is used in some shops .Let i t be said , however , that same wil l not apply correctly

unless the lay out Of the valve gear is good .

After the eccentric cranks , etc . , are set as per previousexplanations j ust given , in this chapter , catch a dead centreas shown in Figure 134 .

Move the reverse l ever back and forth through the entirelength of i ts quadrant .I f valve does not move the eccentric rod length is O .K.

I f valve moves proceed as fol lows .

Check up the length of rad ius rod and i f correct , take atram Of convenien t length and place one point in centre Ofl ink foot pin . With the other tram point scribe an arc , see“A ” Figure 134 , on a gu ide bar or bracket , which is convenientfor same .

S cribe a hor i zontal l ine through th is are as seen at D

Figure 134 .

Now move main dr ivers around careful ly wi th al l sl ack takenup unti l l ink arr ives at a posi tion where valve does not movewhen reverse lever is moved through the ent i re length Ofquadrant , and then stop .

Apply the tram again to centre of l ink foot pin and scr ibeanother arc as seen at “ B ” Figure 134 .

The d istance between A and B ” along the horizontall ine is the amount of change to make to eccentr ic rod length ,In the case shown

,eccentri c rod has to be lengthened . Make

the change right away .

S hop H ints on Locomotive Valve Setting 14 7

Now catch a dead centre properly and re - check by reverselever movement , to see i f eccentr ic rod length is O .K .

Some workers go as far as taking one l ead l ine only , whilston th is dead centre , making allowance for specified l ead be tweenthe lead l ine and the nearest po rt mark and any di fferenceshown , they affect the valve stem length accordingly .

I t is good pol icy however , even with th is method to sc ribethe two leads l ines and find the centre O f same , see Figure 134 .

The distance be tween the cen tre Of port mark and the centreOf lead l ines , see

“ C Figu re 134 , is the amount of change tomake in the valve stem length . In the example Shown inFigure 134 , according to the rule

,

of br inging centre of portmarks to centre of sc ribed l ines , the val ve stem needs shortening the amount shown .

Some S hops favor changing radius rods length in preferenceto the valve stem length , i f the amount Of change is M" orless , to save pul l ing the valves out .

A SURE METHOD OF SQUAR ING ECCENTRIC ROD AND VALVES TEM LENGTHS TO LEAD LINES .

A method more su re , to use in squar ing up eccent ri c rod andvalve stem lengths , after eccentr ic crank has been se t , l i fterlengths and reach rod lengths adj usted , i s as fol lows

For example , take the case of a swi tch engine .

Figure 135 represents a reading of forward and back up ful lgear Jre ad l ines .I t is seen that the centre Of the forward l ead l ines A i sahead of the centre Of por t marks .

The centre of back up lead l ines B i s M" be hind the centreOf port marks .Find the centre point C be tween A and B , wi th a

pair Of d ividers .The d istance between A and B being the po in tC " would have to come ahead to reach the centreA Of the forward lead l ines .

I t i s seen in Figure 136 i f the valve stem connec tion has tocome ahead 3116

" that the rad ius rod connection to combinationlever has to move ahead a l i ttle more . This is ow ing to theproportions Of the combination lever .Locomotives in service to- day are such that one can be

governed in al l cases for“ inside " admiss ion valves to increase


When the v alv e s tem l ength is changed and the port marksare re - taken , one finds that the common centre of lead l inesfal ls in

'

the same spot as the centre of port marks .The rule for the aforementioned setting isBring the centre O f the two centres of forward and back

up lead l ines to the centre of the forward lead l ines and cons ider whether the motion is d i rect or ind irect

,in forward gear

,

in order to determine whether to l engthen or shorten theeccentric rod .

Bring the centre of port marks to the centre Of the twocentres O f the forward and back gear lead l ines to determinerequ ired change of valve stem length .

ADJUSTABLE ECCENTRIC RODS .

To save time in some shops , an adj ustable pair Of eccentricrods are provided for each class Of engine in which case , aftervalve S etting is completed , the pai r of eccentr ic rods intendedfor Service on the engine can be made the exact length accordingto resul ts the adj ustable pair Obtained .

Again , cu t OHS can be tri ed before valve stem lengths arechanged .

Make the common centre C Figure 135 , of the centreO f the forward and the centre of the back up lead l ines , the newcentre of port marks . The new port marks can be laid Off

with a pair Of d ividers and centre popped , hammer ing out or

d isfigur ing the or iginal port marks to prevent mistakes . .

I f the new port marks are used don ’ t forget the actual valvestem length change al ready known , which has to be madetogether w i th any further . change which may be necessarywhen squaring the cut OHS .

One can almost hear the question Why go to al l th l S troublewhen eccentric rods and valve stems can be adj usted so easilythe same as before detailed in th is chapter ”

The answer to th is is ow ing to the many lay outs Of Walschaert Valve Ge ar on engines now in service i t is a good pol icyfor the valve setter to play “

S afety Fi rst ,"unless he rece ives .

defini te instructions as to the method Of valve S ett ing to beused from the foreman of the shop .

SQUARING THE CUT OFFS .

A close approximate method O f final ly squar ing eccentricrod and valve stem lengths to the cut OHS , on al l classes of


engines equ ipped w i th Walschaert Gear is as fol lows

Assume that a swi tch engine has been squared up to the leadl ines and the cut oHs have been taken .

F igure 138 shows the front and back cut OHS in the forwardand back ful l gear on one side O f a locomotive .

First add the back and front cut OHS in forward gear togetherand 22 1 4

” equals 4 734”

Add the back and front cu t OHS in back gear togetherand equals

Take the smal les t from the largest .In th is our case take the back gear from the forward gear ,

less equals 1X7,”

Halve th is diHerence wh ich resul ts in

Take th is resul t from each Of the front and back cut OHSwhose sum was the larges t , in th is our case , the forward gear .The front cut OH “A " becomes see “ B .

" Theback cut OH

“ C in forward gear 22 1 4" becomes

see D .

The foregoing has simply equal ized the sum Of the forwardand the - sum Of the back up cut OHS figuratively .

The front cut OH in back gear is shown at“E as

and the back cut OH in back gear is seen at F as

In order to determine change to make in eccentric rod

l ength , take“ D , wh ich is the smal lest Of the back cut OHS

in both gears from the larges t back cut OH F ,

”i .e . ,

from gives a diHerence Of

Halve th is diHerence , which resul ts in 1The eccentr ic rod has to be al tered in length an amount

wh ich wil l aHect the cut oHs al l round favorably , to eq ual izethe two

'

back cut oHs and the two front cut oHs respec tively .

(Explained later in th is chapter) .S uppose the al terat ion in eccentr ic rod length is made , the

back cut OH in forward gear “D " equal to is broughtto see “G .

I f you move d iagonal ly in figure 138 , the back gear front cutOH E ,

" which is becomes see“H .

The al teration to the eccentr ic rod aHects al l the cut OHSon that side O f l ocomotive . This means that the back gear


C in the forward gear , Figure 138 . Move d r ivers forwardto take slack out Of the valve motion wi th the reverse lever inthe forward corner notch , in th is our case Of a swi tch engine .

Pick up the back cut OH“ C

"at 22 1 4

" and stop engine . Theengine has been stopped when the valve stem tram point j ustdropped into the centre pop “A ” Figure 139 , wh ich is a portmark .

Move drivers around in forward d irection unti l 1 is addedto the back cu t OH and stop , i .e . , the crosshead is nowfrom the beginning of i ts stroke .

Scribe an arc B on the read ing with the valve stem tram .

Aer/ms: I” MD i rec t N or/ on I / rM e nd

Move d r ivers around again in a forward di rection untilanother is tacked onto the back cut OH in forward gear ,then stop . The crosshead is now 23 from the beginningOf i ts stroke .

S cribe another smal l are C on the read ing plate wi th thevalve stem tram .

TO consider the amount Of al terat ion in the length Of eccentr ic rod one has to figure the proportion Of D to E ” Figure136 , in th is example , 7 i s to 21 .

The rule Of br inging the port mark to the,tram l ine holds

good and in th is case Of d irect motion , in forward gear , theeccentric rod has to be shortened , three times the distancebetween “A " and “ B " Figure 139 , or i f A isfrom “B . I f the eccentr ic rod length change were made at

S hop H ints on Locomotive Va lve S etting 155

th is time , and new port marks were taken one of them wouldoccu r at

“ B .

The amount Of al terat ion in the length Of valve stem isthe exact d istance between B and “ C

”shown in Figure

139 as TO determine whether to lengthen or shortenvalve stem this amount , imagine you can hold

“C"in one

hand and bri ng the point “ B to i t . This means shorteningOf the valve stem

I f i t is requ ired to try the cu t OHS w i th the last changesmade , before releas ing the engine , make the eccentric rodchange r igh t away , and i f inconvenient to change the valvestem lengths at th is t ime , l ay OH the port marks , one Of wh ichw i l l be made at “ C Figure 139 .

This method , as i n al l other cases of squaring by the cut OHSin one calculation , i s approximate only , and there may be anoccasional class of engine blow along where , after the caleulation is made , and the changes a rranged accordingly , a matterOf a diHerence Of to w i l l . occur in the cu t OHS which

you aimed at equal iz ing .

In case s where exceptional sl ip Of the l ink block in l inkoccurs , where the extent Of the ful l gear valve travelsare widely diHerent , al though the lead may be ,

squared up inthe firs t place , the above diHerence mentioned w i l l crop upi f a big al terat ion is to be made .

I f squar ing up a freigh t or passenger engine by the cu t oHs,

the proportion Of the distance between the l ink block centreand l ink fulcrum centre as compared w i th the d istance betweenthe l ink foot pin centre and the centre Of l ink fulcrum must beconsidered when figuring the eccentr ic rod length change .

The aforementioned example is somewhat exaggerated torender i t more clear .

IMPORTANT POINTS TO REMEMBER WITH WAL SCHAE RT VALVE

GEAR .

Al though there are certain methods employed in someshops to set the valves qu ickly on engines equipped wi thWalschaert Valve Gear , be governed by the shop rules .I t pays one to be careful , howev er, owing to the many de

signers who have diHerent ideas as to what is real ly consideredgood practice in the layout Of the valve gear .


Unless ordered to pursue a part icular shop practice by theforeman Of the shop , i t i s good pol icy on the first engine Of anew class or

.

on a strange engine , to consider the fol lowingImportant poInts.

Before attempting to take a valve stem reading,check up the

valve gear according to blue prin t requ irements,adj ust the

length Of reach rod or rods as the case may be,adj ust the

l engths Of rad ius rod l i fte rs and main rods , also se t the eccentric crank arms properly and bol t them securely

,to prevent

same'

mov ing on main pin dur ing the remainder of the valvesetting .

Take ful l gear valve travel l ines to enable you to check upful l port Openings in ful l gear and the clearance Of the valvesfrom the valve bump marks later on , when changes have to bemade in the lengths of the eccentr ic rods and valve stems .Figure the fi rst changes required in the length Of the eccen

tric rods and valve stems from lead l ines taken wi th the reverselever In the corner notches respect ively .

The first eccentric rod changes are m ade as soon as determined and before trying the cu t OHs.

Figure the final changes to eccentr ic rod and valve stemlengths from th e cu t OHS , i .e In the case Of a swi tch engine ,from the ful l gear cut oHs. In the case Of a freight or passenger engine from the hook up or running cu t OHs.

Check lead col lectively for valve setting pu rposes in a similarmanner to that used for S tevenson Motion .

Check lead separately for shop report , after changes havebeen made to square the cut OHS .

I f the cu t oHs prove to be practically equal after the lengthsO f the eccentr ic rods and valve stems have been adj usted fromthe ful l gear lead l ines on an engine Of a certain class , then allother engines Of that class may be squared to the ful l gearlead l ines as detai led in th is chapter , and let go w i thout tryingthe cu t OHs.


Tigh ten u p main d r iver binder bol ts .

S et up main driving wedges .Pu t u p main rods .

S po t eccentric crank arms approximately correct and niptigh t wi th tempo rary bol ts .S et eccentri c rods sidewise , remove any twists necessary .

Pu t up eccentric rods .

The correct setting of l inks , l ink fu lcrums , and their brackets ,rad ius rods , combination levers and union l inks , are taken careO f by the fi tter who erec ts the valve gear , yet i t i s good pol icyto check up wi th blue pr in t the lengths and location Of same ,al so to try out for twists and sets in rods .

Before taking the read ings , tigh ten up al l motIon pIn nu ts ,adj ust main rod wedges , dr ive al l cotters home , etc .

Place reverse lever in the forward corner notch .

Find the fou r dead centres on the righ t main d r iving wheel .Scribe crosshead travel s , when passing each dead centrerespectively .

S ee that valve gear does not foul du r ing a complete revolution .

Adj ust main rod lengths at th i s time .

Replace main rods .S et eccentr i c cranks correctly , marking OH the dowel pinholes as a check and bol t tigh t wi th temporary bo l ts .S cr ibe forward fu l l gear lead and valve travel l ines .Measu re l ink block clearances .Measure Sl i p Of l ink block in l ink i f requ ired ;Place reverse lever in back up corner notch and wi th one

turn of the main drivers .

Scribe back up fu l l gear lead and valve travel l i nes .Measure l ink block clearances in back gear .Measu re sl i p of l ink block in l ink i f requ i red .

See that valve gear does not fou l during this completerevolu tion .

Any foul ing that occurs clear at thI s t ime .

Check lead col lectively and i f not as specified , re check thesteam lap Of the valve , the w id th Of and distance between thesteam pOrt edges , al so the proportionate lengths Of combinationlever and un ion l ink and the proper location Of union l inkconnection to crosshead . Check up the back set Of combination lever lower end i f present , and the correct setting Of eccentric crank arm .


Determine changes requ ired to eccentr i c rod and valve stemlength s .I f adj ustable eccentri c rods are used for valve setting ,

adj ust eccen tri c rods righ t away , i f not , get the eccentric rodsadj usted for length at th is time by the blacksmith , checkingsame before and after the change i s made .

Note down the valve stem length changes and make newport marks in order to try out OHS .

Check up valve travels to see i f fu l l port Openings occu r i nful l gear , al so i f valve wi l l clear the valve bump marks whenchanges are made .

Take the Cu t OHS i n bo th gears wi th the reverse lever in these rvice or running notches respe ctively , i .e . , for

'

aSwitch engine , i n the corner notches .

Freigh t engine , w i th reverse lever abou t s ix inches from midgear no tch .

Passenger engine abou t four inches from mid gear notch .

Determine further changes to eccen tr ic rods and valve stemsfrom the cu t OHS taken .

Make the final change to eccentri c rods .

Make the change to Valve stem lengths , consider ing thefirst changes determined from the l ead l ine reading .

Check before and after final changesaremade . IMPORTANTDr i l l the dowel holes in mai n pin and eccentr ic crank arms ,

drive the dowels , ream and bol t as requ i red .

In the case where boi ler expansion aHects the valve gear ,lengthen the reach rod to al low for same .

SOme valve setters prefer to take the lead l ines In the caseOf a

"

freigh t or passenger engine w i th the reverse lever In thehOOk up notches respec tively in order to determine the valvestem length and eccen tri c rod leng th changes requ i red . Thecu t OHS on some engines prove O .K . when handled in th ismanner which means one has to be guided by thei r exper iencewi th each class Of engine .

I f the lead , po r t Openings , cu t OHS ,etc . , are requi red in shop

repo r t , make al l changes necessary ,F IRST , and take that which

i s requ i red afterwards .

APPROXIMATE ADJ USTMENT OF LENGTH OF ECCENTRIC RoDsAND VALVE S TEM S

Each side Of locomoti ve may be treated respectively asfol lows :Spo t the main pin as nea rly as possible on the back dead

160 S hop H i nts on Locomotive Valve S etting

centre . This may be done by moving engine slowly ahead,

untI l a dead centre i s nearly reached .

Stop the wheels wi th a block Of wood or a chain placed on

the rai l .

Use a special scriber wi th a straigh t edge to scr ibe two l inesacross the ends Of or near to the end Of driving axle as showna t

“A and “ B " Figu re 140.

Measure the d istance C to see i f‘

i t equals the distanceD .

" I f not , apply a j ack ( to sl i p the driving wheel s) asshown at “ E ” until “

C”equals “D , both being measured

from the centre Of driving axle .

This i s in order i f C and D are equal when measuredfrom the centre l ine O f main rod to the ou tside faces Of big

'

end

strap . I f otherwise , al low for same , when j acking drivingwheel s and measu r ing from centre Of axle to the scribed l ines .

The eccen tric crank arms are general ly dowel led to mainpin an d as th is method i s appl icable to a hurry up j ob , don

'tmonkey wi th the re - setti ng O f eccentri c crank arms whichbelongs to the back shop .

I f eccentr i c crank arms must be set , do i t righ t and pu trol lers under engine , etc .

Move reverse lever back and forth the ful l length of i tsrack , when main pin is on th is dead centre .

I f valve does not move the eccentric rod is O .K . for length .


I f the valve moves take a tram Of convenien t length,place

one poInt In centre Of l ink foot pin , and wi th other tram poin t ,scribe an arc , see

“A,Figure 14 1 , on a guide bar for instance .

S c a horIzontal l Ine“ F " to cu t the arc .

When movi n g reverse lever n ote which way to move wheelto bring the l ink into a posi tion where valve w i l l remain deaddur ing the reverse lever movement . Move wheels (sl i p themwi th a j ack) ahead or back up as the case requires

,unti l the

valve becomes stationary , during reverse lever movement , andthen stop .

Place tram poin t in centre Of l ink foot pin again , and withother tram poin t , scribe another are

“ B to cu t the straightl ine “F .

” The distance be tween .

“A” and “ B ” i s the amount

Of al teration to make in the length of eccentric rod . TO

bring the first arc to the second means shortening the eccentr icrod in th i s case .

Whil‘

st engine is in th is last posi t ion , spot reverse lever inmid gear notch and disconnect the combination lever from theun ion l ink . Move the combination lever into a posi tion wherethe part Figure 14 1 stands at righ t angles to the l ineOf travel Of the valve as shown .

(Sometimes the lower end Of combination lever i s back set) .

S cribe the valve stem at the packing gland represented atA ,

" Figure 14 2 .

In cases where peep hole plugs can be removed, the combination lever can be moved over each way unti l valve is onthe “ point Of admiss ion ,

" and the valve stem scribed again foreach end respectively and shown at “ B and “

C . , Fig . 14 2 .

S hop H i nts onLocomotive Valve S etting 163

I f a case of D Valve , set the brakes on the locomotive .

Open cyl inder cocks .Open steam throttle valve somewhat , i .e . , just crack i t to

al low a l i t tle s team to reach steam chests after brake is set .Move bottom end Of combination lever over ahead gradual ly

unt il steam escapes from the front cyl inder cock , then stop .

(“ Inside Admission Valve taken for example) .

Scribe valve stem at the packing gland .

Move bottom end Of combination lever over in a backwarddirection unti l steam is seen to escape from the back cyl indercock in abou t the same volume as that which escaped at thefront cyl inder cock , then stop .

Scribe valve stem again at the packing gland .

In ei ther of the two cases , whether peep hole plugs areremoved to advantage

'

or not , suppose A , Figure 14 2 wasthe first l ine scr ibed on the valve stem and B ” and

“ C thesecond and th ird l ines scribed on same . Find the centre Of“ B ” and C " shown at “D . The d istance be tween “A ”

and D ” i s the amount Of al teration to make in the length Ofvalve stem .

To bring the centre D Of port marks B and C to

the scr i bed l ine “A ” means lengthening the valve stem anamount equal to the d istance between “A and “D ”

in th i sour case Of “ Inside Admission Valves .

”

When the aforementioned principles are grasped one findsa pos i tion is reached by means Of which much unnecessarylabor can Often be saved dependent on the lay out Of the valvegear to a certain extent .

Chapter X .

BAKER VALVE GEAR

HERE I s a type Of reversible valve gear appl ied to locomotives cal led the Baker V alve Gear .This ge ar was ori gi nal ly used on traction engines but

later appl ied to locomotives and became known as the BakerPilliod Valve Gear.Certain improvements were made , the ou tcome Of wh ichwas the presen t up to date Baker Locomotive Valve Gear .”

A combination lever and union l ink are u sed In thi s gear toovercome the steam lap of the valve and to give a constantl ead in a manner Similar to that wh ich Ob ta ins in the “Wals.chaert Valve Gear .”

1 T here are only two s tandard design s Of Baker Valve Gear ,one appl icable to al l engines wi th ou tside admi ssion and One

to al l engine s wi th inside admission valves .

The combination lever propo rti ons are arranged however tosu i t each class Of engine , dependent on the steam lap Of thevalve , the l ead S pecified and the throw Of the

“main drivi ngcrank pin .

’

Owing to the fact that one manufacturer on ly , havingdetermined for both stan dards , that the eccentric crank p inshal l fol lowthe main pin in forward , and lead the main pin i nback up gear

, one can be assured that thi s wi l l occur in ALL

CASES .

This gear i s an ou tside motion , i .e . , the source Of the valvemotion is at the eccentric crank pin which l ies outsIde themain frames .

The sketches for this gear are made ou t Of proportion to

faci l i ta te an easy understanding . Let us star t in wi th a valvehaving no steam lap and wi th no arrangement made to givelead

,yet otherwise Operated in a manner simi lar to the Baker

Valve Gear ,” see Figure 14 3 .

One Side Of locomotive i s shown wi th reverse lever in forwardfu l l gear .

An inside admission valve 15 represented .

The main reach rod “A” connects wi th the reverse lever Band wi th the reverse shaft arm “ C .

”

166 S hop H i nts on Locomotive Valve Setting

The reverse shaft has two arms , one for each side Of locomotIve t ch are connected to the reverse yokes as at “D

,

"

by two short reach rods . as shown at“ E ” cal led Gear Reach

Rods .Each

Freverseyoke moves abou t i ts lower end or fu lcrum pin

as atThe direc tion in which the engine moves depends on the

posi tion the reverse yoke i s placed in .

Note the posi tion of the reverse yokes in forward gear .The radius bars move about their own fu lcrum pins as

shown at G "on the reverse yokes .

The lower end Of each radius bar connects wi th a gear connecting rod as at

“J .

”

The gear connecting rods are practical ly floating levers .The eccentric rod connec ts wi th the lower end Of gea r con

necting rod as at K .

"

The upper ends of gear connecting rods connect wi th thebel l cranks as at H .

The bel l crank L has a fulcrum point at M and isconnected to the valve rod at N .

”

In the example chosen Of an Inside Admission Valve ,note how the u pper arm of hel l crank extends from the fu lcrumpoint i n a direction away from the cylinders .In the case Of ou tside admission valves the upper arm Of

bell crank extends from its f u lcrum po in t in a direc tion towardthe cyl inders as shown by the do tted l ines atI f i t i s considered that the valve motion i s d irect when the

valve moves in the same direc tion as the eccen tr ic rod at al ltimes and ind irect when they move in Opposi te d irec tions , theni t may be said

Wi th “ Inside Admission Valves in forward gear the motion5 D i rec t ” and in back gear “ Indirec t .”

With Ou tside Admission Valves , the motIon Is Ind irec tin forward gear and D i rect in the back up .

I t wi l l be read i ly seen that as far as we have gone , theeccentric pin i s the only sou rce O f motion to the valve and i tcauses what i s known as the “

Long ” travel Of the Valve .

I f the engine i s moved around in a forward direction , fromthe posi tion shown in Figure 14 3 , the lower end

“K ”Of Gea r

connec ting rod is d rawn backwards .S uppose for a moment that the point H i s a fulcrumpoin t then the poin t “ J moves backwards .

S hop H i nts on Locomotive Valve Setting 167

The rad ius bar having a fu lcrum poin t at G on the

rev erse yoke , i ts other end“

J has to sweep upwards as wel las backwards in the path of an are shown by the do tted l inesweeping from “

J .

This movement cau ses the gear connecting rod to push theuppe r bel l crank arm upwards thereby moving the lower be l lcrank arm , incidental ly giving movemen t to the valve andopening the back steam port .There i s no l ink u sed in th is type Of valve gear .

Figure 14 4 shows the reverse lever in fu l l back gear .

When engine moves in the back up d irec tion the eccentr icrod pushes K ”

ahead .

The po in t“J moves ahead bu t upwards as wel l , owi ng to

the rad iu s bar having i ts fu lcrum po in t a t “G .

"

The gear connec ting rod rises taking the po in t H Of theBell Crank upper arm wi th i t , inciden ta l ly moving the valvewhich i s conn ected by a valve rod to the lower arm Of be l lcrank . The back po rt i s thus Opened up .

I t i s unnecessary to de ta i l steam distr ibu t ion again wi ththis gear . Each valve gear i s design ed wi th one goal in sigh t ,i .e . , to Obtain an

“ ideal servi ce and steam distribu tion .

In th is case insofar as chosen , a Baker Valve Gear , wi thvalves hav ing no steam lap nor l ead given , the valve eventssuch as admi ss ion and release occur du ring the enti re strokeand causes a wastefu l engine . The valve events are simi lar tothose explained , wi th valves having no steam lap nor leadgiv

‘

en in the case Of Stevenson Link Motion ” and “Walschaert Valve Gear .AS the reverse lever i s hooked up towards mid gear thevalve travels are shortened .

Figure 14 5 shows the reverse lever in the mid gea r notch .

Note that the lower bel l crank arm in th is posi tion is plumbwhen the main frames a‘re level .The engine can be tu rned a complete revolu tion wi th reverse

lever in the mid gear no tch w i th practi ca l ly no movemen t tothe valve .

The reason is because the length Of the radius Bar G .J .

i s so nea rly equal to the length Of the upper part “ J .H . Of the

gear connecting rod , that no appreciable movement is causedto the .be l l crank when engine is moved around .

Shop H ints on Locomotive Valve Setti ng

equal to twice the lap added to twice the spec ified lead , willoccur i f the combination lever and union l ink proportions

,etc

,

are 0.K .

There is a certain sl i p of the lower radius bar pin whichoccurs in th is gear and has a similar eHect on valve travels as

gxe sl ip of the l ink block in the l ink of a Walschaert Valveear .

I.

This means that anover travel Of the valve occurs on one

side of the centre of the valve seat . more so than on the otherand I s most pronounced in ful l gear when valves are set .

Atwh ich end the longest overtravel occurs depends whetherthe valves are inside or outside admission .

This diHerence in valve travels on e ither s ide Of the centreOf valve seat whilst pronounced in ful l gear is not detr imentalas the ful l port open ings are Obtained and again the diHerencesare considerably and quickly reduced as reverse lever ishooked up towards the mid gear notch .

When th is gear has been squared up , i .e . , the eccentric rodsand valve stems to the ful l gear lead l ines and the gear reachrods adj usted to equal ize the hook up valve travels wh ichrender 50% cut OHS , do not expect to see equal ful l gear valvetravels on each side Of centre Of valve seats or bushings .

Figure 14 7 shows a lay out for inside admiss ion valves .Fi gure 14 8 shows a lay out for ou ts ide admission valves .

By kind permission of The Pi l li od Company ,thei r ori gi nal

pri nted drawi ngs of the Baker Valve Gear”were used to produce

figures 14 7 and 1 48 andfull advantage was taken to assist in’

the

production of other printed sketches in this chapter.

174 S hop H ints on Locomotive Valve S etting

MAIN REACH ROD ADJUSTMENT

When main frames are level , the length of the long reachrod,

“A"i s adj u sted by placing the reverse lever in mid gea r

notch See“ B , Figu re 14 5 . Lengthen or shorten main reach

rod unti l reverse shaft arms Show plumb as at C . Achange in the length of a main reach rod aHects both sides oflocomotive .

GEAR REACH ROD ADJUSTMENT FO R VALVE S ETT ING

Wi th reverse lever in mid gear notch and reverse shaft armsplumb lengthen or shorten each gear reach rod un ti l thecentres Of al l reverse yoke pins “D “G ” and “ F ” and thecentre Of the upper bel l crank arm pIn H are i n one straigh tl ine , as near as possible by Observation , as seen in Figure 14 5 .

A change in the length Of a gear reach rod aHec ts one sideof locomotive , i .e . , the side on which i t i s connected .

REVERSE LEVER TRAVEL

Stops shou ld be arranged to al low the spec ified travel Of themain reach rod pin which connec ts wi th reverse lever to allowOf i ts correct travel on ei ther side Of the mid gear notch .

Check up as cal led for on blue prin t .

CHECKING THE COMB INATION LEVERS W ITH A PLUMB LINE

Place the reverse lever in midgear notch .

Spo t the piston crosshead central be tween crosshead bumpmarks , when motion is assembled . See that long arm Of combination lever i s plumb or wi th in hal f an inch Of same .

I f out Of plumb , Check up the lengths and location Of theparts involved , i .e . , bel l crank , valve rod, combination leverand union l ink .

APPLICATION OF ROLLERS

Rollers are pu t under main d r iving wheels in exactly the

same manner and wi th the same precau ti ons explained in thecase of Walschaert Gear , particularly when equal iz ing the sideplay between the driving wheel centres and axle boxes andmain frames , al so respecting the heigh t Of the main frames .above axle boxes , when setting valves as cal led for on blue

prInt .

S hop H i nts on Locomotive Valve S etting 175

ECCENTRI C RODS

When adj ustable eccentric rods are provided for valvese tti ng purposes , use same un ti l valve setti ng Operations arecompleted , then make the eccen tri c rods intended for regu larservice the same resu l tant length , se t properly and take umnecessary twist out .

DEAD CENTRES AND CRO SSHEAD TRAVELSDead Centres and Crosshead Travel marks are found in the

same manner as explained for other gears .

MAIN ROD ADJUSTMENTMain rods are adj usted properly for length and replaced

before any valve stem readings are taken wi th thi s gear

SETTING CRANK ARM S

The se tti ng Of an eccentric crank arm wi th th is gear i sexactly the same as detai led in the case Of se tting an eccen triccrank arm for Walschaert Valve Gear , the fron t eccen tri c rodpin centre being used when trammel l ing .

ADJUST ING ECCENTRI C ROD AND VALVE S TEM LENGTHS FROMFULL GEAR LEAD LINES

Take i t for granted that Figure 149 shows a reading Of fu l lgear forward and fu l l gea r back up lead l ines .

“H

"and “

J are port marks and “ K i s the cen tre Ofsame .

“A ” and B are forward fu l l gear lead l ines .

D and E are back up fu l l gear lead l ines

Find the centre C Of the forward l ead l ines A and Bwi th a pai r Of d ividers .

The centre C ” occurs ahead Of the centre of port

marks .Find the centre F Of the back up lead l ines D and E

wi th the d ividers . The centre “F occu rs beh ind Kthe centre Of port marks .

Now find G "the central po int be tween C and F .

Bring the po in t “G "towards the centre C "

of forwardful l gear l ead l ines . In our example i t amounts to “G be ingpushed ahead V3

”.


Take the d istance H .J . from AB . and halve thediHerence . The resu l t i s the lead in forward gear when theeccentric rod and valve stem lengths are adj usted to the ful lgear l ead l ines .

Measure the distance between L and A . Add to th isd istance “

LA . the forward fu l l gear lead . Compare theresul t wi th the wid th Of the steam port and i t can be read i lyObserved whether a fu l l port Opening occurs or not .i

The di stance “L .A . added to the forward ful l gear lead is

the d istance the valve moves from the po in t Of admission atthe back port when valve i s Opening the port in the case Ofan inside admission valve .

In the case of an ou tside admission valve , same wouldapply to the port Opening at the fron t port . The other po rtopening in forward ful l gear , also both port openings in backup fu l l gear can be checked in a simi lar manner .

FINAL ADJUSTMENT OF GEAR REACH ROD LENGTHSThis fi nal adj ustmen t is by equal iz ing the hook up valvetrave ls which render abou t 50% cu t OHS .

The eccentr ic rod lengths are adj usted from 'the ful l gearlead l ine read ing before hook up valve travel l ines are takento adj ust the length Of the gear reach rods properly . Thisserves as a check on eccentric rod length adj ustment whenhOOk up valve travels are taken .

Let Figure 150 represent the hOOk up valve travel read ingfor the forward and back up gears taken wi th reverse lever innotches which al low Of about 50% cut OHS . The eccentric rodlength has been adj usted from ful l gear lead l ines .Measure the d istance between the forward valve travel

l ines “P ” and “Q .

"

Measure the distance between the back up valve travell ines “R ” and S .

"

Take the Shortest from the longest . In ou r example P.Q .

equals 3” and is less than R .S . which showsThe lengthening Of a gear reach rod increases the valve

travel in forward gear and decreases same in the back up .

TO equal ize and “RS .

” the gear reach rod needslengthening .

One turn on a reach rod knuckle having ten threads to theinch adds to the valve travel in one gear and reduces the


valve travel in the other gear V3 on same side of locomotive .

Ou r example cal l s for lengthen ing gear reach rod one turnOf the knuckl e , same having ten threads to the inch , makingbo th hOOk up valve travels equal toMake the change at th is t ime .

TRYING THE CUT OFFSWhen the eccentric rod lengths have been actually adj usted

to su i t the ful l gear l ead l ine read ing , l ay OH a new se t Of portmarks , the centre Of wh ich is made at

“G , Figure 149 .

Proceed to take the cu t OHS in the ord inary manner beforeexplained .

The reverse lever would be placed in a notch accord ing to

the engine to Obtain approximately 25% cut OHS for a passenger , 33% for a freigh t and about 50% for a swi tch enginewi th thi s part icular valve gear .Figu re ou t the diHerence in cut OHS , i f any , requ ired by a

further change to eccentr ic rod and valve stem length in amanner similar to that explained for Walschaert Valve Gear .The diHerence in cut OHS with th is type Of gear when erected

wi th ord inary care are very sl ight .I f the cut OHS demand a further Change in eccentr ic rod

length , set the crosshead to the short cut OH.

Tram in a hori zontal l ine from the centre Of front eccentricrod pin . Move engine around to arr ive at the requiredaddi tional hal f diHerence i n cut oHs and tram again from thefrontx eccentric rod pin centre .

The diHerence between the two tram marks along the horizontal l ine is the actual amount to Change eccentric rod length .

The further adj ustment to valve stem lengths owing to adiHerence in cu t OHS can be determined by trammell ing thevalve stem and measuring exactly the Change required in amanner the same as descr ibed forWalschaert Valve Gear .The actual Change required to valve stem length must surely

include the first Change figured from the ful l gear lead l ines .

I MPORTANT POINTS TO REMEMBERAssemble the gea r and Check same careful ly as per

prin t requirements .I f not 0.K . to print , remedy the error a t this time .

Adj ust the length Of main reach rod and gear reachready for valve se tting .

180 Shop H ints on Locomotive Valve Setti ng

Square eccentric rOds in the first place to ful l gear l ead l inestaken and make the change before proceeding further wi th thesettIng .

Determine the Change requ ired to valve stem lengths fromful l gear lead l ines in the fi rs t place , note i t down for laterreference and make new port marks , the centre Of which wi l lcoincide wi th the common centre Of the centres Of the forwardand back up fu l l gear lead l ines .DO not make an actual change to valve stem lengths unti l

valve setting final Changes are made .

Adj ust finally the gear reach rod lengths to equal ize hookup valve travel s taken wi th reverse lever placed in notcheswhere approximately 50% cu t OHS are Obtained .

Final ly adj ust the length Of eccentric rods and valve stemsi f necessary to equal ize the cu t OHS Obtained when reverselever i s placed to Obtain 50% cu t oHs i n the case Of a switchengine

, 33% cu t OHS i n the case Of a freigh t engine and 25%cu t oHs i n the case Of a passenger engine .

Al low for the eHec t on valve gear owing to bo i ler expansionby lengthening the main reach rod accordingly , after valvesetting i s completed .

Apply the reverse lever rack stopsso that the pin connec tingthe main reach rod to reverse lever has the specified travel ,as per blue print .Take a ful l card or complete motion report only when valves

have been set and al l changes have been made . This i s onlytaken when especial ly requested .

An engine's valves are considered wel l set when the dIHerencebetween any two cu t OHS taken with reverse lever in anyposi tion i s not more thanWhi lst the “ Baker Valve Gear I S set W I th reverse lever

placed in certain notches , i t i s up to the engineer’

s j udgment

to find by actual experience the economIcal or runn Ing notch .


Put up main reach rod

Adj ust main reach rod.

See that reverse lever works freely before pu tting up gearreach rods .See that reverse yokes , radius bars and gear connec ting

rods work freely before putting up gear reach rods .See that the gear connec ting rod se t i s i n the O .K . directions , as per prin t .Put u p gear reach rods .Adj ust gear reach rods as Closely as possible .

See that reverse lever can be moved freely when lowerends O f gear connec ting rods are held steady , making dueal lowance for frIctIon . This In order to locate unnecessarysets or twists which may be present in one part or another .

Now check up the travel Of the main reach rod pin , whichconnects wi th reverse lever , to see i f stops are adj usted to

al low of the specified travel , as per blue prin t . I f not O Karrange i t at th is time .

Piston crossheads are to be moved by hand when unionl i nks and combination levers are fi tted up , before the mai nrods go up .

Place reverse lever in mid gear notch , crossheads in thecen tre Of thei r bump marks and try out the plumb l ine on

combination levers .

Pu t rol lers under main drivers properly .

Equal ize side play be tween axle boxes and wheel centres Ofmain drivers .Tighten up maIn drl v er horn bInder bol ts .S et up main d r iving wedges .Pu t up main rods .S et eccentr ic crank arms in thei r approx1mately correctposi tions and tigh ten up wi th temporary bol ts .One can be sure O f this at a glance . The eccentric crank

pin i s a l i ttle more than 90° behind the main pin in forwardgear for i nside admission valves and leads the main pin , by al i ttle less than 90° i n forward gear for ou tside admi ssion valves .

Take out unnecessary sets and twist from eccentr ic rods .Put up eccentr ic rods .

,Use adj ustable eccentric rods for valve setting pu rposes

when provided . Before attempting to take a reading Of anykind see that al l motion pin nu ts are tigh t , main rod wedgesor cotters are adj usted properly , etc .


Place reverse lever in the back up corner notch , i n the caseOf;inside admission valves or in the forward fu l l gear posi tionin

'

the case Of ou tside admi ssion valves .

With one tu rn Of the main drivers

( 1) Pick up the four dead centres on the righ t main drivingwheels .(2) Scribe crosshead travel marks .

(3) S ee that gear does not fou l i n ful l gear .

Determine Changes to make in main rods and make themrigh t away .

Replace main rods .Se t eccentr i c crank arms prope rly .

Mark OH the dowel pin holes for a check on any furthermovement Of eccentr ic crank arms wi th respec t to main pinand tigh ten up temporary bo l ts i n same .

Place reverse lever in forward corner no tch .

Scri be forward ful l gear lead and valve travel l ines .Place reverse lever in the back up corner notch .

Scribe back up ful l gear lead and valve travel l ines .

Check up the lead col lectively from these readings .

Determine changes to make to eccen tric rod and valvestem length .

Make the eccentric rod length Change at this time .

Note down the valve stem length change , bu t do not make i tat this time .

Check up ful l port openings for each ful l gear from the ful lgear valve travels .

Make new port marks requ ired to try the cu t OHS and Cleanou t the Old ones .Place reverse lever i n forward gear , hooked up to a notch

which wil l render approximately the 50% cu t OHS , i .e . , at abou thal f the cyl inder stroke .

Scribe forward hOOk up valve travel l ines .Place reverse lever in the back up hook up notch which wi l l

give abou t 50% cu t OHS .

Sc ri be back up hOOk up valve travel l ines .Eq ual ize the forward and back up hook up valve travel s

thus gotten on each side Of engine , by adj ustment of therespec tive gear reach rods .


Take the cu t OHS w i th reverse lever placed in each gearrespec tively to Obta in approximately as fol lows :

For a Swi tch Engine , abou t 50% cu t OHS .

Freigh t 33%Passenger 25%

I f the resul tant cu t OHS are practical ly O .K. , i .e . ,the di f

fere nce in same is not more than 34”to l et her go.

I f the resul tant cu t OHS Show a diHerence Of more than 1figure the Changes requ ired to eccentric rod and valve stemlengths to square them properly .

Re - check the d imensions Of the gear , i f diHerence in cu tOHS i s abnormal .

_Owing to the fact th at two standard gears only are used ,

W I th reasonabl e care exercised during assembly there w i l l beno abnormal diHerences in cu t OHS .

Make the final change to eccentric rOds .

Make the final Changes to valve stems , not forgetting thefirs t Change required , which was figured from ful l gear leadl ines .

Check up rods for required Changes before and after sameare made . IMPORTANT .

Make sure ful l gear valve travels clear valve bump markswhen final changes are made .

Don ’ t trust you r own brother in th is game , go r ight afterthe goods yoursel f and then i t may be the other bird ’

s funeral ,not yours .

Before leaving the engine , after valve setting proper , lengthenthe main reach rod to al low for boiler expansion eHect i f present .Dri l l eccentr ic crank arm dowel pin holes , drive dowels ,

ream holes and d r ive bol ts in eccentr ic crank arms and finishOHminor detail s , such as Spl i t pinning , etc .

I f shop report demands a ful l card Of any engine , such aslead

,port openings , pre - admiss ion , cut oHs, etc .

,take same

after al l changes are made , except the al lowance In reach rodlength for boi ler expansion .

There i s one important poin t to rememberw i th locomotivevalve gears in order to save many unnecessary subsequentre - settings Of eccentric crank arms , eccentrIc sheaves andeccentr ic rod lengths .

CLEAR understanding on valve setting betweenemployers and employees allows of a mutua lbenefit. The employer reduces the cost of sub

sequent re- settings to a minimum and the employeeexperi ences more confidence i n turning out an engi ne .

Certain specifications are made as a rule concerni ngsteam lap and exhaust clearance of a valve, etc. , and

i ssued to the valve setter for guidance.

An information sheet for each class of engi ne saves

time and labor in the erecti ng shop as wel l as derivingthe satisfaction that al l i nformation i s obtained in the

first place very carefully , i .e

Amount of boi ler expansion efi'

ect, if any , on a reach

rod.

The effect of a given reach rod or l ink lifter lengthchange on lead, full gear and hookup valve travels.

Which reverse gear posi tion to use to finally square

the valve gear.

Whether to finally square the rods, etc. , to ful l gear’

lead l ines, full gear or hook up valve travels, or ful l

gear or hook up out of s.

The distance the main driving axle centre must be

from the top of the top rai l of main frames duringvalve setti ng thereby saving many re - settings of eccen

tri c sheaves, eccentri c crank arms and eccentric rods

owi ng to the difi'

erence of opinions.

When one real izes that al l the necessary informationhas to be actual ly found or guessed at, more or less,during valve setting, the results of a common under

standing and appl i cation at al l points of a rai lwaysystem are very apparent.

INDE X

0 0 0 0 0

Admission , the point OfAngular advance of eccentric SheaveAngular advance of eccentric sheave , laying off

Be ll crankBump marks, piston,

how to find

Bump marks, va lv e , how to find

Changes, actua l , keeping check ofC learance , crosshead , shop understandingC learance , exhaust , .

Clearance , exhaust, how tomeasureClea rance , exhaust , the eHect Of .

C learance , piston, shop understandingC learance , as understood by some outside Of valve setter's provinceClearance , valve , shOp understandi ngComb ination lever, back set ofCombinat ion lever, Checking OfCompressionCompression, the riod OfCrosshead trave l, ow to findCut OH, aCut OH, exhaust , the point ofCut O ff , how to measureCut OH, the point OfCut OHS , acceptedCut OHS , approximate method Of squaring eccentric rods and va lve stems

to 150, 179Cut oHs, exhaust , squaring of 100Cut OHS , ful l gear, how to square by eccentric rod adjustment 9 1

Cut OHS , given, how to find rev erse lever position for 96

Cut OHS , hook up, how to square by eccentric rod adj ustnierit 97

Cut OHS , points worth wh ile 100Cut OHS , service 46

Cut OHS, unequa l 9 1

Cylinder centre line 46

I N D E X

Dead centres, how to find with use Of main rodDead centres, how to find with use of tramDriver wedges, setting up

Eccentric crank arm, approximate setting OfEccentric crank arm, proper se tting OfEccentric crank in, lead ing or fol lowing main pinEccentric rod, e ects Of Changing length OfEccentric rod, removing twist fromEccentric rod, setting ofEccentric rod twistersEccentric rods, adjustab leEccentric rods, adjustment from full gear read ingEccentric rods, adjustment from hook up readingEccentric rods, approximate adjustment ofEccentric rods, approximate length ofEccentric rods, squaring length of , a sure methodEccentric rods, squaring length Of, one methodEccentric sheave , back up , how to determineEccentric sheave , cHect Of movement around axleEccentric sheave , forward , how to determ ineEccentric sheave , ful l throw OfEccentric sheave , ful l throw Of, how to find

Eccentric sheave keyways, laying OH

Eccentric sheave position,how to trace approximately

Eccentric sheave ,re lation to main pi n

Eccentric sheave , throw OH

Eccentric straps, fit OfEighths, main pinEngine , lameEngine , left leadEngine ,

non- reversib le, crudeEngine , non reversib le , crude ,

direction In which engine OperatesEngine , non

- reversib le , crude , layout considerationsEngine , non

- reversible , crude , names Of partsEngine , non reversib le , crude , operation dependent uponEngine , non reversib le , crude , waste fulEngine , reversib le , crudeEngine , right leadExhaustE xhaust , cut OH, the point OfExhaust, the point ofExpansion ,

boi ler, al lowance forExpansion ,

boiler, eHects on cut OHS

Expansion ,boiler, sHects on lead and valve trave ls

Expansion ,boi ler, records

Expansion , steam

I NDEX

Main pin, ful l throw of

Main pin, ful l throw of, how toMain pin ,

throw ofMain rods, adjusting lengt h ofMain rods, putting upM inor deta ilsMotion, centre line ofMotion, d irectMotion ,

hanging the .

Mot ion,im rcperly balanced

Motion,in irect

Motion, lost

Notch , corner, back upNotch

,corner

,front

Notch , corner, p lugging, effects ofNotch,corner, plugging, to prevent fouling, etc.

Notch , running

Out of square , valvesOv erreach ing

Peep hole plugs, use of

Piston bump marksPort marksPort marks, al lowance made formsrde admission va lvesPort marks, exhaust, how to find

Port marks, how to find with slack D valve bucklesPort opening, ful l gear, how to checkPre- adm issionPre - re lease

Quarters, ma in pinQuarters, working, main pin

Rad ius rod, length ofRadius rod, l ifter length , adjustment ofReach rod, actual length changeReach rod, adjustab leReach rod, adjustment of length

I N D EX

Reach rod, boi ler expansion eHect onReach rod, effects of length change on cut 08 5

Reach rod, sHects of length change on lead and va lve travelsReach rod,

figurative length change during va lve sett ingReach rod, lengths ofReach rod, main, adjustment of lengthReach rod , non

- adjustab leRea lese , the point of .

Reve rse lever, dropping downReverse lever,hooking up

Reverse lev er, hooking up, effect oncut 05 5Reverse lever, hooking up, efi

‘ect on lead and valve trave ls

Reverse lever,tightReverse lever trave l

Rocker, d irectRocker, ind irectRollers, placing under mai n drivers for va lve se tting

She p reports, requirements ofSlip of the l inkSl ip of the l ink b lockSlip of the li nk , how to measureSlip of the lower rad ius bar pinSli p of the lower rad ius bar pin, cHectofSteam passage from boi ler to atmosphereSteam passages , b lowing throughStevenson l ink mot ionStevenson l ink motion , a pecularity of

Stevenson link motion, assemb ly

Stevenson link motion ,important pointsto remember

Stevenson l ink motion,names of parts

Valve , Al len portedValve , DValve events

Valve Gear, BakerValve Gear, Baker, how to determine whether i nside or outside adrins

sion va lvesValve Gear

,crude , Baker principles, names of parts

Va lve Gear, important points, Walschaert GearValve Gear, up to date Baker, lay outs for inside andoutside adm ission

va lvesValve Gear, Walschaert

Va lve Gear, Walschaert , how to determine whether inside or outsideadmission va lves

Valve Gear, Walschaert , layout considerationsVa lve , inside adm issionValve ,

l ine and l ine

I N D E X

PAGE

Va lve , movement of 30Va lve motion , inside 36Valve motion, outside 36Valve , outside adm ission 7Va lve , overtrave l of 27Valve , piston 27Valve rod , length of 66Va lve setting, details 73

,173

Va lve setting , freight or passenger engine , Stevenson LinkMotion 1 17Va lve sett ing, important points 125 , 179Valve setting, switch engine , Stevenson Link Motion 1 10Valve setting, switch , fre ight or passenger engine , Baker Valve Gear 181Valve se tting, switch , freight or passenger engine Walschaert Va lve Gear 157Valve spind le tram 57Va lve stem , approximate lengthadjustment 159Valve stem reading , protect ion of 63Va lve stem , squaring length of 146 , 175Valve stem , squaring length of, sure method 147Va lve stems, fit of 54Valve stems

, setting D 57Va lve to just cover steam ports, result of 12

Valve trave l 27

Valve trave l , ful l gearVa lve trave l , ful l gear, how to figure approximate lyValve trave l

,ful l gear, reach rod or link l ifter change effect

.

on, how to

measureValve trave l

,hook up, how to square ecentric rods from

Va lve trave l,hoop up,

how to takeValve trave l , hook up ,

reach rod or l ink l ifter length change eff ect on ,

how to measureValve trave l , how to measure forvalve sett ing purposesVa lve trave l , length of, dependent uponVa lve trave l l ines, how to takeValve trave l , longVa lve trave l , long,

how to find approximate length ofValve trave l , shortVa lve trave l

,variab le

Valve, when not to use oil

· pre fa c e say , bo— de kko th is bi rd "a real hunky bunch of practical shop stunts for...

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