,,! ,,slide ,,valve1 ,,simply ,,expla9$4 ,,by ,w4 ,j4 ,,t5nant1 ,,asso4 ,m4,i4,m4,e ,,revis$ ,,& ,,mu* ,,enl>g$ ,,by ,j4 ,h4 ,,k9ealy1 ,d4 ,e41 ,pr(essor ( ,me*anical ,eng9e]+ 9 ,wa%+ton ,univ]sity2 ,m4 ,am4 ,soc4 ,me*4 ,engrs4 ,au?or ( 8,/eam ,eng9es & ,boil]s20 8,l[ ,pressure ,/eam ,heat+ ,*>ts40 ------------------ ,,fully ,,illu/rat$ ,,) ,,orig9al ,,draw+s ,,& ,,diagrams4 ------------------ ,,spon ,,*amb]la91 #ab ,,cortl&t ,,/reet1 ,,new ,,york4 #ahii4 ---------------------------------------- -------------------------------- ,ent]$ accord+ to ,act ( ,congress 9 ! ye> #ahii1 ,,by ,,spon ,,*amb]la91 9 ! ,(fice ( ! ,libr>ian ( ,congress1 ,wa%+ton1 ,d4,c4 ---------------------------------------- ----------------- ,,! ,,burr ,,pr9t+ ,,h\se1 ,,new ,,york1 ,u4 ,s4 ,a4 ---------------------------------------- -------------------------------- ,,preface4 ,?is "w is bas$ ^u notes & diagrams :i* 7 prep>$ by ! writ] ) no m ambiti\s object1 orig9ally1 ?an to help 8 railway /ud5ts t[>d ! obta9m5t ( cle> g5]al notions ^u ! important subject ( ! slide valve4 ,= practical demon/ration ( ! functions & op]ation ( ! slide valve1 a l>ge sectional model eng9e1 ) provision = v>iation ( ! op]ation ( its p>ts1 is v valuable2 b x seems to ! writ] to be desirable t ea* /ud5t %\ld h 9 8 own possession a model to cogitate ^u1 & t 8 model %\ld give him1 graphically1 results :i* %\ld be n m]ely qualitative1 b also1 9 "s degree1 quantitative1 to enable him to in/itute comp>isons betwe5 ! actions ( diff]5t valves op]at$ "u v>y+ conditions4 ,) ?is end 9 view1 ! writ] conceiv$ ! idea ( us+ on a base-bo>d a rot>y disc to repres5t a crank-%aft1 toge!r ) ! idea ( obta9+ conc5tric circul> diagrams ( results 7see fig4 #ba1 = in/ance7 by us+ a crank-arm m>k$ on ! disc z an index-f+]1 & record+ on ! base-bo>d ! beg9n+s & ends ( ! arcs swept ?r\gh by ! crank 9 ! v>i\s di/ribution-p]iods4 ,foll[+ ^u ?is1 x 0 ?\ght t ! ecc5tric & its rod c\ld be elim9at$ by br++ ! disc "u ! valve & fix+ ^u ! valve a rigid slott$ arm to ext5d d[n across ! face ( ! disc & engage a p9 on ! latt]1 s t rotation ( ! disc w\ld cause reciprocation ( ! slott$ arm & ! valve4 ,?is promis$1 h[ev]1 to be unme*anical & exp5sive1 & 0 disc>d$ 9 favor ( ! model describ$ 9 ,*apt] ,i41 :i* comprises ! simple me?od ( correlat+ 7z describ$ 9 ,*apt] ,,ii47 ! movem5ts ( valve & crank-%aft by scales adjac5t to ea*1 s t ! read+ giv5 by ! valve on ! valve-scale at any position ( ! valve w\ld %[ :at position on ! ecc5tric-scale ! ecc5tric ought correspond+ly to occupy4 ,! fact t ?is involv$ a /ep-by-/ep adju/m5t ( ! valve & %aft alt]nately 0 f\nd 9 practice to be advantage\s r ?an ! rev]se4 ,z to ! diagrams & sket*es1 ! writ] has s\ght1 9 "s ( !m1 to cle> up graphically "s ( ! incid5tal m9or difficulties relat$ to ! subject2 see1 = in/ance1 figs4 #ab & #ac1 illu/rat+ 8,ord] ( ,cranks10 fig4 #bb on 8,wid? ( ,port02 also comp>e figs4 #bc1 #bd1 & #be1 8,d\ble-port$ ,valve10 & see fig4 #cg1 :i* la/ is 9 effect a graphical summ>y ( results f ne>ly all ! diff]5t examples :i* prec$e x4 ,fig4 #cf1 :i* conc]ns ! rev]sal ( an eng9e 9 motion "u /eam1 w probably h a special int]e/ to /ud5ts ( ! locomotive4 ,w4 ,j4 ,t4 ---------------------------------------- -------------------------------- ,,cont5ts4 ,,page ,,introduction ,,to ,,am]ican ,,edition1 #a ,,*apt] ,i4 ,,! ,,simple ,,slide1 #e ,,*apt] ,,ii4 ,,! ,,ecc5tric ,a ,,crank4 ,,special ,,model ,,to ,,give ,,quantitative ,,results1 #ac ,,*apt] ,,iii4 ,,advance ,,( ,,! ,,ecc5tric1 #bj ,,*apt] ,,iv4 ,,dead ,,c5tre4 ,,ord] ,,( ,,cranks4 ,,cu%ion+ ,,& ,,lead1 #bd ,,*apt] ,v4 ,,expansion--,,inside ,,& ,,outside ,,lap ,,& ,,lead2 ,,advance ,,affect$ ,,!reby4 ,,compression1 #ca ,,*apt] ,,vi4 ,,d\ble-,,port$1 ,,multiple ,,admission ,,& ,,pi/on ,,valves1 #dc ,,*apt] ,,vii4 ,,! ,,effect ,,( ,,alt]ations ,,to ,,valve ,,& ,,ecc5tric1 #eg ,,*apt] ,,viii4 ,,note ,,on ,,l9k ,,motions1 #ff ,,*apt] ,,ix4 ,,note ,,on ,,v ,,e>ly ,,cut-,,(f1 ,,& ,,on ,,rev]s+ ,,ge>s ,,9 ,,g5]al1 #gc ---------------------------------------- -------------------------------- ,,introduction ,,to ,,am]ican ,,edition4 ,!re is no m important "p ( ! /eam-eng9e ?an ! valve--! "p :i* det]m9es :5 & = h[ long ! /eam %all be admitt$ to ! cyl9d]1 h[ long x %all /ay !re & h[ long x %all be all[$ = leav+4 ,& ! pr9ciples :i* %\ld gov]n ! con/ruction ( ! valve ( an eng9e 9 ord] t ! /eam %all be prop]ly admitt$ & releas$ are ! same = ,am]ican1 ,engli%1 ,fr5* & ,g]man eng9es4 ,! pr9ciples ( _! con/ruction & action are ! same1 b ! details v>y4 ,! action ( e /eam-eng9e dep5ds ^u its valve1 & h5ce x is important t e eng9e] ( :atev] c\ntry %\ld be ?or\ghly conv]sant ) ! pr9ciples ( ! con/ruction ( valves ( diff]5t types2 %\ld "k ! mean+ ( 8lap10 8lead10 8advance10 etc42 & %\ld "k h[ a *ange ( "o ( ^! w affect ! o!rs & ! admission & release ( ! /eam4 ,"o ( ! be/ ways to le>n all ab\t valves & valve motions is to /udy !m ) ! aid ( sectional models1 made s t ! inside z well z ! outside ( ! p>ts may be se51 b su* models are difficult to obta9 except at consid]able co/4 ,diagrams1 su* z are s freely us$ 9 ?is "w1 rank next to models 9 utility & z a means ( enabl+ "o to ?or\ghly und]/& ! work+s ( ! diff]5t p>ts ( ma*9es4 ,! use ( diagrams requires no k ( ma!matics1 & enables explanations to be pres5t$ 9 a cle>1 concise mann]4 ,f an educational po9t ( view1 diagrams possess an advantage :i* models d n1 z !y make "o ?9k m4 ,_! use gets "o 9 ! habit ( =m+ m5tal pictures ( ! p>ts ( ! ma*9es discuss$1 & ?us enables "o to m readily & quickly ?9k out ! effect ( a *ange 9 "o "p on o!r p>ts4 ,& ?is ability to picture 9 ! m9d ! v>i\s relations ( ! p>ts to "o ano!r is absolutely necess>y 9 ord] t ^! relations may be ?or\ghly und]/ood4 ,! man :o is accu/om$ to "w out 8 problems f diagrams & draw+s1 reasons f cause to effect & f effect to cause2 :ile ! man :o mu/ h a model to "w )1 works on ! 8cut-&-try0 me?od4 ,?is little book is conf9$ /rictly to an explanation ( ! pr9ciples :i* und]lie ! action ( ! diff]5t types ( slide valves4 ,! pla91 simple ,d-valve1 z x is call$ 9 ?is c\ntry1 )\t lap or lead1 is fir/ tak5 up & discuss$2 & gradually lap & lead are introduc$1 & ! effect ( ea* ^u ! admission1 ! cut-(f1 ! release1 & ! compression is fully work$ out & %[n4 ,!n o!r types ( slide valves are tak5 up & discuss$4 ,! advance is made /ep by /ep1 f ! mo/ simple =m ( slide valve to ! m complicat$ =ms us$ = atta9+ c]ta9 results n s easily atta9$ by ! use ( ! simple =ms4 ,! =m ( multi-port$ valve %[n 9 fig4 #be is s mu* l ! ,gidd+s valve us$ on ! ,russell & "s o!r s+le-valve eng9es1 t any "o read+ ! explanation giv5 "h w h no tr\ble 9 und]/&+ ! ,gidd+s valve 7%[n 9 fig4 #bf74 ,! multiple admission valve is us$ to su* an ext5t 9 ,am]ica t x is b prop] t a few words %\ld be said ( x1 & t ! mo/ common =m ( multiple admission valves %\ld be discuss$4 ,& h5ce ! ,/raight ,l9e & ! ,woodbury valves are %[n 9 figs4 #bg & #bh4 ,!re are s _m eng9es 9 ?is c\ntry 9 ! front rank ( automatic1 high-spe$ eng9es :i* use pi/on-valves1 t a treatise on slide valves w\ld be incomplete )\t "s m5tion ( ?is type ( slide valve4 ,! =m ( pi/on-valve %[n 9 fig4 #cj1 9 :i* ! /eam is admitt$ at ! middle & exhau/$ at ! ends1 is well kn[n to all eng9e]s :o h us$ an ,ide or an ,ideal eng9e4 ,! valve us$ on ^! eng9es is %[n 9 fig4 #ca4 ,_m ,am]ican eng9e]s pref] eng9es on :i* ! cut-(f may be *ang$ )\t 9 any way affect+ ! lead1 release1 or compression1 &1 !re=e1 ! description ( ! ,mey] valve w be read ) int]e/4 ,_m w recognize at once 9 ! valve us$ on ! ,wat]t[n eng9e ! ,mey] valve 9 almo/ its orig9al =m1 & 9 ! valve ( ! ,buckeye eng9e 7%[n 9 section 9 fig4 #ci71 ! ,mey] valve 9 a modifi$ =m4 ,j4 ,h4 ,,k9ealy1 ,d4,e41 ,pr(4 ( ,me*4 ,eng41 ,wa%+ton ,univ41 ,/4 ,l\is1 ,mo4 ---------------------------------------- -------------------------------- ,,! ,,slide ,,valve4 ,,*apt] ,i4 ,,! ,,simple ,,slide4 ,! slide valve has always be5 reg>d$ by ! writ] z ! pons as9orum ( ! /ud5t ( ! /eam-eng9e4 ,8 own e>ly attempts at cross+ t bridge 7 greatly facilitat$ by ! simple little device to be pres5tly submitt$ to ! read]2 ) ! aid ( ?is exp$i5t ! /ud5t may easily obta9 cle> notions ^u all ! functions & op]ations ( ! slide valve1 at a nom9al co/1 & ) b a small exp5diture ( "t & tr\ble4 ,x is necess>y t at ! outset ! nature ( ! con/ruction above allud$ to %\ld be cle>ly appreciat$1 = ! reason t _m ( ! explanations giv5 9 ! succe$+ pages are ref]r$ !reto4 ,9 pass+1 x may be rem>k$ t mu* ( ! difficulty :i* ! ord9>y /ud5t exp]i5ces 9 ! /udy ( valves & valve ge> arises because he approa*es ! subject ) a false impression t x is ( necessity a difficult "o2 ?is idea is g5]at$ on ! "o h& 9 ! atmosph]e ( my/]y :i* 9 ! %op is made to surr\nd ! matt]1 & on ! o!r h& by ! some:at =midable aspect ( mo/ ( ! geometrical treatises on ! subject4 ,if ! beg9n] c br+ himself to believe t ! slide valve is no?+ m complex ?an a slid+ %utt] ) a cavity 9 its face1 travell+ backw>ds & =w>ds ov] ?ree ports1 ! out]mo/ ( :i* are alt]nately op5$ to /eam & plac$ 9 communication ) ! c5tral exhau/-port1 he w h made a satisfactory comm5cem5t4 ,take a piece ( /\t :ite c>dbo>d & ^u x set out an enl>g$ copy ( fig4 #a4a ,illu/ration3 ,,fig4 #a4--;,explanatory ,diagram4 ----- ,footnote #a3 ,see also fig4 #da4 ,! upp] portion ( ?is diagram repres5ts a section tak5 at "r angles to ! port-face ?r\gh a set ( /eam & exhau/-ports z ord9>ily arrang$2 ! graduat$ r+ b5ea? ! section w receive consid]ation lat]4 ,po/pon+ = ! mom5t ! fur!r inve/igation ( fig4 #a1 ref]5ce %\ld "h be made to figs4 #b1 #c1 & #d4 ,fig4 #b %[s1 9 p]spective1 a cyl9d] & valve-*e/ ) p>ts remov$ to make cle> ! mann] 9 :i* ! two /eam-ports 7,s#a,s#b7 at ! upp] ends ( ! two out] passages 7,p#a,p#b7 af=d a communication betwe5 ! valve-*e/ 7,,vc7 & ! opposite ends 7,c#a;,c#b7 ( ! cyl9d] 7,c71 & to %[ ! passage f ! c5tral exhau/-port 7,,ep7 to ! outlet 7,o7 at :i* ! exhau/ /eam is dis*>g$4 ,! relation%ip betwe5 ?is view & ! upp] "p ( fig4 #a w be obvi\s ^u a comp>ison ( ! two4 ,illu/ration3 ,,fig4 #b4--,p]spective ,section ( ,/eam-,eng9e ,cyl9d]4 ,a typical slide valve is %[n 9 section1 9 its place above ! ports 9 fig4 #b1 & sep>ately 9 figs4 #c & #d4 ,f ^! latt]1 ! l>ge ratio ( ! wid? to ! l5g? ( ! valve is app>5t1 & x w be se5 f fig4 #b t ! ports are correspond+ly made wide & %ort4 ,?is arrangem5t enables a small l9e> movem5t ( ! valve to effect ! uncov]+ ( a l>ge area ( port1 & to secure free passage = ! /eam ) b a small am\nt ( valve-travel1 & s to r$uce to a m9imum ! "w unavoidably wa/$ 9 ov]com+ friction betwe5 ! port-face & ! valve heavily load$ by ! pressure ( /eam ^u its back4 ,illu/ration3 ,,figs4 #c & #d4--,sep>ate ,views ( ! ,slide ,valve4 ,let u return n[ to fig4 #a4 ,draw1 ne> ! edge ( a /rip ( mod]ately /iff pap]1 ! section ( ! elem5t>y =m ( slide valve illu/rat$ by fig4 #e1 tak+ its dim5sions f ! ports ( fig4 #a1 s t ! two views agree 9 ! mann] indicat$4 ,by slid+ ?is diagram backw>ds & =w>ds across ! ports ( fig4 #a1 ! foll[+ explanation ( ! action ( ?is1 ! simple/ =m ( slide valve1 w be readily appreciat$4 ,illu/ration3 ,,fig4 #e4--,section ( ,slide ,valve4 ,?is valve has fir/ to op5 "o port to /eam1 & :5 ! /eam ?us admitt$ has =c$ ! pi/on t[>ds ! opposite end ( ! cyl9d]1 to put ! same port 9 communication ) ! exhau/1 :ile op5+ ! o!r port to ! /eam :i* effects ! return movem5t ( ! pi/on4 ,! duration ( ! admission ( /eam is ! same z t ( ! exhau/1 ! admission1 ow+ to ! dim5sions ( ! valve 9 relation to ! ports1 necess>ily tak+ place on "o side ( ! pi/on simultane\sly ) ! occurr5ce ( exhau/ f ! o!r side 7see fig4 #f74 ,! travel ( ?is rudim5t>y valve equals twice ! am\nt to :i* ! port is op5$ to /eam4 ,x happ5s to op5 ea* port fully 9 ?is case 7al?\gh ?is is r>ely ! case ) mod]n slide valves71 s t ! 8travel0 equals twice ! wid? ( /eam-port3 twice1 because 7/>t+ ) ! valve 9 its c5tral position1 z %[n 9 fig4 #e7 x has to move to ! "r1 say1 by an am\nt equal to ! wid? ( ! left-h& port1 9 ord] to op5 t port fully to /eam1 & !n x moves back aga9 & travels to ! o!r side ( ! c5tral position by an equal am\nt1 9 ord] to op5 ! equally dim5sion$ "r-h& port to /eam4 ,9 fig4 #f ! valve is %[n at ! two extremes ( its travel1 9 full l9es at "o end1 & 9 dott$ l9es at ! o!r end4 ,illu/ration3 ,,fig4 #f4--,section %[+ ,position ( ,slide ,valve 9 relation to ,/eam & ,exhau/-,ports4 ---------------------------------------- -------------------------------- ,,*apt] ,,ii4 ,,! ,,ecc5tric ,a ,,crank4 ,,special ,,model ,,to ,,give ,,quantitative ,,results4 ,! necess>y travel ( ! valve is giv5 to x by means ( an ecc5tric1 :i* is key$ ^u or =m$ z "p ( ! crank-%aft4 ,! ecc5tric is1 9 effect1 a crank1 ^: ?r[ equals ! am\nt ( ecc5tricity ( ! %eave4 ,?is may n be obvi\s2 let u inve/igate a little4 ,suppose t we h a big crank-%aft1 & want to put a little crank 9 ! middle ( x 7= ?is is :at happ5s 9 ! case ( a /eam-eng9e1 ! travel ( ! valve be+ su* t a crank ( ! usual =m w\ld be disproportionate to ! %aft ( :i* x =m$ "p--l fig4 #g1 p]haps74 ,n[1 t su* a %aft w\ld be extremely weak at ! p9 goes )\t say+4 ,imag9e1 t to less5 ! weakness ! crank-p9 ( ?is little crank is made ( great] diamet]1 z 9 fig4 #h1 or ev5 m s1 z 9 fig4 #i2 /ill we get ! same result1 :i* is t ! ?r[ ( ! crank rema9s ! same1 & equals ! di/ance ( ! c5tre ( ! crank-p9 f ! c5tre ( ! crank-%aft--i4e41 ! am\nt t ?is crank-p9 is 8ex-c5tric10 out ( c5tre1 & ! ecc5tric %eave be+ simply an exagg]at$ crank-p9 we get back to our orig9al /atem5t t x is virtually a crank ^: ?r[ equals ! half-travel ( ! valve1 :i* 9 turn equals ! am\nt ( ecc5tricity ( ! %eave4 ,illu/ration3 ,,fig4 #g4--;,half-travel ( ,valve4 ,illu/ration3 ,,fig4 #h4--;,half-travel ( ,valve4 ,illu/ration3 ,,fig4 #i4--;,half-travel ( ,valve4 ,be+ fix$ to ! crank-%aft & mov+ ) x1 always 9 a fix$ relation%ip to ! ma9 crank1 ! ecc5tric op]ates ! valve 9 ! necess>y accordance ) ! movem5t ( ! crank & pi/on1 z w pres5tly be expla9$4 ,return+ n[ to fig4 #e1 x mu/ be und]/ood t a valve ( ! type exemplifi$ !re9 mu/ be 9 ! middle ( its travel :5ev] ! pi/on is at ei!r end ( its /roke4 ,! reason = ?is mu/ be cle>ly appreciat$ = ! sake ( :at foll[s h]eaft]2 x may be arriv$ at v easily ) ! aid ( fig4 #a4 ,put a disc ( c>d 9 ! circle provid$ 9 t figure1 & let x turn ab\t a draw+-p9 /uck ?r\gh its c5tre2 ?is disc is ! equival5t ( a crank-%aft4 ,a crank-arm 7,c7 may be p]man5tly m>k$ ^u x 9 ink1 z 9 fig4 #aj2 ano!r arm1 :i* may be m>k$ ^u x 9 p5cil1 w s]ve to repres5t a 8valve-crank10 ! equival5t ( ! ecc5tric by :i* ! valve is to be op]at$4 ,illu/ration3 ,,fig4 #aj4 ,actual connection betwe5 t valve-crank & ! valve be+ disp5s$ )1 "s means = mak+ ! movem5t ( ! valve correspond accurately ) t ( its crank mu/ be provid$4 ,?is provision is made by ! numb]$ scales#b 9 fig4 #a2 ! circul> scale )9 :i* ! c>d disc revolves is numb]$ 9 correspond5ce ) scales on ! ports1 & to ^! latt] an arr[ on ! /rip ( pap] :i* c>ries ! valve is adju/$ 7see also fig4 #aj74 ,to f9d ! position 9 :i* to m>k ! arr[ on ! valve1 put ! latt] 9 ! c5tre ( its travel & m>k ! arr[-head j above ! 8#j0 on ! ,no4 #a scale4 ,:5 ! disc is turn$1 ! end ( ! ecc5tric-arm or valve-crank travels ) x ar\nd ! circul> scale4 ,:5 ! ecc5tric-arm is mov$ /ep by /ep ar\nd ! circle to ! v>i\s numb]$ graduations1 ! valve mu/ be mov$ /ep by /ep to br+ its arr[-head to ! correspond+ numb]s on ! horizontal scale on ! ports4 ,?us ! ecc5tric & valve1 al?\gh n mov$ simultane\sly1 z !y w\ld be if a rod connect$ !m1 are kept 9 accurate relation%ip :il/ mov$ indep5d5tly4 ,if ! read] w n[ read ! preface1 :i* he has probably skipp$1 he w ! m readily appreciate ! pr9ciple ( ?is arrangem5t4 ----- ,footnote #b3 ,! horizontal scales on ! port-faces are obta9$ by project+ up equidi/ant circumf]5tial m>ks f v>i\s circles hav+ diff]5t valve-cranks = _! radii4 ,! scale 7,no4 #a7 is = ! elem5t>y =m ( valve1 )\t lap2 x s]ves also = l9k-motion 9 mid-ge>2 ,no4 #b is = a valve hav+ outside lap2 & ,no4 #c is = l9k-motion 8l9k$ up40 ,! /ud5t ne$ n1 unless he pleases1 tr\ble himself to inve/igate ! con/ruction ( ! diagram1 :i* is drawn to scale1 s t if copi$ accurately x w s]ve to give him ! demon/rations desir$4 ,fur!r1 tak+ ! ma9 crank-arm 7,c7 z an index-f+]1 ! position ( its end at ! po9ts ( cut-(f1 release1 etc41 ) diff]5t valves & ecc5trics1 may be m>k$ 9 p5cil on ! circul> scale1 or bett]1 on a piece ( trac+-pap] int]pos$ betwe5 ! disc & t scale2 by ?is means ! /ud5t w obta9 circul> diagrams enabl+ him to comp>e ! results due to diff]5t sett+s & proportions ( ge>1 & he w also discov] 9 :at mann] ^? results are affect$ by individual elem5ts ( ! me*anism 9 any giv5 example4 ---------------------------------------- -------------------------------- ,,*apt] ,,iii4 ,,advance ,,( ,,! ,,ecc5tric4 ,assume a horizontal eng9e1 ) ! ma9 crank mov$ into a horizontal position s t ! pi/on w\ld be at1 say1 ! left-h& end ( its /roke4 ,assume also t ! eng9e is at re/1 & put ! valve 9 ! c5tre ( its travel 7z 9 fig4 #e71 :5 its faces exactly cov] ! /eam-ports & its cavity cov]s ! bridges & ! exhau/-port2 ! fir/ movem5t ( ! valve is want$ to be to ! "r1 9 ord] to admit /eam to ! left-h& end ( ! cyl9d] to move ! pi/on also to ! "r1 no matt] :e!r ! crank-%aft is to h negative or positive rotation4 ,n[1 a valve ( ?is patt]n evid5tly w n admit /eam to ! cyl9d] to />t ! movem5t ( ! pi/on 7suppos+ t ! eng9e has n yet be5 />t$71 :i* w !re=e h to be help$ by "s ext]nal ag5cy2 admitt+ ?is z a po9t :i* %all be t\*$ aga9 pres5tly1 place ! crank next1 s t ! pi/on w\ld be at ! opposite end ( its /roke2 ! valve1 :i* _h to move to ! "r z expla9$1 mu/ h come back into ! position :5ce x />t$1 & be 9 read9ess to move equally to ! left1 aft]w>ds return+ once m to ! c5tral position by ! "t t ! pi/on gets back to ! left-h& end ( ! cyl9d]4 ,h5ce we see t1 :5ev] ! pi/on is at ei!r end ( its /roke1 ?is valve mu/ be 9 ! middle ( its travel4 ,if ?is be grant$1 we may proce$ fur!r3--,hav+ ! pi/on at ! "r-h& end ( its /roke1 = in/ance1 draw a l9e on ! disc at "r angles ) ! crank 7see fig4 #aj72 ?is w repres5t two 8ecc5tric-arms0 ( ! necess>y ?r[ if ea* arm equals 9 l5g? ! half-travel ( ! valve2 ei!r ( !m at pres5t suits ! position ( ! valve1 :i* is 9 ! middle ( its travel4 ,*oose1 n[1 ! direction 9 :i* y\r crank-%aft %all rotate2 let u suppose1 = example1 t x %all h 8"r-h&$0 rotation1 & place an arr[ on ! disc to indicate ! direction ( rotation4 ,"u ^! conditions ! upp] ecc5tric w foll[ ! crank r\nd1 op]at+ ! valve to close ! "r-h& port & op5 ! left-h& "o1 admitt+ /eam to /op ! eng9e4 ,cross ?is upp] arm out1 !n1 = manife/ly we h to use ! l[] ecc5tric1 :i*1 go+ ahead ( ! crank1 w cause ! valve to op5 ! "r-h& port :5 requir$4 ,b n[ conv]sely1 suppose t ! eng9e is to be run 9 ! opposite direction2 ! upp] ecc5tric 7repres5t$ by ! cross$-out l9e7 n[ goes ahead ( ! crank1 & gives ! valve motion 9 ! "r direction1 consequ5tly ! l[] "o mu/ n[ g out ( use1 = "u ! alt]$ conditions ( work+ x t5ds to move ! valve 9 ! wrong direction4 ,! d$uction f ?is reason+ is1 t 9 :i*ev] direction an eng9e runs1 ! ecc5tric us$ = ! "t be+ mu/ be set 9 advance ( ! crank1 & t advance mu/ be at lea/ #ij4 ,if x 7 less ?an #ij ! wrong port w\ld be op5$--! port at ! opposite end ( ! cyl9d] to t at :i* ! pi/on might happ5 to be4 ,?is effect may be %[n by purposely giv+ ! ecc5tric less advance4 ,! am\nt :i* ! angle betwe5 ! ecc5tric & ! crank exce$s #ij is ! 8angle ( advance02 & ! di/ance :i* ! valve is mov$ f midposition :5 ! pi/on is at ! end ( ! /roke is ! 8l9e> advance40 ,because ( ! necessity = diff]5t sett+s ( ! ecc5tric = diff]5t directions ( rotation ( ! crank1 eng9es requir$ to be rev]sible usually h ei!r3 7#a7 ,means = %ift+ ! position ( a s+le ecc5tric ^u ! %aft1 t x may always be plac$ s z to lead ! crank4 ,or 7#b7 ,two ecc5trics fix$ ^u ! crank-%aft s t "o ( !m is always ahead ( ! crank 9 :i*ev] direction x rotates1 me*anism be+ arrang$ 9 connection ) ! ecc5trics1 s t ! valve c be driv5 by ! lead+ ecc5tric1 or op]at$ by ! conjo9t action ( bo? ecc5trics4 ,or 7#c7 ,radial or o!r special valve ge>s4 ,! simple =m ( slide valve %[n 9 fig4 #aj does n p]mit ( ! economical use ( /eam1 inasmu* z x all[s /eam at full pressure to foll[ ! pi/on = ! :ole ( ! /roke1 & does n admit ( ! use ( its expansive prop]ties1 = ! simple reason t1 at ! in/ant ! admission ( /eam ceases1 ! exhau/ ( ! same body ( /eam mu/ imm$iately comm5ce1 z may be cle>ly se5 f ! circul> diagram4 ---------------------------------------- -------------------------------- ,,*apt] ,,iv4 ,,dead ,,c5tre4 ,,ord] ,,( ,,cranks4 ,,cu%ion+ ,,& ,,lead4 ,x is desirable at ?is po9t to cle> ! gr\nd by t\*+ = a mom5t ^u "o or two elem5t>y matt]s :i*1 if n n[ expla9$1 might cause confusion subsequ5tly4 ,dead ,c5tres4--,a crank is said to be 8on ! c5tre0 or 8on ! dead c5tre0 :5 ! connect+-rod & crank are 9 l9e1 & ?is occurs twice 9 e revolution1 z %[n 9 fig4 #aa4 ,illu/ration3 ,,fig4 #aa4--;,dead ,c5tre--,connect+ ,rod & ,crank 9 ,l9e4 ,"r-h& ,crank to ,lead4--,! phrases 8"r-h& crank to lead10 or 8left-h& crank to lead10 are sometimes us$1 & are confus+ to beg9n]s2 ! 8lead+0 crank is t "o :i* leads :5 ! eng9e is runn+ ahead4 ,9 mo/ two-crank eng9es "o ( ! cranks w be a qu>t] ( a revolution 7or less ?an half a revolution1 :]e ! cranks are n set at #ij degs47 9 advance ( its neighb\r1 & w1 !re=e1 lead x 9 ! direction 9 :i* x %\ld g4 ,( c\rse1 t neighb\r might be said to lead ! o!r by be+ ?ree-qu>t]s ( a revolution 9 advance 7or m ?an half a revolution1 :]e ! cranks are n set at #ij degs471 & ?is is :]e a little confusion sometimes arises2 ! lead+ crank mu/ always be tak5 z t "o :i* is less ?an half a revolution 9 advance ( its fell[ :5 ! eng9e is runn+ ahead1 & 9 locomotives & simil> eng9es is 8left-h&0 or 8"r-h&10 accord+ z x lies to ! left or "r ( a spectator look+ f beh9d ! crank-%aft t[>ds ! cyl9d]s4 7,see fig4 #ab1 :i* %[s two arrangem5ts ( ! driv+ cranks ( an ,engli% locomotive4 ,! cyl9d]s are suppos$ to be to ! "r ( ! :eels47 ,illu/ration3 ,,fig4 #ab4--,ord] ( ,cranks4 ,! accompany+ diagram 7fig4 #ac7 w p]haps s]ve to make cle> )\t fur!r explanation ! mean+ ( ! expression1 us$ ) ref]5ce to ?ree-crank m>9e eng9es1 ( 8ord] ( cranks1 high1 int]m$iate1 l[10 or 8ord] ( cranks1 high1 l[1 int]m$iate10 z ! case may be4 ,illu/ration3 ,,fig4 #ac4--,ord] ( ,cranks4 ,let u rev]t "h to "o ( ! po9ts previ\sly not$1 :i* 0 t ! simple valve1 :5 we _h x 9 connection ) an ecc5tric set #ij degs4 9 advance ( ! crank1 w\ld n admit /eam to ! cyl9d] at ! exact comm5cem5t ( ! /roke1 i4e41 :5 ! crank is on ei!r ( ! 8dead c5tres40 ,keep+ ?is fact 9 m9d1 we w consid] ! matt]s ( ,cu%ion+ & ,lead4--,x has long be5 f\nd desirable 7especially 9 quick-runn+ eng9es7 t ! motion ( ! return+ pi/on %\ld be oppos$ z x arrives at ei!r end ( its /roke1 s t ! mov+ weights ( pi/on1 pi/on-rod1 & connect+-rod may be 8cu%ion$10 to prev5t injuri\s /resses & to conduce to easy runn+4 ,to use a homely illu/ration1 "o might say t j 9 ! same way is x desirable1 :5 /rik+ out f ! %\ld]1 to h "o's adv]s>y )9 range1 t he may provide ! necess>y 8cu%ion+10 & s prev5t /resses 9 "o's arm & possible dislocations4 ,?is 8cu%ion+0 is provid$ 9 "p by *eck+ ! exit ( ! exhau/ /eam1 z w be %[n lat]1 & 9 "p by sett+ ! ecc5tric a little m ?an #ij degs4 7fig4 #ad7 9 advance ( ! crank1 s t ! valve comm5ces to op5 ! port to admit /eam 9 front ( ! return+ pi/on be=e x arrives at ! end ( its /roke1 cont9u+ to op5 ! port z ! pi/on comes to a re/1 & is />t$ on ! return /roke4 ,illu/ration3 ,,fig4 #ad4 ,! am\nt to :i* ! port is f\nd to be op5 :5 ! pi/on is at ! end ( its /roke is call$ ! 8lead0 ( ! valve1 & x w\ld be express$ z 8"o-eigh? ( an in* lead10 or 8?ree-sixte5?s ( an in* lead40 etc41 z ! case might be4 ,to set ?is valve = lead1 keep ! pi/on at ! end ( its /roke1 & set ! ecc5tric back until ! valve is op5$ to ! desir$ lead2 !n ! ecc5tric w\ld be fix$ 9 its newly-f\nd position1 z %[n 9 fig4 #ad4 ,! radius ( ! 8ecc5tric-arm10 :i* is ! light] ( ! two radial l9es on ! disc 9 fig4 #ad1 is equal 9 l5g? to "o-half ( ! travel ( ! valve1 & !re=e does n rea* ! edge ( ! disc1 at :i*1 h[ev]1 !re is a %ort guid+-m>k 9 ! l9e ( ! ecc5tric-arm 8produc$40 ,by us+ ?is guid+-m>k & mov+ ! arr[-head ( ! valve ov] ! scale on ! ports1 9 correspond5ce ) ! movem5t ( ! guid+-m>k on ! edge ( ! disc )9 ! circul> scale1 ! valve1 ! ma9 crank 7,c71 & ! ecc5tric c be op]at$ 9 concord1 v mu* z if !y 7 me*anically connect$4 ,! explanation j giv5 ( ! mean+ ( lead1 & ( its effect1 %\ld be borne 9 m9d1 z we %all pres5tly h to consid] x 9 conjunction ) o!r matt]s1 =1 z has be5 said1 !re is some?+ m ?an 8lead0 employ$ 9 ! production ( cu%ion+4 ---------------------------------------- -------------------------------- ,,*apt] ,v4 ,,expansion--,,inside ,,& ,,outside ,,lap ,,& ,,lead2 ,,advance ,,affect$ ,,!reby--,,compression4 ,expansion4--,9 ord] t ! expansive prop]ties ( /eam may be utilis$1 x mu/ be cut (f be=e ! pi/on arrives at ! end ( its /roke1 & on be+ cut (f mu/ n be all[$ to comm5ce exhau/+ imm$iately1 b mu/ be conf9$ 9 ! cyl9d]1 9 ord] t by exp&+ x may =ce ! pi/on fur!r be=e x4 ,! old valve1 z we h se5 x1 did n all[ ?is1 & to effect x ! faces ( ! valve are l5g!n$1 s t aft] ! /eam is cut (f by ! edge 7a7 ( ! valve 7fig4 #ae7 ! /eam is conf9$1 & exp&s 9 ! cyl9d] until ! edge 7b7 arrives at c1 :5 exhau/ imm$iately comm5ces4 ,n[ put ! pi/on at ! end ( its /roke1 & put ! new valve 9 a c5tral position 7fig4 #af74 ,! di/ance t ! valve1 :5 9 ?is c5tral position1 ov]laps ! out] edge ( ! /eam-port1 is call$ ! 8outside or /eam lap10 or m commonly ! 8lap0 ( ! valve1 t is1 ! di/ance d a 7fig4 #af74 ,illu/ration3 ,,fig4 #ae4 ,illu/ration3 ,,fig4 #af4 ,! fir/ ?+ noticeable is t ?is valve mu/ be giv5 consid]ably m travel ?an ! old "o1 z1 to op5 fully ea* port to /eam1 we h to br+ ! edge a to c1 fir/ = "o end ( ! valve & !n = ! o!r1 s t ! travel ( ?is valve mu/ be twice ! di/ance f a to c--i4e4 7lap plus port-op5+7 #b1 :]eas = ! old valve x 0 ! di/ance f d to c :i* _h to be multipli$ by two to give ! travel4 ,increas$ travel means increas$ ?r[ ( ! ecc5tric1 & we draw on ! disc 9 fig4 #af two long] ecc5tric-arms ?an be=e 7! bold] dott$ l9es7 = ! =w>d & backw>d ecc5trics4 ,we want 8lead0 ) ?is valve1 & we mu/ !re=e give ea* ecc5tric m advance ?an ! #ij degs4 %[n4 ,n[ ) ! old valve we give ea* ecc5tric an advance ^u ! #ij degs4 :i* 0 det]m9$ solely by ! lead1 no lap be+ !n 9 "q2 b we n[ h a lap to deal )1 !re=e ea* ecc5tric mu/ be set on pa/ #ij degs4 until x fir/ has drawn edge a ( ! lap to ! out] edge ( ! port1 & !n /ill fur!r until ! edge a gives ! necess>y 8lead40 ,h5ce we see t ! l9e> advance ( ! ecc5tric lap plus lead1 s z to draw ! valve out ( its c5tral position by t am\nt4 ,travel1 !n1 dep5ds ^u outside lap & port-op5+1 & lead does n affect x4 ,advance dep5ds ^u lap & lead4 ,! advance ( ! ecc5tric is usually /at$ by specify+ ! angle ( advance or ! numb] ( degrees exce$+ #ij degs4 t ! ecc5tric is 9 advance ( ! crank--= in/ance1 8an angle ( advance ( #aj degs40 means #ij degs4 #aj degs4 #ajj degs4 9 advance ( ! crank4 ,! l9e ( travel ( ! valve is sometimes incl9$ to ! l9e ( travel ( ! pi/on2 9 su* cases1 "o ( :i* is illu/rat$ 9 fig4 #ag1 ! angle ( advance mu/1 ( c\rse1 be measur$ f a l9e at "r angles to ! valve-travel l9e1 & n at "r angles to ! l9e ( pi/on-travel1 z we h hi!rto assum$4 ,illu/ration3 ,,fig4 #ag4--;,eng9e 9 :i* ! ,l9e ( ,travel ( ,valve is ,incl9$ 9 ,relation to t ( ! ,pi/on4 ,we mu/ n[ c>efully consid] ! fur!r results obta9$ by ! use ( a valve hav+ lap & giv+ lead1 & ^: ecc5tric ( great] ?r[ is advanc$ accord+ly4 ,we %\ld expect cut-(f to take place e>li] ?an ) ! old valve1 = ! ecc5tric is advanc$1 & ! edge a 7fig4 #ae7 w\ld arrive at e a little e>li] ?an w\ld ! edge d ( ! old valve1 ev5 )\t advance ( ! new ecc5tric4 ,?is se51 we c und]/& t 9 caus+ ! edge a 7fig4 #ah7 to rea* ! edge e e>li] 9 ! /roke ( ! pi/on ?an x o!rwise w\ld d1 we %all h ha/5$ all ! o!r op]ations s t !y mu/ occur e>li] 9 ! /roke 7n necess>ily by exactly ! same am\nt = ea*1 h[ev]1 z we %all see fur!r on71 h5ce ! edge b 7fig4 #ah7 arriv+ e>li] at c1 exhau/ w comm5ce be=e ! pi/on completes its /roke1 & also 9 return+ to ! "r 7fig4 #ai7 ! valve is e>li]1 & in/ead ( ! exhau/ la/+ dur+ ! :ole ( ! return /roke "s ( x w be %ut 9 by b & compress$ be=e ! return+ pi/on until ! edge a arrives at e1 :]eupon ! lead comm5ces com+ 9 on & re9=c+ ! compress$ /eam4 ,?us x is t compression & lead toge!r affect ! cu%ion+1 & consequ5tly ! pi/on is eas$ 9 /opp+1 & ! return /roke is comm5c$ )\t injuri\s %ock or j>4 ,a simil> op]ation1 ( c\rse1 takes place at ! opposite end ( ! cyl9d] :5 ! pi/on arrives !re4 ,illu/ration3 ,,fig4 #ah4 ,illu/ration3 ,,fig4 #ai4 ,! di/ribution-diagram = a valve ) lap1 lead1 & a suitable ecc5tric is giv5 9 fig4 #bj1 :i* %\ld be comp>$ c>efully ) figs4 #aj & #ad4 ,illu/ration3 ,,fig4 #bj4 ,inside ,lap1 exhau/ lap1 or 8cov]0 z x is sometimes call$1 is possess$ by _m slide valves1 & x is ! am\nt t ! valve :5 9 its c5tral position ov]laps ! inn] edges ( ! /eam-ports4 ,conv]sely1 ,inside ,lead is ! am\nt ( space left1 9 c]ta9 cases1 betwe5 ! inn] edge ( ! valve & ! inn] edge ( ! /eam-port :5 ! valve is 9 its c5tral position4 ,! am\nt ( inside lap does n affect ! sett+ ( ! ecc5tric1 nei!r does x necessitate any alt]ation 9 ! travel ( ! valve4 ,) a giv5 cut-(f1 /eam is conf9$ long] 9 ! cyl9d] by a valve hav+ inside lap because ( ! l5g!n+ ( ! valve-face due to ! inside lap1 & compression w comm5ce e>li] & w be ( long] duration f ! same cause2 exhau/ be+ %ort5$ 9 two ways--by ! am\nt add$ to ! duration ( expansion at its end1 & by a simil> am\nt add$ to ! compression at ! comm5cem5t !re(4 ,inside lead may be consid]$ z some?+ tak5 (f ! exhau/ edge ( ! valve1 & 9 effect1 exactly ! opposite to exhau/ lap1 =1 z may easily be se51 x %ort5s expansion & compression by reason ( ! %ort5+ ( ! valve-face1 & l5g!ns ! exhau/ at comm5cem5t & end by ! am\nts by :i* ! op]ations ( expansion & compression are %ort5$4 ,! left-h& side ( ! valve 9 fig4 #ba has inside lap1 :il/ ! "r-h& side has inside lead1 & ! circul> di/ribution-diagram bel[ comp>es ! di/ribution 9 ! case ( valves hav+ inside lap & inside lead ) ! di/ribution = an ord9>y valve su* z 0 consid]$ ) ref]5ce to fig4 #bj4 ,by ref]5ce to ! l[] portion ( fig4 #ba1 x may be se5 t ! op]ations ( admission & cut-(f are unaffect$1 z !y are p]=m$ by ! out] edges ( ! valve2 b ,illu/ration3 ,,fig4 #ba4 is %ort] & exhau/ e>li] ) inside lead4 ,expansion is long] & exhau/ lat] ) inside lap4 is lat] & %ort] ) inside lead4 ,compression is e>li] & long] ) inside lap4 ,f ?is x w be obvi\s :y _m express locomotives are giv5 inside lead1 & :y _m good eng9es h inside lap4 ,free ,exhau/4--,9 ord] to give z free a passage z possible to ! exhau/ /eam1 s t x may leave ! cyl9d] easily1 & n h to be =c$ out by ! return+ pi/on & cause back pressure !reupon1 x is cu/om>y to make ! /eam-ports wid] ?an ! am\nt to :i* !y are op5 to /eam4 ,?is mu/ on no acc\nt be confus$ ) inside lead1 :i* is q a di/9ct matt]4 ,! effect ( hav+ wide ports is t ! exhau/ may be op5$ to any ext5t up to ! half-travel ( ! valve1 al?\gh ! /eam-op5+ may be mu* small]1 z may be und]/ood f ! exagg]at$ diagram 7fig4 #bb71 :5ce also %\ld be se5 t ?is wid5+ ( ! port does n affect ! duration ( expansion or ( any o!r op]ation ( ! valve1 nei!r does x necessitate any all[ance 9 ! sett+ ( ! ecc5tric4 ,x simply provides a free exhau/4 ,illu/ration3 ,,fig4 #bb4 ---------------------------------------- -------------------------------- ,,*apt] ,,vi4 ,,d\ble-,,port$1 ,,multiple ,,admission1 ,,& ,,pi/on ,,valves4 ,d\ble-port$ ,valves4--,9 l>ge m>9e eng9es us+ consid]able quantities ( /eam p] /roke1 & consequ5tly requir+ a l>ge am\nt ( port-op5+1 ! ord9>y slide valve w\ld require an undue am\nt ( travel4 ,to obviate ?is1 ea* end ( ! cyl9d] may h two /eam-ports1 bo? ports op5+ into "o passage z %[n1 & a d\ble-port$ valve4 ,! d\ble-port$ valve is virtually a comb9ation ( two slide valves 9 a s+le ca/+ 7fig4 #bc71 "o valve = ! inn] set ( /eam-ports & ! exhau/-port1 ! o!r valve be+ halv$1 z x 71 = ea* out] /eam-port4 ,! exhau/ cavity ( ea* ( ! out] 8half-valves0 hav+ a passage lead+ to ! exhau/ cavity ( ! inn] valve1 bo? ! valves exhau/ into ! c5tral port1 :i* is wid5$ accord+ly4 ,! fig4 #bc is m]ely diagrammatic1 to enable ! pr9ciple ( ?is valve to be easily borne 9 m9d2 ! next draw+ 7fig4 #bd7 %[s 9 section a d\ble-port$ valve z actually con/ruct$1 ) ! exception t ! valve-sp9dle & its *amb] are omitt$ 9 ord] t ! =m ( ! valve may be m cle>ly %[n4 ,! section is tak5 9 two planes1 "o ^u ! longitud9al c5tre l9e ( ! valve1 & ! o!r 7! left-h& half ( ! valve7 a little to ! ne> side ( ! c5tre l9e4 ,fig4 #be %[s a sectional view ( a d\ble-port$ valve 9 p]spective4 ,illu/ration3 ,,fig4 #bc4--;,diagram %[+ ,fl[ ( ,/eam & ,exhau/ ?r\gh a ,d\ble-port$ ,slide ,valve4 ,illu/ration3 ,,fig4 #bd4--,v]tical ,section ?r\gh a ,d\ble-port$ ,slide ,valve4 ,illu/ration3 ,,fig4 #be4--,p]spective view 79 ,section7 ( a ,d\ble-port$ ,slide ,valve4 ,n[1 any movem5t giv5 to ! 8inn] valve0 is giv51 ( c\rse1 to ! out] "o1 s t if ! inn] valve be mov$ s z to give1 say1 #b ins4 ( port-op5+1 ! out] valve gives at ! same "t ano!r #b ins4 ( port-op5+2 !re=e1 ) a giv5 movem5t ( a d\ble-port$ valve we get d\ble ! am\nt ( port-op5+ t we %\ld h obta9$ ) ! ord9>y valve4 ,h5ce ! travel ( ! d\ble-port$ valve 7lap half ! two port-op5+s7 #b2 :]eas t ( ! ord9>y valve 7lap ! port-op5+ requir$7 #b4 ,! inn] & out] valves ( ! d\ble-port$ con/ruction1 act+ simultane\sly1 h ea* ! same am\nt ( lap2 b !y give ! lead betwe5 !m1 & ! ecc5tric is set ) a l9e> advance equal to "o ( ! laps & "o ( ! lead-op5+s4 ,! di/ribution ( /eam ) ?is valve is simil> to t ( ! ord9>y valve ^: di/ribution-diagram 0 %[n 9 fig4 #bj4 ,! diff]5t p]iods are ( ! same duration 9 ! example *os51 b ! op]ations ( cutt+ (f /eam & ( op5+ exhau/ are p]=m$ by ! edges ( ! inn] & out] valves in/ead ( by a s+le edge z 9 ! ord9>y valve4 ,a valve v simil> to ! d\ble-port$ valve1 %[n 9 fig4 #bc1 is ! ,gidd+s valve us$ on ! ,russell eng9es & "s o!r automatic high-spe$ eng9es 9 ,am]ica4 ,by its peculi> con/ruction1 ?is valve obviates ! necessity ( d\ble /eam ports1 yet x is s mu* l ! d\ble-port$ valve t x may be notic$ "h r ?an "u ! head ( multiple admission valves1 :]e x might be said to prop]ly belong4 ,?is valve accompli%es exactly :at ! d\ble-port$ valve does1 & 9 pretty mu* ! same way4 ,! ,gidd+s valve 9 fig4 #bf %[s /eam be+ admitt$ to ! "r-h& end ( ! cyl9d] & exhau/$ f ! left-h& end4 ,! travel ( ?is valve is1 z 9 ! case ( ! d\ble-port$ valve 7lap half ! port op5+ requir$7 #b4 ,! valve %\ld be set ) a l9e> advance equal to ! lap plus "o-half ! requir$ lead4 ,illu/ration3 ,,fig4 #bf4--,! ,gidd+s ,valve4 ,,multiple ,,admission ,,valves4 ,9 ,am]ica1 ! type ( eng9e kn[n z ! automatic high-spe$ eng9e is v mu* us$4 ,^! eng9es h a wide range ( cut-(f1 f almo/ #j to /roke1 & 9 ord] to avoid a long valve & a long travel & to secure a quick admission & cut-(f ( ! /eam1 rec\rse is _h to multiple admission valves4 ,^! valves are s con/ruct$ t :5 "o ( !m is mov$ f midposition1 a di/ance equal to1 say1 ( an in* m ?an ! /eam lap1 ! wid? ( ! op5+ = ! /eam to pass ?r\gh into ! cyl9d] is multipli$ by ! numb] ( admissions ( ! valve4 ,?us1 if ! valve is a d\ble admission valve1 & x is mov$ plus ! /eam lap f midposition1 ! port is op5$ a di/ance equal to #b ( an in*4 ,d\ble admission valves are q common & !re are also a numb] ( quadruple admission valves us$4 ,!y are made z flat valves & z pi/on valves1 b all are made ) a common object 9 view1 t is1 to secure an e>ly cut-(f & quick op5+ & clos+ ( ! ports ) a valve ^: l5g? & travel %all be %ort4 ,"o ( ! be/-kn[n =ms ( d\ble admission valves is ! 8,/raight ,l9e0 or 8,sweet0 valve1 :i* 0 inv5t$ by ,pr(essor ,john ,e4 ,sweet1 =m]ly ( ,cornell ,univ]sity1 & fir/ us$ by him on ! ,/raight ,l9e eng9es4 ,?is valve is n[ us$ by a l>ge numb] ( manufactur]s ( automatic high-spe$ eng9es4 ,! valve is %[n 9 section 9 fig4 #bg1 :]e a is ! 8cov] plate10 & b is ! valve1 prop]4 ,! valve1 b1 moves back & =? betwe5 ! cov] plate1 a1 & ! valve seat4 ,! cov] plate re/s on pieces call$ 8di/ance pieces10 plac$ at ! sides ( ! valve4 ,^! di/ance pieces are made ( su* a ?ickness t :ile ! cov] plate _c t\* ! valve1 x is s close to x z to make a /eam tight jo9t betwe5 ! plate & ! valve4 ,!re=e1 ! valve acts z a pi/on ( rectangul> cross-section1 mov+ back & =? betwe5 ! cov] plate & ! valve seat4 ,! result ( its peculi> con/ruction is t a balanc$ flat valve is secur$2 a valve :i* works ) v little friction1 z !re is no surface ^u :i* ! /eam c act s z to press ! valve aga9/ ! valve seat4 ,! cov] plate is kept 9 place by ! pressure ( ! /eam aga9/ its back1 aid$ by "o or two small spr+s ins]t$ betwe5 ! plate & ! /eam-*e/ cov]4 ,illu/ration3 ,,fig4 #bg4--,! ,/raight ,l9e ,valve4 ,?is valve %\ld be set s t ! di/ance ! valve is f midposition :5 ! pi/on is at ! end ( its /roke1 or ! l9e> advance1 %all be equal to ! /eam lap plus "o-half ! desir$ lead4 ,! travel ( ! valve is equal to twice ! sum ( ! /eam lap & "o-half ! maximum op5+ ( ! port = /eam1 or #b 7/eam lap maximum op5+ ( port = /eam74 ,9 ! case ( a quadruple admission valve1 su* z ! ,woodbury valve %[n 9 fig4 #bh1 ! travel is equal to twice ! sum ( ! /eam lap & "o-f\r? ! maximum op5+ ( ! port = /eam1 or #b 7/eam lap maximum op5+ ( port = /eam74 ,illu/ration3 ,,fig4 #bh4--,! ,woodbury ,valve4 ,! diff]5t phases ( ! movem5t ( a multiple admission valve are j ! same z = ! ord9>y slide valve1 ! only diff]5ce be+ 9 ! sudd5ness ) :i* ! ports are op5$ & clos$4 ,pi/on ,valves4--,x may be readily se5 t betwe5 ! ord9>y flat slide valve & ! valve-seat consid]able friction is set up1 because ! /eam pressure on ! back ( ! valve is only p>tly balanc$ by ! v>y+ pressure 9 ! cyl9d] /eam-passages act+ ^u small portions ( ! area ( ! 8rubb+0 or "u-side ( ! valve2 b by mak+ ! port-faces cyl9drical & mak+ ! faces ( ! valve 9 ! =m ( pi/ons1 ! pressure is giv5 no surface ^u :i* to press 9 ! direction ( ! valve-seat2 or1 9 ! case ( holl[ pi/on valves 7an example ( :i* w be pres5tly illu/rat$71 al?\gh ! /eam has access to ! int]ior ( ! tube1 pressure on p>ts !re( is balanc$ by an equal pressure 9 an opposite direction ^u exactly opposite p>ts1 & !re=e is conf9$ to /ress+ ! valve & has no t5d5cy to =ce any "p ( x on to ! valve-seat4 ,9 ! pla9 pi/on valve %[n 7fig4 #bi7 ! faces are =m$ by ! two valve pi/ons1 :i* "w 9 a cyl9d] :]e9 /eam & exhau/ op5+s are made4 ,illu/ration3 ,,fig4 #bi4 ,sometimes ! /eam-supply ent]s betwe5 ! two pi/ons1 z 9 figs4 #cj & #ca1 exhau/ tak+ place into ! spaces at ! ends ( ! valve1 :i* spaces are connect$ by passages =m$ 9 ! valve1 :i* is tubul>1 z %[n4 ,9 su* valves ! /eam-lap mu/ be put ^u ! inn] edges ( ! valve pi/ons1 = ! /eam & exhau/ edges h _! positions rev]s$2 & ! lead w also be giv5 by ! inn] edges4 ,illu/ration3 ,,fig4 #cj4 ,illu/ration3 ,,fig4 #ca4--,! ,ide ,valve4 ,! ecc5trics = a valve ) int]nal /eam-supply mu/ be plac$ #ahj degs4 9 advance ( ! positions :i* !y w\ld occupy if ! valve 7 ( simil> proportions1 b ) ext]nal /eam-supply1 = ! reason t ! int]nally suppli$ valve mu/ be mov+ up1 = in/ance1 :5 ! ord9>y valve w\ld be mov+ d[n1 & vice v]sa4 ,if ! valve be an ext]nally suppli$ valve1 b driv5 f "o end ( a two-arm$ rock+-%aft1 ! valve ge> actuat+ ! o!r end1 z 9 ,am]ican locomotive practice1 ! ecc5trics mu/1 = obvi\s reasons1 be set #ahj degs4 9 advance ( _! usual position4 ,fig4 #cj is giv5 by ! k9d p]mission ( ,messrs4 ,w4 ,d5ny ,company1 ! well-kn[n ,clyde %ip-build]s1 & x possesses _m po9ts ( int]e/1 "o ( :i* is t ! pack+ 9 ! valve-sp9dle /uff+-box bel[ ! valve1 & n %[n 9 ! draw+1 is subject only to ! influ5ce ( ! temp]ature & pressure ( exhau/ /eam1 in/ead ( to t ( ! high] temp]ature & pressure ( ! supply /eam2 ?is is a matt] ( importance1 hav+ 9 view ! high pressures ( /eam :i* are n[ us$4 ,fur!r1 x may be se5 t ! upp] pi/on ( ! valve is ( great] area ?an ! l[] "o1 & t ! high-pressure /eam ent]+ betwe5 ! two pi/ons w consequ5tly ex]t a total pressure upw>d ^u ! l>g] pi/on great] 9 am\nt ?an ! d[nw>d pressure ex]t$ ^u ! l[] & small] "o2 ?us ! valve has a t5d5cy to rise1 s long z /eam is on4 ,?is upw>d t5d5cy balances :olly or 9 "p ! d[nw>d t5d5cy due to ! weight ( ! valve1 :i* has n to be lift$ by ! valve ge>1 :i* may be ( a light] "* ?an usual1 & give less tr\ble 9 work+1 ow+ to dim9ution ( we> & te>4 ,! valve-sp9dle ( ! ord9>y flat valve is sometimes prolong$ 7:]e ! valve works v]tically7 to end 9 a small pi/on expos$ to /eam pressure1 & act+ s z to balance ! weight ( ! valve4 ,9 ! 8,joy0 assi/ant-cyl9d]1 a balance-pi/on is provid$ ) special passages :i*1 9 ! movem5t ( ! valve-sp9dle1 are br\ght opposite ports 9 ! assi/ant-cyl9d] wall1 s t /eam is let 9 to propel ! balance-pi/on up or d[n1 & !reby assi/ ! valve ge> 9 ea* /roke4 ,! balance-pi/on acts z its own exhau/ valve 9 slid+ ov] exhau/-ports 9 ! assi/ant-cyl9d] wall4 ,fig4 #ca %[s ! pi/on valve us$ 9 ,am]ica on ! well-kn[n ,ide & ,ideal eng9es4 ,x is v simil> to ! valve %[n 9 fig4 #cj1 & has ! same advantages :i* h be5 po9t$ out z belong+ to t valve4 ,z1 h[ev]1 x is pr9cipally us$ on horizontal eng9es1 ! two pi/ons are made ( ! same diamet]1 9 ord] to secure a p]fectly balanc$ valve4 ---------------------------------------- -------------------------------- ,,*apt] ,,vii4 ,,! ,,effect ,,( ,,alt]ations ,,to ,,valve ,,& ,,ecc5tric4 ,advance ( ! ,ecc5tric4--,x %\ld "h be e/abli%$ t to any giv5 example ( valve1 ports1 & ecc5tric 7leav+ ! pi/on out ( consid]ation = a mom5t7 belongs a c]ta9 cycle ( op]ations1 ! occurr5ce ( ^! op]ations & _! duration1 express$ 9 fractions ( a revolution ( ! rotat+ ecc5tric1 be+ con/ant = a giv5 case1#c b ! fraction ( /roke trav]s$ by ! pi/on betwe5 or dur+ any ( ^! op]ations ( ! valve w dep5d ^u :]e 9 ! /roke ( ! pi/on ! cycle ( op]ations is />t$1 tak+ any conv5i5t op]ation z be+ ! comm5cem5t ( ! cycle1 = ! spe$ ( ! pi/on rises f nil at ! comm5cem5t ( its /roke to a maximum ne> ! middle1 fall+ aga9 to nil at ! end4 ----- ,footnote #c3 ,to make ! idea cle> "o might plot ^! op]ations r\nd a circle repres5t+ "o revolution ( ! ecc5tric1 :5 x w\ld be se5 t ! op]ations ( ! valve c\ld be consid]$ q indep5d5tly ( ^? ( ! pi/on--!n x w\ld rema9 to %[ :at ! pi/on might d1 or h done ^u x1 by comp>+ its motion "u v>y+ conditions ) ! unv>y+ op]ations ( ! valve1 9 ! mann] expla9$ lat]4 ,n[ we may g on to consid] ! effect ( increas+ ! advance ( an ecc5tric beyond t :i* x w\ld ord9>ily h 7fig4 #cb74 ,if we suppose our ecc5tric & valve to give u a cut-(f at ,c & an exhau/ at ,e1 expansion la/+ #j4ag ( ! /roke 7z %[n 9 full l9es1 fig4 #cb71 & t by advanc+ ! ecc5tric we get a cut-(f at ,c#a #j4ad e>li]1 we mu/ n expect to f9d t exhau/ also w be #j4ad e>li] 7dott$ l9es1 fig4 #cb71 = al?\gh ! exhau/ edge ( ! valve always gives exhau/ at a c]ta9 con/ant p]iod ( "t lat] ?an /eam is cut (f by ! /eam edge1 yet 9 t int]val ! spe$ ( ! pi/on slack5s less 9 ?is second case ?an 9 ! fir/ example1 & x !re=e travels ?r\gh a great] di/ance ?an 9 ! same "t-int]val tak5 lat] 9 ! /roke 9 ! fir/ case4 ,h5ce1 ) increas$ advance we get e>li] cut-(f1 ) expansion ( l5g!n$ duration because exhau/ is n e>li] 9 ! same degree1 nei!r are all ! o!r op]ations p]=m$ by ! valve1 al?\gh !y ea* comm5ce e>li] & la/ long] 9 ! /roke1 lead includ$1 b admission1 ( c\rse1 except$4 ,! idea may1 p]haps1 be m easily grasp$ by keep+ ! ecc5tric & valve 9 view at an unalt]+ /&>d ( ref]5ce1 & :5 x is desir$ to consid] ! effect ( advanc+ ! ecc5tric1 to imag9e in/ead t x is ! sett+ ( ! ma9 crank :i* is alt]$--:i* 9 effect is ! same ?+1 & is1 p]haps1 easi] to reason out4 ,illu/ration3 ,,fig4 #cb4 ,l5g!n+ or ,%ort5+ ! ,ecc5tric ,rod--,%ift+ ! ,valve on its ,sp9dle4--,/>t+ ) ! valve 9 its c5tral position1 & l5g!n+ or %ort5+ ! ecc5tric rod or %ift+ ! valve on its sp9dle1 or comb9+ bo? op]ations 9 ! same s5se1 ! di/ance betwe5 ! c5tre ( ! crank-%aft & ! c5tre ( ! valve is alt]$1 & ! travel ( ! valve is %ift$ bodily to ! "r or left1 i4e41 ! valve :5 9 ! c5tre ( its travel 7! ext5t ( travel rema9+ ( c\rse unalt]$7 w be ei!r fur!r f or ne>] to ! crank-%aft ?an be=e1 :ile ! position ( ! ports rema9s unalt]$2 !re=e ! arr[ ^u ! valve at its c5tre 7see fig4 #af7 lies to ! "r or left ( ! c5tre l9e ( ! port-face1 &1 t arr[ be+ no long] appropriate z a po9t] at mid-travel to ! z]o ( ! scale on ! ports1 we mu/ adopt z our index-f+] ! graduation m>k made adjac5t to ! arr[ & ly+ ov] ! said z]o1 9 ord] t :5 ! disc may indicate t ! valve %\ld move1 say1 f #j to #f ! new m>k or index-f+]1 & n ! arr[1 may be giv5 t movem5t4 ,if ! valve _h previ\sly be5 prop]ly set = lead1 & ! alt]ation %ift$ x 94 to ! left1 = example1 we %\ld f9d t ! lead at ! left-h& end w\ld be dim9i%$ by t am\nt1 & t subsequ5tly1 at cut-(f1 release1 & compression1 = bo? ends ( ! cyl9d]1 ! valve w\ld always be f\nd 94 to ! left ( its prop] position4 ,! result w\ld be1 z %[n 9 fig4 #cc1 t3 ,at left-h& ( cyl9d] 7see l9es ( da%es73-- ,lead decreases e>li]1 ^! op]ations ,cut-(f takes place tak+ place ,exhau/ comm5ces z ! valve moves t[>ds ! left4 ,compression comm5ces lat]1 ?is op]ation tak+ place z ! valve moves f ! left4 ,at "r-h& end ( cyl9d] 7see l9es ( dots73-- ,lead increases lat]1 because :5 ,exhau/ comm5ces effect+ !m ! ,cut-(f takes place valve is mov+ f ! left4 ,illu/ration3 ,,fig4 #cc4 ,compression comm5ces e>li]1 = x occurs :il/ ! valve is mov+ to ! left4 ,! alt]ations at opposite ends be+ 9 opposite s5se4 7,! normal di/ribution is %[n by full l9es = comp>ison47 ,& al?\gh ! comm5cem5t ( ! op]ations is advanc$ & ret>d$ by ! same am\nt ( error1 op]at+ 9 opposite s5se on opposite sides ( ! pi/on1 yet !re is a diff]5ce 9 ! "w done ^u ! opposite sides because ( ! comm5cem5t ( ! two cycles ( op]ation at diff]5t times1 :5ce we inf] diff]5ces 9 ! spe$s ( ! pi/on1 9 ! quantities ( /eam admitt$1 & 9 ! expansion-curves4 ,9 "s cases su* a diff]5ce is desirable1 & ) ! work+ diagram sugge/$ 9 ,*apt] ,i4 ano!r s]ies ( results may be obta9$ by us+ ! ord9>y valve = di/ribution on "o side ( ! pi/on1 & = ! o!r side us+ a diff]5tly-proportion$ valve ) a diff]5t index-po9t]1 z ?\gh opposite ends ( "o valve 7 diff]5tly proportion$1 z 9 c]ta9 l>ge v]tical eng9es4 ,add+ ,extra ,lap to a ,valve4--,9 "s cases cut-(f may be want$ e>li] 9 ! /roke1 p]man5tly1 ) expansion ( long] duration4 ,"u su* circum/ances m lap may be add$ to ! valve4 ,if ?is be done1 & ! valve ) its extra lap be re-set by giv+ ! ecc5tric great] advance 9 ord] to get ! same lead z be=e 7travel ( valve rema9+ unalt]$71 ! /eam-ports w n be op5$ to s great an ext5t z =m]ly1 & w close e>li]1 p>tly because ( ! add$ lap1#d & p>tly because ( ! increas$ advance4 ,! increas$ l5g? ( ! valve-face w1 aft] cut-(f1 conf9e ! /eam long] 9 ! cyl9d]1 & x %\ld be obvi\s 7! effect ( advanc+ ! ecc5tric hav+ already be5 %[n ) ref]5ce to fig4 #cb7 t 9 addition to ! e>li] comm5cem5t & l5g!n$ duration ( expansion1 ! exhau/ & compression w beg9 some:at e>li] because ( ! increas$ advance1 & ! compression w be ( long] duration because ( ! increas$ l5g? ( ! valve-face4 ----- ,footnote #d3 ,to assure "o's self ( ?is1 take an extreme case & imag9e an excessive am\nt ( lap to be add$4 ,9 su* a case1 ) travel unalt]$1 ! ports might n be op5$ to /eam at all1 ! valve simply slid+ backw>ds & =w>ds )\t uncov]+ !m2 n[1 tak+ ?is lap (f piecemeal ! port w\ld fir/ be op5$ to an exce$+ly small degree & in/antly %ut aga91 ! am\nt & duration ( op5+ increas+ ) ea* successive removal ( lap4 ,g5]al4--,x is "h se5 t 9 alt]+ ei!r ! outside or ! inside laps ) int5t to affect only ! /eam admission ) ! =m]1 or only ! exhau/ ) ! latt]1 we mu/ p]=ce affect o!r ?+s4 ,= in/ance1 we alt] ! outside lap1 ) ! int5tion1 say1 ( simply mak+ cut-(f e>li] or lat] z ! case may be--b hav+ alt]$ ! l5g?s ( ! valve-faces1 !y w alt] ! duration ( expansion & ( compression1 & ! alt]ation necessitat$ 9 ! advance ( ! ecc5tric 9 ord] t ! lead may rema9 unalt]$ has its own effect 9 addition4 ,?is int]dep5d5ce1 :i* is (t5 inconv5i5t1 is *>act]i/ic ( ! slide valve work$ by an ecc5tric1 & has l$ to ! use ( valve ge>s & valves :i* p]mit1 m or less1 ( ! indep5d5t regulation ( "s or all ( ! v>i\s op]ations 9 ! di/ribution ( /eam4 ,"s ( ^! ge>s are us$ ) a slide valve 7z 9 ! case ( ! ,joy & o!r well-kn[n valve ge>s71 :ile o!rs op]ate special valves4 ---------------------------------------- -------------------------------- ,,*apt] ,,viii4 ,,note ,,on ,,l9k ,,motions4 ,! ,l9k ,motion4--,9 eng9es ^: duty frequ5tly v>ies1 z 9 ! famili> case ( a locomotive1 p]man5t alt]ation ( lap w\ld n meet ! requirem5ts ( ! case1 = ! am\nt ( expansion %\ld be susceptible ( ready v>iation at any "t1 9 accordance ) alt]ations 9 ! weight ( tra91 gradi5ts1 & wea!r4 ,! l9k motion1 9 addition to be+ a rev]s+ ge>1 is also a 8v>iable expansion0 ge>4 ,a precise analysis ( any giv5 case ( l9k motion is a some:at difficult op]ation1 b1 speak+ broadly1 ! l9k motion may be said to provide :at is virtually an ecc5tric ( diff]5t ?r[ & advance = ea* degree ( expansion4 ,al?\gh1 actually1 ! same two ecc5trics rema9 con/antly 9 use1 ! l9k motion may be s adju/$ z to h an effect on ! valve simil> to t :i* w\ld ensue ^u ! sub/itution1 "o = ano!r1 ( diff]5t ecc5trics z /at$4 ,assum+ t ! l[e/ range ( expansion is be+ us$1 ! valve w h ! travel1 cut-(f1 & lead due = ! mo/ "p to ! ?r[ ( ! actual ecc5tric & to its position ) relation to ! crank1 almo/ z 9 ! case ( an ecc5tric ^: rod is directly connect$ to ! valve-sp9dle2 n[1 z ! l9k is rais$ 7an op]ation sometimes t]m$ 8l9k+-up07 its c5tre gets ne>] to ! block on ! end ( ! valve-sp9dle ?an x 0 be=e 7i4e41 ne>] to 8mid-ge>071 & we get 9 effect3-- ,a s]ies ( ecc5trics ( ,) l9k motion decreas+ ?r[1 b ( hav+ 8op50 rods4 increas+ angul> & l9e> advance4 ,a s]ies ( ecc5trics ( decreas+ ?r[ & ( increas+ angul>1 b ,) l9k motion decreas+ l9e> advance2 hav+ 8cross$0 rods4 ?r[1 !re=e1 decreas+ m rapidly ?an 9 ! case ( ! l9k motion ) 8op50 rods4 ,take ! case ( a p>tially l9k$-up motion ) op5 rods2 we %all f9d t because ! ?r[ ( ! ecc5tric is less5$1 ! travel ( ! valve to ! "r & left ( its c5tral position w be dim9i%$1 & ! ports w n be op5$ s wide to /eam or exhau/2 because ( ! increas$ advance ( ! ecc5tric1 /eam w be cut (f e>li]1 compression & lead w also be e>li]1 expansion & compression la/+ long]1 & exhau/ & admission be+ %ort5$4 ,! diff]5ce betwe5 work+ 9 full ge> & l9k$ up is %[n by ! diagram 9 fig4 #cd4 ,illu/ration3 ,,fig4 #cd4 ,bel[ are diagrams %[+ ! effect ( putt+ ! l9k motion 9 8mid-ge>0 7fig4 #ce7 & ( putt+ ! l9k motion into 8back ge>0 7fig4 #cf7 :ile ! eng9e is runn+ ahead1 z = a locomotive1 b x w be und]/ood t ! effect ( ! compression %[n 9 ! latt] w be modifi$ by ! lift+ ( ! valve f its face1 ) ! result t "s compress$ air & /eam w g up ! exhau/4 ,illu/ration3 ,,fig4 #ce4 ,illu/ration3 ,,fig4 #cf4 ,! set ( diagrams =m+ fig4 #cg is int5d$ to give a comp>ative view ( ! effect ^u ! di/ribution ( /eam1 ( diff]5tly arrang$ valves & ecc5trics4 ,! op]ations tak+ place ^u only "o side ( ! pi/on are %[n1 except 9 t section ( ! diagram :i* conc]ns a %ift$ valve1 9 ord] to avoid confusion4 ,! upp] l9e ( ea* diagram1 be+ read f left to "r1 %[s ! op]ations :i* take place on ! =w>d /roke1 ^? ( ! return /roke be+ read f "r to left ^u ! l[] portion ( ea* diagram4 ,illu/ration3 ,,fig4 #cg4 ---------------------------------------- -------------------------------- ,,*apt] ,,ix4 ,,note ,,on ,,v ,,e>ly ,,cut-,,(f1 ,,& ,,on ,,rev]s+ ,,ge>s ,,9 ,,g5]al4 ,v e>ly ,cut-(f4--,!oretically !re is no limit to ! range ( cut-(f :i* may be obta9$ f an ord9>y slide valve1 b a mom5t's consid]ation w %[ t if we require a valve to cut (f /eam v e>ly 9 ! /roke ( ! pi/on s z to cause x to exp& ?r\gh\t an increas$ fraction ( t /roke1 ! lap mu/ be consid]ably increas$ beyond t :i* is usual1 if ! valve-face is to be enabl$ to keep ! /eam conf9$ 9 ! cyl9d] = a suffici5t p]iod aft] cut-(f is effect$4 ,z a consequ5ce ( increas$ lap1 ! travel ( ! valve1 made up ( lap plus ! requir$ port-op5+1 w ne$ to be increas$ correspond+ly2 ! l9e> advance 7! sum ( lead plus an increas$ lap7 w be increas$ also1 & ! valve w !re=e come back e>li] into its c5tral position 7:]e compression beg9s7 ?an w\ld ! normal valve1 s mak+ compression beg9 e>li] & la/ long] ?an be=e4 ,9 an unbalanc$ valve1 ?is increas$ travel1 toge!r ) ! abnormal compression1 _c be tol]at$1 s t = obta9+ an e>ly cut-(f )\t too mu* compression1 ) a slid+ valve1 ge> ( ! 8sep>ate cut-(f slide10 or ,mey] type1 is employ$4 ,?is is *>act]is$ by a cut-(f plate or plates on ! back ( a ma9 slide valve1 :i* may h ! usual exhau/ cavity1 & 9 addition possesses supply /eam-conduits lead+ ?r\gh ! valve f ! back to ! 8lap-edges0 7fig4 #ch74 ,exhau/ & compression are tim$ by ! edges ( ! c5tral exhau/ cavity2 lead is giv5 by ! 8lap-edges10 b cut-(f is controll$ by movem5t ( ! cut-(f plates on ! back ( ! mov+ ma9 valve1 s t ?\gh a 8lap-edge0 may n at any "t h clos$ "o ( ! /eam-ports prop]1 a cut-(f plate work$ by a sep>ate ecc5tric c close ! appropriate /eam-conduit above ref]r$ to1 & s /op ! curr5t ( /eam fl[+ pa/ ! lap-edge to ! /ill op5 port4 ,moreov]1 by a suitable sett+ ( ! ecc5trics ( ! ma9 & cut-(f valves1 x is possible to arrange t1 at ! in/ant ( cut-(f1 ! two valves %all be mov+ 9 opposite directions1 & s %all effect a %>p cut-(f1 :]eby wire-draw+ is r$uc$4 ,illu/ration3 ,,fig4 #ch4--,slide ,valve1 ) ,cut-(f ,plate on back4 ,) ! model ref]r$ to 9 ! e>li] *apt]s1 ! action ( a ,mey] or simil> ge> c be readily inve/igat$ if an extra ecc5tric-arm be add$ to ! crank-p9 disc & an extra travel-scale m>k$ ^u ! baseplate4 ,9 fig4 #ci is %[n ! 8,buckeye0 valve us$ 9 ,am]ica on ! ,buckeye eng9e2 a is ! ma9 valve1 :i* det]m9es ! admission1 release & compression ( ! /eam2 & b is ! small auxili>y valve :i* rides on ! top ( ! ma9 valve a1 & :i* effects ! cut-(f4 ,?is valve is con/ruct$ s z to h all ! advantages ( a p]fectly balanc$ valve z well z ^? ( ! ,mey] valve4 ,!re are two faces betwe5 :i* ! ma9 valve slides /eam tight1 & ! small valve works on a face inside ( ! ma9 valve1 z %[n 9 ! figure4 ,/eam is exhau/$ pa/ ! out] edges ( ! ma9 valve4 ,9 ord] t /eam may ent] ! cyl9d]1 ! port 9 ! ma9 valve mu/ be 9 communication ) ! /eam port & at ! same "t x mu/ n be cov]$ by ! auxili>y valve b4 ,9 ! figure ! valves are %[n 9 su* a position z to admit /eam to ! left-h& end ( ! cyl9d] & to all[ x to exhau/ f ! "r-h& end1 z indicat$ by ! arr[s4 ,illu/ration3 ,,fig4 #ci4--,! ,buckeye ,valve4 ,ea* valve is mov$ by its own ecc5tric1 q indep5d5tly ( ! o!r4 ,by *ang+ ! advance or ecc5tricity1 or bo?1 ( ! auxili>y valve1 ! cut-(f may be *ang$ z desir$1 )\t 9 any way affect+ ! motion ( ! ma9 valve4 ,& z ! ma9 valve det]m9es ! admission1 release1 & compression ( ! /eam1 x is possible1 ) ?is valve1 to *ange ! cut-(f z desir$ )\t affect+ ^! at all4 ,! ,trick or ,all5 ,valve4--,9 connection ) ! subject ( e>ly cut-(fs ! ,trick or ,all5 valve may be m5tion$4 ,x is made ) a passage-way ?r\gh ! back ( ! valve1 z %[n 9 fig4 #dj1 adapt$ to deliv] an extra supply ( /eam into ! port by r5d]+ available an additional proportion ( ! area !re(1 :5 ! n>r[ port-op5+ giv5 by ! lap-edge alone1 dur+ l9k$-up work+1 is f\nd to wire-draw ! /eam4 ,:il/ ! lap-edge a1 = in/ance1 uncov]s ! edge b ( ! "r-h& port1 ! left-h& end ( ! ,trick passage becomes uncov]$ by mov+ beyond ! edge c ( ! port-face1 s t a curr5t ( /eam fl[s f left to "r ?r\gh t passage to jo9 ! /ream pass+ ! edge a4 ,! total area ( ! two supply-/reams fl[+ into ! "r-h& port be+ practically twice t :i* w\ld be available 7 ! ,trick passage abs5t4 ,illu/ration3 ,,fig4 #dj4 ,! occurr5ce & duration ( ! op]ations ( /eam-di/ribution are exactly ! same ) ?is valve z ) an ord9>y slide-valve ( correspond+ proportions1 ! di/9ctive feature ( ! valve hav+ no effect ^u !m s f> z _! tim+ is conc]n$4 ,rev]sal4--,x may be ( int]e/ to consid] ! "q--8,:y d we ne$ rev]s+ ge>s80 ,! ge>s 9 common use are ne>ly all v>iable expansion ge>s1 z well z be+ rev]s+ ge>s1 b x is desir$ to consid] n[ only ! "q ( rev]s+4 ,are rev]s+ ge>s really ne$$8 ,suppose t "o c\ld h a transp>5t cyl9d] & valve-*e/1 s t movem5t ( ! pi/on & valve c\ld be cle>ly se54 ,suppose also t ! connect+-rod1 crank1 valve ge>1 & fly-:eel c\ld n be se54 ,we look into ! cyl9d] & see valve & pi/on reciprocat+ regul>ly1 & 9 h>mony ) "o ano!r4 ,we turn away1 & be=e we look aga91 ! eng9e1 let u assume1 has be5 rev]s$ )\t our k2 yet :5 we turn aga9 to ! eng9e !re are ! pi/on & valve reciprocat+ j z !y 7 at fir/ 7al?\gh !y mu/ h 8*ang$ /ep10 z we %all pres5tly f9d71 &1 look z int5tly z we may1 ) no?+ else visible we %all be unable to tell t ! eng9e has be5 rev]s$4 ,! valve is do+ n[ exactly :at x did be=e1 p]=m+ its op]ations 9 ! same ord]4 ,:y h we _h to employ rev]s+ ge>8 ,solely because--:5 ! eng9e ceases to run ahead = in/ance1 /opp+ at half-/roke ! pi/on & valve w be 9 a c]ta9 position1 & w h be5 mov+ 9 c]ta9 directions relatively to "o ano!r4 ,& to rev]se ! pi/on's motion1 we want ! valve ,fir/ly--,to take up a new position on ! port-face1 s z1 = example1 to give /eam :]e x _h previ\sly giv5 exhau/1 & ?us we get rev]sal ( ! eng9e2 & ,secondly--,to move away f t new position1 aft] ! eng9e has />t$ a/]n1 9 ! same direction z t 9 :i* x 0 mov+ :5 ! eng9e 0 runn+ ahead4 ,& see+ t ! valve ge> d]ives motion f ! crank-%aft directly or indirectly1 we _c give ! valve motion 9 ?is same direction f an eng9e n[ mov+ rev]sely1 unless we also rev]se ! ge>4 ,& ?us we may conclude t a rev]s+ ge> is ne$$ simply = ! purpose ( regulat+ ! direction ( ! fir/ motion ( ! valve aft] /opp+ 7i4e41 = 8*ang+ ! /ep071 = aft] x next rea*es ! end ( its travel its motion w be 9 all respects j z x 0 :5 ! eng9e ran ahead1--s t1 if we _h a s+le-cyl9d] eng9e & nev] /opp$ x except on ! dead c5tres1 we c\ld drive its valve by a sep>ate valve-eng9e always runn+ "o way1 & our ma9 eng9e w\ld1 if pu%$ (f by h&1 run equally well ei!r ahead or a/]n1 :il/ s]v$ by a valve hav+ lap1 lead1 & travel z is cu/om>y4 ,x is hop$ t ?is little speculation may n appe> unpr(itable1 = x has a be>+ on ! action ( ! rev]s+ slides 9 radial valve ge>s su* z ^? ( ,hackwor?1 ,wals*a]t1 & ,joy4 ,illu/ration3 ,,fig4 #da4 ,,fig4 #da ,,%[s ,,enl>g$ ,,key-,,view ,,( ,,c>dbo>d ,,crank-,,disc1 ,,:i* ,,%\ld ,,turn ,,)9 ,,! ,,circle ,,drawn ,,9 ,,! ,,c5tre ,,( ,,fig4 #a4 ,! arm m>k$ ,c is ! crank-arm1 & s]ves z an index f+] 9 ! record+ & read+ ( results4 ,! m>k #a is ! index-m>k = ! =w>d ecc5tric to op]ate a valve )\t lap4#e ,! m>k #b is ! index = a =w>d ecc5tric set = lead1 us+ a valve )\t lap4#e ,! m>k #c is = a =w>d ecc5tric = a valve ) lap & lead run 9 8full ge>40#f ,! m>k #d is = a =w>d ecc5tric = a valve ) lap & lead run ) a l9k motion p>tially 8l9k$ up40#f ,! m>k #e is = a valve ) lap & lead run ) ! l9k motion 9 mid-ge>4#e ,! m>k #f is = a backw>d ecc5tric = a valve ) lap & lead1 run ) a l9k motion p>tially l9k$-up4#f ,! m>k #g is a backw>d ecc5tric = a valve ) lap & lead run 9 8full ge>40#f ,! m>k #h is = a backw>d ecc5tric set = lead1 us+ a valve )\t any lap4#e ,! m>k #i is = a backw>d ecc5tric = a valve )\t lap4#e ----- ,footnote #e3 ,us$ ) ,no4 #a travel-scale1 fig4 #a4 ,footnote #f3 ,us$ ) ,no4 #b travel-scale1 fig4 #a4 ,! radial l9es betwe5 ! c5tre ( ! disc & ! small circles repres5t ! actual ?r[ assum$ = ! v>i\s ecc5trics & _! angul> position 9 relation to ! crank2 :]e ! actual ?r[ is n suffici5t to enable ! arms to rea* ! edge ( ! disc1 ! ?r[-l9es are produc$ to ! edge4 ---------------------------------------- -------------------------------- ,transcrib]'s ,notes ,miss+ or obscur$ punctuation 0 sil5tly correct$4 ,typographical errors 7 sil5tly correct$4 ,! 8#j0 9 fig4 #a 0 transcrib$ z ! numb] z]o to repres5t ! c5t] ( ! scale1 & ! 8,o0 9 fig4 #b 0 transcrib$ z ! lett] ,o to repres5t ! outlet4 ,text 9 italics is enclos$ by und]scores 7italics74 ,sup]scripts are writt5 us+ a c>et 77 foll[$ by ! text enclos$ 9 braces 7sup]script74 ,subscripts are writt5 us+ an und]score 77 foll[$ by ! text enclos$ 9 braces 7subscript74