file :i* includes ! orig9al illu/rations4 ,see #cdgja-;h4htm or #cdgja-;h4zip3 7https3_/_/www4gut5b]g4org_/ca*e_/epub_/ #cdgja_/pg#cdgja-;images4html7 or 7https3_/_/www4gut5b]g4org_/files_/#cdgj a_/cdgja-;h4zip7 ,images ( ! orig9al pages are available ?r\gh ,int]net ,ar*ive4 ,see http3_/_/www4ar*ive4org_/details_//eam5g 9es#jjnewyri* ---------------------------------------- ------------------ ,transcrib]'s note3 ,inconsi/5cies h n be5 correct$ 7hyph5at$ vs non-hyph5at$ or spac$ words71 except horse-p[] *ang$ to horsep[] & cut (f to cut-(f4 ,m9or typographical errors h be5 correct$4 ,text 9 italics is enclos$ by und]score *>act]s z 9 italics4 ,subscripts are indicat$ by 4441 z 9 subscript4 ,9-l9e multi-l9e =mulas h be5 *ang$ to s+le-l9e =mulas1 :]e necess>y ) ! addition ( brackets to prev5t ambiguity4 ---------------------------------------- ------------------ ,ma*9]y's ,ref]5ce ,s]ies ,ea* ,numb] ,is a ,unit 9 a ,s]ies on ,electrical & ,/eam ,eng9e]+ ,draw+ & ,ma*9e ,design & ,%op ,practice ,,numb] #gj ,,/eam ,,eng9es ,,cont5ts ,action ( ,/eam ,eng9es #c ,rat+ & ,g5]al ,proportions ( ,/eam ,eng9es #aa ,/eam ,eng9e ,details #ae ,/eam ,eng9e ,economy #cj ,types ( ,/eam ,eng9es #cf ,/eam ,eng9e ,te/+ #da ,copyright1 #aiaa1 ,! ,indu/rial ,press1 ,publi%]s ( ,,ma*9]y1 #di-ee ,lafayette ,/reet1 ,new ,york ,city4 ,,*apt] ,i ,,action ,,( ,,/eam ,,eng9es ,a /eam eng9e is a device by means ( :i* heat is trans=m$ into "w4 ,"w may be def9$ z ! result produc$ by a =ce act+ ?r\gh space1 & is commonly measur$ 9 foot-p\nds2 a foot-p\nd repres5ts ! "w done 9 rais+ #a p\nd #a foot 9 height4 ,! rate ( do+ "w is call$ p[]4 ,x has be5 f\nd by exp]im5t t !re is a def9ite relation betwe5 heat & "w1 9 ! ratio ( #a !rmal unit to #ggh foot-p\nds ( "w4 ,! numb] #ggh is commonly call$ ! heat equival5t ( "w or ! me*anical equival5t ( heat4 ,heat may be trans=m$ into me*anical "w ?r\gh ! m$ium ( /eam1 by conf9+ a giv5 am\nt 9 a clos$ *amb]1 & !n all[+ x to exp& by means ( a movable wall 7pi/on7 fitt$ into "o side ( ! *amb]4 ,heat is giv5 up 9 ! process ( expansion1 z %[n by ! l[]$ pressure & temp]ature ( ! /eam1 & "w has be5 done 9 mov+ ! wall 7pi/on7 ( ! clos$ *amb] aga9/ a resi/+ =ce or pressure4 ,:5 ! expansion ( /eam takes place )\t ! loss ( heat by radiation or conduction1 ! relation betwe5 ! pressure & volume is practically con/ant2 t is1 if a giv5 quantity ( /eam exp&s to twice its volume 9 a clos$ *amb] ( ! k9d above describ$1 its f9al pressure w be "o-half t ( ! initial pressure be=e expansion took place4 ,a p\nd ( /eam at an absolute pressure ( #bj p\nds p] squ>e in* has a volume ( practically #bj cubic feet1 & a temp]ature ( #bbh degrees4 ,if n[ x be exp&$ s t its volume is d\bl$ 7#dj cubic feet71 ! pressure w drop to approximately #aj p\nds p] squ>e in* & ! temp]ature w be only ab\t #aij degrees4 ,! drop 9 temp]ature is due to ! loss ( heat :i* has be5 trans=m$ into "w 9 ! process ( expansion & 9 mov+ ! wall 7pi/on7 ( ! *amb] aga9/ a resi/+ =ce1 z already not$4 ,pr9ciple ( ! ,/eam ,eng9e ,! /eam eng9e makes use ( a clos$ *amb] ) a movable wall 9 trans=m+ ! heat ( /eam into me*anical "w 9 ! mann] j describ$4 ,fig4 #a %[s a longitud9al section ?r\gh an eng9e ( simple design1 & illu/rates ! pr9cipal p>ts & _! relation to "o ano!r4 ,! cyl9d] ,a is ! clos$ *amb] 9 :i* expansion takes place1 & ! pi/on ,b1 ! movable wall4 ,! cyl9d] is ( ca/ iron1 accurately bor$ & f9i%$ to a circul> cross-section4 ,! pi/on is c>efully fitt$ to slide easily 9 ! cyl9d]1 be+ made practically /eam tight by means ( pack+ r+s4 ,! "w g5]at$ 9 mov+ ! pi/on is transf]r$ to ! crank-p9 ,h by means ( ! pi/on-rod ,c1 & ! connect+-rod ,f4 ,! pi/on-rod passes out ( ! cyl9d] ?r\gh a /uff+ box1 :i* prev5ts ! leakage ( /eam ar\nd x4 ,! cross-head ,d s]ves to guide ! pi/on-rod 9 a /raight l9e1 & also conta9s ! wri/-p9 ,e :i* jo9s ! pi/on-rod & connect+-rod4 ,! cross-head slides ^u ! guide-plate ,g1 :i* causes x to move 9 an accurate l9e1 & at ! same "t takes ! d[nw>d ?ru/ f ! connect+-rod4 ,! crank-p9 is connect$ ) ! ma9 %aft ,i by means ( a crank arm1 :i* 9 ?is case is made 9 ! =m ( a disk 9 ord] to give a bett] balance4 ,! balance :eel or fly:eel ,j c>ries ! crank pa/ ! dead c5t]s at ! ends ( ! /roke1 & gives a uni=m motion to ! %aft4 ,! v>i\s p>ts ( ! eng9e are c>ri$ on a rigid b$ ,k1 usually ( ca/ iron1 :i* 9 turn is bolt$ to a f\ndation ( brick or concrete4 ,! p[] develop$ is tak5 (f by means ( a belt$ pulley atta*$ to ! ma9 %aft1 or1 9 c]ta9 cases1 9 ! =m ( electrical en]gy f a direct-connect$ dynamo4 ,illu/ration3 ,fig4 #a4 ,longitud9al ,section ?r\gh ! ,ames ,high-spe$ ,eng9e ,:5 9 action1 a c]ta9 am\nt ( /eam 7#a_/d to #a_/c ( ! total cyl9d] volume 9 simple eng9es7 is admitt$ to "o end ( ! cyl9d]1 :ile ! o!r is op5 to ! atmosph]e4 ,! /eam =ces ! pi/on =w>d a c]ta9 di/ance by its direct action at ! boil] pressure4 ,aft] ! supply is %ut (f1 ! =w>d movem5t ( ! pi/on is cont9u$ to ! end ( ! /roke by ! expansion ( ! /eam4 ,/eam is n[ admitt$ to ! o!r end ( ! cyl9d]1 & ! op]ation repeat$ on ! backw>d or return /roke4 ,an enl>g$ section ( ! cyl9d] %[+ ! action ( ! valve = admitt+ & exhau/+ ! /eam is %[n 9 ,fig4 #b4 ,9 ?is case ! pi/on is %[n 9 its extreme backw>d position1 ready = ! =w>d /roke4 ,! /eam *e/ ,l is fill$ ) /eam at boil] pressure1 :i* is be+ admitt$ to ! n>r[ space back ( ! pi/on ?r\gh ! valve ,n1 z indicat$ by ! arr[s4 ,! exhau/ port ,m is 9 communication ) ! o!r end ( ! cyl9d] & all[s ! pi/on to move =w>d )\t resi/ance1 except t due to ! pi/on-rod1 :i* transf]s ! "w done by ! exp&+ /eam to ! crank-p94 ,! valve ,n is op]at$ automatically by a crank or ecc5tric atta*$ to ! ma9 %aft1 & op5s & closes ! supply & exhau/ ports at ! prop] "t to secure ! results describ$4 ,"w ,diagram ,hav+ discuss$ briefly ! g5]al pr9ciple ^u :i* an eng9e op]ates1 ! next /ep is to /udy m c>efully ! trans=mation ( heat into "w )9 ! cyl9d]1 & to become famili> ) ! graphical me?ods ( repres5t+ x4 ,"w has already be5 def9$ z ! result ( =ce act+ ?r\gh space1 & ! unit ( "w z ! foot-p\nd1 :i* is ! "w done 9 rais+ #a p\nd #a foot 9 height4 ,= example1 x requires #a x #a #a foot-p\nd to raise #a p\nd #a foot1 or #a x #aj #aj foot-p\nds to raise #a p\nd #aj feet1 or #aj x #a #aj foot-p\nds to raise #aj p\nds #a foot1 or #aj x #aj #ajj foot-p\nds to raise #aj p\nds #aj feet1 etc4 ,t is1 ! product ( weight or =ce act+1 times ! di/ance mov$ ?r\gh1 repres5ts "w2 & if ! =ce is tak5 9 p\nds & ! di/ance 9 feet1 ! result w be 9 foot-p\nds4 ,?is result may be %[n graphically by a figure call$ a "w diagram4 ,illu/ration3 ,fig4 #b4 ,section ( ,cyl9d]1 %[+ ,slide ,valve ,9 ,fig4 #c1 let di/ances on ! l9e ,,oy repres5t ! =ce act+1 & di/ances on ,,ox repres5t ! space mov$ ?r\gh4 ,suppose ! figure to be drawn to su* a scale t ,,oy is #e feet 9 height1 & ,,ox #aj feet long4 ,let ea* division on ,,oy repres5t #a p\nd pressure1 & ea* division on ,,ox #a foot ( space mov$ ?r\gh4 ,if a pressure ( #e p\nds acts ?r\gh a di/ance ( #aj feet1 !n an am\nt ( #e x #aj #ej foot-p\nds ( "w has be5 done4 ,ref]r+ to ,fig4 #c1 x is evid5t t ! height ,,oy 7! pressure act+71 multipli$ by ! l5g? ,,ox 7! di/ance mov$ ?r\gh71 gives #e x #aj #ej squ>e feet1 :i* is ! area ( ! rectangle ,,ycxo2 t is1 ! area ( a rectangle may repres5t "w done1 if ! height repres5ts a =ce act+1 & ! l5g? ! di/ance mov$ ?r\gh4 ,if ! diagram 7 drawn to a small] scale s t ! divisions 7 #a in* 9 l5g? in/ead ( #a foot1 ! area ,,ycxo w\ld /ill repres5t ! "w done1 except ea* squ>e in* w\ld equal #a foot-p\nd in/ead ( ea* squ>e foot1 z 9 ! pres5t illu/ration4 ,illu/ration3 ,fig4 #c4 ,a ,simple ,"w ,diagram ,9 ,fig4 #d ! diagram1 in/ead ( be+ rectangul> 9 =m1 takes a diff]5t %ape on acc\nt ( diff]5t =ces act+ at diff]5t p]iods ov] ! di/ance mov$ ?r\gh4 ,9 ! fir/ case 7,fig4 #c71 a uni=m =ce ( #e p\nds acts ?r\gh a di/ance ( #aj feet1 & produces #e x #aj #ej foot-p\nds ( "w4 ,9 ! second case 7,fig4 #d71 =ces ( #e p\nds1 #d p\nds1 #c p\nds1 #b p\nds1 & #a p\nd1 act ?r\gh di/ances ( #b feet ea*1 & produce 7#e x #b7 7#d x #b7 7#c x #b7 7#b x #b7 7#a x #b7 #cj foot-p\nds4 ,?is is also ! area1 9 squ>e feet1 ( ! figure ,y#edcba,,xo1 :i* is made up ( ! areas ( ! five small rectangles %[n by ! dott$ l9es4 ,ano!r way ( f9d+ ! total area ( ! figure %[n 9 ,fig4 #d1 & det]m9+ ! "w done1 is to multiply ! l5g? by ! av]age ( ! heights ( ! small rectangles4 ,! av]age height is f\nd by add+ ! sev]al heights & divid+ ! sum by _! numb]1 z foll[s3 #e #d #c #b #a ----------------- #c1 & #c x #aj #cj squ>e feet1 z be=e4 #e ,illu/ration3 ,fig4 #d4 ,ano!r ,=m ( ,"w ,diagram ,?is1 !n1 means t ! av]age =ce act+ ?r\gh\t ! /roke is #c p\nds1 & ! total "w done is #c x #aj #cj foot-p\nds4 ,9 ,fig4 #e ! pressure drops uni=mly f #e p\nds at ! beg9n+ to #j at ! end ( ! /roke4 ,9 ?is case also ! area & "w done are f\nd by multiply+ ! l5g? ( ! diagram by ! av]age height1 z foll[s3 #e #j ----- x #aj #be squ>e feet1 #b or #be foot-p\nds ( "w done4 ,illu/ration3 ,fig4 #e4 ,"w ,diagram :5 ,pressure drops ,uni=mly ,! object ( ,figs4 #c1 #d & #e is to %[ h[ foot-p\nds ( "w may be repres5t$ graphically by ! areas ( diagrams1 & also to make x cle> t ?is rema9s true :atev] ! =m ( ! diagram4 ,x is also evid5t t kn[+ ! area1 ! av]age height or pressure may be f\nd by divid+ by ! l5g?1 & vice v]sa4 ,fig4 #f %[s ! =m ( "w diagram :i* w\ld be produc$ by ! action ( ! /eam 9 an eng9e cyl9d]1 if no heat 7 lo/ by conduction & radiation4 ,/>t+ ) ! pi/on 9 ! position %[n 9 ,fig4 #b1 /eam is admitt$ at a pressure repres5t$ by ! height ( ! l9e ,,oy4 ,z ! pi/on moves =w>d1 suffici5t /eam is admitt$ to ma9ta9 ! same pressure4 ,at ! po9t ,b ! valve closes & /eam is cut (f4 ,! "w done up to ?is "t is %[n by ! rectangle ,y,bb,o4 ,f ! po9t ,b to ! end ( ! /roke ,c1 ! pi/on is mov$ =w>d by ! expansion ( ! /eam1 ! pressure fall+ 9 proportion to ! di/ance mov$ ?r\gh1 until at ! end ( ! /roke x is repres5t$ by ! v]tical l9e ,,cx4 ,at ! po9t ,c ! exhau/ valve op5s & ! pressure drops to #j 7atmosph]ic pressure 9 ?is case74 ,z x is always desirable to f9d ! "w done by a complete /roke ( ! eng9e1 x is necess>y to f9d ! av]age or mean pressure act+ ?r\gh\t ! /roke4 ,?is c only be done by det]m9+ ! area ( ! diagram & divid+ by ! l5g? ( ! /roke4 ,?is gives :at is call$ ! mean ord9ate1 :i* multipli$ by ! scale ( ! draw+1 w give ! mean or av]age pressure4 ,= example1 if ! area ( ! diagram is f\nd to be #f squ>e in*es1 & its l5g? is #c in*es1 ! mean ord9ate w be #f _/ #c #b in*es4 ,if ! diagram is drawn to su* a scale t #a in* on ,,oy repres5ts #aj p\nds1 !n ! av]age or mean pressure w be #b x #aj #bj p\nds1 & ?is multipli$ by ! actual l5g? ( ! pi/on /roke w give ! "w done 9 foot-p\nds4 ,! practical application ( ! above1 toge!r ) ! me?od ( obta9+ /eam eng9e indicator diagrams & measur+ ! areas ( ! same1 w be tak5 up 9 detail "u ! head+ ( ,/eam ,eng9e ,te/+4 ,def9itions ,relat+ to ,eng9e ,diagrams ,be=e tak+ up ! con/ruction ( an actual eng9e diagram1 x is fir/ necess>y to become famili> ) c]ta9 t]ms :i* are us$ 9 connection ) x4 ,illu/ration3 ,fig4 #f4 ,! ,ideal ,"w ,diagram ( a ,/eam ,eng9e ,cut-(f4--,! cut-(f is ! po9t 9 ! /roke at :i* ! admission valve closes & ! expansion ( /eam beg9s4 ,ratio ( ,expansion4--,?is is ! reciprocal ( ! cut-(f1 t is1 if ! cut-(f is #a_/d1 ! ratio ( expansion is #d4 ,9 o!r words1 x is ! ratio ( ! f9al volume ( ! /eam at ! end ( ! /roke to its volume at ! po9t ( cut-(f4 ,= example1 a cyl9d] takes /eam at boil] pressure until ! pi/on has mov$ "o-f\r? ! l5g? ( its /roke2 ! valve n[ closes & expansion takes place until ! /roke is complet$4 ,! "o-f\r? cyl9d]ful ( /eam has become a cyl9d]ful1 t is1 x has exp&$ to f\r times its orig9al volume1 & ! ratio ( expansion is said to be #d4 ,po9t ( ,release4--,?is is ! po9t 9 ! /roke at :i* ! exhau/ valve op5s & relieves ! pressure act+ on ! pi/on4 ,?is takes place j be=e ! end ( ! /roke 9 ord] to r$uce ! %ock :5 ! pi/on *anges its direction ( travel4 ,compression4--,?is acts 9 connection ) ! premature release 9 ord] to r$uce ! %ock at ! end ( ! /roke4 ,dur+ ! =w>d /roke ( an eng9e ! exhau/ valve 9 front ( ! pi/on rema9s op5 z %[n 9 ,fig4 #b4 ,%ortly be=e ! end ( ! /roke ?is closes1 leav+ a c]ta9 am\nt ( /eam 9 ! cyl9d]4 ,! cont9uation ( ! /roke compresses ?is /eam1 & by rais+ its pressure =ms a cu%ion1 :i*1 9 connection ) ! removal ( ! pressure back ( ! pi/on by release1 br+s ! pi/on to a /op & causes x to rev]se its direction )\t %ock4 ,high-spe$ eng9es require a great] am\nt ( compression ?an ^? runn+ at l[ spe$4 ,cle>ance4--,?is is ! space betwe5 ! cyl9d] head & ! pi/on :5 ! latt] is at ! end ( its /roke2 x also includes t portion ( ! /eam port betwe5 ! valve & ! cyl9d]4 ,cle>ance is usually express$ z a p]c5tage ( ! pi/on-displacem5t ( ! cyl9d]1 & v>ies 9 diff]5t types ( eng9es4 ,! foll[+ table gives approximate values = eng9es ( diff]5t design4 ,,table ,i4 ,,cle>ance ,,( ,,/eam ,,eng9es ,type ( ,eng9e ,p] ,c5t ,cle>ance ,corliss #a4e to #c4e ,mod]ate-spe$ #c to #h ,high-spe$ #d to #aj ,a l>ge cle>ance is evid5tly objectionable because x repres5ts a space :i* mu/ be fill$ ) /eam at boil] pressure at ! beg9n+ ( ea* /roke1 & f :i* b a comp>atively small am\nt ( "w is obta9$4 ,z compression increases1 ! am\nt ( /eam requir$ to fill ! cle>ance space dim9i%es1 b on ! o!r h&1 increas+ ! compression r$uces ! mean effective pressure4 ,initial ,pressure4--,?is is ! pressure 9 ! cyl9d] up to ! po9t ( cut-(f4 ,x is usually slightly less ?an boil] pressure ow+ to wire-draw+ 9 ! /eam pipe & ports4 ,t]m9al ,pressure4--,?is is ! pressure 9 ! cyl9d] at ! "t release occurs1 & dep5ds ^u ! initial pressure1 ! ratio ( expansion1 & ! am\nt ( cyl9d] cond5sation4 ,back ,pressure4--,?is is ! pressure 9 ! cyl9d] :5 ! exhau/ port is op51 & is t aga9/ :i* ! pi/on is =c$ dur+ ! work+ /roke4 ,= example1 9 ,fig4 #b ! small space at ! left ( ! pi/on is fill$ ) /eam at initial pressure1 :ile ! space at ! "r ( ! pi/on is expos$ to ! back pressure4 ,! work+ pressure v>ies ?r\gh\t ! /roke1 due to ! expansion ( ! /eam1 :ile ! back pressure rema9s con/ant1 except = ! effect ( compression at ! end ( ! /roke4 ,! !oretical back pressure 9 a non-cond5s+ eng9e 7"o exhau/+ into ! atmosph]e7 is t ( ! atmosph]e or #ad4g p\nds p] squ>e in* above a vacuum1 b 9 actual practice x is ab\t #b p\nds above atmosph]ic pressure1 or #ag p\nds absolute1 due to ! resi/ance ( exhau/ ports & connect+ pipes4 ,9 ! case ( a cond5s+ eng9e 7"o exhau/+ into a cond5s]7 ! back pressure dep5ds ^u ! effici5cy ( ! cond5s]1 av]ag+ ab\t #c p\nds absolute pressure 9 ! be/ practice4 ,effective ,pressure4--,?is is ! diff]5ce betwe5 ! pressure on ! /eam side ( ! pi/on & t on ! exhau/ side1 or 9 o!r words1 ! diff]5ce betwe5 ! work+ pressure & ! back pressure4 ,?is value v>ies ?r\gh\t ! /roke ) ! expansion ( ! /eam4 ,mean ,effective ,pressure4--,x has j be5 /at$ t ! effective pressure v>ies ?r\gh\t ! /roke4 ,! mean effective pressure 7,m4 ,e4 ,p47 is ! av]age ( all ! effective pressures1 & ?is av]age multipli$ by ! l5g? ( /roke1 gives ! "w done p] /roke4 ,l9e ( ,absolute ,vacuum4--,9 ! diagram %[n 9 ,fig4 #f1 ! l9e ,,ox is ! l9e ( absolute vacuum2 t is1 x is assum$ t !re is no pressure on ! exhau/ side ( ! pi/on4 ,9 o!r words1 ! eng9e is exhau/+ into a p]fect vacuum4 ,illu/ration3 ,fig4 #g4 ,con/ruct+ a ,/eam ,eng9e ,"w ,diagram ,atmosph]ic ,l9e4--,?is is a l9e drawn p>allel to ! l9e ( absolute vacuum at su* a di/ance above x z to repres5t #ad4g p\nds pressure p] squ>e in*1 accord+ to ! scale us$4 ,con/ruction ( ,ideal ,diagram ,"o ( ! fir/ /eps 9 ! design ( a /eam eng9e is ! con/ruction ( an ideal diagram1 & ! eng9e is plann$ to produce ?is z ne>ly z possible :5 9 op]ation4 ,fir/ assume ! initial pressure1 ! ratio ( expansion1 & ! p]c5tage ( cle>ance1 = ! type ( eng9e "u consid]ation4 ,draw l9es ,,ox & ,,oy at "r angles z 9 ,fig4 #g4 ,make ,,or ! same p]c5tage ( ! /roke t ! cle>ance is ( ! pi/on displacem5t2 make ,,rx equal to ! l5g? ( ! /roke 7on a r$uc$ scale74 ,erect ! p]p5dicul> ,,ra ( su* a height t x %all repres5t1 to scale1 an absolute pressure p] squ>e in* equal to #j4ie ( ! boil] pressure4 ,draw 9 ! dott$ l9es ,,ak & ,,kx1 & ! atmosph]ic l9e ,,lh at a height above ,,ox to repres5t #ad4g p\nds p] squ>e in*4 ,locate ! po9t ( cut-(f1 ,b1 accord+ to ! assum$ ratio ( expansion4 ,po9ts on ! expansion curve ,,bc are f\nd z foll[s3 ,divide ! di/ance ,,bk into any numb] ( equal spaces1 z %[n by a1 b1 c1 d1 etc41 & connect !m ) ! po9t ,o4 ,?r\gh ! po9ts ( int]section ) ,,bp1 z a'1 b'1 c'1 d'1 etc41 draw horizontal l9es1 & ?r\gh a1 b1 c1 d1 etc41 draw v]tical l9es4 ,! int]section ( correspond+ horizontal & v]tical l9es w be po9ts on ! !oretical expansion l9e4 ,if ! eng9e is to be non-cond5s+1 ! !oretical "w1 or indicator diagram1 z x is call$1 w be b\nd$ by ! l9es ,,ab*g4 ,! actual diagram w v>y some:at f ! !oretical1 z %[n by ! %ad$ l9es4 ,! admission l9e betwe5 ,a & ,b w slant d[nw>d slightly1 & ! po9t ( cut-(f w be r\nd$1 ow+ to ! sl[ clos+ ( ! valve4 ,! fir/ half ( ! expansion l9e w fall bel[ ! !oretical1 ow+ to a drop 9 pressure caus$ by cyl9d] cond5sation1 b ! actual l9e w rise above ! !oretical 9 ! latt] "p ( ! /roke on acc\nt ( re-evaporation1 due to heat giv5 out by ! hot cyl9d] walls to ! l[-pressure /eam4 ,in/ead ( ! pressure dropp+ abruptly at ,c1 release takes place j be=e ! end ( ! /roke1 & ! diagram is r\nd$ at ,,cf in/ead ( hav+ %>p corn]s4 ,! back pressure l9e ,,fd is drawn slightly above ! atmosph]ic l9e1 a di/ance to repres5t ab\t #b p\nds p] squ>e in*4 ,at ,d ! exhau/ valve closes & compression beg9s1 r\nd+ ! bottom ( ! diagram up to ,e4 ,! area ( ! actual diagram1 z %[n by ! %ad$ l9es 9 ,fig4 #g1 w be small] ?an ! !oretical1 9 ab\t ! foll[+ ratio3 ,l>ge m$ium-spe$ eng9es1 #j4ij ( !oretical area4 ,small m$ium-spe$ eng9es1 #j4he ( !oretical area4 ,high-spe$ eng9es1 #j4ge ( !oretical area4 ,,*apt] ,,ii ,,rat+ ,,& ,,g5]al ,,proportions ,,( ,,/eam ,,eng9es ,! capacity or p[] ( a /eam eng9e is rat$ 9 horsep[]1 "o horsep[] 7,h4 ,p47 be+ ! equival5t ( #cc1jjj foot-p\nds ( "w done p] m9ute4 ,! horsep[] ( a giv5 eng9e may be comput$ by ! =mula3 ,,apln ,h4 ,p4 ------ #cc1jjj 9 :i* ,a area ( pi/on1 9 squ>e in*es1 ,p mean effective pressure p] squ>e in*1 ,l l5g? ( /roke1 9 feet1 ,n numb] ( /rokes p] m9ute numb] ( revolutions x #b4 ,! d]ivation ( ! above =mula is easily expla9$1 z foll[s3 ,! area ( ! pi/on1 9 squ>e in*es1 multipli$ by ! mean effective pressure1 9 p\nds p] squ>e in*1 gives ! total =ce act+ on ! pi/on1 9 p\nds4 ,! l5g? ( /roke1 9 feet1 times ! numb] ( /rokes p] m9ute gives ! di/ance ! pi/on moves ?r\gh1 9 feet p] m9ute4 ,x has already be5 %[n t ! pressure 9 p\nds multipli$ by ! di/ance mov$ ?r\gh 9 feet1 gives ! foot-p\nds ( "w done4 ,h5ce1 ,a x ,p x ,l x ,n gives ! foot-p\nds ( "w done p] m9ute by a /eam eng9e4 ,if "o horsep[] is repres5t$ by #cc1jjj foot-p\nds p] m9ute1 ! p[] or rat+ ( ! eng9e w be obta9$ by divid+ ! total foot-p\nds ( "w done p] m9ute by #cc1jjj4 ,= ease 9 rememb]+ ! =mula giv51 x is commonly writt5 ,,plan ,h4 ,p4 ------1 #cc1jjj 9 :i* ! symbols 9 ! num]ator ( ! second memb] spell ! ^w ,plan4 ,example3--,f9d ! horsep[] ( ! foll[+ eng9e1 work+ "u ! conditions /at$ bel[3 ,diamet] ( cyl9d]1 #ab in*es4 ,l5g? ( /roke1 #ah in*es4 ,revolutions p] m9ute1 #cjj4 ,mean effective pressure 7,m4 ,e4 ,p471 #dj p\nds4 ,9 ?is problem1 !n1 ,a #aac squ>e in*es2 ,p #dj p\nds2 ,l #a4e feet2 & ,n #fjj /rokes4 ,sub/itut+ 9 ! =mula1 #dj x #a4e x #aac x #fjj ,h4 ,p4 -------------------- #abc4 #cc1jjj ,! mean effective pressure may be f\nd1 approximately1 = diff]5t conditions by means ( ! factors 9 ! foll[+ table ( ratios1 cov]+ ord9>y practice4 ,! rule us$ is z foll[s3 ,multiply ! absolute initial pressure by ! factor correspond+ to ! cle>ance & cut-(f z f\nd f ,table ,,ii1 & subtract ! absolute back pressure f ! result1 assum+ ?is to be #ag p\nds = non-cond5s+ eng9es1 & #c p\nds = cond5s+4 ,example #a3--;,a non-cond5s+ eng9e hav+ #c p] c5t cle>ance1 cuts (f at #a_/c /roke2 ! initial pressure is #ij p\nds gage4 ,:at is ! ,m4 ,e4 ,p48 ,! absolute initial pressure is #ij #ae #aje p\nds4 ,! factor = #c p] c5t cle>ance & #a_/c cut-(f1 f ,table ,,ii1 is #j4ga4 ,apply+ ! rule we h3 7#aje x #j4ga7 - #ag #eg4e p\nds p] squ>e in*4 ,example #b3--;,a cond5s+ eng9e has a cle>ance ( #e p] c5t4 ,x is suppli$ ) /eam at #adj p\nds gage pressure1 & has a ratio ( expansion ( #f4 ,:at is ! ,m4 ,e4 ,p48 ,! absolute initial pressure is #adj #ae #aee4 ,! factor = a ratio ( expansion ( #f 7#a_/f cut-(f7 & #e p] c5t cle>ance is #j4e1 :i* gives 7#aee x #j4e7 - #c #gd4e p\nds p] squ>e in*4 ,! p[] ( an eng9e comput$ by ! me?od j expla9$ is call$ ! indicat$ horsep[] 7,i4 ,h4 ,p471 & gives ! total p[] develop$1 includ+ t requir$ to ov]come ! friction ( ! eng9e itself4 ,! deliv]$ or brake horsep[] 7,b4 ,h4 ,p47 is t deliv]$ by ! eng9e aft] d$uct+ f ! indicat$ horsep[] ! p[] requir$ to op]ate ! mov+ p>ts4 ,! brake horsep[] commonly v>ies f #hj to #ij p] c5t ( ! indicat$ horsep[] at full load1 dep5d+ ^u ! type & size ( eng9e4 ,9 proportion+ an eng9e cyl9d] = any giv5 horsep[]1 ! design] usually has ! foll[+ data1 ei!r giv5 or assum$1 = ! special type ( eng9e "u consid]ation3 ,initial pressure1 back pressure1 cle>ance1 cut-(f1 & pi/on spe$4 ,^! quantities v>y 9 diff]5t types ( eng9es1 b 9 ! abs5ce ( m specific data ! values 9 ,table ,,iii w be f\nd useful4 ,! back pressure may be tak5 z #ag p\nds p] squ>e in*1 absolute1 = non-cond5s+ eng9es1 & z #c p\nds = cond5s+ eng9es z previ\sly /at$4 ,,table ,,ii4 ,,factors ,,= ,,f9d+ ,,mean ,,effective ,,pressure ---------------------------------------- --------------- ,po9t ( ,cut-(f ,p]c5tage ------------------------------------ ( ,cle>ance #a_/aj #a_/f #a_/d #a_/c #a_/b #c_/d ---------------------------------------- ---------- #a4ge #j4ce #j4dh #j4fj #j4gj #j4he #j4if #c4jj #j4cg #j4di #j4fa #j4ga #j4he #j4if #e4jj #j4ci #j4ej #j4fb #j4gb #j4hf #j4ig #g4jj #j4da #j4eb #j4fc #j4gc #j4hf #j4ig #i4jj #j4dc #j4ed #j4fd #j4gc #j4hf #j4ig ---------------------------------------- ---------- ,! fir/ /ep 9 proportion+ ! cyl9d] is to compute ! approximate mean effective pressure f ! assum$ initial pressure1 cle>ance1 & cut-(f1 by ! me?od already expla9$4 ,next assume ! pi/on spe$ = ! type ( eng9e to be design$1 & det]m9e ! pi/on area by ! foll[+ =mula3 #cc1jjj ,h4 ,p4 ,a -----------------------4 ,m4 ,e4 ,p4 x pi/on spe$ ,?is =mula usually gives ! diamet] ( ! pi/on 9 in*es & fractions ( an in*1 :ile x is desirable to make ?is dim5sion an ev5 numb] ( in*es4 ,?is may be done by tak+ z ! diamet] ! ne>e/ :ole numb]1 & *ang+ ! pi/on spe$ to correspond4 ,?is is done by ! use ( ! foll[+ equation4 ,fir/ pi/on spe$ x fir/ pi/on area -------------------------------------- new pi/on spe$4 new pi/on area ,9 calculat+ ! effective pi/on area1 ! area ( ! pi/on rod ^u "o side mu/ be all[$ =4 ,! effective or av]age pi/on area w !n be 7#b;,a - a7_/#b1 9 :i* ,a area ( pi/on1 a area ( pi/on rod4 ,?is latt] area mu/ be assum$4 ,aft] assum+ a new pi/on diamet] ( ev5 in*es1 its effective or av]age area mu/ be us$ 9 det]m9+ ! new pi/on spe$4 ,! l5g? ( /roke is commonly proportion$ to ! diamet] ( cyl9d]1 & ! pi/on spe$ divid$ by ?is w give ! numb] ( /rokes p] m9ute4 ,example3--,f9d ! diamet] ( cyl9d]1 l5g? ( /roke1 & revolutions p] m9ute = a simple high-spe$ non-cond5s+ eng9e ( #bjj ,i4 ,h4 ,p41 ) ! foll[+ assumptions3 ,initial pressure1 #ij p\nds gage2 cle>ance1 #g p] c5t2 cut-(f1 #a_/d2 pi/on spe$1 #gjj feet p] m9ute2 l5g? ( /roke1 #a4e times cyl9d] diamet]4 ,,table ,,iii4 ,,pressure1 ,,cle>ance1 ,,cut-,,(f ,,& ,,pi/on ,,spe$ ,,( ,,/eam ,,eng9es ---------------------------------------- ----------------------------- ,initial ,cle>ance1 ,cut-(f1 ,pi/on ,type ( ,eng9e ,pressure1 ,p] ,c5t ,proportion ,spe$1 ,feet 7,gage7 ( ,/roke p] ,m9ute ---------------------------------------- ----------------------------- ,simple high-spe$ #hj to #ij #d to #aj #a_/d to #a_/c #fjj to #hjj ,simple m$ium-spe$ #hj to #ij #c to #h #a_/d to #a_/c #ejj to #gjj ,simple ,corliss #hj to #ij #a4e to #c4e #a_/d to #a_/c #djj to #fjj ,comp\nd high-spe$ #acj to #adj #d to #aj #a_/aj to #a_/h #fjj to #hjj ,comp\nd m$ium-spe$ #acj to #adj #c to #h #a_/aj to #a_/h #ejj to #gjj ,comp\nd ,corliss #acj to #adj #a4e to #c4e #a_/aj to #a_/h #djj to #fjj ---------------------------------------- ----------------------------- ,by us+ ! rules & =mulas 9 ! =ego+1 we h3 ,m4 ,e4 ,p4 7#ij #ae7 x #j4fc - #ag #di p\nds4 #cc1jjj x #bjj ,a ------------ #aib4d squ>e in*es4 #di x #gjj ,! ne>e/ pi/on diamet] ( ev5 in*es is #af1 :i* corresponds to an area ( #bja squ>e in*es4 ,assume a pi/on rod diamet] ( #b-a_/b in*es1 correspond+ to an area ( #d4i squ>e in*es1 f :i* ! av]age or effective pi/on area is f\nd to be 77#b x #bja7 - #d4i7_/b #aih4e squ>e in*es4 ,det]m9+ n[ ! new pi/on spe$1 we h3 #gjj x #aib4d ----------- #fgh4e feet p] m9ute4 #aih4e ,assum+ ! l5g? ( /roke to be #a4e times ! diamet] ( ! cyl9d]1 x w be #bd in*es1 or #b feet4 ,?is w call = #fgh4e _/ #b #cdj /rokes p] m9ute1 approximately1 or #cdj _/ #b #agj revolutions p] m9ute4 ,,*apt] ,,iii ,,/eam ,,eng9e ,,details ,"s ( ! mo/ important details ( a /eam eng9e are ^? ( its valve ge>4 ,! simple/ =m ( valve is t kn[n z ! pla9 slide valve1 & z ne>ly all o!rs are a modification ( ?is1 x is ess5tial t ! design] %\ld fir/ famili>ize himself ) ?is p>ticul> type ( valve 9 all its details ( op]ation4 ,aft] ?is has be5 done1 a /udy ( o!r =ms ( valves w be f\nd a comp>atively easy matt]4 ,! s call$ ,corliss valve diff]s radically f ! slide valve1 b ! results to be obta9$ & ! t]ms us$ 9 its design are practically ! same4 ,! valve ge> ( a /eam eng9e is made up ( ! valve or valves :i* admit /eam to & exhau/ x f ! cyl9d]1 & ( ! me*anism :i* gov]ns ! valve movem5ts1 ! latt] usually consi/+ ( "o or m ecc5trics atta*$ to ! ma9 %aft4 ,illu/ration3 ,fig4 #h4 ,longitud9al ,section ( ,slide ,valve ) ,ports ,! ,slide ,valve ,fig4 #h %[s a longitud9al section ( a slide valve ) ! ports1 bridges1 etc4 ,! valve is %[n 9 mid-position 9 ord] t c]ta9 po9ts relat+ to x may be m easily und]/ood4 ,! valve1 ,v1 consi/s ( a holl[ ca/+1 ) ends project+ beyond ! ports z %[n2 ! l[] face is smoo?ly f9i%$ & fitt$ to ! valve seat ,,ab4 ,9 op]ation x slides back & =?1 op5+ & clos+ ! ports :i* connect ! /eam *e/ ) ! cyl9d]4 ,/eam is admitt$ to ! cyl9d] :5 ei!r port ,,cd or ,,dc is op5$1 & is releas$ :5 ! ports are br\ght into communication ) ! exhau/ port ,,mn4 ,?is is accompli%$ by ! movem5t ( ! valve1 :i* br+s "o ( ! cyl9d] ports & ! exhau/ port bo? "u ! holl[ ar* ,k4 ,! portions ,,dm & ,,nd ( ! valve seat are call$ ! bridges4 ,x w be se5 by ref]5ce to ,fig4 #h t ! portions ,,oi & ,,io are wid] ?an ! ports :i* !y cov]4 ,?is extra wid? is call$ ! lap1 ,,oc be+ ! outside lap & ,,di ! inside or exhau/ lap4 ,! object ( outside lap is t ! /eam may be %ut (f aft] ! pi/on has mov$ =w>d a c]ta9 di/ance1 & be exp&$ dur+ ! rema9d] ( ! /roke4 ,if !re 7 no outside lap1 /eam w\ld be admitt$ ?r\gh\t ! entire /roke & !re w\ld be no expansion4 ,if !re 7 no inside lap1 exhau/ w\ld take place ?r\gh\t ! :ole /roke1 & ! advantages ( premature release & compression w\ld be lo/4 ,h5ce1 outside lap affects ! cut-(f1 & inside lap affects release & compression4 ,a valve has lead :5 x beg9s to uncov] ! /eam port be=e ! end ( ! return /roke ( ! pi/on4 ,?is is %[n 9 ,fig4 #i1 :]e ! pi/on ,p is j ready to />t on its =w>d /roke z indicat$ by ! arr[4 ,! valve has already op5$ a di/ance equal to ! lead1 & ! /eam has _h an opportunity to ent] & fill ! cle>ance space be=e ! beg9n+ ( ! /roke4 ,! lead v>ies 9 diff]5t eng9es1 be+ great] 9 high-spe$ ?an 9 l[-spe$ types4 ,illu/ration3 ,fig4 #i4 ,illu/ration %[+ ,lead ( ,slide ,valve ,illu/ration3 ,fig4 #aj4 ,diagrammatical ,view ( ,ecc5tric ,! ,ecc5tric ,! slide valve is usually driv5 by an ecc5tric atta*$ to ! ma9 %aft4 ,a diagram ( an ecc5tric is %[n 9 ,fig4 #aj4 ,an ecc5tric is1 9 reality1 a %ort crank ) a crank-p9 ( su* size t x surr\nds ! %aft4 ,! arm ( a crank is ! di/ance betwe5 ! c5t] ( ! %aft1 & ! c5t] ( ! crank-p94 ,! ?r[ ( an ecc5tric corresponds to ?is1 & is ! di/ance betwe5 ! c5t] ( ! %aft & ! c5t] ( ! ecc5tric disk1 z %[n at a 9 ,fig4 #aj4 ,! disk is key$ to ! %aft1 & z ! %aft revolves1 ! c5t] ( ! disk rotates ab\t x z %[n by ! dott$ l9e1 & gives a =w>d & backw>d movem5t to ! valve rod equal to twice ! ?r[ a4 ,illu/ration3 ,fig4 #aa4 ,relations ( ,crank & ,ecc5tric ,9 ,fig4 #aa let ,a repres5t ! c5t] ( ! ma9 %aft1 ,b ! crank-p9 to :i* ! connect+-rod is atta*$ 7see ,h1 ,fig4 #a71 & ! dott$ circle ?r\gh ,b ! pa? ( ! crank-p9 ar\nd ! %aft4 ,= simplicity1 let ! ecc5tric be repres5t$ 9 a simil> mann] by ! crank ,ab1 & its pa? by ! dott$ circle ?r\gh b4 ,fig4 #ab %[s a simil> diagram ) ! pi/on ,p & ! valve 9 ! positions correspond+ to ! positions ( ! crank & ecc5tric 9 ,fig4 #aa1 & 9 ! diagram at ! "r 9 ,fig4 #ab4 ,! pi/on is at ! extreme left1 ready to />t on its =w>d /roke t[>d ! "r4 ,! crank-p9 ,b is at its extreme inn] position4 ,:5 ! valve is at its mid-position1 z 9 ,fig4 #h1 ! ecc5tric arm ,ab w co9cide ) ! l9e ,,ac1 ,fig4 #aa4 ,if ! ecc5tric is turn$ on ! %aft suffici5tly to br+ ! left-h& edge ,o1 ,fig4 #h1 ( ! valve 9 l9e ) ! edge ,c ( ! port1 ! arm ( ! ecc5tric w h mov$ f its v]tical position to t %[n by ! l9e ,ab' 9 ,fig4 #aa4 ,! angle ?r\gh :i* ! ecc5tric has be5 turn$ f ! v]tical to br+ ab\t ?is result is call$ ! angul> advance1 & is %[n by angle ,c,ab' 9 ,fig4 #aa4 ,! angul> advance evid5tly dep5ds ^u ! am\nt ( lap4 ,if ! valve is to be giv5 a lead1 z indicat$ 9 ,fig4 #ab1 ! ecc5tric mu/ be turn$ /ill fur!r on ! %aft to op5 ! valve slightly be=e ! pi/on />ts on its =w>d movem5t4 ,?is br+s ! ecc5tric to ! position ,ab %[n 9 ,fig4 #aa4 ,! angle ?r\gh :i* ! ecc5tric is turn$ to give ! necess>y lead op5+ to ! valve is call$ ! angle ( lead1 & is %[n by angle b',ab4 ,by ref]5ce to ,fig4 #aa1 x is se5 t ! total angle betwe5 ! crank & ! ecc5tric is #ij degrees1 plus ! angul> advance1 plus ! angle ( lead4 ,?is is ! total angle ( advance4 ,illu/ration3 ,fig4 #ab4 ,pi/on j beg9n+ ,=w>d ,/roke ,! relative positions ( ! pi/on & valve at diff]5t p]iods ( ! /roke are illu/rat$ 9 ,figs4 #ab to #af4 ,fig4 #ab %[s ! pi/on j beg9n+ ! =w>d /roke1 ! valve hav+ uncov]$ ! admission port an am\nt equal to ! lead4 ,! crank is 9 a horizontal position1 & ! ecc5tric has mov$ f ! v]tical an am\nt suffici5t to move ! valve t[>d ! "r a di/ance equal to ! outside lap plus ! lead4 ,! arr[s %[ t /eam is ent]+ ! left-h& port & is be+ exhau/$ ?r\gh ! "r-h& port4 ,illu/ration3 ,fig4 #ac4 ,/eam ,port fully ,op5$ ,9 ,fig4 #ac x is se5 t ! valve has travel$ =w>d suffici5tly to op5 ! /eam port to its fulle/ ext5t1 & ! pi/on has mov$ to ! po9t indicat$4 ,! exhau/ port is /ill wide op51 & ! relative positions ( ! crank & ecc5tric are %[n 9 ! diagram at ! "r4 ,9 ,fig4 #ad ! ecc5tric has pass$ ! horizontal position & ! valve has />t$ on its backw>d /roke1 :ile ! pi/on is /ill mov+ =w>d4 ,! admission port is clos$1 cut-(f hav+ tak5 place1 & ! /eam is exp&+4 ,! exhau/ port is /ill p>tially op54 ,illu/ration3 ,fig4 #ad4 ,valve has />t$ on ,backw>d ,/roke ,illu/ration3 ,fig4 #ae4 ,bo? ,/eam ,ports ,clos$ ,9 ,fig4 #ae bo? ports are clos$ & compression is tak+ place 9 front ( ! pi/on :ile expansion cont9ues back ( x4 ,release occurs 9 ,fig4 #af j be=e ! pi/on rea*es ! end ( its /roke4 ,! ecc5tric crank is n[ 9 a v]tical position1 po9t+ d[nw>d1 & exhau/ is j beg9n+ to take place ?r\gh ! left-h& port4 ,?is completes ! diff]5t /ages ( a s+le /roke1 ! same features be+ repeat$ ^u ! return ( ! pi/on to its orig9al position4 ,! conditions ( lap1 lead1 angul> advance1 etc41 p]ta9 to practically all valves1 :atev] _! design4 ,illu/ration3 ,fig4 #af4 ,exhau/ ,beg9s ,diff]5t ,types ( ,valves ,9 ! foll[+ are %[n "s ( ! valves 9 common use1 be+1 ) ! exception ( ! ,corliss1 modifications ( ! pla9 slide valve1 & simil> 9 _! action4 ,illu/ration3 ,fig4 #ag4 ,eng9e ) ,pi/on ,valve ,d\ble-,port$ ,balanc$ ,valve4--,a valve ( ?is type has already be5 %[n 9 ,fig4 #b4 ,?is valve is flat 9 =m1 ) two f9i%$ surfaces1 & works betwe5 ! valve-seat & a plate1 ! latt] be+ prev5t$ f press+ aga9/ ! valve by special be>+ surfaces :i* hold x ab\t #j4jjb in* away4 ,! con/ruction ( ! valve is su* t :5 op5 ! /eam rea*es ! port ?r\gh two op5+s z indicat$ by ! arr[s at ! left4 ,! object ( ?is is to r$uce ! motion ( ! valve & quick5 its action 9 admitt+ & cutt+ (f /eam4 ,illu/ration3 ,fig4 #ah4 ,section ?r\gh ,cyl9d] ( ,eng9e ( ! ,f\r-valve ,type ,illu/ration3 ,fig4 #ai4 ,diff]5t ,types ( ,corliss ,valves ,pi/on ,valve4--,! pi/on valve %[n 9 ,fig4 #ag is id5tical 9 its action ) ! pla9 slide valve %[n 9 ,fig4 #h1 except t x is circul> 9 section in/ead ( be+ flat or rectangul>4 ,! advantage claim$ = ?is type ( valve is ! great] ease 9 fitt+ cyl9drical surfaces z comp>$ ) flat ones4 ,! valve slides 9 special bu%+s :i* may be r5ew$ :5 worn4 ,pi/on valves are also made ) d\ble ports4 ,illu/ration3 ,fig4 #bj4 ,longitud9al ,section ?r\gh ,corliss ,eng9e ,illu/ration3 ,fig4 #ba4 ,! ,gridiron ,valve ,f\r-,valve ,type4--,fig4 #ah %[s a horizontal section ?r\gh ! cyl9d] & valves ( an eng9e ( ! f\r-valve type4 ,! admission valves are %[n at ! top ( ! illu/ration & ! exhau/ valves at ! bottom1 al?\gh1 9 reality1 !y are at ! sides ( ! cyl9d]4 ,! advantage ( an arrangem5t ( ?is k9d is t ! valves may be set indep5d5tly ( ea* o!r & ! "w done by ! two ends ( ! cyl9d] equaliz$4 ,! v>i\s ev5ts1 su* z cut-(f1 compression1 etc41 may be adju/$ )\t reg>d to ea* o!r1 & 9 su* a mann] z to give ! be/ results1 a condition :i* is n possible ) a s+le valve4 ,gridiron ,valve4--,"o ( ! pr9cipal objects s\ght 9 ! design ( a valve is quick action at ! po9ts ( admission & cut-(f4 ,?is requires ! uncov]+ ( a l>ge port op5+ ) a comp>atively small travel ( ! valve4 ,! gridiron valve %[n 9 ,fig4 #ba is con/ruct$ especially = ?is purpose4 ,?is valve is ( ! f\r-valve type1 "o /eam valve & "o exhau/ valve be+ %[n 9 ! section4 ,bo? ! valve & its seat conta9 a numb] ( n>r[ op5+s or ports1 s t a %ort movem5t ( ! valve w op5 or close a comp>atively l>ge op5+4 ,= example1 ! /eam valve 9 ! illu/ration has #ab op5+s1 s t if !y are #a_/d in* 9 wid? ea*1 a movem5t ( #a_/d in* ( ! valve w op5 a space #ab x #a_/d #c in*es 9 l5g?4 ,illu/ration3 ,fig4 #bb4 ,! ,mon>* ,eng9e ) ,corliss ,valve ,ge>4--,a1 ,rod to ,ecc5tric2 ,b1 ,gov]nor2 ,c1 ,rea* ,rod2 ,d1 ,radial ,arm2 ,e1 ,/eam ,valve2 ,f1 ,bell-crank2 ,g1 ,wri/ ,plate2 ,h1 ,exhau/ ,valve2 ,k1 ,da%-pot ,corliss ,valve4--,a section ?r\gh an eng9e cyl9d] equipp$ ) ,corliss valves is %[n 9 ,fig4 #bj4 ,!re are f\r cyl9drical valves 9 ?is type ( eng9e1 two /eam valves at ! top & two exhau/ valves at ! bottom4 ,?is arrangem5t is us$ to secure prop] dra9age4 ,! action ( ! admission & exhau/ valves is indicat$ by ! arr[s1 ! upp] left-h& & ! l[] "r-h& valve be+ op5 & ! o!r two clos$4 ,side & sectional views ( diff]5t =ms ( ?is type ( valve are %[n 9 ,fig4 #ai4 ,!y are op]at$ by means ( %ort crank-arms :i* are atta*$ to a wri/-plate by means ( radial arms or rods1 z %[n 9 ,fig4 #bb4 ,! wri/-plate1 9 turn1 is giv5 a p>tial backw>d & =w>d rotation by means ( an ecc5tric atta*$ to ! ma9 %aft & connect$ to ! upp] "p ( ! wri/-plate by a rod z indicat$4 ,! exhau/ valves are bo? op5$ & clos$ by ! action ( ! wri/-plate & connect+ rods4 ,! /eam valves are op5$ 9 ?is mann]1 b are clos$ by ! suction ( da% pots atta*$ to ! drop lev]s on ! valve /ems by means ( v]tical rods1 z %[n4 ,illu/ration3 ,figs4 #bc to #bf4 ,action ( ,corliss ,valve ,ge> ,! action ( ! /eam or admission valves is be/ expla9$ by ref]5ce to ,figs4 #bc to #bf4 ,ref]r+ to ,fig4 #bc1 ,a is a bell-crank :i* turns loosely ^u ! valve /em ,v4 ,! l[] left-h& ext5sion ( ,a c>ries ! grab hook ,h1 :ile ! upp] ext5sion is connect$ ) ! wri/-plate z indicat$4 ,ord9>ily ! hook ,h is press$ inw>d by ! spr+ ,s1 s t ! long] arm ( ! hook is always press$ aga9/ ! knock-(f cam ,c4 ,! cam ,c also turns ^u ! valve /em ,v & is connect$ ) ! gov]nor by means ( a rea* rod z indicat$ 9 ,fig4 #bc & %[n 9 ,fig4 #bb4 ,! drop lev] ,b is key$ to ! valve /em ,v1 & is connect$ ) ! da% pot by a rod z indicat$ by ! dott$ l9e4 ,?is is also %[n 9 ,fig4 #bb4 ,! end ( ! drop lev] c>ries a /eel block 7%[n %ad$ 9 ,fig4 #bc71 :i* engages ) ! grab hook ,h4 ,:5 9 op]ation1 ! bell-crank is rotat$ 9 ! direction ( ! arr[ by ! action ( ! wri/-plate & connect+-rod4 ,z ! bell-crank rotates1 ! grab hook engages ! /eel block at ! end ( ! drop lev] ,b & lifts x1 ?us caus+ ! valve to op51 & to rema9 s until ! bell-crank has advanc$ s f> t ! long] arm ( ! grab hook ,h is press$ outw>d by ! projection on ! knock-(f cam1 z %[n 9 ,fig4 #bd4 ,! drop lev] n[ be+ releas$1 ! valve is quickly clos$ by ! suction ( ! da% pot1 :i* pulls ! lev] d[n to its orig9al position by means ( ! rod previ\sly m5tion$4 ,illu/ration3 ,fig4 #bg4 ,gov]nor = ,corliss ,eng9e ,! gov]nor op]ates by *ang+ ! po9t ( cut-(f ?r\gh ! action ( ! cam ,c4 ,) ! cam 9 ! position %[n 9 ,fig4 #be1 cut-(f occurs e>li] ?an 9 ,fig4 #bd4 ,%\ld ! cam be turn$ 9 ! opposite direction 7clockwise71 cut-(f w\ld take place lat]4 ,a detail$ view ( ! complete valve me*anism describ$ is %[n assembl$ 9 ,fig4 #bf1 ) ea* "p prop]ly nam$4 ,a detail ( ! gov]nor is %[n 9 ,fig4 #bg4 ,an increase 9 spe$ causes ! revolv+ balls ,,bb to sw+ outw>d1 ?us rais+ ! weight ,w & ! sleeve ,s4 ,?is 9 turn op]ates ! lev] ,l ?r\gh rod ,r & a bell-crank atta*m5t1 z %[n 9 ! "r-h& view4 ,an upw>d & d[nw>d movem5t ( ! balls1 due to a *ange 9 spe$ ( ! eng9e1 sw+s ! lev] ,l backw>d & =w>d z %[n by ! full & dott$ l9es4 ,! ends ( ?is lev] are atta*$ by means ( rea*-rods to ! knock-(f cams1 ?is be+ %[n m cle>ly 9 ,fig4 #bb4 ,! connections betwe5 ! lev] ,l & cam ,c are su* t a rais+ ( ! balls1 due to increas$ spe$1 w r$uce ! cut-(f & ?us sl[ d[n ! eng9e4 ,on ! o!r h&1 a fall+ ( ! balls w l5g!n ! cut-(f ?r\gh ! same me*anism4 ,illu/ration3 ,fig4 #bh4 ,da%-pot = ,corliss ,eng9e ,illu/ration3 ,figs4 #bi & #cj4 ,plan & ,longitud9al ,section ( ,adju/able ,pi/on ,m5tion has already be5 made ( ! da% pot :i* is us$ to close ! valve sudd5ly aft] be+ releas$ f ! grab hook4 ,! da%-pot rod is %[n 9 ,fig4 #bf1 & indicat$ by dott$ l9es 9 ,figs4 #bc to #be4 ,a detail$ view ( "o =m ( da% pot is %[n 9 ,fig4 #bh4 ,:5 ! valve is op5$1 ! rod atta*$ to lev] ,b1 ,figs4 #bc & #bd1 raises ! pi/on ,p1 ,fig4 #bh1 & a p>tial vacuum is =m$ b5ea? x :i* draws ! pi/on & connect+ rod d[n by suction z soon z ! lev] ,b is releas$1 & ?us closes ! valve sudd5ly & )\t %ock4 ,! /r5g? ( ! suction & ! air cu%ion = ?is pi/on are regulat$ by ! inlet & outlet valves %[n on ! sides ( ! da% pot4 ,eng9e ,details ,figs4 #bi to #cg %[ v>i\s eng9e details1 & illu/rate 9 a simple way "s ( ! m important pr9ciples involv$ 9 /eam eng9e design4 ,illu/ration3 ,fig4 #ca4 ,a ,typical ,cross-head ,illu/ration3 ,figs4 #cb & #cc4 ,me?ods ,commonly ,us$ = ,tak+ ,up ,we> 9 a ,connect+-rod ,a p>tial cross-section ( an adju/able pi/on is %[n 9 ,fig4 #bi1 & a longitud9al section ( ! same pi/on 9 ,fig4 #cj4 ,! pr9cipal feature to be emphasiz$ is ! me?od ( automatic expansion employ$ to take up any we> & keep ! pi/on tight4 ,9 sett+ up ! pi/on a h& adju/m5t is made ( ! out] sleeve or r+ ,r by means ( ! set-screws ,,aa4 ,r+ ,r is made 9 sev]al sections1 s t x may be exp&$ 9 ! =m ( a true circle4 ,fur!r tightness is secur$ )\t undue friction by means ( ! pack+ r+ ,p :i* fits 9 a groove 9 ,r & is =c$ lightly aga9/ ! walls ( ! cyl9d] by a numb] ( coil spr+s1 "o ( :i* is %[n at ,s4 ,z ! cyl9d] & pi/on become worn1 screws ,a are adju/$ f "t to "t1 & ! f9e adju/m5t = tightness is c>$ = by ! pack+ r+ ,p & ! coil spr+s ,s4 ,! po9ts to be br\ght out 9 connection ) ! cross-head are ! me?ods ( alignm5t & adju/m5t4 ,a typical cross-head is %[n 9 cross & longitud9al sections 9 ,fig4 #ca4 ,alignm5t 9 a /raight l9e1 longitud9ally1 is secur$ by ! cyl9drical =m ( ! be>+ surfaces or %oes1 %[n at ,s4 ,^! are sometimes made ,v-%ap$ 9 ord] to secure ! same result4 ,! we> on a cross-head comes on ! surfaces ,s1 & is tak5 up by ! use ( screw w$ges ,w1 %[n 9 ! longitud9al section4 ,z ! slid+ surfaces become worn1 ! w$ges are =c$ 9 slightly by screw+ 9 ! set-screws & clamp+ !m 9 place by means ( ! *eck-nuts4 ,illu/ration3 ,fig4 #cd4 ,outbo>d ,be>+ = ,corliss ,type ,eng9e ,illu/ration3 ,fig4 #ce4 ,inn] ,be>+ & ,b$ ( ,corliss ,eng9e ,! me?od commonly employ$ 9 tak+ up ! we> 9 a connect+-rod is %[n 9 ,figs4 #cb & #cc4 ,! we> at ! wri/-p9 is tak5 by ! s call$ brasses1 %[n at ,b 9 ! illu/rations4 ,! inn] brass1 9 bo? cases1 fits 9 a suitable groove1 & is held /ation>y :5 once 9 place4 ,! out] brass is adju/able1 be+ =c$ t[>d ! wri/-p9 by a slid+ w$ge :i* is op]at$ by "o or m set-screws4 ,9 ,fig4 #cb ! w$ge is held 9 a v]tical position1 & is adju/$ by two screws z %[n4 ,! arrangem5t made use ( 9 ,fig4 #cc has ! w$ge pass+ ?r\gh ! rod 9 a horizontal position1 & adju/$ by means ( a s+le screw1 z %[n 9 ! l[] view4 ,) ! arrangem5ts %[n1 tight5+ up ! brasses %ort5s ! l5g? ( ! rod4 ,9 practice ! w$ges at ea* end ( ! rod are s plac$ t tight5+ "o %ort5s ! rod1 & tight5+ ! o!r l5g!ns x1 ! total effect be+ to keep ! connect+-rod at its orig9al l5g?4 ,a common =m ( outbo>d be>+ = an eng9e ( ! sl[-spe$ or ,corliss type is illu/rat$ 9 ,fig4 #cd4 ,! v>i\s adju/m5ts = alignm5t & = tak+ up we> are ! important po9ts consid]$ 9 ?is case4 ,! plate ,b is fa/5$ to ! /one f\ndation by an*or bolts n %[n4 ,sidewise movem5t is secur$ by loos5+ ! bolts ,c1 :i* pass ?r\gh slots 9 ! be>+1 & adju/+ by means ( ! screws ,s4 ,v]tical adju/m5t is obta9$ by use ( ! w$ge ,w1 :i* is =c$ 9 by ! screw ,a1 z requir$4 ,! inn] be>+ & b$ piece ( a heavy duty ,corliss eng9e is %[n 9 ,fig4 #ce4 ,! be>+ 9 ?is case is made up ( f\r sections1 s arrang$ t ei!r horizontal or v]tical adju/m5t may be secur$ by ! use ( adju/+ screws & *eck-nuts4 ,eng9es ( ! slide-valve type are usually provid$ ei!r ) a fly-ball ?rottl+ gov]nor1 or a %aft gov]nor4 ,a common =m ( ?rottl+ gov]nor is %[n 9 ,fig4 #cf4 ,z ! spe$ increases ! balls ,w are ?r[n outw>d by ! action ( ! c5trifugal =ce1 & be+ atta*$ to arms h+$ above !m1 any outw>d movem5t causes !m to rise4 ,?is op]ates ! sp9dle ,s1 :i*1 9 turn1 p>tially closes ! balanc$ valve 9 body ,b1 ?us cutt+ d[n ! /eam supply deliv]$ to ! eng9e4 ,! action ( a ?rottl+ gov]nor ^u ! "w diagram ( an eng9e is %[n 9 ,fig4 #ch4 ,let ! full l9e repres5t ! =m ( ! diagram ) ! eng9e work+ at full load4 ,n[1 if a "p ( ! load be ?r[n (f1 ! eng9e w spe$ up slightly1 caus+ ! gov]nor to act z describ$1 ?us br++ ! admission & expansion l9es into ! l[] positions1 z %[n 9 dott$ l9es4 ,illu/ration3 ,fig4 #cf4 ,common ,=m ( ,?rottl+ ,gov]nor ,! %aft gov]nor is us$ almo/ univ]sally on high-spe$ eng9es1 & is %[n 9 "o =m 9 ,fig4 #cg4 ,x consi/s1 9 ?is case1 ( two weights ,w1 h+$ to ! spokes ( ! :eel ne> ! circumf]5ce by means ( suitable arms4 ,atta*$ to ! arms1 z %[n1 are coil spr+s ,c4 ,! ends ( ! arms beyond ! weights are connect$ by means ( lev]s ,l to ! ecc5tric disk4 ,:5 ! eng9e spe$s up1 ! weights t5d to sw+ outw>d t[>d ! rim ( ! :eel1 ! am\nt ( ! movem5t be+ regulat$ by ! t5sion ( ! spr+s ,c4 ,z ! arms move outw>d1 ! lev]s at ! ends turn ! ecc5tric disk on ! %aft1 ! effect ( :i* is to *ange ! angle ( advance & %ort5 ! cut-(f4 ,:5 ! spe$ falls bel[ ! normal1 ! weights move t[>d ! c5t] & ! cut-(f is l5g!n$4 ,! effect ( ?is =m ( gov]nor on ! diagram is %[n 9 ,fig4 #ci4 ,! full l9e repres5ts ! diagram at full load1 & ! dott$ l9e :5 ! eng9e is "u-load$4 ,illu/ration3 ,fig4 #cg4 ,%aft ,gov]nor = ,high-spe$ ,eng9e ,,*apt] ,,iv ,,/eam ,,eng9e ,,economy ,"u ! g5]al head+ ( /eam eng9e economy1 su* items z cyl9d] cond5sation1 /eam consumption1 effici5cy1 ratio ( expansion1 "u- & ov]-load+1 cond5s+1 etc41 are treat$4 ,! pr9cipal wa/e ( /eam 9 ! op]ation ( an eng9e is due to cond5sation dur+ ! fir/ "p ( ! /roke4 ,?is cond5sation is due to ! fact t dur+ expansion & exhau/ ! cyl9d] walls & head & ! pi/on are 9 contact ) comp>atively cool /eam1 &1 !re=e1 give up a consid]able am\nt ( heat4 ,:5 fre% /eam is admitt$ at a high temp]ature1 x imm$iately gives up suffici5t heat to raise ! cyl9d] walls to a temp]ature approximat+ t ( ! ent]+ /eam4 ,?is results 9 ! cond5sation ( a c]ta9 am\nt ( /eam1 ! quantity dep5d+ ^u ! "t all[$ = ! transf] ( heat1 ! area ( expos$ surface1 & ! temp]ature ( ! cyl9d] walls4 ,dur+ ! p]iod ( expansion ! temp]ature falls rapidly1 & ! /eam be+ wet1 absorbs a l>ge am\nt ( heat4 ,aft] ! exhau/ valve op5s1 ! drop 9 pressure all[s ! moi/ure t has collect$ on ! cyl9d] walls to evaporate into /eam1 s t dur+ ! exhau/ p]iod b little heat is transf]r$4 ,) ! admission ( fre% /eam at boil] pressure1 a mi/ is cond5s$ on ! cyl9d] walls1 :i* greatly increases ! rapidity ) :i* heat is absorb$4 ,! am\nt ( heat lo/ ?r\gh cyl9d] cond5sation is be/ %[n by a practical illu/ration4 ,"o horsep[] is equal to #cc1jjj foot-p\nds ( "w p] m9ute1 or #cc1jjj x #fj #a1ihj1jjj foot-p\nds p] h\r4 ,?is is equival5t to #a1ihj1jjj _/ #ggh #b1eej heat units4 ,! lat5t heat ( /eam at #ij p\nds gage pressure is #hha heat units4 ,h5ce1 #b1bej _/ #hha #b4i p\nds ( /eam at #ij p\nds pressure is requir$ p] horsep[]1 provid$ !re is no loss ( /eam1 & all ( ! conta9$ heat is *ang$ into useful "w4 ,z a matt] ( fact1 f #cj to #ce p\nds ( /eam are requir$ 9 ! av]age simple non-cond5s+ high-spe$ eng9e4 ,!re are ?ree rem$ies :i* are us$ to r$uce ! am\nt ( cyl9d] cond5sation4 ,! fir/ to be us$ 0 call$ /eam jacket+1 & consi/$ 9 surr\nd+ ! cyl9d] ) a lay] ( high-pressure /eam1 ! idea be+ to keep ! inn] walls up to a temp]ature ne>ly equal to t ( ! incom+ /eam4 ,?is arrangem5t is b little us$ at ! pres5t "t1 ow+ bo? to ! exp5se ( op]ation & to its ineffectiv5ess z comp>$ ) o!r me?ods4 ,! second rem$y is ! use ( sup]heat$ /eam4 ,x has be5 /at$ t ! transf] ( heat takes place mu* m rapidly :5 ! int]ior surfaces are cov]$ ) a coat+ ( moi/ure or mi/4 ,sup]heat$ /eam has a temp]ature consid]ably above ! po9t ( saturation at ! giv5 pressure2 h5ce1 x is possible to cool x a c]ta9 am\nt be=e cond5sation beg9s4 ,?is has ! effect ( r$uc+ ! transf] ( heat = a %ort p]iod foll[+ admission1 & ?is is ! "t t cond5sation takes place mo/ rapidly "u ord9>y conditions ) saturat$ /eam4 ,?is1 9 fact1 is ! pr9cipal advantage d]iv$ f ! use ( sup]heat$ /eam1 al?\gh x is also light] = a giv5 volume1 & !re=e1 a less weight ( /eam is requir$1 to fill ! cyl9d] up to ! po9t ( cut-(f4 ,! economical degree ( sup]heat+ is consid]$ to be t :i* w prev5t ! cond5sation ( any /eam on ! walls ( ! cyl9d] up to ! po9t ( cut-(f1 ?us keep+ !m at all times free f moi/ure4 ,! objections to sup]heat$ /eam are its cutt+ effect 9 ! passages ?r\gh :i* x fl[s1 & ! difficulty exp]i5c$ 9 lubricat+ ! valves & cyl9d] at su* a high temp]ature4 ,! ?ird & mo/ effective rem$y = cond5sation losses is t kn[n z comp\nd+1 :i* w be treat$ "u a sep>ate head+ 9 ! foll[+4 ,multiple ,expansion ,eng9es ,x has be5 expla9$ t cyl9d] cond5sation is due pr9cipally to ! *ange 9 temp]ature ( ! int]ior surfaces ( ! cyl9d]1 caus$ by ! v>iation 9 temp]ature ( ! /eam at initial & exhau/ pressures4 ,!re=e1 if ! temp]ature range be divid$ betwe5 two cyl9d]s :i* are op]at$ 9 s]ies1 ! /eam cond5s$ 9 ! fir/ or high pressure cyl9d] w be re-evaporat$ & pass$ into ! l[-pressure cyl9d] z /eam1 :]e x w aga9 be cond5s$ & re-evaporat$ z x passes into ! exhau/ pipe4 ,!oretically1 ?is %\ld r$uce ! cond5sation loss by "o-half1 & if ?ree cyl9d]s are us$1 ! loss %\ld be only "o-?ird ( t 9 a simple eng9e4 ,9 actual practice ! sav+ is n z great z ?is1 b ) ! prop] relation betwe5 ! cyl9d]s1 ^! results are approximat$4 ,eng9es 9 :i* expansion takes place 9 two /ages are call$ comp\nd eng9es4 ,:5 ?ree /ages are employ$1 !y are call$ triple expansion eng9es4 ,comp\nd+ adds to ! fir/ co/ ( an eng9e1 & also to ! friction1 s t 9 det]m9+ ! mo/ economical numb] ( cyl9d]s to employ1 ! actual relation betwe5 ! cond5sation loss & ! increas$ co/ ( ! eng9e & ! friction loss1 mu/ be consid]$4 ,9 ! case ( p[] plant "w1 x is n[ ! practice to use comp\nd eng9es = ! l>ge sizes1 :ile triple expansion eng9es are m commonly employ$ 9 pump+ /ations4 ,_m designs ( multiple expansion eng9es are provid$ ) *amb]s betwe5 ! cyl9d]s1 call$ receiv]s4 ,9 eng9es ( ?is type ! exhau/ is frequ5tly reheat$ 9 ! receiv]s by means ( brass coils conta9+ live /eam4 ,9 ! case ( a cross-comp\nd eng9e1 a receiv] is always us$4 ,9 ! t&em design x is (t5 omitt$1 ! pip+ betwe5 ! two cyl9d]s be+ made to answ] ! purpose4 ,! ratio ( cyl9d] volumes 9 comp\nd eng9es v>ies ) diff]5t mak]s4 ,! usual practice is to make ! volume ( ! l[-pressure cyl9d] f #b4e to #c times t ( ! high-pressure4 ,! total ratio ( expansion 9 a multiple expansion eng9e is ! product ( ! ratios 9 ea* cyl9d]4 ,= example1 if ! ratio ( expansion is #d 9 ea* cyl9d] 9 a comp\nd eng9e1 ! total ratio w be #d x #d #af4 ,! effect ( a triple-expansion eng9e is sometimes obta9$ 9 a measure by mak+ ! volume ( ! l[-pressure cyl9d] ( a comp\nd eng9e #f or #g times t ( ! high-pressure4 ,?is arrangem5t produces a consid]able drop 9 pressure at ! end ( ! high-pressure /roke1 ) ! result ( ?r[+ a consid]able increase ( "w on ! high-pressure cyl9d] )\t increas+ its ratio ( expansion1 & at ! same "t secur+ a l>ge total ratio ( expansion 9 ! eng9e4 ,9 ! case ( v]tical eng9es1 ! l[-pressure cyl9d] is sometimes divid$ into two p>ts 9 ord] to r$uce ! size ( cyl9d] & pi/on4 ,9 ?is arrangem5t a receiv] ( l>g] size ?an usual is employ$1 & ! l[-pressure cranks are (t5 set at an angle ) ea* o!r4 ,ano!r advantage ga9$ by comp\nd+ is ! possibility to exp& ! /eam to a great] ext5t ?an c be done 9 a s+le cyl9d] eng9e1 ?us utiliz+1 z useful "w1 a great] proportion ( ! heat conta9$ 9 ! /eam4 ,?is also makes x possible to employ high] initial pressures1 9 :i* !re is a /ill fur!r sav+1 because ( ! comp>atively small am\nt ( fuel requir$ to raise ! pressure f t ( ! common practice ( #hj or #ij p\nds = simple eng9es1 to #abj to #adj p\nds1 :i* is entirely practical 9 ! case ( comp\nd eng9es4 ,) triple expansion1 initial pressures ( #ahj p\nds or m may be us$ to advantage4 ,! ga9 f comp\nd+ may am\nt to ab\t #ae p] c5t ov] simple cond5s+ eng9es1 tak+ /eam at ! same initial pressure4 ,:5 comp\nd cond5s+ eng9es are comp>$ ) simple non-cond5s+ eng9es1 ! ga9 9 economy may run f #cj to #dj p] c5t4 ,,table ,,iv4 ,,/eam ,,consumption ,,( ,,eng9es ---------------------------------------- ----------------- ,p\nds ( ,/eam p] ,indicat$ ,horsep[] p] ,h\r ,k9d ( ,eng9e ------------------------------- ,non-cond5s+ ,cond5s+ ---------------------------------------- ---------------- ,high-spe$ #cb #bd ,simple ,m$ium-spe$ #cj #bc ,corliss #bh #bb ,high-spe$ #bf #bj ,comp\nd ,m$ium-spe$ #be #ai ,corliss #bd #ah ---------------------------------------- ---------------- ,/eam ,consumption & ,ratio ( ,expansion ,! /eam consumption is commonly call$ ! wat] rate1 & is express$ 9 p\nds ( dry /eam requir$ p] indicat$ horsep[] p] h\r4 ,?is quantity v>ies widely 9 diff]5t types ( eng9es1 & also 9 eng9es ( ! same k9d work+ "u diff]5t conditions4 ,! wat] rate dep5ds ^u ! cyl9d] losses1 :i* are due pr9cipally to cond5sation1 al?\gh ! effects ( cle>ance1 radiation f cyl9d] & /eam *e/1 & leakage ar\nd valves & pi/on1 =m a "p ( ! total loss4 ,table ,,iv gives ! av]age wat] rate ( diff]5t types ( eng9es work+ at full load4 ,! mo/ economical ratio ( expansion dep5ds l>gely ^u ! type ( ! eng9e4 ,9 ! case ( simple eng9es1 ! ratio is limit$ to #d or #e on acc\nt ( excessive cyl9d] cond5sation 9 case ( l>g] ratios4 ,?is limits ! initial pressure to an av]age ( ab\t #ij p\nds = eng9es ( ?is type4 ,9 ! case ( comp\nd eng9es1 a ratio ( f #h to #aj is commonly employ$ to advantage1 :ile ) triple-expansion eng9es1 ratios ( #ab to #ae are f\nd to give good results4 ,illu/ration3 ,fig4 #ch4 ,action ( ,?rottl+ ,gov]nor on ,indicator ,diagram ,illu/ration3 ,fig4 #ci4 ,effect ( ,%aft ,gov]nor on ,indicator ,diagram ,illu/ration3 ,fig4 #dj4 ,increas+ ,p[] ( ,eng9e by ,cond5s+ ,illu/ration3 ,fig4 #da4 ,decreas+ ,/eam ,consumption by ,cond5s+ ,! !rmal effici5cy ( an eng9e is ! ratio ( ! heat trans=m$ into "w to ! total heat suppli$ to ! eng9e4 ,9 ord] to det]m9e ?is1 ! absolute temp]ature ( ! /eam at admission & exhau/ pressures mu/ be kn[n4 ,^! pressures c be measur$ by a gage1 & ! correspond+ temp]atures tak5 f a /eam table1 or bett]1 ! temp]atures c be measur$ direct by a !rmomet]4 ,! absolute temp]ature is obta9$ by add+ #dfa to ! read+ 9 degrees ,fahr5heit 7,f474 ,! =mula = !rmal effici5cy is3 ,t#a - ,t#b ----------------- ,t#a 9 :i* ,t#a absolute temp]ature ( /eam at initial pressure4 ,t#b absolute temp]ature ( /eam at exhau/ pressure4 ,example3--,! temp]ature ( ! /eam admitt$ to ! cyl9d] ( an eng9e is #cdj degrees ,f41 & t ( ! exhau/ /eam #bbj degrees ,f4 ,:at is ! !rmal effici5cy ( ! eng9e8 7#cdj #dfa7 - 7#bbj #dfa7 ,!rmal effici5cy ------------------------- #j4ae 7#cdj #dfa7 ,! me*anical effici5cy is ! ratio ( ! deliv]$ or brake horsep[] to ! indicat$ horsep[]1 & is repres5t$ by ! equation3 ,b4 ,h4 ,p4 ,me*anical effici5cy -------- ,i4 ,h4 ,p4 9 :i* ,b4 ,h4 ,p4 brake horsep[]1 ,i4 ,h4 ,p4 indicat$ horsep[]4 ,all eng9es are design$ to give ! be/ economy at a c]ta9 develop$ indicat$ horsep[] call$ full load4 ,!re mu/1 ( c\rse1 be m or less fluctuation 9 ! load "u practical work+ conditions1 especially 9 c]ta9 cases1 su* z electric railway & roll+ mill "w4 ,! losses1 h[ev]1 )9 a c]ta9 range on ei!r side ( ! normal load1 are n great 9 a well design$ eng9e4 ,! effect ( increas+ ! load is to raise ! initial pressure or l5g!n ! cut-(f1 dep5d+ ^u ! type ( gov]nor4 ,?is1 9 turn1 raises ! t]m9al pressure at ! end ( expansion1 & all[s ! exhau/ to escape at a high] temp]ature ?an be=e1 ?us l[]+ ! !rmal effici5cy4 ,! effect ( r$uc+ ! load is to l[] ! mean effective pressure4 7,see ,figs4 #ch & #ci47 ,?is1 9 ?rottl+ eng9es1 is due to a r$uction ( initial pressure1 & 9 ! automatic eng9e to a %ort5+ ( ! cut-(f4 ,! result 9 ea* case is an increase 9 cyl9d] cond5sation1 & z ! load becomes light]1 ! friction ( ! eng9e itself becomes a m important "p ( ! total indicat$ horsep[]2 t is1 z ! load becomes light]1 ! me*anical effici5cy is r$uc$4 ,effect ( ,cond5s+ ,s f> z ! design ( ! eng9e itself x conc]n$1 !re is no diff]5ce betwe5 a cond5s+ & a non-cond5s+ eng9e4 ,! only diff]5ce is t 9 ! fir/ case ! exhau/ pipe f ! eng9e is connect$ ) a cond5s] in/ead ( dis*>g+ into ! atmosph]e4 ,a cond5s] is a device = cond5s+ ! exhau/ /eam z fa/ z x comes f ! eng9e1 ?us =m+ a p>tial vacuum & r$uc+ ! back pressure4 ,! atta*+ ( a cond5s] to an eng9e may be made to produce two results1 z %[n by ! "w diagrams illu/rat$ 9 ,figs4 #dj & #da4 ,9 ! fir/ case ! full l9e repres5ts ! diagram ( ! eng9e :5 runn+ non-cond5s+1 & ! area ( ! diagram gives a measure ( ! "w done4 ,! effect ( add+ a cond5s] is to r$uce ! back pressure on an av]age ( #aj to #ab p\nds p] squ>e in*1 :i* is equival5t to add+ ! same am\nt to ! mean effective pressure4 ,! effect ( ?is on ! diagram1 :5 ! cut-(f rema9s ! same1 is %[n by ! dott$ l9e 9 ,fig4 #dj4 ,! p[] ( ! eng9e p] /roke is increas$ by an am\nt repres5t$ by ! area enclos$ by ! dott$ l9e & ! bottom ( ! orig9al diagram4 ,assum+ ! r$uction 9 back pressure to be #aj p\nds1 :i* is (t5 exce$$ 9 ! be/ practice1 ! ga9 9 p[] by runn+ cond5s+ w be proportional to ! increase 9 mean effective pressure "u ^! conditions4 ,= example1 if ! mean effective pressure is #dj p\nds :5 runn+ non-cond5s+1 x w be increas$ to #dj #aj #ej p\nds :5 runn+ cond5s+1 t is1 x is #ej_/dj #a4be times z great z be=e4 ,!re=e1 if ! eng9e develops #ajj ,i4 ,h4 ,p4 "u ! fir/ condition1 its f9al p[] w be increas$ to #ajj x #a4be #abe ,i4 ,h4 ,p4 "u ! second condition4 ,fig4 #da %[s ! effect ( add+ a cond5s] & %ort5+ ! cut-(f to keep ! area ( ! diagram ! same z be=e4 ,! result 9 ?is case is a r$uction 9 ! quantity ( /eam requir$ to develop ! same indicat$ horsep[]4 ,! !oretical ga9 9 economy "u ^! conditions w run f ab\t #bh to #cj p] c5t = simple1 & f #bj to #bb p] c5t = comp\nd eng9es4 ,! actual ga9 w dep5d ^u ! co/ & op]ation ( ! cond5s] :i* v>ies greatly 9 diff]5t localities4 ,,*apt] ,v ,,types ,,( ,,/eam ,,eng9es ,!re are v>i\s ways ( classify+ /eam eng9es accord+ to _! con/ruction1 ! mo/ common1 p]haps1 be+ accord+ to spe$4 ,if ?is classification is employ$1 !y may be gr\p$ "u ?ree g5]al head+s3 ,high-spe$1 f #cjj to #djj revolutions p] m9ute2 mod]ate-spe$1 f #ajj to #bjj revolutions2 & sl[-spe$1 f #fj to #ij revolutions2 all dep5d+1 h[ev]1 ^u ! l5g? ( /roke4 ,?is classification is aga9 sub-divid$ accord+ to valve me*anism1 horizontal & v]tical1 simple & comp\nd1 etc4 ,! diff]5t =ms ( eng9es %[n 9 ! foll[+ illu/rations %[ repres5tative types 9 common use = diff]5t purposes4 ,! ,ball eng9e1 z %[n 9 ,fig4 #db1 is a typical horizontal s+le valve high-spe$ eng9e ) a direct-connect$ dynamo4 ,x is v rigid 9 design & especially compact = ! p[] develop$4 ,! valve is ( ! d\ble-port$ type %[n 9 ,fig4 #b1 hav+ a cov] plate = remov+ ! /eam pressure f ! back ( ! valve4 ,! pi/on is holl[ ) int]nal ribs simil> to t %[n 9 ,fig4 #bi1 & is provid$ ) spr+ pack+ r+s c>efully fitt$ 9 place4 ,! gov]nor is ( ! %aft type1 hav+ only "o weight in/ead ( two1 z %[n 9 ,fig4 #cg4 ,illu/ration3 ,fig4 #db4 ,! ,ball ,eng9e ,! ,/urtevant eng9e %[n 9 ,fig4 #dc is a v]tical high-spe$ eng9e ( a =m especially adapt$ to electrical "w4 ,eng9es ( ?is g5]al design are made 9 a v>iety ( sizes1 & are (t5 us$ on acc\nt ( ! small floor space requir$4 ,9 ! matt] ( detail1 su* z valves1 gov]nors1 etc41 !y d n diff] mat]ially f ! high-spe$ horizontal eng9e4 ,fig4 #dd illu/rates a mod]ate-spe$ eng9e ( ! f\r-valve type4 ,^! eng9es are built ei!r ) flat valves1 or ) positively driv5 rot>y or ,corliss valves1 ! latt] be+ us$ 9 ! eng9e %[n4 ,x w be notic$ t ! drop-lev] & da%-pot arrangem5t is omitt$1 ! valves be+ bo? op5$ & clos$ by means ( ! wri/-plate & its connect+ rods4 ,?is arrangem5t is us$ on acc\nt ( ! high] spe$ at :i* ! eng9e is run1 ! regul> ,corliss valve ge> be+ limit$ to comp>atively l[ spe$s4 ,all eng9es ( ?is make are provid$ ) an automatic sy/em ( lubrication4 ,! oil is pump$ ?r\gh a filt] to a c5tral res]voir1 se5 above ! c5t] ( ! eng9e1 & f "h deliv]$ to all be>+s by gravity4 ,! pump is atta*$ to ! rock] arm1 & !re=e easily accessible = repairs4 ,! /&>d ,h>ris ,corliss eng9e %[n 9 ,fig4 #de1 is typical ( its class4 ,x is provid$ ) ! gird] type ( frame1 & ) an outbo>d be>+ m\nt$ ^u a /one f\ndation4 ,! valve ge> is ( ! regul> ,corliss type1 driv5 by a s+le ecc5tric & wri/-plate4 ,! da% pots are m\nt$ on ca/-iron plates set 9 ! floor at ! side ( ! eng9e1 :]e !y may be easily inspect$4 ,! gov]nor is simil> 9 con/ruction to ! "o already describ$1 & %[n 9 ,fig4 #bg4 ,! f\r eng9es s f> describ$ are simple eng9es1 ! expansion tak+ place 9 a s+le cyl9d]4 ,figs4 #df to #dh %[ ?ree diff]5t types ( ! comp\nd eng9e4 ,illu/ration3 ,fig4 #dc4 ,! ,/urtevant ,v]tical ,eng9e ,! eng9e %[n 9 ,fig4 #df is ( a type kn[n z ! t&em comp\nd4 ,9 ?is design ! cyl9d]s are 9 l9e1 ! l[-pressure cyl9d] 9 front ( ! high-pressure1 z %[n4 ,!re is only "o pi/on rod1 ! high-pressure & l[-pressure pi/ons be+ m\nt$ on ! same rod4 ,! g5]al appe>ance ( an eng9e ( ?is design is ! same z a simple eng9e1 except = ! addition ( ! high-pressure cyl9d]4 ,! gov]nor is ( ! %aft type & op]ates by *ang+ ! cut-(f 9 ! high-pressure cyl9d]4 ,! cut-(f 9 ! l[ pressure cyl9d] is adju/$ by h& to divide ! load equally betwe5 ! two cyl9d]s = ! normal load :i* ! eng9e is to c>ry4 ,illu/ration3 ,fig4 #dd4 ,mod]ate ,spe$ ,eng9e ( ! ,f\r-valve ,type ,! eng9e %[n 9 ,fig4 #dg is kn[n z a duplex comp\nd4 ,9 ?is design ! high-pressure cyl9d] is plac$ directly bel[ ! l[-pressure cyl9d]1 z indicat$1 & bo? pi/on rods are atta*$ to ! same cross-head4 ,! rema9d] ( ! eng9e is practically ! same z a simple eng9e ( ! same type4 ,illu/ration3 ,fig4 #de4 ,! ,h>ris ,corliss ,eng9e ,fig4 #dh %[s a cross-comp\nd eng9e ( heavy design1 built especially = roll+ mill "w4 ,9 ?is arrangem5t two complete eng9es are us$1 except = ! ma9 %aft & fly:eel1 :i* are common to bo?4 ,! eng9e is s pip$ t ! high-pressure cyl9d] exhau/s into ! l[-pressure1 ?r\gh a receiv]1 ! connection be+ "u ! floor & n %[n 9 ! illu/ration4 ,"o ( ! advantages ( ! cross-comp\nd eng9e ov] o!r =ms is t ! cranks may be set #ij degrees ap>t1 s t :5 "o is on a dead c5t] ! o!r is approximately at its position ( greate/ ef=t4 ,selection ( an ,eng9e ,! selection ( an eng9e dep5ds ^u a numb] ( conditions :i* v>y to a consid]able ext5t 9 diff]5t cases4 ,among ^! may be m5tion$ fir/ co/1 size & "* ( plant1 available space1 /eam economy1 & utilization ( ! exhau/ /eam4 ,! "q ( fir/ co/ is usually consid]$ 9 connection ) t ( op]ation1 & items su* z int]e/ & depreciation are comp>$ ) ! sav+ made ?r\gh ! sav+ 9 /eam ) high pric$ eng9es4 ,illu/ration3 ,fig4 #df4 ,! ,sk9n] ,t&em ,eng9e ,illu/ration3 ,fig4 #dg4 ,am]ican ,ball ,duplex ,comp\nd ,eng9e ,! pr9cipal use ( ! /ation>y eng9e is conf9$ to ! driv+ ( electric g5]ators & ! furni%+ ( motive p[] 9 %ops & factories4 ,= ! fir/ ( ^! uses1 9 cases :]e floor space is limit$1 z 9 (fice build+s1 & :]e ! p[] does n exce$ ab\t #ajj ,i4 ,h4 ,p41 ! simple non-cond5s+ high-spe$ eng9e is probably employ$ m ?an any o!r type4 ,= l>g] in/allations1 a sav+ may usually be made by ! sub/itution ( ! mod]ate-spe$ f\r-valve eng9e4 ,! "q ( simple & comp\nd eng9es 9 ?is class ( "w dep5ds l>gely ^u ! use made ( ! exhau/ /eam4 ,9 w9t] "t ! exhau/ is ne>ly always utiliz$ 9 ! heat+ sy/em1 h5ce /eam economy is n ( great importance1 & ! simple eng9e answ]s all purposes at a small] fir/ co/4 ,9 localities :]e ! heat+ season is comp>atively %ort & fuel high1 !re is a decid$ advantage 9 us+ comp\nd eng9es on acc\nt ( _! great] /eam economy :5 op]at$ )9 _! economical range z reg>ds load4 ,illu/ration3 ,fig4 #dh4 ,! ,mon>* ,corliss ,eng9e ,9 l>ge c5tral plants :]e l[ co/ ( op]ation is always ( fir/ importance1 x is common practice to use ! be/ class ( comp\nd cond5s+ eng9es ( mod]ate or l[ spe$4 ,^? equipp$ ) "s =m ( ,corliss valve ge> are frequ5tly f\nd 9 ?is class ( "w4 ,9 ! g5]ation ( p[] = %ops & factories1 :]e !re is pl5ty ( floor space1 l[-spe$ eng9es ( ! ,corliss type are mo/ commonly us$4 ,:5 space is limit$1 v satisfactory results may be obta9$ by us+ ! mod]ate-spe$ f\r-valve eng9e4 ,9 decid+ ^u an eng9e = any p>ticul> case1 ! problem mu/ be /udi$ f all sides1 & "o be *os5 :i* be/ answ]s ! greate/ numb] ( requirem5ts4 ,,*apt] ,,vi ,,/eam ,,eng9e ,,te/+ ,! pr9cipal in=mation s\ght 9 ! usual te/ ( a /eam eng9e is3 #a4 ,! indicat$ horsep[] develop$ "u c]ta9 /&>d conditions4 #b4 ,! friction ( ! eng9e1 f :i* is det]m9$ ! me*anical effici5cy4 #c4 ,! /eam consumption p] indicat$ horsep[]4 #d4 ,! g5]al action ( ! valves4 #e4 ,! pressure conditions 9 ! cyl9d] at diff]5t p]iods ( ! /roke4 ,! ultimate object ( an effici5cy te/ is to det]m9e ! foot-p\nds ( "w deliv]$ by ! eng9e p] p\nd ( coal burn$ 9 ! boil] furnaces4 ,! g5]al me?od ( f9d+ ! p\nds ( dry /eam evaporat$ p] p\nd ( coal has be5 treat$ 9 ,,ma*9]y',s ,ref]5ce ,s]ies ,no4 #fg1 ,boil]s1 "u ! head ( ,boil] ,te/+4 ,9 ! pres5t case x is1 !re=e1 only necess>y to c>ry ! process a /ep fur!r & det]m9e ! foot-p\nds ( "w develop$ p] p\nd ( /eam4 ,! app>atus us$ 9 eng9e te/+1 9 addition to t us$ 9 boil] te/+1 consi/s ( a /eam eng9e indicator & r$uc+ device = tak+ diagrams1 & a planimet] = measur+ !m aft]w>ds4 ,if ! te/ is made indep5d5tly ( ! boil] te/1 a calorimet] = measur+ ! am\nt ( moi/ure 9 ! /eam %\ld be add$ to ! outfit4 ,x has already be5 %[n h[ a diagram may be made to repres5t graphically ! "w done 9 a /eam eng9e cyl9d] dur+ "o /roke ( ! pi/on4 ,! diagrams %[n ?us f> h be5 !oretical or ideal c>ds con/ruct$ f assum$ relations ( ! pressure act+ & ! di/ance mov$ ?r\gh by ! pi/on4 ,an indicator is a device = mak+ a diagram ( :at actually takes place 9 an eng9e cyl9d] "u work+ conditions4 ,su* a diagram %[s ! po9ts ( admission1 cut-(f1 & release1 & indicates accurately ! pressures act+ ^u bo? sides ( ! pi/on at all po9ts ( ! /roke4 ,a common =m ( /eam eng9e indicator is %[n 9 ,fig4 #di4 ,x consi/s ( a cyl9d] ,c :i* is plac$ 9 communication at ,e ) "o end ( ! eng9e cyl9d] by a prop] pipe connection1 provid$ ) a quick op5+ & clos+ cock or valve4 ,! cyl9d] ,c conta9s a pi/on1 above :i* is plac$ a coil spr+ ( su* /r5g? t a giv5 pressure p] squ>e in* act+ ^u ! l[] side ( ! pi/on w compress ! spr+ a def9ite & kn[n am\nt4 ,ext5d+ ?r\gh ! cap or head ( cyl9d] ,c is a /em atta*$ to ! pi/on bel[1 & connect$ by suitable lev]s ) a p5cil po9t ,p4 ,! arrangem5t ( ! lev]s is su* t a c]ta9 rise ( ! pi/on causes ! po9t ,p to move upw>d 9 a v]tical l9e a proportional am\nt4 ,! spr+s us$ above ! pi/on v>y 9 /r5g?1 & are designat$ z #bj-p\nd1 #dj-p\nd1 #fj-p\nd1 etc4 ,a #bj-p\nd spr+ is ( su* /r5g? t a pressure ( #bj p\nds p] squ>e in*1 act+ b5ea? ! pi/on 9 cyl9d] ,c1 w raise ! p5cil po9t #a in*4 ,) a #dj-p\nd spr+1 a pressure ( #dj p\nds p] squ>e in* w be requir$ to raise ! p5cil #a in*1 & s on = ! o!r /r5g?s ( spr+4 ,! holl[ drum ,d rotates back & =? ^u a v]tical /em at its c5t]1 its motion be+ produc$ by ! /r+ ,h1 :i* is atta*$ by means ( a suitable r$uc+ motion to ! cross-head ( ! eng9e4 ,! return motion to ! drum is obta9$ f a coil spr+ conta9$ )9 x & n %[n4 ,! pap] ^u :i* ! diagram is to be drawn is w\nd ar\nd ! drum ,d1 & held 9 place by ! spr+ clip ,f4 ,9 tak+ an indicator c>d1 ! l5g? ( /roke mu/ be r$uc$ to come )9 ! limits ( ! drum1 t is1 x mu/ be some:at less ?an ! circumf]5ce ( drum ,d4 ,9 practice1 ! diagram is commonly made f #c to #d in*es 9 l5g?4 ,!re are a numb] ( devices 9 use = reproduc+ ! /roke ( ! eng9e on a small] scale4 ,! mo/ accurate consi/s ( a s]ies ( pulleys ov] :i* ! cord passes on its way f ! cross-head to ! indicator drum4 ,! indicator is connect$ ) ! eng9e cyl9d] by means ( special op5+s tapp$ close to ! heads & ei!r plugg$ or clos$ by means ( /op-cocks :5 n 9 use4 ,9 "s cases two indicators are us$1 "o be+ connect$ to ea* end ( ! cyl9d]1 :ile 9 o!rs a s+le indicator is made to answ] ! purpose by be+ s pip$ t x c be connect$ ) ei!r end by means ( a ?ree-way cock4 ,aft] ! indicator is connect$ & ! cord adju/$ to give ! prop] motion to ! drum1 a c>d is atta*$1 aft] :i* ! ?ree-way cock is op5$ & /eam all[$ to bl[ ?r\gh ! indicator to w>m x up4 ,! cock is n[ clos$ & ! p5cil press$ aga9/ ! drum to get ! s-call$ atmosph]ic l9e4 ,! cock is aga9 op5$1 & ! p5cil press$ lightly aga9/ ! drum dur+ "o complete revolution ( ! eng9e4 ,! cock is !n ?r[n ov] to connect ! indicator ) ! o!r end ( ! cyl9d] & ! op]ation is repeat$4 ,illu/ration3 ,fig4 #di4 ,/eam ,eng9e ,indicator ,! indicator c>d obta9$ 9 ?is way is %[n 9 ,fig4 #ej4 ,x is sometimes pref]r$ to take ! diagrams ( ! two ends on sep>ate c>ds1 b x is simpl] to take !m bo? on ! same "o1 & also easi] to comp>e ! work+ ( ! two ends ( ! cyl9d]4 ,! analysis ( a c>d = practical purposes is %[n 9 ,fig4 #ea4 ,suppose1 = example1 t ! l5g? ( ! diagram measures #c4f in*es2 ! di/ance to ! po9t ( cut-(f is #a4b in*2 & ! di/ance to ! po9t ( release is #c4c in*es4 ,!n1 by divid+ #a4b by #c4f1 ! cut-(f is f\nd to occur at #a4b _/ #c4f #a_/c ( ! /roke4 ,release occurs at #c4c _/ #c4f #j4ib ( ! /roke4 ,compression beg9s at 7#c4f - #j4e7 _/ #c4f #j4hf ( ! /roke4 ,! diagrams %[n 9 ,figs4 #ej & #ea are f non-cond5s+ eng9es1 & ! back-pressure l9e is !re=e above ! atmosph]ic l9e1 z indicat$4 ,! indicator diagram gives a means ( det]m9+ ! mean effective pressure1 f :i* ! p[] ( ! eng9e c be f\nd f ! previ\sly giv5 equation ,,apln ,i4 ,h4 ,p4 ------4 #cc1jjj ,! me?od ( det]m9+ ! mean effective pressure is z foll[s3 ,fir/ measure ! area ( ! c>d 9 squ>e in*es1 by means ( a planimet] 7an in/rum5t describ$ lat]71 & divide ?is area by ! l5g? 9 in*es4 ,?is gives ! mean ord9ate2 ! mean ord9ate1 9 turn1 multipli$ by ! /r5g? ( spr+ us$1 w give ! mean effective pressure 9 p\nds p] squ>e in*4 ,= example1 suppose t ! c>d %[n 9 ,fig4 #ea is tak5 ) a #fj-p\nd spr+1 & t ! area1 z measur$ by a planimet]1 is f\nd to be #b4f squ>e in*es4 ,divid+ ! area by ! l5g? gives #b4f _/ #c4f #j4gbb in* z ! mean ord9ate1 & ?is multipli$ by ! /r5g? ( spr+ gives a mean effective pressure ( #j4gbb x #fj #dc4c p\nds p] squ>e in*4 ,illu/ration3 ,fig4 #ej4 ,a ,typical ,indicator ,diagram ,9 practice1 diagrams tak5 f ! two ends ( ! cyl9d] usually v>y m or less1 due to inequalities 9 ! valve action4 ,aga91 ! effective area ( ! pi/on on ! crank end is less ?an t on ! head end1 by an am\nt equal to ! area ( ! pi/on rod4 ,= ^! reasons x is cu/om>y to compute ! mean effective pressure ( all ! c>ds sep>ately1 & take1 = use 9 ! =mula1 ! av]age ( ! v>i\s computations4 ,! correct$ value ( ! pi/on area is1 z already /at$1 equal to 7#b;,a - a7_/#b1 9 :i* ,a is ! area ( ! pi/on1 & a ! area ( ! pi/on rod4 ,sub/itut+ ^! values = ,a & ,p 9 ! =mula1 toge!r ) ! l5g? ( /roke & av]age numb] ( revolutions p] m9ute1 ! indicat$ horsep[] is easily comput$4 ,9 mak+ an ord9>y te/1 diagrams are tak5 f bo? ends ( ! cyl9d] at #aj-m9ute int]vals = sev]al h\rs1 dep5d+ ^u ! accuracy requir$4 ,! revolutions ( ! eng9e are c\nt$ = two or ?ree-m9ute p]iods ea* "t a pair ( c>ds are tak51 or /ill bett]1 an automatic c\nt] is us$ = ! run1 f :i* ! av]age numb] ( revolutions p] m9ute may be det]m9$4 ,illu/ration3 ,fig4 #ea4 ,diagram = ,illu/rat+ ,me?od ( ,computation ,! friction ( ! eng9e is det]m9$ by tak+ a pair ( c>ds :ile runn+ light1 t is1 ) ! belt ?r[n (f1 or ! eng9e unc\pl$1 f ! dynamo1 if "p ( a direct-connect$ outfit4 ,! friction load is !n comput$ 9 horsep[] f ! indicator c>ds1 & subtract$ f ! indicat$ horsep[] :5 load$4 ,?us we obta9 ! deliv]$ or brake horsep[]4 ,! deliv]$ horsep[] divid$ by ! indicat$ horsep[] gives ! me*anical effici5cy4 ,?is may be express$ 9 ! =m ( an equation z foll[s3 ,i4 ,h4 ,p4 - friction loss ------------------------ me*anical effici5cy4 ,i4 ,h4 ,p4 ,planimet] ,! planimet] is an in/rum5t = measur+ areas 9 g5]al1 & especially = measur+ ! areas ( indicator c>ds4 ,"s =ms give ! mean effective pressure directly1 )\t computations1 by *ang+ ! scale to correspond ) ! spr+ us$ 9 ! indicator4 ,a planimet] ( ?is type is %[n 9 ,fig4 #eb4 ,! me?od ( manipulat+ ?is in/rum5t is z foll[s4 ,set ! arm ,,bd equal to ! l5g? ( ! c>d ,,ef1 by means ( ! ?umb screw ,s1 & set ! :eel at z]o on ! scale1 :i* mu/ correspond to ! spr+ us$ 9 ! indicator4 ,next1 place ! po9t ,d at ab\t ! middle ( ! area to be measur$1 & set po9t ,c s t ! arm ,,cb %all be approximately at "r angles ) ,,bd4 ,!n move ,d to ! upp] left-h& corn] ( ! diagram1 & ) ! left h& move ,c ei!r to ! "r or left until ! :eel comes back exactly to ! z]o po9t on ! scale2 !n press ! po9t firmly into ! pap]4 ,n[1 g ar\nd ! outl9e ( ! diagram ) po9t ,d f left to "r1 f9i%+ exactly at ! />t+ po9t4 ,! mean effective pressure may n[ be read f ! scale opposite ! edge ( ! :eel4 ,:5 v accurate results are requir$1 ! trac] po9t ,d may be pass$ ov] ! diagram sev]al times1 & ! read+ divid$ by ! numb] ( times x is ?us pass$ ar\nd4 ,) %ort c>ds1 #c in*es & "u 9 l5g?1 x is be/ to make ! arm ,,bd twice ! l5g? ( ! c>d1 & g ar\nd ! diagram twice1 tak+ ! read+ directly f ! scale z 9 ! fir/ case4 ,det]m9+ ,/eam ,consumption ,:5 x is desir$ to det]m9e accurately ! wat] rate ( an eng9e1 a boil] te/ %\ld be c>ri$ on simultane\sly ) ! te/ ^u ! eng9e1 f :i* ! p\nds ( dry /eam suppli$ may be det]m9$ z describ$ 9 ,,ma*9]y',s ,ref]5ce ,s]ies ,no4 #fg1 ,boil]s4 ,kn[+ ! av]age weight ( /eam suppli$ p] h\r = ! run1 & ! av]age indicat$ horsep[] develop$ dur+ ! same p]iod1 ! wat] rate ( ! eng9e is easily comput$4 ,sometimes ! av]age cyl9d] cond5sation = a giv5 type & make is kn[n = c]ta9 /&>d conditions4 ,9 ?is case an approximation may be made f an indicator diagram :i* repres5ts ! av]age op]ation ( ! eng9e dur+ ! te/4 ,illu/ration3 ,fig4 #eb4 ,g5]al ,con/ruction ( ,planimet] ,a diagram %[s by direct measurem5t ! pressure & volume at any po9t ( ! /roke1 & ! weight ( /eam p] cubic foot = any giv5 pressure may be tak5 directly f a /eam table4 ,! me?od1 !n1 ( f9d+ ! weight ( /eam at any po9t 9 ! /roke is to f9d ! volume 9 cubic feet1 includ+ ! cle>ance & pi/on displacem5t to ! giv5 po9t1 :i* mu/ be tak5 at cut-(f or lat]1 & to multiply ?is by ! weight p] cubic foot correspond+ to ! pressure at ! giv5 po9t measur$ on ! diagram4 ,z ?is includes ! /eam us$ = compression1 x mu/ be correct$1 z foll[s1 to obta9 ! actual weight us$ p] /roke4 ,take "s conv5i5t po9t on ! compression curve1 z ,q1 9 ,fig4 #ec2 measure its absolute pressure f ! vacuum l9e ,,ox & compute ! weight ( /eam to ?is po9t4 ,subtract ?is weight f t comput$ above = ! giv5 po9t on ! expansion l9e1 & ! result w be ! weight ( /eam us$ p] /roke4 ,! be/ po9t on ! expansion l9e to use = ?is purpose is j be=e release1 bo? because ! maximum am\nt ( leakage has tak5 place1 & also because ( ! re-evaporation ( a portion ( ! /eam cond5s$ dur+ admission4 ,! actual computation ( ! /eam consumption f an indicator diagram is be/ %[n by a practical illu/ration4 ,example--,let ,fig4 #ec repres5t a diagram tak5 f ! head end ( a #af x #cj-;in* non-cond5s+ eng9e1 runn+ at a spe$ ( #aej revolutions p] m9ute2 ! c>d is tak5 ) a #fj-p\nd spr+2 ! cle>ance ( ! eng9e is #f p] c5t2 ! av]age cyl9d] cond5sation is #bj p] c5t ( ! total /eam consumption2 ! diamet] ( ! pi/on rod is #c in*es4 ,illu/ration3 ,fig4 #ec4 ,diagram = ,calculat+ ,/eam ,consumption ,measur+ ! c>d ) a planimet] %[s ! mean effective pressure to be #dh4b p\nds4 ,! area ( ! pi/on is #bja squ>e in*es2 ! area ( ! pi/on rod is #g squ>e in*es2 h5ce1 ! av]age pi/on area 77#b x #bja7 - #g7_/b #aih squ>e in*es1 approximately4 ,!n #aih x #dh4b x #b4e x #cjj ,i4 ,h4 ,p4 ---------------------- #bag4 #cc1jjj ,9 ,fig4 #ec1 ,,gh is ! atmosph]ic l9e2 ,,ox is ! l9e ( vacuum or z]o pressure1 drawn s t ,,g #ad4g p\nds on ! scale2 & ,,oy is ! cle>ance l9e1 s drawn t ,,on #j4jf ,,nx4 ,! l9e ,,pq is drawn f ,,ox to "s po9t on ! compression l9e1 z at ,q4 ,f ,c1 a po9t on ! expansion l9e1 j be=e release1 ! l9e ,,cf is drawn p]p5dicul> to ,,ox4 ,! foll[+ dim5sions are n[ c>efully measur$ f ! actual diagram 7n ! "o %[n 9 ! illu/ration71 ) ! results giv53 ,,ox #c4ga ,,op #j4db ,,nx #c4ej ,,cf #j4ha ,,( #c4bj ,,qp #j4ha ,on ! indicator diagram1 be+ tak5 ) a #fj-p\nd spr+1 all v]tical di/ances repres5t p\nds p] squ>e in*1 9 ! ratio ( #fj p\nds p] in* ( height4 ,! /roke ( ! eng9e is #cj in*es or #b4e feet4 ,! l5g? ( ! diagram ,,nx is #c4e in*es2 h5ce1 ea* in* 9 l5g? repres5ts #b4e_/c4e #j4ga feet4 ,f ! above x is evid5t t v]tical di/ances 9 ,fig4 #ec mu/ be multipli$ by #fj to r$uce !m to p\nds pressure p] squ>e in*1 & t horizontal di/ances mu/ be multipli$ by #j4ga to r$uce !m to feet4 ,mak+ ^! r$uctions gives3 ,,ox #b4fc feet4 ,,op #j4cj foot4 ,,nx #b4di feet4 ,,cf #dh4f p\nds4 ,,( #b4bg feet4 ,,qp #dh4f p\nds4 ,z a c>d f ! head end ( ! cyl9d] is tak5 to avoid corrections = ! pi/on rod1 ! area is #bja squ>e in*es or #a4d squ>e foot4 ,) ! above data ! volume & weight ( ! /eam 9 ! cyl9d] c be comput$ at any po9t 9 ! /roke4 ,:5 ! pi/on is at ,c1 ! volume is #a4d x #b4bg #c4ah cubic feet4 ,:5 ! pi/on is at ,q1 ! volume is #a4d x #j4cj #j4db cubic foot4 ,f a /eam table ! weight ( a cubic foot ( /eam at #dh4f p\nds absolute pressure is f\nd to be #j4aaf p\nds4 ,!re=e1 ! weight ( /eam pres5t :5 ! pi/on is at ,c is #c4ah x #j4aaf #j4cfi p\nds4 ,! weight ( /eam pres5t :5 ! pi/on is at ,q is #j4db x #j4aaf #j4jdi p\nd4 ,t is ! weight ( /eam 9 ! cyl9d] at release is #j4cfi p\nd1 & ! weight kept at exhau/ closure = compression is #j4jdi p\nd4 ,! weight exhau/$ p] /roke is !re=e #j4cfi - #j4jdi #j4cb p\nd4 ,! numb] ( /rokes p] h\r is #aej x #b x #fj #ah1jjj1 f :i* ! /eam acc\nt$ = by ! diagram is f\nd to be #ah1jjj x #j4cb #egfj p\nds1 or #egfj _/ #bag #bf4e p\nds p] indicat$ horsep[] p] h\r4 ,if ! cyl9d] cond5sation = ?is type ( eng9e is #bj p] c5t ( ! total /eam consumption1 ! wat] rate w be #bf4e _/ #j4h #cc4a p\nds p] indicat$ horsep[] p] h\r4 ,9 ! pres5t case x has be5 assum$1 = simplicity1 t ! head- & crank-end diagrams 7 exactly alike1 except = ! pi/on rod4 ,ord9>ily1 ! above process %\ld be c>ri$ out = bo? head & crank ends1 & ! results av]ag$4