con I--'.' - 



\! I < ('KNTHICB. 



pfiilm' U a particular form of crank, lieing A rr.tnk in 



.nnk pin JH large enough to embra< 



lie ecceiit corresponds to the crank pin U call! 



sheave or pulley. The advantage \\hi.-h an eccer- 

 poateesea over a crank U that the ahmft doe* not n juire to be 

 it tin* j.-, ! t! t where the eoceiK m mink, 



! ! .. ' , . ' i . . . I t ! . : ' .:.'.. 



can be used for convi t 



or riff r*l, uh;!-- the eccentric can only i-- t;--.l i"..r con- 



verting rirrulnr into reciprooati :. Thit U owing to 



th.- -i.. it 1. verage At whirh th. f the eccei 



ii the steam-engine, 



r working thr valve gear. 



To ] ^heave being placed on the shaft without 



- ne at all in the COOP of 

 >me operation in i 

 caaes) it in gf>nrr.illy nuul*' in two pieces, as shown in fig. 50. 



-nU one of the eccentrics of a locom-.t 

 two part* of the sheave are connected by 

 part ulii.Ii mbracea the sheave is calM the ec- -rap, 



uiul correspondR to, and is, in fact, a c<>: 



i this in calUnl the ivoentric rod. 



t)l- H)H>U\I> to tin- 



th- shaft is called tin- m./iM. or accent r> lie eccerr 



wirt- tin* eoow 



The sheave i> IL The strap may 



be of brat*, cast ir M : %li-n tin* strap is 



of wrought imn it is rumin i with hrosm. 



-In fig. 50 D B is the 

 sheave, F H the strap, an- 1 K th. , .v< nmc rod. The sheave and 

 strap are made of cast iron, and t h ivrntiric rod i mode of wroofht 

 is a vertical cross section through the d the 



trap ; (/o m a pUn ..f th, , , . .wninc rod and port ot 



