182 



CREAMERY BUTTER MAKING 



friction. A good way to find out whether a piston leaks 

 steam is to put the engine on the dead center on the 

 crank end. Then take off the cylinder cover on the head 

 end and admit steam back of the piston. If the piston 

 leaks, steam may be seen escaping between the packing 



ring and the wall of the cylinder. 



Fig. 51.— Connecting rod end. 



Crosshead. This connects the piston rod and connect- 

 ing rod and serves to guide the former so as to have 

 it move in a straight line. 



Connecting Rod. This forms the connection between 

 the crosshead and crank. The crank end of the rod is 

 shown in Fig. 51. I represents the crank pin key: 2, 

 crank brasses, and 3, burr that fixes the crank pin key. 



Crank. This rotates the shaft of the engine and per- 

 mits the change of rectilinear into circular motion. 



Eccentric. This forms a sort of crank which, as its 

 name implies, does not turn around a true center. It 

 opens and closes the steam ports in the valve chest by 

 means of the eccentric rod which forms the connection 

 between it and the slide valve. 



Setting the Slide Valve. The slide valve should be 



