THE TRACTION GEARING. 



99 



eight or nine oil-holes in the sleeve, three of which are drilled 

 between the teeth of the pinion. There is also an oil-hole 

 iri the upper trunnion of the trunnion-ring. 



FIG. 33. REAR VIEW OF CASE* TRACTION ENGINE. 



The Differential Gear. In order to have both traction 

 wheels pull, when the engine is traveling either forward or 

 backward, and at the same time allow one wheel to travel 

 further than the other in turning corners, the differential gear 

 is necessary. It transmits the power from the intermediate 

 gear to the two counter-shaft pinions, which mesh with the 



