122 



SCIENCE OF SUCCESSFUL THRESHING 



openings stopped by carefully fitted pieces of wood, in 

 order to prevent sand and other gritty substances from en- 

 tering the cannon bearings. 



Lubricating the Gearing. The gearing of a traction- 

 engine should be kept well lubricated. It is true that 



FIG. 37. CUT SHOWING CANNON BEARINGS AND GEARING. 



many men argue that grease collects and holds sand which 

 will cause cutting of gears. To prove the fallacy of this 



