Belting. 5-15 



belts always stretch more at first thr.n after they have been 

 used. 



689. Pulley and Shaft. In order that a belt may run 

 well on the pulley it is essential that the shafts of the two 

 pulleys connected by the belt shall be rigidly parallel with 

 each other and that the pulleys shall turn true on the shafts. 

 When the pulleys are properly placed the belt will run to 

 the center of the pulley and stay there. 



Belts tend to run to the largest part of the pulley and 

 for this reason pulleys are commonly made a little crown- 

 ing in the center so as to cause the belt to run to the center. 

 But where tight and loose pulleys run side by side, so as 

 to throw off the belt without stopping the power, then 

 the faces of the pulleys are flat. 



In running a belt onto a pulley, especially when it is 

 wide, heavy and tight, care needs to be taken not to over- 

 strain it as there is danger of stretching the edge so that 

 it will never run true afterwards, or even of cutting or 

 tearing it, especially if the edge of the pulley happens 

 to be sharp. 



690. Lacing a Belt. In lacing a belt care should be 

 taken to make the lacing plenty strong enough, but to 

 make it unnecessarily so is worse than to have it a little 

 light, especially if it has been done in a bungling manner 

 so as to form an enlarged place in the belt which brings 

 undue strain when the lacing is passing the pulleys. The 

 lacing should be so nicely done that this portion of the 

 belt passes the pulley without a jar or extra strain. To 

 secure this the ends of the belt should be cut true and 

 square by using a try-square. Holes should be punched 

 just large enough to allow the lacing to fill them well 

 without danger of tearing them out by wedging. Space 

 the holes equally, leaving the outside ones just far enough 

 from the edge to be safe against tearing out, and they 

 should be not more than J to ^ an inch from the ends. 



Sew with the smooth side of the lacing out, beginning 



