16 LEATHER BELTING 



sents the total load on shifting belts, gives a total load of 174 

 Ib. per square inch of section. Belts running under this load 

 have already been shown to run much more economically and 

 satisfactorily than cone belts which ran under a total load of 

 in Ib. per inch of width or 358 Ib. per square inch cf section. 

 Evidently then the most economical total load for belting 

 must lie between 174 and 357 Ib. per square inch of section. 



Taylor's Rules for Economical Belting Practice. Basing 

 his conclusions partly upon the experiments and partly upon 

 arbitrary assumptions, Mr. Taylor formulated the following 

 rules as representing the most economical practice : 



1. The average total load on belting should be 200 to 225 



Ib. per square inch of cross-section of belt. 



2. Six- and seven-ply rubber belts and all double leather 



belts except oak-tanned and fulled, will transmit 

 economically a pull of 30 Ib. per inch of width. Oak- 

 tanned and fulled belts will transmit economically 

 a pull of 35 Ib. per inch of width. 



3. The most economical speed of belting is between 4000 



and 4500 ft. per minute. 



The conclusions which Mr. Taylor drew from the series 

 of experiments outlined above were chiefly as follows : 



1. Belts are more durable and work more satisfactorily 

 when made narrow and thick, rather than wide and thin. 

 As belts increase in width they should also be made thicker. 

 On pulleys 12 in. diameter or larger, double belts are advisable 

 and triple belts on pulleys of 20 in. diameter or larger. Quad- 

 ruple belts should be used where possible on pulleys 30 in. 

 diameter or larger. 



2. Double belts will last well when repeatedly tightened 

 under a strain when at rest of 71 Ib. per inch of width or 

 240 Ib. per square inch of cross-section. They will not, 

 however, maintain this tension for any length of time. The 

 most economical average total load for double belting is 

 from 65 to 73 Ib. per inch of width; that is, 206 to 225 Ib. 



