MECHANICS 



71 



W-- 



33,000 H 



CV 



(2) 



EXAMPLE 1. What horsepower can be transmitted by a 

 single leather belt 4 in. wide running at a speed of 2,500 ft. 

 per min., if the belt covers one-third of the circumference of 

 the small pulley? 



SOLUTION. The fraction of the circumference covered by 

 the belt is | = .333. From the table, the allowable effective 

 pull corresponding to this value is 28.8. Substituting in 

 formula 1, 



EXAMPLE 2. A single leather belt is to run at a speed of 

 3,000 ft. per min. and is to transmit 18 H. P. Find the width 

 of the belt, if the arc of contact is 150. 



SOLUTION. The effective pull corresponding to an arc of 

 contact of 150, from the table, is 33.8. Substituting in 

 formula 2, 



33,000X18 



W= = 5.9 in. 



33.8X3,000 



A 6-in. belt would be used. 



ALLOWABLE EFFECTIVE PULL 



The horsepower of a double leather belt may be taken as 

 1^ times that of a single leather belt of the same width running 



