98 The Cultivation and Preparation of Coffee 



METHOD OF CALCULATING THE SPEED AND 

 DIAMETER OF PULLEYS. 



I SHALL call ' ' Driver ' ' the pulley on a main 

 shaft and " Driven " the pulley on a machine. 



1st Problem. Knowing the number of revolu- 

 tions of both " driver " and " driven " and 

 the diameter of the " driven," it is required 

 to know the diameter of the " driver." 



Method. Multiply the diameter of the 

 ' ' driven ' ' by its number of revolutions and 

 divide the result by the number of revolu- 

 tions of the " driver." 



2nd Problem. Knowing the diameter and 

 number of revolutions of the " driver," it 

 is required to know the diameter of the 

 1 ' driven ' ' to give a certain number of 

 revolutions in the same time. 



Method. Multiply the diameter of the 

 ' ' driver ' ' by its number of revolutions and 

 divide the product by the number of 

 revolutions required. 



3rd Problem. Knowing the diameter and 

 number of revolutions of the ' ' driver ' ' and 

 the diameter of the " driven," it is required 

 to know the number of revolutions of the 

 "driven." 



