186 MARKET DAIRYING 



so that the distance P is the same in all. If the holes 

 at the lower ends are all in line the shafting is properly 

 lined up. If not, the shaft needs readjusting. 



CALCULATING SIZE AND SPEED 01? PULLEYS. 



The first thing to remember in determining the required 

 size and speed of pulleys is the following rule : The speed 

 varies inversely with the diameter of the pulley. Thus 

 with the same speed of the engine, the speed of the main 

 shaft becomes less as the diameter of the pulley on that 

 shaft is increased. 



We usually speak of two kinds of pulleys: the drive 

 pulley and the driven pulley. Where the engine drives 

 the main shaft the pulley on the engine is called the drive 

 pulley and that on the main shaft the driven pulley. 

 When we refer to the main shaft driving the separator, 

 then the pulley on the main shaft becomes the driver and 

 that on the separator the driven pulley. 



In dairies there are two problems that present them- 

 selves with respect to pulleys : one is to find the speed of 

 the pulley when the diameter is given; the other is to 

 find the diameter when the speed is given. 



1. To find the speed of a driven pulley: Multiply the 

 diameter of the driver by its speed and divide the product 

 by the diameter of the driven pulley. 



Example : Diameter of engine pulley, 20 inches ; speed 

 of engine 200 revolutions per minute ; diameter of driven 

 pulley, 25 inches. 



2oX20CH-25=i6o=No. rev. per min. of driven pulley. 



2. To find the diameter of driven pulley : Multiply the 



