130 CANADIAN DAIRYING. 



horse power. If mechanical refrigeration is used a 

 larger engine and boiler are necessary. An engine is 

 not a necessity in a cheesery, but is convenient in a 

 large factory for milling the curds. Where electric 

 power is available, a ten or twelve horse power motor 

 is one of the most convenient powers for creamery 

 work. The shafting should be centrally located, so 

 as to drive all the machinery in the building from one 

 line shaft if possible. This shaft should be about one 

 and a half inches in diameter and make from 200 to 

 300 revolutions per minute. Wooden pulleys are 

 convenient and satisfactory if made of good material. 

 Iron pulleys rust and are difficult to change on the 

 shafting. It is important to have pulleys of proper 

 size in order to give the desired speed to the 

 machinery. The following are rules for determining 

 size of pulleys and length of belts : 



To find the diameter of a driven pulley, multiply 

 the diameter of the driver by its number of revolu- 

 tions, and divide the product by the number of 

 revolutions the driven pulley should go. The result 

 will be the diameter of the driven pulley. 



Example : Diameter of pulley on engine, 40 inches ; 

 speed of engine, 160 revolutions ; speed of main shaft, 

 200 revolutions; 40x160^-200=32, which is the 

 diameter in inches required for the driven pulley. 



To find the required size of a driving pulley, multi- 

 ply the diameter of the driven pulley by the number 

 of revolutions it should make, and divide the product 

 by the revolutions of the driver. 



Example : Diameter of the pulley on intermediate 



