CHAPTER VII 



THE PULLEYS AND BELTING OF A 

 SEPARATOR 



PULLEYS are usually held in place on the shafts 

 either by taper-keys or by set-screws. Sometimes 

 straight keys or "feather" keys, as they are called, 

 are used, but as these only prevent the pulley from turning, 

 set-screws or other additional means must be used to 

 secure the key against slipping out and the pulley against 

 sliding on the shaft. When used with feather-keys, set- 

 screws are placed so their points rest on the key and thus 

 do not score or mar the shaft. 



Taper Keys. A taper key when properly fitted, holds 

 a pulley very securely. To do this, however, such a key 

 must be the same width throughout its length and accu- 

 rately fit the slots or "seats" cut for it on the shaft and in 

 the pulley. The thickness should vary to correspond with 

 that of the key-way in the pulley. A key should be driven 

 in hard enough to be safe against working loose, but when 

 well fitted, it is not necessary to drive it so hard that it 

 may not be readily removed. The hubs of most of the pul- 

 leys on the machine run against the boxes, and in keying 

 these, about one-thirty-second of an inch end play should 



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