CHAPTER XIII. 

 THE PULLEYS OF A SEPARATOR. 



ULLEYS 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 means must be used to secure 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 accurately 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 pulleys on the 

 machine run against the boxes, and in keying these, about 

 1/32 of an inch end play should be allowed the shaft, to 

 prevent danger of heating from the pulley rubbing too hard 

 against the end of the box. A key that is too thin, but other- 



