414 



CHAPTER XX 



form in MacFarlane's patent (10034, 1903) » ^'^S- ^^o, and is so made as to 

 afford access to the bearing without dismantling the machine. 



Ball-bearings are claimed generally as applicable to centrifugals in 

 Theissen's patent (15984, 1899), and they appear in MacFarlane's patent 

 (19060 of 1902), and in that of Pott, Cassels, Williamson and Stuart (19069 

 of 1902), Fig. 261. In both these patents the usual inner solid stationary 

 spindle is made hollow to accommodate a stem fixed at its lower end to the 

 hollow rotating spindle which carries the basket. The step bearing is 

 fitted between the upper ends of the stem and of the stationary spindle 

 in an oil retaining casing. 



The solid spindle with the compound ball-bearing appears in Pott and 

 Williamson's patent (8806, 1903), Fig. 262, and in MacFarlane's patent 



Fig. 260 



Fig. 261 



(25097, 1903), Fig. 263. In the former the end thrust is taken up on the 

 large balls, and the side pull on the journal bearing on the smaller balls : 

 in the latter, the end thrust is taken up on the outer two rows of balls, and the 

 side pull on the two inner rows. With the solid spindle the design reverts 

 very closely to the original suspended centrifugal as designed bj' Bessemer. 

 A type of spindle employed by the American Tool and Machine Co. is 

 shown in Fig. 264. It differs from the other designs in employing a ball and 

 socket suspension and in continuing the inner stationary spindle throughout 

 the length of the outer rotating element. 



Cycle of Operations in a Centrifugal. — In dr5dng sugar the cycle of opera- 

 tions is as follows : — Charging, accelerating, running at full speed, stopping, 

 discharging. Often the charging and accelerating will take place simul- 

 taneously. The complete time of a cycle will depend on the design, especially 

 on the power of the prime mover, and on the nature of the material being 



