82 CENTRIFUGAL SEPARATION 



between the steam valve and the separator, a steam gauge and 

 a blow-off valve, or safety, properly set to guard against ex- 

 cessive steam pressure. The steam turbine separator has be- 

 come very popular for both factory and farm machines. Its 

 chief advantages are that the separator can be operated in- 

 dependently of the steam engine or the main shaft. It is compact 

 and does away with the space- wasting objection of the inter- 

 mediate of the belt-driven machine. On the other hand it en- 

 volves somewhat less economic use of steam and requires closer 

 attention in order to insure uniform speed. The latter objection 

 has been largely removed, however, in the latest types of steam 

 turbine separators by equipping them with efficient automatic 

 speed governors. The close proximity of the steam chamber to 

 the lower bearing also is prone to augment the tendency of heat- 

 ing the spindle in the absence of adequate lubrication. 



The electric-driven separator is a later inovation. It is 

 equipped with an electric motor which is a part of the separator 

 and which requires no power transmission arrangement addi- 

 tional to that which forms a part of the separator. It can be 

 operated independent of all other operations, no steam nor gaso- 

 line engine is required, the turning on of the current is all that 

 is necessary. So far these electric-driven separators have not 

 found very extensive use, especially in the case of the larger 

 machines. Their greatest disadvantage so far has been the short 

 life of the motor. Experience has shown that these separator 

 motors are of relatively short usefulness. It seems that the 

 dampness to which they are bound to be exposed in the creamery 

 is injurious to the insulation, necessitating frequent repairs and 

 renewal. This objection is now, however, being rapidly over- 

 come by efforts on the part of the manufacturer to furnish ma- 

 chines with more efficiently protected motors. 



Hand Separators. In the case of the hand separator the 

 power mechanism is a part of the separator proper. It, too, 

 differs in details of arrangement with different makes of ma- 

 chines. The fundamental principle of the mechanism is to pro- 

 duce the relatively high number of revolutions which are re- 

 quired of the bowl, 6,000 to 17,000 revolutions per minute, 



