74 CENTRIFUGAL SEPARATION 



screw whereby the bowl may be lowered or raised in its position 

 in the frame. It also carries brass bushings at the bottom and 

 top of the spindle which serve to guide the position of the spindle 

 and to keep the bowl from wobbling. The upper portion of the 

 frame protects the bowl and serves as support for the pans into 

 which the skim milk and cream are discharged. In the case 

 of hand separators the frame is also equipped with supports for 

 the milk supply tank, and for the skim milk and cream cans. 



The Separator Bowl and Spindle. The bowl is the heart of 

 the separator, in it the separation of the milk takes place. In 

 most separators now in use the bowl extends at its lower ex- 

 tremity into the spindle to which is transmitted, either direct or 

 indirect, the motive power which revolves the bowl. In some 

 separators the bowl and the spindle are one piece while in others 

 the spindle is divided into an upper and lower spindle, connected 

 by an offset in the contact end of each, or by a slot in one and 

 a slot and pin in the other. Occasionally the bowl is entirely 

 separated from the spindle, connecting with the top of the spindle. 

 Then, again, there are separators in which the bowl is attached 

 to the spindle by a permanent hinge joint. In still other ma- 

 chines the bowl is suspended, its spindle which in these machines 

 is at the top of the bowl, is coupled to an overhanging spindle 

 head connecting with the seat of power. 



The bearing on which the spindle revolves may consist of a 

 stationery but adjustable steel point on which a similar steel 

 point at the termination of the spindle rests; or the spindle may 

 terminate in a tapering disc which, rests on a bearing of steel 

 balls or steel rollers. The spindle is guided by an upper and a 

 lower brass bushing. The ease of running and elasticity of the 

 bowl may be enhanced by the use of bushings equipped with 

 springs. 



The bowl proper consists in the main of a cylindrical, or 

 cone-shaped vessel. It opens either at the top or at the bot- 

 tom. It is closed by a coneshaped cover. At the point of con- 

 tact with the cover the bowl carries a groove or rim which admits 

 a rubber ring. This serves to make an absolutely tight seal be- 

 tween bowl and cover, without which the pressure generated in 

 the revolving bowl causes the milk to leak out. The cover must 



