SKIMMING EFFICIENCY OF THE SEPARATOR 



99 



separated by the centrifugal force thus generated, escape from 

 the machine separately. If the machine trembles and jars, a 

 portion of the cream and skim milk may again become mixed 

 by the vibration of the bowl, causing a relatively large amount 

 of fat to escape with the skim milk and thus reducing the 

 skimming efficiency of the separator. This fact is shown in 

 the following 'table which summarizes the results of experi- 

 ments conducted by Hunziker, with smoothly running and 

 trembling machines. 



Table 9. Relative Skimming Efficiency of a Balanced and 

 Unbalanced Separator. 



Balanced 



Unbalanced 



Average 



.03 



.17 



The trembling of the bowl may be due to any one or more 

 of the following conditions : Shaky foundation, machine not 

 setting level, spindle sprung, internal Contrivances of bowl 

 damaged or not properly placed or incomplete, worn-out bear- 

 ings, loose bushings, excessive speed. 



The separator should rest on a solid foundation. For farm 

 separators a solid plank floor is adequate, for factory machines 

 a concrete, brick or stone base is preferable. The foundation 

 must be level, though the newer machines with self-balancing 

 bowls minimize the undesirable effect of machines not setting 

 quite level. The separator, while it should be fastened securely 

 to its foundation, should not be screwed down too rigidly for 

 smooth running. A certain amount of "give", or "resonance" 

 is necessary in order to insure smooth running. For this pur- 

 pose it is advisable to place rubber cushions between the sep- 



