THE EXTRACTION OF JUICE BY MILLS. 



The path, then, which the point p and also the crushed cane describes is 

 a part of a logarithmic spiral ; in order to obtain this path for sugar mills the 

 velocities w and c must be known. The velocity w, which is perpendicular to 

 the radius vector, is always equal to T, the velocity with which the bagasse 

 leaves the first cylinder pair. The velocity c is to be determined experi- 

 mentally, and depends on the elasticity of the crushed cane, and that the 

 cylinder 3 must easily carry forward the bagasse. Before determining 

 empirically the values of c and of the angle a, we will look first at the 

 following considerations : 



In Fig. Ill, 8 is the opening between the cylinders 1 and 2, and d is the 

 thickness of the crushed cane, and when the cane is not elastic d is equal to 8 : 

 in this case the velocity C can be put equal to for there exists absolutely no 



FIG. 117. 



reason why the crushed cane should proceed with a velocity C lying in the 

 direction of the radius vector in order that it should easily and without 

 excessive friction pass over the trash turner. When c = 0, m also = 0, and 

 a 90. It then follows 



r = c = 1 = R or r = R = constant. 



In this case the trash turner is a circle of radius r = R =. + , where D is 

 the diameter of the roller cylinder. 



In practice such a condition never occurs, due to the pressure between the 

 top cylinder and the trash turner following on the elasticity of the crushed 

 cane. 



This is why C must always be greater than 1 . If C becomes too great, 

 then the cylinder 3 cannot take the feed and will cause a stoppage. The 

 velocity C must be such that the angle A is somewhat less than 90. 



The trash turner curve following this argument of Bergmans can be found 

 graphically with close approximation as follows : 



187 



