THE EXTRACTION OF JUICE BY MILLS. 



Patents for the hydraulic regulation of mills were granted to Stewart in 

 England in 1871, and to MacDonald in the United States in 1872. 



In Fig. 12 If is given a view of an hydraulic applied to the back roll of a 

 mill and conforming to the arrangement generally followed by English 

 engineering firms. The hydraulic pressure is applied by means of the ram 

 g ; if in any way the pressure becomes greater than that exercised by the ram, 

 the latter gives way, allows the rollers to move and relieves the pressure. 



FIG. 125. 



The plant consists of a small hand pump a, by means of which a fluid, 

 generally oil, is pumped through the pipe e e into the upright hollow rod d, 

 Through d runs a channel about one quarter of an inch in diameter, 

 communicating by a small aperture with the cylinder b ; c c are weights which 

 rest on the flange k\ as the pressure in the oil increases it raises these weights, 

 and the pressure throughout the system is that due to the weights ; the pipe e 

 is continued through the cap /, the oil filling the hollow space enclosed 

 between the cap / and the ram g. By a well-known principle of hydraulics if 

 the area of the cross section of the ram is a and that of the fluid in the 



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