Rollers 



From the crusher or crushers the mat of cane is passed to 

 the milling plant proper, which usually consists of a train of 

 from four to six 3 -roller mills set in tandem. The rollers of each 

 mill are set in a triangular position with one top roller and two bottom rollers. 

 A heavy bar called the returner bar is placed between the two bottom rollers 

 for the purpose of leading the cane which passes between the top roller and 

 first bottom roller to the opening between the top roller and discharge roller. 

 The usual size of the rollers is from 34 to 36 inches in diameter and from 6 to 7 

 feet in length. They are held together by heavy housings fitted with hy- 

 draulic rams exerting a pressure of from 400 to 600 tons on the top roller. 

 These rollers are driven by engines or electric motors through a train of double 

 reduction gearing, the shafts being directly connected to the top rollers of 

 each 3 -roller mill. The gearing is so arranged that the peripheral speed of the 

 rollers is gradually increased from the first to the last mill. The average 

 speed of the rollers is about 3 revolutions per minute. A slow speed is nec- 

 essary to allow the cane to be under pressure a sufficient length of time to 

 properly extract the juice. 



The process of extraction may be compared in a simple way 



Masceration t o that of cleansing a sponge by immersing it in water and 



expelling the water under pressure, immersing it a second time 



in water and expelling it under pressure as before. By repeating this process 



several | times the sponge will soon be cleansed. It is so with the extraction of 



sugar or sucrose from the cane fibre. It has 

 been found to be of advantage to apply a 

 certain amount of fresh warm water between 

 the last and next to the last mills. This applica- 

 tion of water is known as masceration. The 

 crushed cane as it comes from the crusher is 

 passed through the first 3 -roller mill and as it is 

 discharged from the rollers it receives a spray 

 of water or dilute cane juice. An automatic 

 conveyor receives the cane from the first mill 

 and feeds it to the second mill, where it receives 

 a second crushing ; also a second spray of water 

 or dilute juice. Thus it passes from mill to mill 

 until practically all of the juice has been 

 extracted from the cane fibre. The juice 

 coming from ( the last mill of the train 

 contains comparatively little sugar, and 



Crushing the cane 



38 



