330 CHAPTER XI 



twdst the wall of the cyUnder, separating the fibro-vascular bundles which 

 make up the wall and destroying the resistance to external pressure. The 

 first patent of this type is due to Faure (3003 of 1879) who employed a rotat- 

 ing drum, on which was cut a series of heUcoidal teeth operating in com- 

 bination with a fixed counter plate set eccentric on the drum. Shredders 

 as actually used, however, have employed two drums, co-acting with each 

 other, where the upper drum revolves at a higher rate of speed than the lower, 

 the revolutions per minute usually being about 135 and 35 respectively. 



This system was patented by Cail and Ferron (379 of 1883), who formed on 

 the drums hehcal threads, the section of which was a right-angled triangle^ 

 the threads on the upper cylinder running in the opposite direction to those 



on the lower. -"4 .»-> ■« ^^si*^ 



The form of shredder which has been most commonly used is indicated 

 in Chapin's patent (2553 of 1885) and in Hungerford's patent (U.S. 346817 

 of 1886). This patent claims a shaft on which are arranged rings or annular 

 discs, the peripheries of which are bevelled off on both sides at 45°. The 

 rings are pitched so that the rings on one shaft intermesh, but do not meet> 

 with the rings on the other. This type of shredder is shown in Fig. 139. 



The successful use of the 

 shredder seems to be due to 

 the housing patented by Fiske 

 (13955 of 1887). This is shown 

 in Fig. 140. It combined with 

 adjustable upper and lower 

 bearings a and b the control of 

 the pressure by a spring, c, so 

 that the upper roller was free 

 to move if the feed became 

 too heavy, or if a piece of iron 

 or other foreign matter entered. 

 A patent granted to Kidd 

 (15297 of 1893) includes the 

 above two devices with only 

 small differences of detail. 



The crusher as a preparatory 

 device was distinctly introduced 

 by Thomson and Black in their 

 patent 2586 of 1882, and is often included in the term " 5-roller mill.'* 

 The}' extended the housings of an ordinary' 3-roller mill to receive an ad- 

 ditional pair of rollers, on which were formed a series of circumferential 

 deep grooves and ridges. The ridges in one roller operated in the grooves 

 of the other. This type of crusher is often referred to as " splitting 

 rollers," and it remains a very extended design. 



A crusher which has been and is still very widely used is that due to 

 Krajewski (patent 12012 of 1886), Fig, 141. It claims the combination 

 of rollers with more or less sharp zigzag corrugations in the direction of the 

 rollers, the teeth of one intermeshing, but not coming into contact, with the 

 teeth of the other. The action of this device both crushes the cane and cuts 

 it into small pieces. The cutting action is dependent on the setting of the 

 rollers. Another type of crusher is that due to Marshall (U.S. 584183, 

 1897), shown in Fig. 142. 



Crushers of the above-mentioned types have come to be regarded as an 



Fig. 140 



