MACHINERY AND MANUFACTURE 



193 



brackets relating to the clutch-drive being attached to the bed- 

 plate of the machine. 



Very great improvements have been made regarding the 

 quietness of running. In the early days ordinary straight- 

 moulded driving-wheels were used, and then double helical 

 machine-moulded, and now straight-cut or double helical 

 machine-cut gears are quite the fashion. They are more ex- 

 pensive, but they run very quietly and wear very well. The 

 speed of the back shafting of these machines is generally from 

 75 to i op revolutions per minute. 



If the rubber is in- 

 tended to be sent to 

 the market in the 

 form of block-rubber, 

 such as is manufac- 

 tured on the famous 

 Lanadron estates, the 

 sheets, after they come 

 from the drier, are 

 put one on the top of 

 another till a sufficient 

 number as shown by 

 experience are as- 

 sembled together in a 

 blocking-press. These 

 presses can be either 

 hand-screw presses or, better, worked by means of hydraulic 

 or other power. Under heavy pressure the sheets are com- 

 pressed together into one homogeneous block. This form of 

 rubber has much to commend it. It exposes the smallest 

 possible area for dust or moisture to gather on, and the 

 whole interior of the mass is retained in perfect condition. 

 The only objection which has been raised to this form of 

 rubber was the large size of the blocks in which the rubber 

 was at first sent to the market. This, however, is a matter 

 which is being adjusted. 



Worm-rubber and strip-rubber are simply sheets of freshly- 

 coagulated rubber cut into either small pieces or strips by 

 cutting-machines with revolving blades, in order to ensure 

 more rapid drying. After the strips have been dried they are 



FIG. 52. A Mill Type J.A. driven by Gearing 

 with Friction-clutch (Bridge & Co.). 



