542 



BEPORT 1888. 



ing direction ; but immediately the handle is released and the weight 

 tends to fall, the coil comes into operation, and grips the shaft with a 

 force which not only prevents the weight from falling, but also resists 

 the further load now applied, the two being together equivalent to a total 

 pull of nearly 1,000 lbs. upon the coil. The important applications of 

 this kind of action in self-sustaining hoists, silent feed motions, and for 

 other purposes, are obvious. 



Coming to the applications of metal coil friction which have been 

 proposed, we find that in 1877 Mr. Rider, an American, devised the 

 friction clutch shown in Fig. 1. In this clutch a cone sleeve. A, is moved 



FIC.I 



by means of a lever acting at B, and so throws open a split cone lever, C, 

 and wedges out the tail of the coil against the cylinder in which it is 

 enclosed. The coil, which is revolving, is thus unwound, and so pi-esses 

 upon the inner surface of the cylinder, which it carries round, and with 

 it the pulley to which it is attached. Fig. 2 shows an application of the 

 converse and most usual case, in which the coil winds up and closes upon 

 a shaft or sleeve which it surrounds. This friction clutch was invented 

 by Mr. Sterling in 1882, and its action is easily understood. A sleeve, A, 

 carries along one end of a toggle joint B, and so pushes out the end of 

 the lever C, and thus presses the tail end of the coil. The coil conse- 

 quently tightens upon the boss of the pulley D, ard carries it round. 

 There is also an example of wire rope coil friction shown at E, Fig. 2. 

 An arrangement has been recently devised by M. Gambaro, a French 

 engineer, and applied as a brake to a crab winch. The same inventor 

 has proposed a system of continuous railway brakes on this princi25le. 

 Professor Osborne Reynolds has also applied metal coil friction in an 

 increnious arrangement for turning the valve rods of the experimental 

 steam engine at Owens College, thus enabling the governor to be the 

 means of almost instantly altering the position of the sUdes, thus regu- 



