GB208113A - Improvements relating to slack adjusters for automobile brakes - Google Patents

Abstract

208,113. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Chapin, A. J.). Dec. 7, 1922, [Convention date]. Compensating for wear.-A device for compensating for the wear of the shoes or band of a cam-operated brake comprises a member 4, rotatably mounted on the cam shaft 3, which carries a pawl 11 adapted to drive a ratchet wheel 8 keyed to the shaft, and a pawl 12, adjustably mounted on an eccentric stud 13, which also engages the ratchet wheel and is urged to the right by a spring 28 so that a threaded stop 16 normally engages the casing 6 surrounding the mechanism. The member 4 is secured to the fixed casing 6 by first engaging slots 18 with lugs 17 on the casing and then rotating the member 4, and felt washers 19, 20 serve to keep the casing free from dust. When the brake is applied, as, for example, by supplying compressed air to a diaphragm chamber 2, the rod 1 rotates the lever 4, and the pawl 11 drives the ratchet wheel 8 to rotate the shaft 3, while the pawl 12 moves to the left against its spring. On release of the brake the wheel 8 follows the return movement of the pawl 11, but when the wear of the shoes is sufficient to permit a tooth of the wheel to slip past the pawl 12 during application of the brake, then, on release, the pawl 12 limits the return of the wheel 8, and the pawl 11 slips past a tooth, so that subsequent applications are effected with diminished angular movement of the lever 4. The pawls 11. 12 are so mounted that thev mav be reversed when the ratchet wheel is reversed to permit the device to be used with a lever moving oppositely to the lever 4.