GB441430A - Improvements in or relating to brake adjusting devices - Google Patents

Abstract

441,430. Compensating for wear in brakes. MOLD, A. W., 3, Wharncliffe Road, East, and McINNES, J. H., 45, Bective Street, both in Liverpool. Jan. 9, 1935, No. 718. [Class 103 (i)] Adjusting means for brakes of the kind in which application and release of the brake is effected by the longitudinal movement of a cam connected to a longitudinally - moving applying member are operated by angular movement of the applying member into which a part of the longitudinal movement of the member is converted. The cam may have an oval cross-section so that it serves also as the adjusting means or a separate adjusting cam may be provided. The cam 57 engaging the brake shoes 10 by rollers 58 is given a longitudinal movement by the applying member or rod 59 which slides in a fixed casing 60. The cam 57 is of oval cross-section. The rod 59 has a pin 70 engaging a helical groove in a slidable block 62. When the rod is moved to the right to apply the brake, the block moves with it and if the movement is excessive, a pawl 64 engaging a rack on the block abuts on a stop 68 so that the pawl slips a tooth. On the return movement the block is held by the pawl when it returns to its position against the part 67 of the casing and the further movement of the rod 59 results in an angular movement thereof and of the cam and an adjustment of the shoes 10. In a modification, the rack and pawl are omitted, the angular movement of the rod and cam being effected during the application movement. In Fig. 6, the angular movement of the rod 59 which carries the brake applying cam 85 operates through linkage 86 a separate adjusting cam 84 which engages the opposite ends of the shoes 80. The cam 85 may be conical or it mav be of oval cross-section so that adjustment of the shoes is effected at both ends. Indicators, applications of.-To indicate when the friction linings of the shoes have been worn to a predetermined extent, a casing 26 fixed, for example, to the dashboard of a vehicle, contains a vane 28 normally visible through an aperture 27. The vane is pivoted at 29 and has an arm 30 resting upon a cam 31 connected by a cable 25 to the brake applying rod 59. When the adjustment of the shoes reaches the predetermined limit, the cam is turned and the vane moves away from the aperture 27. The vane may also close the circuit of a bell 34 through a contact 35. The cable may instead actuate a mercury switch in the circuit of a lamp or bell or the liquid instead of being mercury may be a solution and the contacts such that when the liquid covers the contacts a permanent metallic bridge is built between the contacts.