GB873522A - Improvements in or relating to devices for automatically compensating for friction lining wear - Google Patents

Abstract

873,522. Automatic adjusting devices for brakes. REGIE NATIONALE DES USINES RENAULT. June 2, 1958 [June 4, 1957], No. 17570/58. Class 103 (1). A device for automatically compensating for wear of a friction lining of a mechanism such as a disc brake comprises a first member, which, when displaced, causes the friction lining to be applied against the part capable of moving with respect to the lining and a second member cooperating with the first member through a screw-and-nut arrangement, the pitch thread form of which is such that upon the screw being displaced rotatively with respect to the nut in one axial direction the position of the nut relative to the screw is varied to compensate for wear of the lining, movement of the screw in the other direction effecting no relative movement between the nut and the screw. In an automatic adjusting device for a disc brake illustrated, the screw-and-nut device is situated between the hydraulically actuated pistons 7, 8 such that when fluid under pressure is introduced into chamber 10, pistons 7 and 8 are forced apart and a shouldered rod 15, secured to the piston 8, carries along a screw-threaded socket 14 formed with a buttress-type thread which rotates in nut 17 integral with piston 7 in this direction of movement such that the pistons may be adjusted to take up the lining wear. A clearance 16 is left between threaded socket 14 and the bottom of the piston 8 at the end of the brake applying movement. When the brakes are released, however, the hydraulic pressure in chamber 10 is reduced and return spring 11 moves piston 7, 8 towards each other and in this direction the axial movement of the threaded socket 14 of the piston cannot rotate in the nut 17 integral with piston 7. The piston 7 and the threaded socket thus constitute an integral unit which is returned to its inoperative position and as the socket 14 engages the bottom of the piston 8, the axial clearance 16 is taken up. The play resulting from lining wear is adjusted automatically during the subsequent brake application due to spring on the threaded socket in the nut 17. In addition to the hydraulic actuation of the disc brake, a hand brake control device 18, 19 may be provided.