GB519787A - Improvements relating to brakes - Google Patents

Abstract

519,787. Brakes. ROVER CO., Ltd., and IVERSEN, P. A. SCOTT-. Oct. 1, 1938, No. 28558. [Class 103 (i)] The co-operating friction surfaces of brakes or parts of them are normally held lightly in contact or there normally exists in the operating system a force which in the absence of friction inherent in the system would hold them in light contact, the arrangement being such in the latter case that the movable surfaces return a constant amount after each application. Fig. 1 shows a hydraulically operated brake in which the reservoir l normally communicates with the system by the pipe k the outlet of which is covered when the piston h is operated. Release springs for the shoes b are dispensed with and the reservoir is arranged at such a height that the shoes are normally held in light contact with the drum by the hydraulic pressure. The shoes may also be held in contact by gravity acting on the shoes themselves or by a spring or weight. Fig. 5 shows a mechanical arrangement in which the shoes are held in contact with the drum by a spring x. The cam' lever t is freely mounted on the cam spindle and carries a pawl w which is normally held disengaged from a ratchet wheel v secured to the cam spindle but which engages the ratchet when the lever is operated to apply effective pressure to the shoes. Variations due to wear and temperature changes are thus accommodated by the freely movable shoes. In Fig. 6, a part 2 of the shoe b which is radially displaceable to a limited extent on the main part is normally held in contact with the drum by the normal pressure in the hydraulic system acting through a spring 3 which also maintains the main part of the shoe slightly displaced'from the drum. In Fig. 7, the piston e of rubber has a deformable bellows-like end part 7 which may be reinforced by a deformable metal sheath. The shoes b are normally displaced as shown from the drum. When the hydraulic pressure is increased beyond the normal the friction of the piston in the cylinder also increases, so that the piston extends to contact the shoes with the drum but as wear occurs the piston moves bodily and when the pressure is reduced, the piston again contracts so that a constant clearance of the shoes is maintained. The cylinder may be elastically deformable instead of the pistons. The invention may be applied to cone disc or other types of brake.