GB822662A - Improvements relating to drum brake mechanisms particularly for vehicles - Google Patents

Abstract

822,662. Drum brakes. DELOREAN, J. Z. June 12, 1957 [June 14, 1956], No. 18566/57. Class 103 (1). A combined expanding and contracting shoe drum brake comprises a drum having a web member 22 contoured to receive a liner 28 providing radially spaced concentric braking surfaces 30 and 32. Inner and outer brake shoes 48 and 50 are applied to the surface 30 and 32 by an hydraulic cylinder and piston 76, 78. Since the inner shoe 48 is held against rotation by a pin 60 passed through a hole 58 in one end thereof, the drum rotation, as indicated by the arrow 86, tends to move the outer shoe 50 relative thereto so that the interaction of the rollers 72 on the ramps 68 and 70 tends to spread the shoes apart against the drum surfaces. Automatic adjustment of the shoe clearance may be carried out by a piston 92 having a non-return valve 98 therein in the hydraulic line to the cylinder 76. In another embodiment shown in Fig. 7, the hydraulic actuator cylinder 329 is disposed circumferentially between the adjacent ends of the friction members 321 and 323 which are of band form. The hydraulic actuators 459 may be disposed outside the drum as shown in Fig. 11, and operate against the ends of the shoes, by means of levers 455 and 461 pivoting on a floating link 465. The web member 22 of the drum is preferably provided with a plurality of cooling fins 534, as shown in Fig. 13.