GB631880A - Improvements in fluid operated disc brakes - Google Patents

Abstract

631,880. Fluid-pressure-actuated disc brakes. DUNLOP RUBBER CO., Ltd., and BUTLER, H. J. Oct. 1, 1946, No. 29190. [Class 103 (i)] A fluid-pressure actuated disc brake adapted for dual control comprises a brake cylinder, two pistons therein, and two systems of fluid supply, the ports to the cylinder for the fluid supply being so placed that the pistons tend to move in the same direction or in opposite directions according to the systems of fluid supply in use. In one form Fig. 1, axially-movable inner and outer annular discs 5 and 7, formed with teeth 6 and 8 engaging corresponding teeth 2 and 4 on the wheel hub and rim, are arranged to be gripped. between friction elements 33 and 34 mounted on a sleeve 26 secured to a fixed plate 9 formed with a cylinder 10. Two pistons 15 and 17 having abutment faces 19 are slidable in the cylinder and on a piston-rod 21 which has a head 20 located in a bore in the piston 15 and passes through the sleeve 26. The end of the cylinder is closed by a resilient cap 11, secured by a band clip 13, and this cap engages the piston 15 and head 20 so as to act as a return spring when the brake is released. The end of the rod is screw-threaded for the reception of an adjusting nut 30 which engages a backing plate 32 now rotatably mounted on the sleeve 26 and is arranged to be turned automatically to compensate for wear by a spiral spring 37 as described in Specification 631,877. Fluid is admitted either to the righthand side of piston 17 or to the space between the pistons through a passage 36 or 35. In a modification, Fig. 2 (not shown), the piston 17 abuts against a shoulder 38 formed on the piston-rod. In a second form, Fig. 3, the piston 17 abuts against the head 20 of a pushrod 21 encircled by a return spring 40, and fluid is admitted either to the left-hand side of piston 15 through a passage 41 or to the space between the pistons through a passage 35. A single cylinder and associated parts may be employed, or several cylinders spaced at equal intervals around the discs. In the latter case the plate 9 is formed as a spider. According to the Provisional Specification, the arrangement may be such that braking pressure is applied directly to the friction elements adjacent the cylinders and through the pistonrod to the elements remote from the cylinders. Specification 625,726 is referred to in the Complete Specification and Specification 625,739 in the Provisional Specification.