Patent GB-1286626-A (GB)
Title: Improvements in or relating to disc brakes
Inventor: MOSS NORMAN SIDNEY
IPC: F16D65/56
Filed: 1968-10-11
Abstract: 1286626 Spot-type disc brakes; actuation; slack-adjusting GIRLING Ltd 3 Oct 1969 [11 Oct 1968] 48419/68 Heading F2E Two mechanical actuators, one of which is shown at 9, Fig. 1, which together operate a directly-applied pad 7, are spaced apart circumferentially in relation to the disc D, Fig. 3, and are arranged for simultaneous operation by, in sequence, a fluid pressure actuator motor 24, Fig. 2, a push-rod 23, an articulated lever 22, a shaft 21 and a common driving pinion 19, Fig. 3. Each mechanical actuator 9 includes an inner thrust race member 14 having gear teeth meshing with pinion 19 and having tapering recesses for co-operation with ball-bearings 13, corresponding recesses are provided in an outer thrust race member 11 coupled to a boss member 16 by a tension-spring 17. Brake pads 7, 7 are located in opposed gaps in a medial yoke section 1, Fig. 1, which is secured to a vehicle frame structure in the vicinity of the disc D. Inboard and outboard yoke sections 2, 3 are joined together by tie-rods 4 which are located in holes in all the parts 1, 2, 3 by rubber 0-rings 6 forming resilient bush members. The further pad 7 is applied by reaction of the yoke members 2, 3, and is separated from outboard yoke member 3 by a distance dependent upon the setting of two "reaction abutment members", one of which is shown at 26, forming part of an automatic slack adjuster mechanism. The tie-rods 4 lie in the plane of the lines of action of the mechanical actuators, Fig. 2. The slack adjuster mechanism includes two rotatable internally-threaded cups 28, Fig. 1, each accommodating one of the reaction abutment members 26. Each cup has gear teeth 29 near its outer end which mesh with teeth on a common drive pinion 31, the drive pinion having crown ratchet teeth 37 on one face which normally engage co-operating teeth on the adjacent face of a mainly-circular drive-plate 38. The drive-plate 38 has a peripheral recess (39), (Fig. 4, not shown), for engagement with a stop-pin (41) at the ends of its travel, and a radiallyprotruding hook (42) in which is located one of the beaded ends of the core 43 of a sheathed cable 44. The cable extends around the brake (see Fig. 1) to the inboard side, Fig. 2, where its other end 49 is secured in a hook 51 at the end of lever 22. When excessive wear of the pads has occurred, the abnormally large angular movement of lever 22 on brake application is transmitted to drive-plate 38 which on this occasion will engage a fresh tooth 37 on pinion 31 and when the braking pressure is relieved a spring returns drive-plate 38 to its starting position with consequent rotation of pinion 31 and cups 28. Since members 26 are keyed against rotation they are moved axially outwards. Prior to fitting new shoes, members 26 are screwed back into their cups by inserting a screwdriver in the end of a spindle 33, pressing down to connect spindle 33 with the tubular spindle of pinion 31, and rotating to rotate cups 28 indirectly. Lever 22 is made in two parts pivoted at 52 to enable initial design clearances to be set and the cable length adjusted on assembly. The brake actuating force may be hydraulic or manual instead of air as shown.