Patent GB-1278136-A (GB)
Title: Brake or clutch retractor mechanism
Inventor: PLAAT C L
IPC: F16D65/54
Filed: 1970-08-26
Abstract: 1278136 Wear-compensating disc-brake retractors; friction clutches B F GOODRICH CO 26 Aug 1970 [27 Aug 1969] 41005/70 Headings F2C and F2E A retractor assembly including a spring 24 and rod 18 has a clamping arrangement 27, 28 which is released during brake actuation when wear of a lining carrier 12 has occurred and is re-applied when the rod has been moved through the clamping arrangement sufficiently to take up the wear. Thereafter, retractor movement is restored to the normal clearance X, Fig. 1, until further wear occurs. In the assembly as shown, incorporated in a disc brake only, the retractor spring 24 is preloaded, and through a washer 25 forces two inter-engaging loops 27, 28, hinged together at 29, 31, externally of rod 18, into positions where each loop has a clamping surface 44 or 45 in contact with a flat upper or lower surface of rod 18, in the release position of the brake, Fig. 1. Ears 36, 37, are in contact with a threaded ring 38 in this phase. When fluid pressure is applied to cylinder 16, lining carrier 12 carried by torque frame 11 is moved into contact with disc 13 splined to a rotary member, e.g. a wheel part 14. Carrier 12 pulls rod 18 with it, and loops 27, 28, gripping the rod, compress spring 24 through washer 25, the increased spring compression increasing the grip of loops 27, 28 on the rod. If no wear has occurred, spring 24 returns the carrier 12, rod 18, loops 27, 28 and washer 25 to the positions shown in Fig. 1 when the brake is released. If wear has occurred, ears 36, 37 make contact with housing shoulder 46 during the applying stroke, thereby causing tilting of loops 27, 28 about their hinges 29, 31. Consequently, clamping surfaces 44, 45 are lifted from rod 18, permitting hydraulic pressure at 16 to move rod 18 through the clamping arrangement without further compression of spring 24. Thereafter, spring 24 through washer 25 rotates the loops into clamping position again. On release of the brake, spring 24 can only force loops 27, 28, and with them the rod 18, through a distance sufficient for ears 36, 37, to contact ring 38 again-a distance X. An indication of wear is provided by the observed position of rod 18, which may carry a mark to signify need for lining replacement. When replacement is necessary, a tool inserted inside ring 38 serves to release the clamping pressure of loops 27, 28, whereupon the rod may be moved back. Thereafter the lining carrier may be removed, without removing the retractor assembly, by turning it circumferentially, so that slot 21 in the carrier may be slid from enlarged head 19 of rod 18. The release clearance X may be varied by rotation of ring 38 in threads 39 of the housing 17. Removal of ring 38 permits disassembly of the retractor assembly except for rod 18. Another lining carrier 12 and retractor assembly 10 may be mounted on the torque frame on the other side of rotatable disc 13. Depending on brake size, a number of retractor assemblies 10 may be located in circumferentially spaced positions on the torque frame 11 (on each side of disc 13).