Patent GB-1295755-A (GB)
Inventor: HALL J A
IPC: F16D65/54
Filed: 1970-05-01
Abstract: 1295755 Controlling clutches; brake retractors and slack adjusters B F GOODRICH CO 1 May 1970 [5 May 1969] 21159/70 Headings F2E and F2L A retractor and wear compensating assembly for a clutch or brake incorporates an automatic slack-adjusting mechanism which has a locking plate carried by a sleeve member surrounding a retractor rod; the locking-plate is held in tilted locking position during retraction of the clutch or brake member and is automatically moved into unlocked position during actuation of the member when the rod is moved beyond the normal clutch or brake release clearance distance. In the brake shown, a pressure plate 17 and a disc 12 are splined to a torque frame 11 fixed to a vehicle, while a brake-lining carrier 13 is splined to a part 14 of a wheel. Pressure plate 17 is screwed at 36 to a retractor rod 35 slidable within a sleeve 22, itself slidably located in a cylindrical housing 19 secured in the torque frame 11. Sleeve 22 is urged leftwards by a helical retractor spring 23 pre-stressed between an annular washer 32, in which sleeve 22 is slidable, and a collar 24 located on sleeve 22. An annular locking-plate 37 surrounding the rod 35 between the end of sleeve 22 and pressureplate 17 has an axial flange 39 ending, at the top, in an inturned lip 41 by which the locking-plate is located on an end flange 34 of sleeve 22, and, at the bottom, an out-turned ear 42; the lip 41 is so shaped that normally the locking plate 37 is tilted, and thus frictionally grips the retractor rod 35. Also, in the "brakes off" position shown, spring 23 ensures that lip 41 is retained between flange 34 and washer 32. In operation, the brake is applied by hydraulic pressure acting on a piston 15 working in a cylinder 16 integral with the torque frame 11, until parts 17, 13, 12 and reaction plate 18 of torque frame 11 are all in contact. Rod 35 carries with it locking plate 37 which in turn takes with it sleeve 22, whereby spring 23 is further stressed. The normal release clearance (no wear) is equal to X, the distance between ear 42 on locking plate 37 and a flange 43 on housing 19. If this distance is not exceeded, locking plate 37 remains in tight frictional engagement with rod 35, and the brake members may be engaged and released repeatedly. If wear takes place, pressure plate 17 carries rod 35 further to the right until ear 42 engages flange 43, whereupon locking plate 37 is straightened and releases the rod, which now slides to the right within sleeve 22 and plate 37. On release of the actuating system, re-engagement of the locking plate on the rod is effected, so that the retraction movement of the sleeve and rod is limited to the amount necessary to maintain a uniform brake release clearance. A screw 44 threaded into rod 35 indicates by its head position (initially aligned with the end of sleeve 22) the amount of lining wear, and by engagement with step 45 indicates fully-worn linings. To draw the rod 35 back into sleeve member 22 and thus pull pressure-plate 17 back to the desired position (e.g. for re-lining), screw 44 is sufficiently unscrewed until a horse-shoe washer can be inserted under its head. The screw is now tightened to draw rod 35 back, the rod being retained in position by locking plate 37. Thereafter the horse-shoe washer is removed and screw 44 re-set to indicate wear.