Patent GB-971799-A (GB)
Title: Brake
IPC: F16D65/14
Filed: 1962-12-04
Abstract: 971,799. Disc brakes. D.B.A. S.A. Dec. 4, 1962 [Dec. 20, 1961], No. 45829/62. Heading F2E. In a disc brake of the type having a floating caliper including a piston and cylinder motor acting directly on one pad and by reaction through the caliper on another pad so that the two pads are thereby applied to opposite faces of a disc, automatic adjustment for wear is effected by mechanism comprising a screw-andnut assembly of which one part is connected to the motor piston and the other to the motor cylinder, one of the parts comprising a cylindrical portion around which is tightened a helical clutch spring anchored at one end and free at the other, whereby relative rotation of the screw and nut is allowed only in the direction corresponding to forward movement of the piston in the motor cylinder. In one embodiment, Fig. 1, a rod 22 having an external thread of coarse pitch is slidably mounted in the end wall of a cylinder 12 but normally maintained in the position shown by fluid pressure acting on a stop flange 34 and by a resilient sleeve 24 acting on a split ring engaged in a groove in the rod. A sleeve 20 is internally threaded to engage the rod 22. Rotation of the sleeve in a direction to move it inwardly of the cylinder is prevented by a spring 36 anchored at one end to the piston and closely wound upon the sleeve to act as a one-way brake. A ball race 38 is interposed between a ring 40 carried by the sleeve and a return spring 44 whereby the piston abuts the sleeve when the brake is released. When fluid is supplied to the cylinder spring 44 is compressed. If sufficient wear of the pads has taken place spring 44 is fully compressed and sleeve 20 is rotated in the permitted direction to compensate for this. Alternative manual operation is effected via a lever 28 having a cam member 26 acting on the rod 22 by way of a flattened end portion 32 engaged in a cam groove in the member 26, whereby rotation of rod 22 is prevented. The resilient sleeve 24 is thereby compressed and acts as releasing means. When new pads are to be fitted lever 28 and cam member 26 are dismantled to allow rod 22 to be rotated. In a second embodiment, Fig. 2, manual operation is effected via a lever 50 secured to a rod 22<SP>1</SP> which is similar to rod 22 of the previous embodiment excepting that its flange 34<SP>1</SP> has a ball race for ball bearings 52 to facilitate rotation by which the brake is manually applied. The automatic adjuster is identical to that of the previous embodiment. When new linings are required a stop-pin 54 is removed to allow the necessary rotation of rod 22<SP>1</SP>. In a third embodiment, Fig. 4, the manual applying means comprises a shaft 88 extending through slotted holes in the piston 62 and caliper structure 60 which incorporates the cylinder. The shaft rests in open-ended slots in a pair of lugs 90 on member 86 which is slidable within a bore in the piston and abuts the end of an internally threaded sleeve 72 engaging an externally threaded rod 74 passed sealingly through the piston and adjustably anchored to the end wall of the cylinder by a threaded connection, locked by a nut 76. Shaft 88 carries cams (Fig. 3, not shown) which engage the pad 66 directly to apply it to the disc (not shown), the reaction force on the caliper 60 applying the other pad 68. Automatic adjustment to re-position shaft 88 to compensate for wear of the pads is effected as in the previous embodiments, after return spring 82 is fully compressed, through ball race 78, the one-way brake formed by spring 84 preventing reverse rotation of the sleeve 72. In a further embodiment, Fig. 5, the arrangement is similar to that of Fig. 4 except that the assembly of the sleeve 72<SP>1</SP>, ball race 78<SP>1</SP> and spring 84<SP>1</SP> are positioned in the pressure chamber of the cylinder so as to be lubricated by the pressure fluid, a piston 104 being slidable within a bore in the piston 100 to support the cam shaft 88<SP>1</SP> so that movements of the sleeve 72<SP>1</SP> are caused to reposition shaft 88<SP>1</SP>.