GB1343545A - Disc brakes with automatic adjustment means - Google Patents

Abstract

1343545 Spot-type disc brakes; wear-adjusting BENDIX CORP 20 July 1972 33989/72 Heading F2E In the spot-type, sliding caliper, fluid-pressure operated disc brake shown, fluid-pressure operation after pad wear results in piston 32 being spaced from portion 74 of an adjusting member 72 at the annular region 86. Washer 78 attached to the piston thereupon entrains adjusting member 72 via bearing 76, causing it to unscrew out of annular member 61, the effective length of assembly 58 being thereby increased. On relief of fluid pressure, the piston 32 is urged leftwards by seal 36, so piston 32 and portion 74 again make contact at 86, so backward rotation of member 72 is prevented, and the piston can retract only until the clearance between threads is taken up. (Member 61 is prevented from rotating). Over - adjustment during high - pressure ("panic") application is prevented by providing an annular clearance 66, 68, between member 61 and a "seat" 62 forming part of the assembly 58. During normal application, caliper 18 moves leftwards and the far end of member 61 is maintained in contact with a flange on "seat" 62 by a spring 64. When the application pressure is excessive, the pressure in the annular clearance 66, 68, separates member 61 and seat 62, overcoming spring 64. Member 61 thus travels rightwards with member 72 and unscrewing of member 72 is prevented. Re-setting.-When during servicing, access is gained to piston 32, the piston may be pushed to the left to re-screw member 72 into member 61 if, first, a bolt (84), (Fig. 3, not shown), pressing a washer 80 against an adjacent surface of caliper 18 is unscrewed. Washer 80 is splined at 82 to member 61, so normally it prevents it from rotating. When the washer is freed, however, and leftward pressure on piston 32 prevents rotation of member 72 (by contact at 86), this same pressure forces member 61 (and washer 80) to rotate by inter-action of the threads so member 72 is retracted into member 61. Parking. (mechanical) operation is by pivotal movement of a lever 42, Fig. 2, against the force of a torsion spring 48, by cable 46, which by ball and ramp mechanism 50, 52, 56 results in axial movement of the lever and consequent axial movement of piston 32 via bearings 60, "seat" 62 and members 61, 72. Wear adjustment cannot occur. The slope of ramps 50, 52, is non-uniform, the initial part providing for quick take-up of clearances, the later part providing for high force multiplication. In Fig. 4 (not shown), pressure fluid is applied through an orifice at the left end of the caliper, through a tube (90) extending through ramp member 54 and lever 42, and through a passage (94) in the end of "seat" 62.