| 摘要 |
1,267,709. Shoe drum brakes. NORTH AMERICAN ROCKWELL CORP. 16 Sept., 1969 [12 Nov., 1968], No. 45478/69. Heading F2E. In an automotive vehicle brake assembly including an automatic brake shoe adjustment mechanism having a rotatably mounted actuator member 49 provided with a toothed periphery 56, there is a one-piece retainer 64 having a slotted portion 73 for non-rotatably receiving a brake shoe 14 and opposed arms 68 reversely bent to form substantially U-shaped, resilient clips adapted to extend around the toothed periphery of the member 49, each clip being shaped to provide an internal detent 72 adapted to be interlocked with the toothed periphery, whereby the retainer operatively prevents rotation of the member during automatic adjustment while permitting selective rotation for manual adjustment. As shown, brake shoes 14, 15 are displaced outwardly to engage a brake drum by a fluid-pressure operated reciprocable rod 31 carrying a wedge disposed between rollers 33, 34 extending in the grooved ends 35, 36 of plungers 23, 24. Rotation of the plunger 24 is prevented by a pin 41 coacting in a slot 39 in the plunger, and the plunger 23 slidably mounts a member 46 internally screw-threaded to receive the member 49 and formed with spiral ratchet teeth 51 engaged by ratchet teeth 52 on a spring-loaded pin 53 slidable in a bore 50. During brake operation, plunger assembly 23 is displaced outwardly and member 46 moves relative to pin 53, whereby if the displacement is greater than the pitch of the teeth 51 on the return stroke, ratchet action of the teeth 51, 52 results in rotation of the member 46 and consequent relative rotation between that member and the member 49 to produce automatic length adjustment of the plunger assembly. |
