| 摘要 |
A brake actuator 10 comprising a piston 12 slidably mounted within a cylinder bore 14 comprises an anti- knock back assembly 30 comprising an expanded resilient split ring 32 in frictional contact with a main portion 26 of bore 14 and loosely axially located in an annular groove 28 adjacent a conical head portion 22 of piston 12. The resilient ring 32, when unexpanded, is a sliding fit within the main portion 26 of bore 14, and the resilient ring is provided with abutment spacer means (shaped frustum or leg portion) which, when the ring is placed into contact with an end wall 20 of the cylinder bore 14, the plane of the ring is spaced far enough from wall 20 to allow insertion of the conical head 22 within the ring so as to expand the resilient ring over conical head portion 22 until it snaps into position in said annular groove 28. This gives frictional grip of ring 32 with bore 26, and ring also acts to adjust for friction surface wear to provide constant retraction distance (w-t). <IMAGE> |
