Adjustable brake actuator, especially for vehicle drum brakes

摘要

A casing (10) has a bore (14) and a clutch face (48) concentric with the bore. In the bore (14) a tappet (30) of variable length is slidably guided and includes two threaded members (34,36) interconnected by a self-locking screw thread pair (38). A clutch member (50) connected to one of the two threaded members (34) by a non-self-locking screw thread pair (52) is associated with the clutch face (48). A support member (60 ) having an aperture (68) through which the other one of the two threaded members (36) extends is fixed to the casing (10). A clutch spring (70) is inserted between the support member (60) and the clutch member (50) and urges the clutch member (50) into abutment against the clutch face (48). A sealing boot (72) which is disposed outside of the support member (60) with respect to the casing (10) provides an external seal for the screw thread pairs (38,52) and the clutch member (50). The support member (60) and the sealing boot (72) are separately fixed to the casing (10).