Actuator with automatic adjustment mechanism for vehicle brake

摘要

In a housing (32) which has a housing axis (A) and encloses a first cam surface (54) arranged around the latter, a body of revolution (38) is mounted to rotate about the housing axis (A). The body of revolution (38) has an axial extension (76) for coupling an actuating member (80) and, on its circumference, has a toothing (86) and, furthermore, a second cam surface (40) by means of which it is supported against the first cam surface (54) in order to bring about an axial displacement dependent on its rotation. A first screwed body (60) is furthermore rotatable about the housing axis (A). A second screwed body (70) is held fast against rotation, is designed to exert an actuating force on a brake shoe (24) and is connected to the first screwed body (60) by means of a pair (72) of readjusting threads. A resetting shaft (90) is mounted at a lateral distance from the housing axis (A). Coupled to the first screwed body (60) is a pinion (112). Arranged around the resetting shaft (90) is a coupling arrangement (98) which is in engagement via a toothing (89) with the toothing (86) of the body of revolution (38), with the result that a limited torque for the axial readjustment of the brake shoe (24) is transmitted from the body of revolution (38), via the coupling arrangement (98) and the pinion (112), to the first screwed body (60). To achieve a frictional engagement, the pinion (112) is spring-loaded in the axial direction and connected to the coupling arrangement (98) by a one-way slipping clutch, rotation of the first screwed body (60) during operation being permitted only in a direction which reduces the brake release clearance. IMAGE