Slack adjuster for a disc brake.

摘要

A slack adjuster is for a disc brake of the type which includes a disc mounted for rotation about an axle and a caliper brake having a housing mounted on the axle in alignment with a friction surface of the disc. A braking piston is mounted in the housing for axial movement toward and away from the friction surface of the disc. Brake actuation produces rotating movement of a powershaft mounted in the housing which will in turn produce a corresponding axial movement of the braking piston through a non-rotating powershaft nut. An adjusting sleeve is between the piston and the powershaft nut and is threadably coupled to the piston and capable of rotation relative thereto to adjust the axial position of the piston. The adjusting sleeve is capable of rotating in a direction which will cause the piston to be adjusted toward the disc and is prevented from rotating in the opposite direction by a one-way clutch shaft between the adjusting sleeve and the housing. A lost motion element allows rotation of the powershaft to produce corresponding rotation of the adjusting sleeve after the piston has moved toward the disc through a desired running clearance without having made any frictional contact therewith and employs a force limiting clutch element to prevent corresponding rotation of the adjusting sleeve when the powershaft is rotated in a direction to produce movement of the piston away from the disc. The clutch shaft can be selectively operated in both directions for initial adjustment of the adjusting sleeve.