Abstract: Disclosed is an automatic slack adjuster (50) for maintaining a substantially constant clearance (C) between a braking member and a rotatable braking surface in a brake released condition between a braking member (8) having a frictional layer (1) and a rotatable braking surface (12) of the type including an elongate power screw (2) having threads (4) threadingly engaged with threads of a rotatable nut member (6). Clearance (C) is maintained upon application of the brake by an operator by means of an adjustment member (16) that is preferably in splined engaged relationship with nut member (18) and causes nut member (6) to rotate and advance braking member (8) in a clearance correcting direction upon application of the brake of an operator by means of a drive train driven by power screw (2) preferably comprising a first drive means (20) integral with power screw (2), rack means (22), second drive means (24) and third drive means (34) operably engaged with adjustment member (16).

Abstract: A power screw type disc brake having an internal automatic slack adjustor of the single acting, clearance sensing type is provided. The actuating/clearance sensing mechanism (10) of the disc brake includes a power screw (18) selectively rotatable by means of a lever (12) which power screw is threadably engaged with a power nut (42) axially moveable but rotationally fixed relative to a housing (22). The power nut is resiliently urged by a spring (70) into constant engagement with a push rod member (50) which carries a pressure member (16) threadably attached thereto. The push rod member is axially and rotationally moveable relative to the housing and the pressure member (16) is axially moveable but rotationally fixed relative to the housing whereby rotation of the push rod member will result in axial movement of the pressure member for slack or running clearance adjustment purposes.

Abstract: An improved automatic slack adjuster (10) for disc brakes is provided. The slack adjuster includes an elongated rod (16) threadably attached to a nut member (28), only one of which rod and nut member is rotatable relative to the housing (12) for slack adjustment purposes. A coil return spring (36) acts on spring seat washer (40) which bears on the nut member. The spring seat washer is rotationally fixed (42, 44) to the non-rotatable one of the rod and nut members to prevent wind-up of the coil return spring during a slack adjustment operation.