Self-adjusting parking brake actuator

Abstract

A parking brake actuator for a cable-operated vehicle parking brake, comprises a mounting bracket on the vehicle, a sector gear mounted on the mounting bracket for rotation about an axis to variably tension the cable. A pedal lever is coaxially pivoted on the mounting bracket for independent rotation between a brake release position and a plurality of brake apply positions. A spiral-wound spring extends between the operating lever and the drive plate for rotating the drive plate relative to the lever to apply an initial tension on the cable. A drive clutch couples the drive plate to the lever upon initial rotation of the lever out of brake release position to enable rotation of the lever to increasingly tension the cable and apply the parking brake. The drive clutch includes a pinion gear mounted on the lever in engagement with the sector gear. A torsion clutch spring is wrapped about the pinion gear hub and has one end fixed to the lever and a free end, and normally contracts to prevent rotation of the pinion gear, thus operatively coupling the drive plate to the lever. A release pin on the mounting bracket is engaged by the torsion clutch spring free end in the brake release position to expand the torsion clutch spring to free the pinion for rotation, thus decoupling the drive plate from the lever. A similar position control clutch employing a torsion spring releasably maintains the drive plate in brake apply position.