Abstract: An actuating assembly for an electronic parking brake includes a housing and motor secured to the housing and having an output shaft. A cable assembly is rotatably driven by the motor. A cable is anchored at a first end to the cable assembly and wraps around the cable assembly as the cable assembly rotates in a first direction. A first spring is secured to the cable assembly such that it is rotatable with the cable assembly. A drum receives the first spring, which is engageable with an interior surface of the drum to prevent rotation of the cable assembly. A plurality of grooves is formed on a surface of the drum. At least one roller element is positioned in a groove of the drum. A spring housing receives the drum and is secured to the housing. Each of a plurality of apertures in the spring housing receives a roller element.

Abstract: An electrically powered actuator mechanism for operating a vehicle parking brake including a reversible electrical motor having output gearing driving a sector gear. A wrapped spring clutch drivingly connects the sector gear to an intermediate operator cable wind up wheel. The intermediate cable is connected to the brake cable to set the brakes when the operator cable is wound up by energization of the motor in one direction, with a load sensor turning off the motor when a predetermined tension load is reached. Locking motor gearing holds the brake in the set condition. Reversal of the motor upwinds the cable to release the parking brake. A self adjusting feature is provided by a pretensioned clock spring creating a torsional bias on the wind up wheel tending to maintain a predetermined tension in the brake cable. A spring clutch is released by engagement of a release arm to allow the clock spring to adjust the wind up wheel.