Gm Global Technolgoy Operations, Inc.

Douglas M Copp

Michael William Fanelli

Frank W Brooks, Sr

Robert W Hyde

Gary G Holliday

A drum brake is provided of the leading-trailing shoe type in which a single piece spring installed as a part of the assembly holds down the brake shoe assemblies against the backing plate and also retracts the shoes after brake actuation. The single piece spring also retains the lower ends of the shoes against the anchor plate. This arrangement eliminates the need for separate shoe hold-down springs and separate upper and lower return springs, resulting in a significant reduction in parts and labor for assembly.

Unispring drum brake assembly

A drum brake assembly having a parking brake actuating lever is provided so that the parking brake cable end may be assembled in a blind fashion to the actuating lever. The cable is provided with a button. A spring is attached to the lever and to the backing plate about a parking brake cable opening. The spring end attached to the lever has a ramp section and a hook end, the ramp section being in a tapered open channel formed on the lever end and the hook end being secured to the lever. The cable button is inserted axially through the backing plate opening through the spring, being guided by the spring, into the channel. Further insertive movement of the cable button causes the button to be deflected upwardly by the coil spring ramp portion and the channel sides, side loading the cable. When the button passes the end of the ramp portion and the channel smaller end, the stored force in the cable because of the side loading moves the cable and the button downwardly in the channel. The button moves into tension a force-transmitting engagement with the edges of the channel smaller end so that as the cable is then tensioned the lever will be moved to actuate the brake.

Blind cable assembly

A single generally U-shaped wire spring has a partial loop formed in the center and fitting over an anchor for a leading-trailing shoe assembly. Each arm of the spring extends along the web of a shoe and terminates in a hook end which fits within a slot in the associated shoe web. The slots are so located in the web to obtain the desired distribution of spring loads on the adjuster/strut assembly and on the anchor plate. The spring will return the brake shoes to the adjuster/strut assembly after actuation of the wheel cylinder during service brake function; retain the lower ends of the shoes against the anchor plate; and hold the shoes against the backing plate by the force component of the spring wire acting against the bottom side of the cable support and against the top of the outer ramp of the anchor plate, resulting in a spring load directed onto the web of each shoe.

Drum brake assembly and shoe hold-down and retraction spring therefor

A one piece spring clip is positioned on a headed brake shoe hold-down pin so that the spring clip is compressed with a camming action until the clip reaches an over-center condition. Further installing movement of the spring clip permits the spring to expand and lock itself in the installed position. The spring has a primary spring section absorbing normal compression loads and secondary spring sections resisting excessive compression loads.

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West Milton, OH, United States of America

Douglas M Copp