Abstract: A disc pack for a wet disc brake assembly includes a plurality of rotating discs. The rotating discs adjacent the axial end of the disc pack are formed of a lower co-efficient of friction material than more centrally located discs. In this way, the wear across the disc pack is more uniform, and a greater load can be carried. In addition, in this way the centrally located discs provide greater braking work than they would if they had the same co-efficient of friction as the axially outermost discs. Applicant has determined that the axially outermost discs see greater force from the braking components, and thus would perform more work than the central discs given equal co-efficients of friction. In this way, the useful life of the disc pack is increased since more work is done by the central discs and wear is more uniform.

Abstract: An improved brake system includes a parking brake piston fixed to the backing plate of a brake friction material for a large vehicle. Service brake pistons are positioned about the parking brake piston. Both the service and parking brake may selectively actuate the brake. Upon actuation by the service brake piston, the parking brake piston moves with the backing plate. The parking brake is set by a parking brake actuator which is connected through a connector to the parking brake piston. When the service brake is set, it causes the connector to move with the parking brake piston. If adjustment is necessary, the connector will hit a stop, and adjustment of the connector along the parking brake piston will occur to compensate for wear on the friction material.

Abstract: An automatic clearance adjuster for a cam actuated vehicle brake. The adjuster is disposed in a pivotal lever and includes a worm and worm gear, an adjusting mechanism for effecting a clearance decreasing rotation of the worm during the brake apply stroke and a clearance increasing rotation of the worm during the brake release stroke, a two-way torque limiting ratchet clutch which slips to prevent rotation of the worm by the adjusting mechanism when the shoes are in contact with the drum, and a roller clutch which allows a predetermined amount of clearance increasing rotation of the worm by the adjusting mechanism during the brake release stroke and then locks up and causes slippage of the torque limiting clutch to prevent further clearance increasing rotation of the worm.