Combined service and parking brake apparatus

摘要

A combined service and parking brake apparatus includes a piston which forms a hydraulic chamber within a cylinder portion; a brake lining which, when pressed by the piston, brakes rotation of a disc rotor; a second piston which divides the hydraulic changer into a first hydraulic chamber and a second hydraulic chamber; a friction clutch which allows rotation of the second piston when the second piston is held at its home position and which disables rotation of the second piston when the second piston moves by a predetermined distance toward the second hydraulic chamber; an adjuster including an internal-thread portion and an external-thread portion and adapted to adjust the clearance between the pistons in accordance with the amount of wear of the brake lining; and a changeover valve for establishing and shutting off the communication between the first hydraulic chamber and the second hydraulic chamber.