| 摘要 |
In a drum brake assembly a hydraulic actuator is engageable with a pair of brake shoes to move the same into engagement with a rotatable member. A parking lever also cooperates with the pair of brake shoes to move the same into engagement with the rotatable member and an anchor plate forms a connecting member between the pair of brake shoes. A backing plate supports the pair of brake shoes and the anchor plate. The anchor plate is movably supported by the backing plate and a latch cooperates with the anchor plate in a first position to fix the anchor plate to the backing plate. The latch is movable to a second position spaced from the anchor plate to permit the latter to move relative to the backing plate. In order to control the position setting of the latch, the latch is coupled to the parking lever so that the latch remains in the first position until the parking lever is moved whereupon the latch is also moved to the second position. Consequently, when the hydraulic actuator is operated in a service brake application, the anchor plate remains fixed to the backing plate to form a nonservo drum brake and when the parking brake is operated, the anchor plate is movable with the pair of brake shoes in the direction of the rotatable member to form a duo-servo drum brake. |
