| 摘要 |
A heavy duty disc brake is disclosed which is provided with an automatic adjuster mechanism to limit retraction of the friction elements to a substantially predetermined amount to thereby maintain the running clearances between the friction elements and the brake rotor substantially constant. The adjustment mechanism includes an extensible member which is slidably mounted within the caliper housing and which interconnects a mechanical actuating mechanism and a piston which engages one of the friction pads. The piston is slidably mounted within the housing and is disposed between the extensible element and the corresponding friction pad, and the piston carries a spring-actuated pawl. The pawl is adapted to engage corresponding ratchet teeth on one portion of the extendible member, which includes a pair of threadedly interconnected, relatively rotatable members, designed so that upon relative rotation between the members, the extendible member extends. When a brake application is effected, the mechanical actuator thrusts the extendible member, and therefore the piston and the friction elements, toward the rotor. Upon brake release, a spring yieldably urges the extendible member toward a predetermined brake release position. If the extendible member must travel more than a predetermined distance relative to the piston to achieve the brake released position, the pawl indexes to another one of the aforementioned teeth carried on the extendible member. Therefore, on a subsequent brake application, the pawl rotates one portion of the extendible member relative to the other portion, consequently extending the member.
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