| 摘要 |
C-4334 DRUM BRAKE AND WEAR ADJUSTER THEREFOR A drum brake comprising a drum; first and second brake shoes which carry friction lining material; at least one hydraulic actuator engaging the brake shoes for moving the friction lining material into contact with the drum on actuation thereof, a clearance existing between the friction lining material and the drum in the non-actuated position of the hydraulic actuator; a wear adjuster for adjusting the value of the clearance, the wear adjuster comprising a screw-threaded rod engaging the first brake shoe, a nut rotatably threaded on the screw-threaded rod and engaging the second brake shoe, ratchet teeth integrally formed on either the screw-threaded rod or the nut, an adjuster actuator having an integral pawl thereon and being pivotally mounted on one of the brake shoes, an actuator spring to bias the pawl into contact with the ratchet teeth; and a heat sensitive member mounted on said one brake shoe, the heat sensitive member being engageable with the adjuster actuator only when the temperature exceeds a predetermined level to prevent or restrict pivoting movement thereof. The wear adjuster adjusts the clearance value when it is above a predetermined maximum prior to actuation on actuation of the drum brake. The heat sensitive member prevents such adjustment when the temperature exceeds the predetermined level.
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