Abstract: A vehicle drum brake comprises an automatic adjuster with thermal compensation, so that the brake does not become over-adjusted following thermal expansion and subsequent contraction of the drum. The adjuster overcomes the problems associated with adjusters which at high temperatures are disabled, and so might leave the brake under-adjusted. The adjuster comprises a bimetallic strip or equivalent incorporated into the adjuster strut to expand the strut when the drum expands, and to contract the strut when the drum contracts. Thus the adjuster takes up excess slack due to lining wear, but not that due to drum expansion. The adjuster is suited for use on those drum brake adjusters where the strut is lengthened by operation of the service brake actuator, and not of the handbrake actuator.

Abstract: A brake has an automatic adjuster including a pawl and ratchet mechanism, the adjuster comprising a bimetallic strip arranged to disengage the pawl from the ratchet when a predetermined temperature is attained. When there is excessive travel of the pawl, the strip permits re-engagement of the pawl with the ratchet to thereby permit adjustment. The pawl is preferably formed on a lever pivotally connected to one of the shoes of the brake and the bimetallic strip is connected to the lever.