Abstract: In a clearance compensator, a rod (12) is fixed to one of the shoes of the brake and is slidable in an intermediate element (13) threadably engaged in another rod (11) secured to the other shoe. A heat-sensitive bi-metallic strip (18) projects from a leaf spring (14) operable to urge the rod (12) away from the intermediate element (13). The bi-metallic strip (18) is orientated substantially tangentially of a ratchet wheel (17) fixed to the intermediate element (13); at its free end, the bi-metallic strip (18) has a stop element (18a) for engaging the ratchet wheel (17). At temperatures above a predetermined value, the strip (18) assumes a heat-induced deflected condition in which the stop element (18a) is disengaged from the wheel (17).