Automatically adjustable and thermally lockable strut for a drum brake

An automatically adjustable and thermally lockable strut for a drum brake, intended to be mounted in the vicinity of brake application means arranged between two first ends of two shoes lined with friction components, the strut, which bears at each end against a respective shoe, having a device which automatically extends according to wear of the friction components and which comprises a nut-and-bolt system operated by a pawl engaging with teeth of one of the members of the nut-and-bolt system, the pawl being mounted on an elastic leaf connected with the strut, the leaf elastically separated from the strut, when the brake is at rest, by means of a rocker lever mouted on the strut, the lever allowing, by tilting, the leaf to move toward the strut when the shoes are pushed apart, characterized in that the strut comprises temperature-sensitive means acting directly on the lever so as to prevent the lever from tilting and, consequently, prohibiting adjustment when the brake overheats, the temperature-sensitive means comprising a bi-metallic strip, the lever being formed by a plate mounted with diametral play on the bolt of the nut-and-bolt system and extended by an arm which forms an angle of less than 180.degree. with the plane of the plate, a free end of the arm cooperating with the leaf carrying the pawl, the lever having an extension of the plate located opposite the arm projecting outside the strut so as to directly engage with the bimetallic strip mounted on the strut in order to lock the lever in a position where the pawl is separated from the teeth.