Abstract: The brake comprises a torque control valve comprising a main piston which cooperates via a bearing piece with a shoe of which the bearing force is representative of the torque supplied by the brake during operation of the brake motor. The main piston controls the pressure admitted to the brake motor by a cut-off valve responsive to displacement of the main piston and by a variable volume decompression chamber of which a movable wall decompresses the fluid contained in the brake motor when the torque generated by the brake exceeds the limit of a predetermined torque-pressure law.

Abstract: A wear indicator for the friction material of a drum brake shoe includes a spring-loaded captive plunger carried in an elongated sleeve attached to the brake shoe. The plunger includes an enlarged head which abuts the sleeve and which is recessed below the surface of the unworn friction material at a depth which corresponds to a worn-out shoe. When the shoe wears to a sufficient degree, the plunger head is worn off by the rotating brake drum and the plunger is released. When freed, the plunger is moved by the spring bias and slides within the sleeve to press against an electrical contact carried by the backing plate of the brake to close an alarm circuit.