Abstract: A disc brake having a spring for mechanical actuation of the brake and a fluid pressure system for releasing and maintaining the brake in the released condition. Upon failure of the fluid pressure system, the brake is automatically actuated by the spring. Interposed between a friction member and a supporting body of the brake is a slant coil spring having an axis extending in a direction generally parallel to the disc surface. The coils are inclined at an angle with respect to the axis of the spring and the opposing edges of each of the coils are in engagement with the supporting body and the friction member to provide a substantially constant braking force over a range of braking positions with a spring requiring a minimum of space.