Normal operating fluid pressure is applied behind a brake release piston in a first pressure chamber in the brake assembly. Variable operator control fluid pressure is applied in a second chamber of the assembly behind a brake applying piston which opposes the brake release piston in the assembly. A dry chamber for stator and rotor discs of the brake lies between the two pistons with a skirt of the brake release piston surrounding the discs and engaging a pressure plate forming the endmost stator disc adjacent to the brake applying piston. Brake applying springs are intervened between the pressure plate and brake applying piston to impart to the disc brake a fail-safe capability as well as a brake "on" condition when the system is depressurized.
