Disc brake assembly including a self-contained actuator with wear take-up and anti-drag device

A brake assembly comprising:

• a friction disc, a brake shoe, a support plate mounted adjacent said friction disc, guide pins extending between said support plate and said brake shoe for movably supporting said brake shoe, return spring means for urging said brake shoe toward said support plate, a self-contained actuator carried by said support plate for urging said brake shoe toward said friction disc;
• said actuator including a cylinder, an actuated piston within said cylinder operatively engaging said brake shoe, an actuating piston, a rotatable threaded shaft member for translating rotational motion to axial motion operatively connected to said actuating piston, means for rotating said shaft member, a fluid-filled chamber between said actuated and actuating pistons defining a fluid link therebetween whereby axial movement of said actuating piston causes axial movement of said actuated piston, wear take-up and anti-drag means for permitting substantially free forward movement of said actuated piston in unison with said actuating piston to move said brake shoe toward said friction disc and for limiting retraction of said actuated piston and said brake shoe against the force of said spring means to a predetermined maximum distance, and fluid supply means contained within said cylinder for supplying additional fluid to said chamber in response to retraction of said actuating piston a distance greater than the predetermined maximum for said actuated piston and brake shoe to thereby accommodate the increase in volume of said chamber occasioned by the resultant separation of said pistons.