Disc brake assembly

A disc brake assembly (1) for a vehicle in which pad assemblies (102, 103) provided with friction linings for engagement on opposite faces of a rotor (101) are mounted in opposed limbs (11, 12) of a carrier (10) which extends over a peripheral edge of the rotor (101), and an actuating mechanism provided in one of the limbs is adapted to apply one of the pad assemblies (102, 103) to an adjacent face of the rotor (101), the other pad assembly being applied to the opposite face of the rotor as a result of the reaction of the actuating mechanism characterized in that the actuating mechanism comprises an annular piston (20) defined by inner and outer concentric walls (22, 23) working in an annular bore (21) in said one of said limbs (11, 12) and moveable between a retracted position which determines the braking clearance and an advanced brake-applying position, a ball and a ramp assembly housed in an annular space between the walls (22, 23) and acting between the piston (20) and said one limb to urge the piston towards the rotor (101) in the brake applying position to apply the brake, and an annular adjustment ring (50) through which the ball and a ramp assembly acts on the piston (20), the ring (50) being in screw threaded engagement with one of the walls, and an adjuster adapted to rotate the ring with respect to the piston to advance the piston (20) relatively towards the rotor (101) to compensate for wear of the friction linings thereby to maintain the piston in a retracted position in which the braking clearance is substantially constant.