Patent ID: 7731001

Claim:
A disc brake having a caliper that straddles a rotor with a bore therein for receiving a piston to define an actuation chamber, said bore having a groove for retaining a seal that engages the piston to seal the actuation chamber from the surrounding environment, a first friction member connected to the piston and aligned with a first side of the rotor, a second friction member connected to the caliper and aligned with a second side of the rotor, said actuation chamber being presented with pressurized fluid from a source that acts on the piston and the caliper to develop an actuation force for respectively moving the first friction member from a first position of rest into engagement with the first side of the rotor and the second friction member from a second position of rest into engagement with the second side of the rotor to effect a brake application, and a retraction arrangement acting on the piston to return the first friction member to the first position of rest on termination of the brake application to define a desired running clearance between the first friction member and the first side of the rotor, said retraction arrangement being characterized by a cylindrical body having a first end and a second end with a plurality of inward projecting fingers that extends from the second end, each finger being defined by a cylindrical section that extends from the second end and transitions into a first arcuate section that transitions into a radial section that transitions into a second arcuate section with the second arcuate section engaging the piston to apply a radial spring force on the piston in the first position of rest, said second arcuate section of each finger being moved by the piston during a brake application such that each finger pivots with respect to the second end of the cylindrical member and as a result the radial spring force decreases while an axial spring force is created in each finger that increases with the movement of the piston from the position rest and on termination of the actuation force applied to the piston the axial spring force returns the piston and correspondingly the first friction member to the first position of rest.