Master cylinder piston with floating sealing ring recuperation valve

Abstract

A hydraulic master cylinder piston carries a circumferential seal ring which allows recuperation flow valving. The floating seal has a reinforcing metal girdle which prevents radial expansion and axial crushing. The seal material resists extrusion and has an outer radius slightly greater than the radius of the circumferential girdle. A forward slotted bearing ring maintains the piston in alignment with the bore. During piston return, recuperation occurs through a path comprising the radial clearance between piston and floating seal ring and at least one slot or groove in the bearing ring. Upon full piston return, the seal is withdrawn from the master cylinder working chamber into a larger diameter bore communicating with the reservoir and thus allows relatively free make-up flow.