Sealing members for master cylinders

Claim 1

An annular sealing member assembly to be disposed in an annular space defined by the inner wall of a cylindrical bore, the outer wall of an operating piston axially movable in said bore, and a pair fixed, axially-spaced annular surfaces, said assembly comprising at least two sealing members, each said sealing member including an annular base portion, an outer annular lip portion integrally formed on said base portion for sealing engagement with said inner wall, an inner annular lip portion integrally formed on said base portion for sliding and sealing contact with said outer wall, and an annular rib portion integrally formed on said base portion radially between said lip portions, said rib portion axially extending in the same direction as and for a distance greater than said lip portions and having a plurality of radially-extending slots permitting uniform distribution of fluid between the peripheries of said sealing member, wherein said sealing members in said assembly are axially abutting and so oriented that the base portion of one sealing member abuts one said annular surface, the base portion of the other sealing member abuts the end of the rib portion of said one sealing member, and the end of the rib portion of the other sealing member abuts the other annular surface.