Lip type oil seal

Claim 1

A lip type seal member for a piston and cylinder wherein the seal member is disposed in an annular seal groove formed on the piston or cylinder and cooperates with the piston and cylinder to define two working chambers and wherein pressurized fluid is admitted to one chamber during a first operating condition and to both chambers during a second operating condition and wherein the pressurized fluid is exhausted from the one chamber more rapidly resulting in a pressure reversal on the seal upon completion of the second operating condition; said seal comprising an annular body portion disposed in the seal groove and having a non sealing annular surface adjacent one side of the annular seal groove facing toward the one chamber which non sealing annular surface has a plurality of radial grooves which permit fluid flow from the other chamber to the one chamber when the one chamber is rapidly exhausted after both chambers have been pressurized, and an annular sealing surface adjacent the other side of the annular seal groove facing toward the other chamber which annular sealing surface seals in the annular seal groove when the one chamber only is pressurized to prevent fluid flow from the one chamber to the other chamber.