Patent ID: 6626438
Filing Date: 2003-09-30
Classification: F15B,F16J

Abstract:
A seal assembly for a telescopic hydraulic cylinder of the type having two cylindrical members fitted one inside the other, a seal groove in one member facing the other member, and a pressure chamber located adjacent on the inner side of the seal groove, said assembly fitted within the seal groove and comprising an annular primary seal member having inner and outer radial side walls and opposed axially spaced inner and outer ends, a first seal rib on each radial side of the primary seal member adjacent the inner end thereof, and a convex annular member extending outwardly from the outer end of the primary seal member; and an annular base seal member located in said seal groove adjacent the outer end of said primary seal member, the base seal member having inner and outer radial side walls, inner and outer axial ends, an annular concave opening in the inner end thereof, a second seal rib on each radial side of the base seal member adjacent the inner end thereof, and a heel located adjacent the outer end of the base seal member spaced axially away from the seal ribs thereof, the base seal member having an axial length about twice the radial thickness of the base seal member, said heel and said first and second ribs extending outwardly from said members when not compressed, said convex member fitted in said concave member, said primary seal member and base seal member each formed from a pressure-deformable elastomer, the hardness of said base seal member elastomer being greater than the hardness of said primary seal member elastomer; and an annular tube bearing member located in said seal groove outwardly from said base seal member, said bearing member engaging the outer end of the base seal member, wherein the seal ribs in said primary and base seal members engage said cylindrical members and are compressed into the primary and base members, the heel engages one of the said two cylindrical members and is compressed into the base seal member so that pressurization of fluid in the chamber pressure-biases the seal ribs against the bottom of the seal groove and against the surface of said one of the said two cylindrical members and the heel is compressed into the base seal member to prevent rolling of the base seal member in the seal groove during relative movement of the cylindrical members.