Piston seal

A seal assembly for use on a piston having a piston seal groove with spaced shoulders formed therein comprising a deformable sealing ring adapted to be maintained in the groove and having generally circular and symmetrical inner and outer peripheral sealing portions, and generally flat and parallel side surfaces which are arranged at about right angles to a horizontal axis extending through a cross-sectional area of said sealing ring, said sealing ring being made from a thermosetting polyurethane elastomeric material having a relatively high shear modulus in comparison to rubber at the same hardness and being wear, tear, and abrasion resistant, said sealing ring having a cross-sectional diameter which is about twice the size of the cross-sectional diameter for a standard O-ring having the same inner diameter as said sealing ring;

• and a pair of unitary bearing means, each of which is juxtaposed opposite said slide surfaces of said sealing ring and being made of a wear-resistant material which is harder than said material of said sealing ring, each of said bearing means including bearing section means, and support section means, said bearing section means being adapted to be seated on a corresponding shoulder formed in the piston groove for providing a bearing support for said seal assembly, and said support section means contacting said sealing ring and including generally concave surface means which generally conform to at least portions of said flat side surfaces of said sealing ring for preventing extrusion and twisting of said sealing ring.