Split sealing ring having a bias cut

An improved, generally rigid annular split back-up ring for a seal assembly, the back-up ring having generally curved radially inner and radially outer surfaces and opposed first and second axial surfaces extending between the radially inner and outer surfaces, the back-up ring having an axially extending, radially centered axis and a cut extending therethrough from the inner radial surface to the outer radial surface to create a gap for facilitating installation and removal of the back-up ring, wherein the improvement comprises:

• the cut extending through the back-up ring along a single continuous cut plane, the orientation of the cut plane being determined by establishing a first reference plane extending radially through the back-up ring and generally parallel to and through the axis, a second reference plane extending generally perpendicular to the first reference plane and generally midway between the first and second axially surfaces to establish a first generally radially extending reference line, and a third reference plane extending generally perpendicular to the first and second reference planes and midway between the inner and outer radial surfaces to establish a second generally axially extending reference line and a third reference line, the cut plane being oriented at a first predetermined angle with respect to the second reference plane and the first reference line, and at a second predetermined angle with respect to the third reference plane and the third reference line, the cut creating opposed surfaces which engage to form a seal when the gap is closed to provide extrusion protection in both the axial and radial directions.