Seal assembly with backup ring

A seal assembly comprising first and second axially spaced members mounted for relative rotation about a common axis, the first member having a counterbore formed in one face, the second member having an end face opposite the counterbore;

• a seal ring of tough abrasion-resistant material having a W-shaped configuration in cross section disposed within the counterbore defining an annular groove facing the side wall of the counterbore, said seal ring including a driving flange engaged in non-rotative driving contact relationship with the side wall and end wall of the counterbore at the juncture of these walls, a sealing flange adapted to be engaged in annular face sealing rotative contact relationship with the end face of the second member, said seal ring also having an intermediate section connecting flanges, the intermediate section of said seal ring being outwardly projected to form the seal ring in W-shaped configuration with the flanges;
• and a backup ring of elastomeric material having substantial resiliency characteristics, said backup ring being disposed within the annular groove of said W-shaped seal ring spaced substantially from the intermediate section of said seal ring so as to define and enclosed space between said backup ring and said seal ring, said backup ring being axially compressed between the driving flange and the sealing flange, whereas the load exerted on the seal flange face is the sum of the compression force of said backup ring and said seal ring and an internal pressure developed in the enclosed space.