Two-piece seal

Claim 1

A composite seal for sealing engagement with a radially extending end wall and an axially extending wall defining an annular cavity in a stationary member and for sealing with a moving member, said seal comprising: a first soft flexible annular sealing ring made of elastomeric material having an annular sealing lip edge for sealing engagement with the moving member at first predetermined pressures, said sealing lip having a chamfered edge inclined to be pressed by higher pressure forces to have greater contact area; a second lip on said first sealing ring being inclined radially away from said first lip said second lip being spaced from said first lip and defining an annularly extending groove therebetween; an axially extending wall on said first sealing ring extending from said second lip and coacting with said second lip for sealing engagement with the axially extending wall defining the annular cavity; a second annular sealing ring of material harder than the material of said first sealing ring and having a friction characteristic lower than that of said elastomeric material, said second sealing ring having a radially directed extending sealing lip and having an edge for engaging said moving member at a position spaced axially downward from said annular sealing lip on said first ring, each of said sealing edges on said first and second seals having a diameter for sealing in interference with said moving member at a low pressure loading of said seal, said first and second sealing rings having surfaces abutting one another to deflect the sealing lip on said second ring to deform into greater contact area with said moving member with increased pressure on said first sealing ring, a radially extending end wall on said flexible sealing ring disposed behind a portion of said second sealing ring for sealing engagement with the radially extending end wall on said stationary member, said axially extending wall on said first sealing ring extending from said second lip to said end wall, and interlocking means on said first and second sealing rings mated with one another to prevent substantial relative displacement bodily of said first sealing ring relative to said second sealing ring and thereby reducing a likelihood of bypass leakage between said first and second sealing rings.