Patent ID: 7073590

Claim:
A seal assembly positioned in a transverse bore of a seal carrier in a valve, the seal carrier shifting from a closed position to an open position, and the valve having a pair of opposing seal plates, the seal assembly being aligned with the seal plates when the seal carrier is in the closed position, and the seal assembly being out of alignment with the seal plates when the seal carrier is in the open position, the seal assembly being exposed alternatively to supply pressure and to function pressure, the seal assembly comprising: a seal spool having a central circular collar and a transverse axle, a first end portion of the axle extending from one side of the collar and a second end portion of the axle extending from the opposite side of the collar; a first seal cup having a through bore, a portion of the bore being sized and arranged to receive the first end portion of the axle, the seal cup having a sealing surface to seal against the opposing seal plate; a second seal cup having a through bore, a portion of the bore being sized and arranged to receive the second end portion of the axle, the second seal cup having a sealing surface to seal against the opposing seal plate; a first O-ring positioned around the first end portion of the axle; a first pair of generally triangular back-up rings having a first triangular back-up ring positioned around and in contact with the first end portion of the axle between the first seal cup and the first O-ring and a second triangular back-up ring positioned around and separated from the first end of the axle between the first seal cup and the first O-ring; a second O-ring positioned around the second end portion of the axle; and a second pair of generally triangular back-up rings having a first triangular back-up ring positioned around and in contact with the second end portion of the axle between the second seal cup and the second O-ring and a second triangular back-up ring positioned around and separated from the second end portion of the axle between the second seal cup and the second O-ring; and the first O-ring compressed by the first seal cup and first pair of triangular back-up rings against the collar and the second O-ring compressed by the second seal cup and second pair of triangular back-up rings against the collar so the O-rings act as seals and as springs urging the seal cups into contact with the opposing seal plates and the first and the second pairs of triangular back-up rings prevent extrusion of the O-rings through the through bore of the seal cups and the transverse bore of the seal carrier.