Abstract: An oil well string member has a cylindrical outer periphery having first and second cylindrical surfaces axially spaced and connected by a tapered ramp. The surfaces are radially inwardly of the outer periphery. The first surface has a smaller diameter than the second surface. A seal assembly is provided along the first surface and arranged to respond to fluid pressure for moving the assembly across the ramp to the second surface to a sealing position.

Abstract: A two-stage fluid seal assembly is provided for sealing between relatively moving parts, such as a piston and cylinder. The assembly comprises a hard-sealing, non-resilient material effective at high pressure and a resilient soft-sealing material effective at low pressures.

Abstract: A sealing ring firmly grips a movable piston, performs the normal sealing function, and when pressure is released on the piston the sealing ring pulls back on the piston so as to retract the piston. The sealing ring is designed so as to fit in a conventional seal or "O" ring groove without any modification of the groove.

Abstract: A sealing ring firmly grips a movable piston, performs the normal sealing function, and when pressure is released on the piston the sealing ring pulls back on the piston so as to retract the piston. The sealing ring is designed so as to fit in a conventional seal or "O" ring groove without any modification of the groove.

Abstract: An annular seal of resilient material is disclosed and having an axially directed groove containing a spring between two interconnected body portions. At least one of said body portions has a sealing lip projecting in a radial direction generally opposite the location of said spring. Said groove has portions spaced from the bottom and in embracing contact with opposite surfaces of said spring. Said groove bottom being a portion of an ellipse and having embracing contact with a juxtaposed portion of said spring only when the sealing lip is under a compressive load.