Floating stem seal assembly

Claim 1

In a valve construction comprising: a valve body with flow passageways therethrough, a valve closure member movable transversely of said flow passageways between blocking and unblocking positions relative thereto, an axially movable valve stem connected to said valve closure member to impart movement thereto, a valve bonnet slidably receiving said valve stem, a pressure fluid cylinder mounted on said valve body, including a cylinder housing end wall opposing said valve bonnet, said valve stem extending freely through said housing wall, and a piston in said cylinder connected to said stem, The improvement comprising: an enlarged recess in said housing end wall around said valve stem forming a first planar surface extending radially of said stem, a sleeve slidably received on said stem and loosely received in said recess, a seal ring on the inner surface of said sleeve sealing around said stem, a retainer plate secured to said housing end wall around said valve stem with a second planar surface thereon holding said sleeve in said recess, and a seal ring on and end surface of said sealing against one of said planar surfaces.