Abstract: Wellhead flow control valve including a valve body, a hydraulic linear actuator means connected to valve body in alignment with operating chamber. Actuator has Belleville spring return. A seat sleeve carrying a valve seat and an internal lining mounts at outlet of operating chamber. Drive shaft moves flow control member of prescribed configuration into and out of valve seat sleeve. Flow control member and valve seat cause complete flow closure. Hydraulic conduit connects into actuator to admit hydraulic fluid to move piston and to compress spring. Activator is responsive to a pilot signal for: activating a pump control switch; to permit operation of pumps; activating a by-pass valve switch to keep closed a by-pass valve between conduit and sump of pump; and activating a blocking valve switch to keep open a blocking valve connected between pump and actuator.

Abstract: Improved tennis racket including a head, a handle, and a two hand hollow elongated grip member. The head is strung with elastic strings installed within a selected range of tension to provide a selected coefficient of restitution. The handle has a flexure section of selected length and of selected stiffness extending from the head to the grip member. Recovery characteristics and stiffness are selected to provide a desired coefficient of restitution and playability for a designated style of racket. The grip member has an inner end, an outer end, and a first longitudinal opening extending from the outer end and terminating at a selected distance to receive a portion of the handle. A second larger opening extends inwardly from the outer end and adjoins the first recess to define an annular cavity around a portion of the flexure section and an outer periphery of selected length along the grip member.