Patent ID: 6206338
Filing Date: 2001-03-27
Classification: E21B,F16K

Abstract:
An actuator for a valve, said valve being opened and closed by sliding a stem between a first and a second position, said actuator comprising:a housing for joining to said valve;an actuator piston reciprocatingly carried within said housing and adapted to couple to said stem, for sliding said stem between said first and said second positions;an elongate gripper shaft coupled to and extending from said actuator piston;a gripping member carried in said housing, said gripping member being moveable between an engaged position restraining movement of said gripper shaft in one direction and a disengaged position, allowing movement of said gripper shaft in both directions;a spring member mounted in said housing in engagement with said gripping member for urging said gripping member to said engaged position;a release piston reciprocatingly carried in said housing for moving said gripping member to said disengaged position; anda hydraulic passage extending from said actuator piston to said release piston for moving said release piston to place said gripping member in said disengaged position when hydraulic fluid pressure exists at said actuator piston.