Torque reducer for high-pressure gate valves

A method for providing a rising stem gate valve to control high pressures of at least 5000 psi, said method comprising:

• providing a valve that defines therein a flow bore through said valve and a gate cavity that intersects said flow bore;
• disposing a gate in said gate cavity across said flow bore, said gate being axially moveable between a valve open position to allow flow through said flow bore and a valve closed position to prevent flow through said flow bore;
• providing a valve stem that is axially movable with said gate, said valve stem being fixed from rotation with respect to said gate;
• providing a torque reducer assembly comprising a ball screw assembly and a plunger gear shaft assembly,
• providing that said ball screw assembly comprises,
• providing a ball screw operatively connected to said gate and said valve stem,
• providing that said ball screw is fixed from rotation with respect to said gate and said valve stem, and providing that said ball screw is axially movable with said valve stem and said gate;
• providing a ball screw nut in surrounding relationship to said ball screw,
• providing that said ball screw assembly is connected so that rotation of said ball screw nut in a valve open direction axially moves said gate towards said valve open position, and rotation of said ball screw nut in a valve close direction axially moves said gate toward said valve closed position;
• providing that said plunger gear shaft assembly comprises,
• providing a gear shaft connected to be axially movable with said ball screw, valve stem, and said gate,
• providing that said gear shaft is fixed from rotation with respect to said ball screw, said valve stem, said gear shaft and said gate;
• and
• providing a plunger operatively connected for rotation around said gear shaft with rotation of said ball screw nut,
• providing that said plunger is movable between an engaged position with said gear shaft and a disengaged position with said gear shaft, in said engaged position said plunger gear shaft assembly being connected to prevent rotation of said ball screw nut in said valve open direction while permitting rotation of said ball screw nut in said valve close direction, in said disengaged position said plunger being disengaged from said gear shaft to permit rotation of said ball screw nut in said valve open direction and said valve close direction.