Hybrid manual and hydraulic override

An apparatus for overriding a valve actuator to move a valve stem from a first stem position to a second stem position, the apparatus comprising:

• an override body with a central axis, the override body having an inner cavity with an open end and a closed end;
• a bushing located within the inner cavity, the bushing being axially moveable within the inner cavity between a first bushing position and a second bushing position, respectively, and being restrained against rotational movement relative to the override body, the bushing further having axially extending threads, and an end surface facing the open end of the override body for selectively engaging the valve actuator;
• a piston located within the inner cavity, the piston having:
• an outer diameter that engages an inner diameter of the inner cavity,
• a central opening extending axially through the piston, and
• a pressure surface facing the closed end of the override body;
• a port extending through the override body for transferring a pressure media into the inner cavity between the pressure surface of the piston and the closed end of the override body;
• and
• an override shaft extending through the central opening of the piston, the override shaft having a first end that passes through an orifice in the closed end of the override body and a second end with threads for mating with the threads of the bushing, wherein the threads of the override shaft mate with the threads of the bushing so that rotation of the override shaft is translated to axial movement of the override shaft relative to the bushing until the override shaft engages the override body and locks the bushing in the second bushing position.

A method for overriding a valve actuator to move a valve stem from a first position to a second position, the method comprising:

• (a) providing an override assembly, the override assembly having an override body with a central axis, a piston located within the override body, a bushing non-rotatably carried within the override body, and an override shaft in threaded engagement with the bushing and extending through a sealed orifice in the override body;
• (b) releasably connecting the override assembly to the valve actuator;
• (c) applying a fluid pressure to the piston to cause the bushing to engage the valve actuator and push the valve stem, and
• (d) locking the position of the bushing relative to the override body through engagement of the override shaft with the override body, and simultaneous threaded engagement between the override shaft and the bushing.