Gate valve actuator override mechanism

摘要

A gate valve hydraulic actuator having a stem extension accessible from outside the actuator body to provide override operation of the gate valve, for example in the event of hydraulic failure. The stem extension is lockable to a spring compression hub in a valve open position and a valve closed position by locking dogs selectively engageable in recesses. The locking dogs are operated by a cam spindle coaxially received in the stem extension.