Patent ID: 7293575

Claim:
A mechanical override for an actuator of a valve, comprising: an outer housing coupled to the actuator, the outer housing having a longitudinal bore therethrough; a shaft extending through the longitudinal bore; a drive ring, wherein the drive ring and shaft move axially through the housing during an automatic operation of the actuator; and a fusible backstop limiting axial movement of the drive ring during a manual operation of the mechanical override, thereby permitting the shaft to traverse axially through the drive ring and the longitudinal bore during the manual operation, wherein the backstop is a member having a smaller inside diameter than an outside diameter of the drive ring, thereby selectively preventing the drive ring from passing through an end portion of the longitudinal bore, and wherein the fusible backstop has a lower melting point than other components of the actuator that can, in a failsafe operation, maintain the valve in a closed position.