Fail-safe actuator and hydraulic system incorporating the same

摘要

The present invention is directed to an improved fail-safe actuator and hydraulic system incorporating the same. The actuator includes energy storage means in the form of a spring adapted to set a control device in a predetermined condition, illustratively in the closed condition, responsive to a failure situation, illustratively, a power failure. The actuator includes a coupling which permits normal operation of the control device without cycling the spring energy storage means, thus increasing the life of the spring and eliminating energy wastage inherent in cocking the spring during each operative cycle.