Fail safe linear actuator system

Claim 1

A fail safe actuator system which comprises: a power source; a controller, coupled to said power source, for transmitting control signals to selected components of said system; a motor which is energized by said power source through said controller; a pump means which is powered by said motor; a fluid reservoir; at least first, second, and third conduits; at least first, second and third valves electrically connected to said controller for receiving said control signals; an actuator comprising a first fluid chamber and a second fluid chamber, said first fluid chamber being in communication with said fluid reservoir via said first conduit and said second fluid chamber being in communication with said fluid reservoir via said second conduit; means for changing fluid flow direction in both said first and second conduits; a fail safe mechanism for returning the actuator to its inoperative position if the actuator system should lose electrical power, including a pressurized fluid storage means connected to said third conduit, said first valve being disposed within said third conduit for controlling fluid flow to and from said pressurized fluid storage means; the second valve being disposed within said first conduit for controlling fluid flow between said pressurized fluid storage means and said actuator; the third valve being operative for dumping fluid from said actuator when said actuator is being returned to its inoperative position; means for signaling and automatically enabling said controller only when said pressurized fluid storage means has been sufficiently charged with fluid to provide fail safe operation, the controller otherwise being disabled from providing control signals to said valves, which signals would ordinarily permit fluid flow to said actuator.