Valve actuators

Claim 1

A VALVE ACTUATOR COMPRISING A CASING, AN OUTPUT SHAFT FOR ACTUATING THE VALVE, AT LEAST ONE DRIVING MEMBER MOUNTED ON SAID OUTPUT SHAFT, POWER VALVE OPERATING MEANS ENGAGING SAID DRIVING MEMBER FOR IMPARTING A DRIVING TORQUE THERETO, SAID POWER VALVE OPERATING MEANS COMPRISING A WORMWHEEL CARRIED COAXIAL WITH AND ABOUT SAID OUTPUT SHAFT AND AXIALLY MOVABLE BETWEEN FIRST AND SECOND POSITIONS RELATIVE TO SAID OUTPUT SHAFT, A SHAFT WITH A WORM MOUNTED THEREON ADAPTED TO BE DRIVEN BY A MOTOR, SAID WORMWHEEL HAVING A AXIAL DIMENSION SUCH THAT SAID WORM ENGAGES SAID WORMWHEEL, WHEN SAID WORMWHEEL IS IN ITS FIRST AND SECOND POSITIONS, FIRST RESILIENT MEANS FOR BIASING SAID WORMWHEEL TOWARD ITS FIRST POSITION, A MANUAL VALVE OPERATING MEANS AXIALLY MOVABLE BETWEEN FIRST AND SECOND POSITIONS RELATIVE TO SAID OUTPUT SHAFT AND HAVING A LOWER END CONTACTING THE UPPER END OF SAID WORMWHEEL, SAID LOWER END INCLUDING MEANS FOR ENGAGING SAID DRIVING MEMBER FOR APPLYING A DRIVING TORQUE THERETO, SAID WORMWHEEL ENGAGING SAID DRIVING MEMBER WHEN IN ITS FIRST POSITION, SAID MANUAL OPERATING MEANS BEING OUT OF ENGAGEMENT WITH SAID DRIVING MEANS WHEN IN ITS FIRST POSITION, SAID MANUAL OPERATING MEANS BEING ADAPTED TO MOVE SAID WORMWHEEL DOWNWARD OUT OF ENGAGEMENT WITH SAID DRIVING MEMBER AGAINST THE BIASING ACTION OF SAID FIRST RESILIENT MEANS WHEN IT MOVES FROM ITS FIRST TO ITS SECOND POSITION AND ENGAGE SAID DRIVING MEMBER WHEN IN ITS SECOND POSITION, AND A RETAINING DEVICE COMPRISING A SECOND RESILIENT MEANS INCLUDING A RESILIENT MEMBER MOUNTED ON THE CASING OF SAID ACTUATOR FOR ENGAGING THE UPPER SURFACE OF SAID WORMWHEEL WHEN SAID MANUAL VALVE OPERATING MEANS IS IN ITS SECOND POSITION SO AS TO HOLD SAID WORKWHEEL IN ITS SECOND POSITION AGAINST THE BIAS OF SAID FIRST RESILIENT MEANS WHEREBY SAID MANUAL OPERATING MEANS MAY REMAIN IN ITS SECOND POSITION, SAID MANUAL VALVE OPERATING MEANS ADAPTED TO BE MANUALLY MOVED FROM ITS SECOND POSITION TO ITS FIRST POSITION AND INCLUDING MEANS FOR DISENGAGING SAID RESILIENT MEMBER FROM THE UPPER SURFACE OF SAID WORMWHEEL SO AS TO ALLOW SAID WORMWHEEL TO RETURN TO ITS FIRST POSITION AND INTO ENGAGEMENT WITH SAID DRIVING MEANS WHEN SAID MANUAL VALVE OPERATING MEANS IS SO MOVED, SAID RESILIENT MEMBER ALSO BEING ADAPTED TO DISENGAGE THE UPPER SURFACE OF SAID WORMWHEEL ALLOWING IT TO RETURN TO ITS FIRST POSITION INTO ENGAGEMENT WITH SAID DRIVING MEANS UPON THE OPERATION OF SAID WORMWHEEL BY SAID SHAFT ADAPTED TO BE DRIVEN BY A MOTOR.