Mechanism for controlling the closure member for a passage opening

Claim 1

IN A CLOSING DEVICE FOR ACTIVATING A MOVABLY MOUNTED CLOSURE MEMBER FOR CLOSING A PASSAGE OPENING, A SAFETY DEVICE FOR DISCONTINUING THE CLOSING MOVEMENT OF THE CLOSURE MEMBER WHEN AN OBSTACLE IS PRESENT IN THE PATH IN THE ADVANCING CLOSURE MEMBER, SAID SAFETY DEVICE COMPRISING HYDRAULIC DRIVE MEANS FOR MOVING THE CLOSURE MEMBER INTO SAID OUT OF A CLOSING POSITION, SAID HYDRAULIC DRIVE MEANS INCLUDING AN ACTUATING CYLINDER-PISTON ASSEMBLY HAVING ITS PISTON DRIVINGLY COUPLED TO THE CLOSURE MEMBER, ACTUATING CONDUIT MEANS CONNECTED TO SAID ACTUATING CYLINDER-PISTON ASSEMBLY ON BOTH SIDES OF THE PISTON THEREOF FOR SUPPLYING PRESSURE FLUID TO ONE SIDE OF THE CYLINDER AND DISCHARGING FLUID FROM THE OTHE SIDE OF THE CYLINDER TO CAUSE MOVEMENT OF THE PISTON AND WITH IT OF THE CLOSURE MEMBER INTO ONE DIRECTION OR THE OTHER DEPENDING UPON THE FLOW DIRECTION OF THE PRESSURE FLUID, AN ACTUATING VALVE MEANS INCLUDED IN SAID CONDUIT MEANS AND OPERABLE FOR SELECTIVELY REVERSING THE FLOW DIRECTION OF THE FLUID THROUGH SAID ACTUATING CONDUIT MEANS TO EFFECT CLOSING AND OPENING RESPECTIVELY OF THE CLOSURE MEMBER, A CONTROL CYLINDER-PISTON ASSEMBLY HAVING ITS PISTON DRIVINGLY COUPLED WITH SAID ACTUATING VALVE MEANS FOR CONTROLLING THE OPERATION THEREOF, A SAFETY VALVE MEANS INCLUDED IN A PART OF THE ACTUATING CONDUIT MEANS CARRYING THE FLOW OF FLUID DISCHARGED FROM THE CYLINDER OF SAID ACTUATING ASSEMBLY WHEN SAID ACTUATING VALVE MEANS IS OPERATED FOR CLOSING THE CLOSURE MEMBER, CONTROL CONDUIT MEANS CONNECTING SAID SAFETY VALVE MEANS WITH THE CYLINDER OF SAID CONTROL ASSEMBLY, SAID SAFETY VALVE MEANS BEING MOVABLE BETWEEN AN INACTIVE POSITION IN WHICH SAID ACTUATING CONDUIT MEANS ARE OPEN FOR CARRYING SAID DISCHARGE FLOW AND A STOP POSITION IN WHICH THE DISCHARGE FLOW IS DIRECTED THROUGH SAID CONTROL CONDUIT MEANS INTO THE CYLINDER OF SAID CONTROL ASSEMBLY WHEREBY THE PISTON THEREOF IS OPERATED TO MOVE SAID ACTUATING VALVE MEANS TOWARDS THE POSITION IN WHICH THE FLUID FLOW THROUGH THE ACTUATING MEANS IS IN THE DIRECTION FOR OPENING THE CLOSURE MEMBER, AND DETECTING MEANS PLACED IN THE CLOSING PATH OF SAID CLOSURE MEMBER TO DETECT AN OBSTACLE IN SAID PATH, SAID DETECTING MEANS BEING OPERABLE BY ENGAGEMENT WITH AN OBSTACLE AND DRIVINGLY COUPLED WITH SAID SAFETY VALVE MEANS TO MOVE THE SAME FROM SAID INACTIVE POSITION INTO SAID STOP POSITION UPON ENGAGEMENT OF SAID DETECTING MEANS BY AN OBSTACLE.