Retractable spanning rail and blast door arrangement

Claim 1

IN A MISSILE LAUNCHER SYSTEM OF THE TYPE HAVING A SPACED LOADER AND LAUNCHER EQUIPPED WITH ALIGNABLE MISSILE SUPPORTING RAILS, A RETRACTABLE SPANNING RAIL AND BLAST DOOR ARRANGEMENT COMPRISING AN ELONGATED SPANNING RAIL FOR SPANNING THE SPACE BETWEEN SAID LOADER AND LAUNCHER RAILS, MEANS TO SLIDINGLY SUPPORT THE SPANNING RAIL, A MOUNTING FRAME, A PAIR OF BLAST DOORS PIVOTALLY MOUNTED IN SAID FRAME FOR SAFEGUARDING A MISSILE ON SAID LOADER FROM SAID LAUNCHER, A HYDRAULIC PISTON HAVING A PISTON ROD, A LINK PIVOTALLY CONNECTED TO ONE END OF THE SPANNING RAIL AND TO SAID PISTON ROD, CONNECTING MEANS JOINING THE OTHER END OF THE SPANNING RAIL AND THE BLAST DOORS, AND CONTROL MEANS, SAID CONTROL MEANS INCLUDING A FLUID METERING VALVE, A SERVO VALVE IN FLUID COMMUNICATION WITH THE METERING VALVE AND THE HYDRAULIC PISTON, A CAM TRUCK CARRIED BY AND MOVABLE WITH SAID PISTON ROD, PISTON MEANS DISPOSED WITHIN SAID SERVO VALVE FOR CONTROLLING THE FLOW OF FLUID TO AND FROM THE HYDRAULIC PISTON AS THE PISTON MEANS MOVES FROM AN OPEN POSITION TO A CLOSED POSITION, A ROLLER CARRIED BY SAID PISTON MEANS ENGAGEABLE WITH THE CAM TRACK FOR MOVING THE PISTON MEANS TO AND FROM SAID POSITIONS, SAID SERVO AND METERING VALVES COOPERATING TO CONTROL THE FLOW OF FLUID INTO THE HYDRAULIC PISTON THEREBY TO CONTROL THE RATE OF SPEED AT WHICH THE HYDRAULIC PISTON MOVES THE SPANNING RAIL THROUGH ITS SUPPORT.