Extensible and retractable device having manually releasable positive locking means

Claim 1

AN EXTENSIBLE AND RETRACTABLE DEVICE AND LOCKING MEANS COMPRISING AN ELONGATED HOLLOW CYLINDER, ONE END SURFACE OF SAID CYLINDER BEING BEVELED OUTWARDLY, A CYLINDER HEAD THREADEDLY RECEIVED ON ONE END OF SAID CYLINDER, AN INWARDLY OPENING ANNULAR RECESS BETWEEN SAID HEAD AND THE ADJACENT END OF SAID CYLINDER, MEANS ON SAID HEAD FOR ATTACHING THE SAME TO A COOPERATING STRUCTURE, A PISTON SLIDABLY RECEIVED IN SAID CYLINDER, A PISTON ROD CONNECTED TO SAID PISTON AND PROJECTING FROM THE OPPOSITE END OF SAID CYLINDER, A CENTRAL AXIAL BORE IN SAID PISTON OPENING TOWARD SAID HEAD, A RADIAL APERTURE IN SAID PISTON COMMUNICATING WITH SAID BORE, A SECOND BORE IN SAID PISTON CONCENTRIC WITH SAID FIRST BORE AND OF SMALLER DIAMETER, A PLUNGER SLIDABLY DISPOSED IN SAID SECOND BORE, AN ANNULAR FLANGE ON THE OUTER END OF SAID PLUNGER, A COMPRESSION SPRING BETWEEN SAID FLANGE AND THE INNER END OF SAID FIRST BORE, A LOCKING DETENT SLIDABLY DISPOSED IN SAID RADIAL APERTURE, A BEVELED SURFACE ON THE OUTER END OF SAID DETENT, COOPERATING LOCKING CAM MEANS ON THE INNER END OF SAID DETENT AND ON SAID FLANGE, SAID MEANS INCLUDING A ROLLER AND A CAMMING SURFACE, SAID ROLLER ROTATABLY ENGAGING SAID CAMMING SURFACE AS THE DETENT MOVES, A MANUALLY OPERABLE LOCK RELEASING PIN SLIDABLY MOUNTED IN SAID HEAD FOR ENGAGING THE OUTER END OF SAID PLUNGER AND SPRING MEANS FOR URGING SAID PIN OUTWARDLY, WHEREBY WITH SAID PISTON AT SAID ONE END OF SAID CYLINDER SAID DETENT WILL BE CAMMED OUTWARDLY INTO SAID RECESS AND LOCKED IN POSITION BY SAID LOCKING CAM MEANS TO LOCK SAID PISTON AGAINST MOVEMENT AND UPON ACTUATION OF SAID PIN TO FORCE SAID PLUNGER INWARDLY, SAID DETENT MAY MOVE INWARDLY TO PERMIT MOVEMENT OF SAID PISTON UPON APPLICATION OF A FORCE TO SAID PISTON ROD.