Piston valve with spring pressed head

Claim 1

A SHUT-OFF VALVE COMPRISING, IN COMBINATION, A VALVE HOUSING HAVING AN INLET AND AN OUTLET AND COMPRISING AN ANNULAR PORTION INTERMEDIATE SAID INLET AND SAID OUTLET; A VALVE MEMBER COMPRISING A SPINDLE HAVING AN END PORTION AND AXIAL SHIFTABLE IN SAI HOUSING IN A FIRST AND SECOND DIRECTION FOR RESPECTIVELY MOVING SAID END PORTION INTO AND OUT OF SAID ANNULAR PORTION, AND A HEAD MOUNTED ON AND MOVABLY BY SAID SPINDLE INTO AND OUT OF SAID ANNULAR PORTION, SAID COMPRISING A FIRST ANNULALR COMPRESSING MEMBER AXIALLY MOVABLE MOUNTED ON SAID SPINDLE, A SECOND ANNULAR COMPRESSING MEMBER AXIALLY MOVABLE MOUNTED ON SAID SPINDLE BETWEEN SAID FIRST MEMBER AND SAID END PORTION, AN ELASTIC RADIALLY EXPANDABLE ANNULAR SEALING ELEMENT DISPOSED BETWEEN SAID COMPRESSING MEMBERS, AND RESILIENT MEANS OPERATING BETWEEN SAID STEM AND SAID FIRST MEMBER AND ARRANGED TO PERMANENTLY BIAS SAID FIRST MEMBER INTO COMPRESSIVE CONTACT WITH SAID SEALING ELEMENT SO THAT THE SEALING ELEMENT IS COMPRESSED AT ALL TIMES; AND STOP MEANS PROVIDED IN THE PATH OF AND ADAPTED TO ARREST SAID SECOND COMPRESSING MEMBER WHEN SAID HEAD IS MOVED INTO SAID ANNULAR PORTION WHEREBY, UPON FURTHER MOVEMENT OF SAID SPINDLE IN SAID FIRST DIRECTION, SAID SECOND COMPRESSING MEMBER MOVES ALONG SAID SPINDLE TOWARD SAID FIRST COMPRESSING MEMBER TO CAUSE DEFORMATION AND TO THUS INCREASE THE BIAS OF SAID RESILIENT MEANS SO AS TO FURTHER COMPRESS AND RADIALLY EXPAND SAID SEALING ELEMENT INTO TIGHT SEALING ENGAGEMENT WITH SAID ANNULAR PORTION.