Gate valve having biased sealing means

Claim 1

A GATE VALVE COMPRISING: (A) AN ELOGNATED BODY; (B) A FLOW PASSAGE EXTENDING TRANSVERSELY THROUGH SAID BODY ADJACENT ONE END THEREOF, (C) SAID FLOW PASSAGE HAVING AN INLET AND AN OUTLET; (D) AN ELONGATED GATE HAVING SUBSTANTIALLY PARALLEL OPPOSITE FLAT SIDES AND BEING SLIDABLY ENGAGED TO MOVE LONGITUDINALLY IN A PATH IN SAID BODY; (E) A PORTION OF SAID OPPOSITE FLAT SIDES ADJACENT ONE END OF SAID GATE BEING ADAPTED TO BE MOVED FROM AN OPEN POSITION INTO A CLOSING POSITION ACROSS SAID PASSAGE BETWEEN SAID INLET AND OUTLET TO SHUT OFF THE FLOW THERETHROUGH; (F) A SEMICIRCULAR RECESS EXTENDING INWARDLY IN SAID ONE END OF SAID GATE AND HAVING ITS CENTER LINE IN A DIRECTION PERPENDICULAR TO SAID OPPOSITE SIDES, (G) SAID SEMICIRCULAR RECESS BEING IN ALIGNMENT WITH SAID FLOW PASSAGE WHEN SAID GATE IS OPEN; (H) SURFACES OF SAID OPPOSITE SIDES EXTENDING AROUND SAID SEMICIRCULAR RECESS; (I) A ROTATABLE SHAFT EXTENDING INTO SAID BODY; (J) A LEVER CONNECTED TO SAID SHAFT AND TO SAID GATE TO MOVE SAID GATE TO ITS OPEN AND CLOSED POSITIONS WHEN SAID SHAFT IS ROTATED; (K) SEAL MEANS IN RESPECTIVE ANNULAR RECESSES IN SAID INLET AND OUTLET ON EACH SIDE OF SAID GATE FORMING A SEAL ON THE GATE AT THE FLOW PASSAGE WHEN THE GATE IS CLOSED;