Plug valve with improved expandable plug

Claim 1

A PLUG VALVE COMPRISING A BODY WITH A FLOW PASSAGE THERETHROUGH, A LATERAL BORE IN SAID BODY, TWO SPACED CYLINDRICAL SEGMENTS, ONE DISPOSED OVER EACH SAID FLOW PASSAGE AND IN SAID LATERAL BORE, SAID CYLINDRICAL SEGMENTS BEING OF SLIGHTLY SMALLER RADII THAN THE RADIUS OF SAID LATERAL BORE, A CYLINDER DISPOSED BETWEEN SAID CYLINDRICAL SEGMENTS WITH ITS AXIS PERPENDICULAR TO THE AXIS OF SAID CYLINDRICAL SEGMENTS, MEANS ON SAID CYLINDRICAL SEGMENTS ON OPPOSITE SIDES THEREOF ENGAGING DIAMETRICALLY OPPOSITE PORTIONS OF SAID CYLINDER, AND MEANS TO COMPRESS SAID CYLINDER LATERALLY BETWEEN SAID CYLINDRICAL SEGMENTS WHEREBY SAID CYLINDRICAL SEGMENTS ARE URGED OUTWARDLY INTO ENGAGEMENT WITH THE OUTER WALLS OF SAID LATERAL BORE, MEANS TO ROTATE SAID CYLINDER TO BRING THE INSIDE THEREOF INTO ALIGNMENT WITH SAID FLOW PASSAGES, SAID ROTATING MEANS COMPRISING A PRESSURE SHOE ATTACHED TO EACH SIDE OF SAID CYLINDER, A PACKING NUT THREADABLY ENGAGING SAID BODY AND ENGAGING ONE SAID PRESSURE SHOE, AND A STEM FOR ROTATING SAID CYLINDER ATTACHED TO ONE SAID PRESSURE SHOE AND EXTENDING THROUGH SAID PACKING NUT.