Cam actuated gate valve

Claim 1

A GATE VALVE INCLUDING A VALVE HOUSING, A VALVE SEAT DEFINING A VALVE APERTURE, A CLOSURE MEMBER OF COMPOSITE CONSTRUCTION AND LATERALLY TRAVERSABLE MEANS FOR MOVING SAID CLOSURE MEMBER ACROSS SAID APERTURE, SAID CLOSURE MEMBER COMPRISING IN COMBINATION: (A) A FIRST SUBSTANTIALLY FLAT MEMBER CAPABLE OF WITHSTANDING FULL ATMOSPHERIC PRESSURE; (B) A SECOND SUBSTANTIALLY FLAT MEMBER ADAPTED TO ABUT SAID FIRST MEMBER IN FACE-TO-FACE RELATIONSHIP AND BEING FORMED WITH AT LEAST ONE PRESSURE RELIEF APERTURE WHICH ENSURES SUBSTANTIAL PRESSURE EQUALISATION ACROSS SAID SECOND MEMBER; (C) CONNECTING MEANS BETWEEN SAID FIRST AND SECOND MEMBERS TO ALLOW LIMITED MOVEMENT AWAY FROM SAID POSITION OF FACE-TO-FACE RELATIONSHIP; (D) CONTROL MEANS ASSOCIATED WITH SAID CONNECTING MEANS CONTROLLABLY TO EFFECT SAID LIMITED MOVEMENT; (E) FIRST SEALING MEANS BETWEEN THE PERIPHERY OF SAID SECOND MEMBER AND SAID VALVE SEAT FOR COMPRESSION THEREBETWEEN AND SAID LIMITED MOVEMENT; AND (F) SECOND SEALING MEANS COMPRISING A FLEXIBLE ANNULAR SEALING MEMBER ATTACHED TO THE PERIPHERY OF SAID FIRST MEMBER AND EXTENDING INWARDLY TO SAID SECOND MEMBER TO PROVIDE AN EFFECTIVE SEAL BETWEEN THE PERIPHERIES OF SAID FIRST AND SAID SECOND MEMBERS WHEN SAID LIMITED MOVEMENT IS EFFECTED.