Abstract: A valve assembly includes a valve closing device that is located within the flow passageway closed by the valve. The valve closure device includes a force member for imparting a closing force on a valve disk adjacent to the portion of the disk that contacts a valve seat. The force member is preferably a lever or fulcrum arm having an abutment extension at one end for directly contacting an edge of the valve disk. The opposite end of the lever preferably includes a weight for urging the disk into a closed position and for imparting a closing force upon the disk. The force member is mounted for movement relative to the valve disk and for movement with the valve disk as the valve disk rotates between an open and closed position.