Abstract: In accordance with a preferred embodiment of this invention, a precessing bottom pour stopper is used to accurately and precisely control the flow of molten metal through the tap hole which is located in the bottom of a metallurgical vessel. The precessional movement of the stopper, as it moves into and/or out of sealing engagement with the tap hole, removes any debris which may be lodged between the sealing surfaces and thereby ensures a tight seal over a prolonged period of operation.

Abstract: A rotator for a valve which is reciprocable along a longitudinal axis between open and closed positions and which is rotatable about such axis. The rotator includes a pair of parts movable axially and rotatably relative to one another along and about the longitudinal axis. Variable force applying means in the form of a spring urges the valve toward its closed position and also urges the pair of parts toward one another with forces which alternately increase and decrease in magnitude during opening and closing movement of the valve. The valve is rotated during axial movement thereof by relative rotation between the two parts which is produced by a plurality of shiftable elements located between the parts and movable along separate paths which are dimensioned and positioned so that all of such paths taken together have a total path length which is greater than the circumference of a reference circle drawn about the longitudinal axis and passing through the midpoints of the paths.