Abstract: In an embodiment of the invention, the valve comprises an apertured valve seat toward and from which a valving element is movably disposed, for occluding and exposing the aperture in the valve seat to fluid flow. An actuating rod is coupled to the valving element and is movable along an axis for effecting movement of the element relative to the seat, and supporting structure is provided to support the actuating rod for its axial movement. However, the supporting structure, too, is movable along the aforesaid axis. Consequently, axial movement of the supporting structure reduces the possibility that, when the actuating rod must be moved, to effect movement of the valving element, it will be found to be stuck (i.e., "frozen") due to contamination, accretion of particulate matter, etc.