Abstract: A support for stabilizing an elongated carriage-driving screw against whipping while permitting the carriage to pass the area at which the screw is supported including an elongated screw for driving a carriage, a base, spaced bearings selectively movable radially into engagement with opposite sides of the screw, and a moving linkage including a fluid piston and cylinder for selectively moving said bearings into and out of engagement with the screw, said bearings being either planar or concave, and in the latter instance, either fixedly or floatingly mounted.