A skew correcting apparatus for a crane supported on spaced apart generally parallel rails by a plurality of wheels including a drive wheel traveling on each of the parallel rails. The drive wheels traveling on the spaced apart rails are driven such that they rotate at the same speed. One of the drive wheels has an axially extending single diameter cylindrical surface engaging the top side of the rail head and a radially extending circumferential flange facing the inner side of the rail head. In one of the skewed positions of the crane, one of the wheels lags the other of the wheels and is subject to high levels of skew force such that the flange of the lagging wheel and the inner side of the rail head it faces engage each other. Each one of the wheels also includes a flange juncture surface joining the cylindrical surface of the flange of each wheel. The flange juncture surface faces the shoulder surface of the rail head and includes a flange cross-sectional curvature having a flange radius greater than the shoulder radius of the faced rail head. In the lagging one of the wheels, in response to small levels of skew force less than the levels of skew force that cause the flange of the lagging wheel and the inner side of the rail head to engage, the flange juncture surface moves into engagement with the facing shoulder surface to increase the diameter of the lagging one of the wheels in engagement with the shoulder surface.