A contour or profile of a bore of a locomotive traction-motor support bearing structure, where such profile preserves the currently center-loading of the upper load zone but moves inboardly the lower load zone to a more general central location. The profile of the bore for the support bearing, according to the invention, takes into account not only truck-axle bending due to locomotive weight, but also that from motor tilt through bearing clearances, and couple action on the axle from heavy radial loads on PE support bearing and adjacent axle gear. The bore is configured such that the upper surface is horizontal, but the lower surface slopes downwardly in the outboard direction at an angle based on a function dependent upon the three misalignment factors. In a preferred embodiment, the bore mid-section is defined as a frustroconical section of a cone with an altitude having a slope of substantially 1.times.M1 to the horizontal, and an apex angle of substantially arctan 2.times.M1, where M1 is the value of the misalignment factor associated with the locomotive load on the axle.