An integral, preferably cast steel center plate includes a generally rectangular flat base portion defining spaced mounting flanges on opposite edges. A central circular boss extends from one face of the base, for engagement with a mating center plate bowl, and a pair of beams extending from the one face between the mounting flanges on opposite sides of the boss. In assembly to a car underframe, the mounting plate flanges are bolted to the longitudinal supporting flanges of the center sill with the beams stiffening the center plate for better resistance of eccentric forces.