Meaning of center plate

cen'ter plate"

Pronunciation: [key]
— Railroads. Railroads.
  1. one of a pair of plates that fit together and support the body of a car on a truck, while allowing the truck to rotate with respect to the body. One plateis attached to the underside of the car body and the otheris part of the car truck.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.