The Collaborative International Dictionary of English v.0.48:

Drawbar \Draw"bar`\, n. (Railroad)
      (a) An openmouthed bar at the end of a car, which receives
          a coupling link and pin by which the car is drawn. It
          is usually provided with a spring to give elasticity
          to the connection between the cars of a train.
      (b) A bar of iron with an eye at each end, or a heavy
          link, for coupling a locomotive to a tender or car.
          [1913 Webster]

WordNet (r) 3.0 (2006):

drawbar
    n 1: a strong metal bar bearing a hook to attach something to be
         pulled