drawspring

from The Century Dictionary.

• noun An apparatus designed to counteract the recoil or shock when a tow-rope or cable breaks
• noun it consists of a cylinder, having a piston-rod to which india-rubber bands are fitted, and a chain to which the tow-rope of a boat or the cable of a ship at anchor is made fast.
• noun A spring connecting the draw-bar of a railroad-car with the car, and designed to resist both tension and compression.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Railroad) The spring to which a drawbar is attached.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun rail transport The spring to which a drawbar is attached.