From draw +‎ hook.

drawhook (plural drawhooks)

1. (rail transport) A coupling hook.
   • 1940 November, “Notes and News: A Highland Collision”, in Railway Magazine, page 612:

     [...] as to wrought iron drawhooks, the failure of one of which, in a coarsely crystalline condition, was the principal cause of the accident, it was laid down in March 1934, that all new wagon drawbars must be of steel to British Standard Specification No. 80, [...].