whippletree

noun

1. A wooden crossbar for a plough or carriage, pivoted in the middle, from which traces are fastened to a draught animal.

   “The single whippletree should have a chain attached to bring it out even with the other two.”

   “Like the whippletree, the wheelbarrow only became known in the Middle Ages.”

   “Note the two-horse whippletree on the beam at the lower left. (A whippletree, of which this is the simplest possible, balances the load on the animals.)”