whippletree

noun, ‘swingletree’: a crossbar pivoted in the middle, to which the traces are attached in a cart, plow, etc (COD)

“The poor horses, they were coming back, the whippletree was hitting their heels.”

“Dad kept a neck rope or a whippletree and a chain hanging right in the horse stable.”

“Come in from the field with the load of hay and unhitch the horses, and then hook them onto the whippletrees, and then drive them out.”

“So then we hitch the horse onto a rope that has whippletrees and everything to the two horses, and somebody’s up on the load of hay and gets this big fork…”