1) Crossbar 2) Swingletree 3) Whippletree 1) Swingletree 2) Whippletree 
• (n.) Same as Whippletree.
Whif'fle·tree` noun Same as Whippletree . 
(whippletree) A device, usually wooden with metal rings or hooks, to which traces are attached; may also be double to hold two single whiffletrees
[n] - a crossbar that is attached to the traces of a draft horse and to the vehicle or implement that the horse is pulling
whippletree noun a crossbar that is attached to the traces of a draft horse and to the vehicle or implement that the horse is pulling