singletree

sin·gle·tree

S0427900 (sĭng′gəl-trē′)n. The pivoted horizontal crossbar to which the harness traces of a draft animal are attached and which is in turn attached to a vehicle or an implement. Also called regionally whiffletree, whippletree.

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[Alteration (influenced by doubletree) of swingletree.]

singletree

(ˈsɪŋɡəlˌtriː) n (Horse Training, Riding & Manège) a variant, esp US and Austral, of swingletree

whif•fle•tree

(ˈʰwɪf əlˌtri, ˈwɪf-)

n. Northern U.S. a crossbar, pivoted at the middle, to which the traces of a harness are fastened for pulling a vehicle or a plow. Also called whippletree , singletree. [1820–30; variant of whippletree]

Singletree

A beam of wood, about three feet long with hooks on each end to which harness Tugs or Traces were attached. The middle of the singletree was attached to either an Evener or a one-horse implement.