doubletree
/ˈdʌbəlˌtri/
noun
- A crossbar on a vehicle or plow to which two animals are harnessed side by side.
- He checked the doubletree to make sure it was securely fastened to the plow.
- The farmer attached the horses to the doubletree before plowing the field.
- The old wagon had a sturdy doubletree made of oak.