Swingletree

thumb|A typical wooden swingletree with iron fittings thumb|The red horizontal bar behind the horse is a swingletree thumb|A swingletree built into a cart. The swingletree is the triangular piece in the foreground; the traces are the leather straps leading forward from this. (Swingletrees are more commonly a simple bar, not a triangle.) A swingletree (British Isles) or singletree (North America) is a small wooden or metal bar behind a harnessed horse. It is used to balance the pull of a driving horse or other draught animal when pulling a vehicle or other load. It is a kind of whippletree, and the term is also used sometimes for other whippletrees.

The swingletree is a horizontal bar, attached or suspended in the middle, and able to pivot in a horizontal plane. The traces (the straps by which the horse pulls the load) attach to the ends of the swingletree, and the load is pulled from the centre point.