Whippletree (draught)
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A whippletree is a device to balance the pulls of draught animals, especially when pulling dragged loads such as a plough, harrow, log or canal boat. It also keeps the traces apart (these are the chains or straps on which the animal pulls). A special kind of whippletree, a swingletree, is sometimes used on a horse-drawn vehicle, and the term swingletree is sometimes used for whippletrees generally.
A whippletree is a loose horizontal wooden or metal bar behind the animal – the traces attach to its ends, and the centre is connected to the load. This balances the pull from each side of the animal.
When two horses are driven abreast, a paired set is sometimes known as a Double-tree.
If several animals are used abreast, further whippletrees may be used behind the first to balance the pulls of each. Thus, with two animals, each will have its own whippletree, then a further whippletree will balance the loads from the two. With three or more animals abreast, even more whippletrees are needed; these are sometimes made asymmetrical to reduce their overall number.
Without whippletrees, a point load such as a plough would pull the traces against the sides of the animal, the load would pull alternately from either side of the animal at each step, and one animal could allow another to take most of the load.
