Harness saddle

Not to be confused with the saddle of a postilion rider.
Carriage harness saddle (left); heavy-cart saddle (right)
Horse wearing a harness saddle with attached breeching and horse collar
Closeup of saddle showing typical metal hardware: rein terrets, overcheck hook, D-ring for crupper

A harness saddle is an element of horse harness which supports the weight of shafts or poles attaching a vehicle to a horse. Like other types of saddle, it lies on the horse's back directly behind the withers, often has an internal supportive framework (referred to as a saddle tree), and usually is secured on either side by a girth passing beneath the horse. Unlike riding saddles, it is an integral part of the harness and is not used as stand-alone equipment.