What is "harness saddle"

n. An element of horse harness which supports the weight of shaft or poles attaching a vehicle to a horse.

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, often called 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.