Wiktionary
shaft bow
n. Part of a horse harness, an arch from shaft to shaft over the horse's shoulders
Wikipedia
Shaft bow
A shaft bow is an element of horse harness that is attached to the front of the shafts of a horse-drawn vehicle and joins them by arching high above the neck of the horse. Use of the shaft bow is widespread in the area east of the Baltic Sea ( Russia, Finland and the eastern Baltic countries). A shaft bow is also used in traditional harness in Sicily. It is seldom seen in other parts of the world.
Usage examples of "shaft bow".
Longtusk saw the thin shaft bow into a curve, and then spring away from Bedrock, as if it was a live thing, hissing through the air.