'Threshing sledges' in the Bible

Araunah said to David, “Let my lord the king take and offer up what is good in his sight. Look, the oxen for the burnt offering, the threshing sledges and the yokes of the oxen for the wood.

Ornan said to David, “Take it for yourself; and let my lord the king do what is good in his sight. See, I will give the oxen for burnt offerings and the threshing sledges for wood and the wheat for the grain offering; I will give it all.”