Wubei Zhi (Vol. 48)

The Dao Che knife-cart is a two-wheeled vehicle with spear blades densely arranged, protruding from the rear. Whenever an enemy attempts to breach or destroy a city gate, this vehicle is used to block the opening.

This entry describes the "knife-cart," a specialized mobile barrier designed to be wheeled into place to physically plug gaps in city gates during a siege.