A castle’s Drawbridge typically formed its entrance and lead to the gateway. It spanned over the moat and could be raised to prevent entry into the fortification.
Drawbridges were commonly made of wood. The wooden deck had one edge hinged or pivoting at the gatehouse threshold so that it could be raised and flushed against the gate. Some might have been designed to be destroyed in the case of an attack.
How the Drawbridge Worked
The drawbridge was usually backed by one or more potcullises. Access to the bridge could also be resisted with missiles from the machicolations and arrow slits in flanking towers.
The drawbridge could be lowered or raised using ropes or chains attached to a windlass in a chamber in the gatehouse. Some form of bascule can usually be found for heavier bridges, as they provided a heavier counterweight. In some cases, the weight was provided by the portcullis. By the 14th century, bascule arrangements such as lifting arms were introduced. These were installed above and parallel to the bridge deck. The ends were linked by chains to the lifting end of the bridge. In the lifted position, the gaffs fit into slots in the gatehouse wall. Inside them, there were usually counterweights.