Double-beam drawbridge

The road surface is connected to the bottom hinge close to street level.

A rotating arm, the balance, is attached to the portal high up off the ground.

The drawback of a traditional double-beam drawbridge is that it has a limited clearance height.

When the pivot point falls behind the column, the tower is loaded eccentrically; this gives both pressure and flexion.

The rack is often not straight, but with a curvature at the end, like a hockey stick—this is to give the electric motor time to rev up and gradually raise (and lower) the bridge.