Machines for attacking defensive walls

Taken from ancient war books, the model proposed by Leonardo represents a machine for attacking defensive walls. It consists of a mobile structure with an armoured bridge that could rest on the enemy walls, allowing the assaulting troops to pass the ditch and penetrate in the city or castle.

For assaulting enemy city walls, Leonardo proposes, in addition to new machines, some classical systems, taken for example from Vitruvio. This ladder is fixed to a special support: a partially toothed wheel grips into a worm screw. A crank turns the wheel back and forth. This movement lifts and lowers the ladder.
Codex Atlanticus, sheet 1084 - Codex Forster, sheet 46 v - about 1480