Fei Gang (飛杠)

Drawing of a Fei Gang, from 'Wu Bei Yao Lue (《武備要略》)'.

Fei Gang (飛杠, lit. 'Flying log bridge') was a wooden siege engine designed for bridge laying. Effectively a bridge on wheels, it allowed besieging troops to quickly set up a bridge over a moat (by simply push the vehicle into the moat), thus saving the time wasted on filling up the moat. It also had the added advantages of being much lighter and simpler to construct than the cumbersome siege tower, allowing besieging troops to set up multiple bridges at the same time.

Fei Gang could also be modified with additional drawbridges for wider moat.

Drawing of a Fei Gang with additional drawbridge, from 'Wu Bei Yao Lue (《武備要略》)'.