Tai Ping Che (太平車)

Drawing of a Tai Ping Che (above) and its various componnets (below), from 'Zhan Shou Quan Shu (《戰守全書》)'.

Tai Ping Che (太平車, lit. 'Peaceful cart') is a unique siege defence weapon used by the Ming army. Despite the name, it is not actually a war cart, and anything but peaceful.

Tai Ping Che is actually a semi-cylindrical mobile gun turret armed with five small cannons. Equipped with two wheels, it can be easily raised or lowered down the wall with the help of a wall-mounted crane, which allows the turret to fend off besieging troops, particularly sappers, hiding in the hard-to-reach "dead zone" of the fortress. Since it'd be nearly suicidal to man the turret with gunners and send them outside the wall, Tai Ping Che is equipped with a Gang Lun Fa Huo (鋼輪發火) so that its five guns can be fired remotely.

It can be considered a successor design of Warring States period Mohist Xian Pi (縣脾, lit. 'Hanging spleen').