These go along with the request for the train cannon. Three types of mobile heavy artillery guns. The top one is a standard large military artillery tank. On the right is wheeled artillery unit. The Vehicle at the bottom is a 'quake' artillery piece. The main gun detaches from the front tractor section when in use, to avoid shocks to the control system and so the tractor can act as a scout/spotter vehicle. The main gun is remotely controlled from the cabin of the tractor unit. It can be controlled via radio, but usually the tractor lays out a fiber optic land line.