From a long time ago, the Thudd Gun. I found two of these in the Loft Full Of Lead and thought they would be great for the Imperial Meridian Infantry. This was originally a Games Workshop Squat Artillery piece from 1988, the early and great days of Warhammer 40,000, before it became Warhammer $40,000.
The weapon below from what I remember is from much later and it was an Ork gun. This too will work very well as another steampunk artillery piece.
Funny how the two models, one for the Squats and one for the Orks have the same wheels. Never noticed that before.