Steam rollers/tractors

I have never been obsessed with automobiles - unless they are chunky, clunky things from the dawn of the non-horse drawn era or some wild Victorian SF or Steam Punk imagining. All the better if they have smoke stacks and armour.
I recently acquired some tin plate steam rollers that I want to convert to steam tractors for pulling heavy artillery.

A Redian cavalry column takes charge of the vehicles.