The engine is a 2 cylinder, driving a disk crank that is up on the frame. The center of the crankshaft passes through a gear box that looks like about 4:1. The output of the gearbox drives a cross shaft and on each side is a chain drive to the main sprocket. The rear axle is solid, no differential. Thats part of why steering is so tough.
The engine is pretty typical of locomotive practice. up to the crank.The Johnson bar has several notches on the forward side, but only one on reverse- I guess you didnt back these up very much, certainly not when hooked to a train of sleds.
It is interesting that the injectors are right on the backhead, and the water input goes into the backhead- the hottest part of the boiler. Locomotives injected the water near the smoke box, but that made a long outside pipe which I suppose they worried about freezing. Even the lubricator is back in the cab, driven by a long push rod form the valve stem, then a long oil line back to the cylinders.
It sure is tempting to start a model of this- particularly now that I have such good access to one. Owls Head has some event each weekend of the summer, the director told me he'd like to run the Lombard a few times a year.