History on the Rails...
Muscular Beauty of a Steam Engine
(Gallery Has Three Pictures)
This shiny beutiful steam engine once hauled coal. I imagine it has had a paint job to look as pretty as it does. The design of this steam engine was unique in that it had two sand domes on top of the boiler to provide sand for the rails to help with traction. The sand domes were on top of the boiler so that the heat would dry out the sand so that it would't clog the sand pipes, which continued to be a problem for steam engines none-the-less.
These big wheels required a lot of power to move them, with power supplied through these drive rods. The cast iron wheels had spokes, but were solid on one side as a counter weight to the drive rod connection, which needed to be heavy duty. The counter weight ensured that the wheels didn't wobble around their axels as they turned.
Freight Truck: "Give me your luggage, sir, and I'll put it on this cart to take it to the luggage car."