Burce,
You woud be surpirsed at how much maintenance live steam locomoives require. Even the "deisels" and rolling stock require quite a bit of maintenance. The steam locomotives especially require, proper lubrication, boiler washing, boiler tube cleaning, brake pad replacement, sometimes bearings need to be replaced. Also everything has to be lubricated constantly. All locomotives have either a hydrostatic lubricator or a mechanical lubricator to get oil into the cylinders. Also all moving parts have either roller bearings, greese cups, or some sort of grease fittings on them.
Spinning the drivers isn't that bad for them. It happens quite often when starting on a grade, or when you hit a patch of slippery track. What really flattens the driving wheels is when they lock up, but either applying the locomotive brakes too hard, or changing the "johnson bar "to the opposite direction the locomotive is moving.
Phil-
Actually the rolling stock, and "deisel" locomotives don't weather that much because they are inside most of the time, and generally kept pretty clean.
The Steam locomotives are another story. They are filthy. There is always coal cinders, oil, greese every where. Although after every run, most are washed. So the locomotives are rather clean most of time.
Thanks,
Andrew