I've studied the Walschaerts valve gear in my spare time before. Yes, it does look quite complex, but you have to remember that what you're showing there is practically the whole engine. It's got no need for a clutch or transmission because of its insane torque delivery and low revs. I submit that even with the valve gear, a steam engine is simpler than even a modern two-stroke, when you take into consideration that the two-stroke does indeed require a transmission, with all its splines and bearings and dogs and shifting forks and shifting cam, etc.
I love steam engines because they don't have the freakiness of internal combustion. With internal combustion, you look at the diagram and think, "Okay, so all that happens 350 times a second. How fast is that? Oh, whatever." You sort-of have to check your common sense at the door when thinking about them, because simple instinct tells you that such fast motion is impossible. With steam, though, even at full speed you could look at it and the whole thing makes sense. Even if the pistons are stroking 11 times a second at 80mph (that's Doyle McCormick's quote on the SP4449), it's still an order of magnitude less than even a relatively low-performance internal combustion engine.
I'm lucky to have this beautiful beast living just fifteen minutes from my home. She's got 78,000lbf of tractive effort, making her one of the best passenger steam locomotives created in the steam era.
SP 4449 Michigan bound 7-3-09
