Lego Power Functions Vulcan Iron Works 0-4-0T
After spending quite some time building a Lego moc of one of the biggest steam engines in the world (the Union Pacific 4-8-8-4 'Big Boy'), I thought it would be fun to see how small of a steam engine I could model in a fairly realistic, in-scale manner, and yet, still have it be completely powered by Power Functions.
I decided that the perfect prototype to model for this project would be a Vulcan Iron Works 0-4-0T.
The main design goal was, of course, to find the most efficient packaging solution possible for the rechargeable battery box, receiver, M sized motor, and wiring. However, the battery box had to be accessible and removable for quick changing, and as such, it could not be used as a structural component in the moc's design.
A few of the other design goals were that it had to have functioning pistons and drive rods, good slow speed characteristics (it was going to spend a lot of it's time being used as a yard goat), and fully functional front and rear couplers. Equal weight distribution between the front and rear axles was also going to be key, as I needed to have a well balanced engine for maximum traction if it was going to have any kind of usable pulling power due to it being as small and light weight it would inevitably be.
You might have noticed that this moc uses the small train wheels, and (although I might be wrong) I think that this is the first steam engine moc with operating pistons and drive rods that uses those sized wheels as drivers.
The prototype that this particular engine is modeled after can be found here:
(BTW-the above link is a GREAT reference site for steam engine moc builders.)