If you've ever ridden a miniature train at an amusement park or zoo, Chances are you've ridden this: Chance Rides' famous C.P. Huntington ([link]
), a train based on a real locomotive with a 4-2-4 wheel arrangement. Of course, the Chance locomotive is powered by gas, not steam, and its drive system is radically different from its prototype's: whereas the real C.P. Huntington was powered by the 2 large wheels on the center axle (connected to the pistons), Chance built their locomotive powered by the wheels on the front and back trucks, leaving the center wheels in the design for decoration only. The powered trucks, connected to the motor via a spinning drive shaft under the boiler, make for an efficient drive system-- but one that is hopelessly unrealistic and ugly-looking for a supposedly rod-driven engine.
In fact, the Chance locomotive is driven in a manner much more closely resembling the real-life Heisler geared logging engines ([link]
)... And that's where I came in. The engine I drew above is what an amusement park engine might look like if it were based on a Heisler. It might not look exactly like a traditional locomotive, but its design is perfect for Chance's mechanical drive system-- it's functional and doesn't look half bad! The only "fake" elements are the cylinders below the running boards, as the drive shaft is actually driven by the gearbox under the firebox. The firebox houses the motor.
(I don’t, of course, have any relation to Chance Rides. They are property of themselves.)