Harlock wrote:
The main drive shaft runs down the center of the engine, the two cylinders acting like a V-twin. Although I guess the Climax is also center-shafted.
So the shaft doesn't have to line up with one side of the trucks, unlike the Shay. Always in the same place regardless of gauge.
--Mike
Harlock,
I think I understand where you are coming from on this. At your original statement, I immeadeatly thought of the Hillcrest #1 24 ton Shay, the Westside #3 Heisler, and the Colo. & NW class C Climax. All of these were converted at least once to a different gauge, the Shay at least more than once. The task for each was not that much different: Change the axles, bolsters, end cross ties, spring planks, etc.. The Shay, as Curtis alluded to, would have the manifold casting changed that the cylinders bolted up to, which would change the angle of the power unit to align with the truck line shafts. Truck wise there is not that much difference between the designs to change the gauge.
However, if you are commenting that it would be the easiest just to roll another set of trucks under a model, Gordon Corwin did that on the Shay he built. He had a pair of trucks for 7.5" gauge, and a set for 4.75" gauge. I never checked, but I suspect the crank center line was between the center lines of the two line shaft center lines.
The Class A Climax was built to operate on 24" gauge up to 8' gauge, with all the others in between. With different sets of trucks, you could run the same 2.5" scale loco on tracks ranging from 4.75" to 20" gauge, and still be prototypical!
Regards,
Doug