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>>1342984>Or was is it more the railroads didn't put these locomotives to good use and wasted their poential?Superpower of course did have many useful applications. The article does list several examples that were well used, such as the N&W J.
Now the thing about steam locomotive power, is that you've got two different kinds--Horsepower, adn Tractive effort.
HP is of course, an actual measure of power. Tractive effort, though, is based purely upon the geometry of the locomotive. And Tractive effort is what actually detirmines the tonnage a locomotive can pull, regardless of horsepower.
Horsepower is for speed, tractive effort is for tonnage.
Now as one might expect, a larger firebox of course means a better steaming locomotive. The problem is that tall drivers can interfere with a well proportioned firebox, and thus the reason for X-X-2, X-X-4, etc.
However, while bogies allow for a larger firebox (and better curve negotiation, for the frotn one), the weight upon them does not contribute to tractive effort, unlike an EMD F unit where it is all adhesive weight.
So we have a tradeoff amidst your locomotive design: bogies for better curving and a better firebox? Or more drive wheels for more poential tonnage?
Therefore, it depends on the trains you're hauling, as well as the what sort of gradients it will have to negotiate.
So if you could choose between a 4-6-6-4, or a 2-8-8-2, both of very similar weight: if you were putting it on a high speed train, with gentle hills, then the 4-6-6-4 will work for you. But if you're going to attach every single car the thing can possibly pull, and/or you have low speed and/or steep hills, thent he 2-8-8-2, with more weight on the wheels and therefore more tractive effort, may be better suited.
