Actually, compounding doesn't have to reduce speed. It does on american compound mallets, but probebly a good chunk of that is due to having massive cylinders (so there's a lot of steam), the need for flexible piping to the front (low pressure) set of cylinders, and simply the distance between the two sets of cylinders. There were plenty of compound express engines in Europe (although only on the continent - England never really went for compounding).
That said, England was big on usng 3 and 4 cylinder engines. In pretty much all cases, there were 2 outside cylinders in the normal place, and the rest were between them inside the frames. There were also engines with only 2 cylinders, both on the inside, and no
driving rods, (but still connecting rods), or cylinders on the outside. This was pretty much limited to England before 1900-1910 or so. In all cases, inside cylinders drove crank axles. Crank axles were a source of trouble at first, but by 1900 or engineering had advanced to the point where that was't a problem. If you want to see how inside cylinders work, look no farther then the Fowler 4F, included in the Settle and Carsile expansion, and in any version of trainz that has Haws junction built in. (so trs2006 at least, and I think trs2009). You can see the animated inside cylinders From the right angle. For a quicker example, good ol' Thomas the tank engine was an inside cylinder locomotive.
Actually compounding
does increase efficency. It doesn't increase power, though, compared to another engine with the same number of cylinders. The french, will little domestic coal supplies, were very big on compounding.
While superheating did kill off compounding in the US and England, where it never really took off in the first place, on connential europe, superheating was added to compounding, to increase efficency farther.
However, compounding might not increase
overall ecomany. While the engine will certainly burn less coal, and less water as well, in reality increased mantaince costs of the extra cylinders, their hard to acess location inside the frames, and worst of all the inside valve gear, nearly always matched, or exceeded, the money saved in coal.
That said, in engines that already had more then 2 cylinders, such as mallets, maintince costs wern't a factor. Insted, simple expansion articulateds replaced mallets in the US becacuse mallets had a limited speed due to choking on the huge volumes of low pressure steam, and the drag freight era was ending, and higher speeds were needed. However, the N&W keep with mallets right up to the end of steam in 1960 (!), the y6b being perhaps the ultimate mallet, and was capable of 60 mph.
But for the origional low-speed mallet concept carried to its extreme, look up the triplex (2-8-8-
8-2, with the last set of drivers under the tender). It failed, since the cylinders couldn't produce enough steam. Another good one is the virginian railroad's 800 class, 2-
10-10-2's, with 4 foot diameter low pressure cylinders. That actually worked, the boiler able to produce enough steam to push a train upgrade at 5.5 mph. With two of them pushing, a 2-8-8-2 at the front, and 5500 tons of train on a 2.11% grade, that would be something to see in trainz.
Some other fun things to see would be a mallet-garret: a 2-6-6-2+2-6-6-2! Since garrets, with their short, fat boiler and plenty of space for a firebox, were good steamers, and with enough attention to the boiler, it might well have been able to actually pull a very heavy train up a very steep grade at walking speed.
One idea I had, which no one else ever seems to have had, was a triple-expansion compound shay. Since a three cylinder shay has a set of cylinders set up nearly identically to a marine triple expansion engine, it would seem it would take next to no, if not actuall no extra complexity, and therefore mantaince costs, and there would be a savings in fuel.
Probebly the reason nobody else ever thought of that are that shay's are small and don't burn much coal to begin with, and that the operators of shays, logging and mining railroads, didn't exactly care about fuel costs.
For some recomended reading, try Brian Hollingsworth's
The Illustrated Encyclopida of North American Locomotives (note: tiles are probeby spelled wrong) for american steam development, and diesels as well, and Brian Hollingsworth's and Arthur Cook's
Steam Locomotives for passenger steam worldwide. It's interesting seeing the paths of development of steam in the varoius countries. If you wan't to see all sorts of early diesel and electric engines, including some that are rod-driven, look up
Modern Locomotives by the same two authers. Of course, both books are long out of print, so start looking at a libary, although
The Illustrated Encyclopida of North American Locomotives I found as a google book online a while back, and the others might be as well.
Hoped this helped!
If anyone has any other questions, go ahead and ask.
). This is shown quite well with the Shay, Climax, Heisler, and other geared locos. Admittedly, they are slow speed tramway locos (designed for power and ability to negotiate sharp curves, on rough track), but they are 'geared' drive.
