The reason the first ABBA dielsels broke draft gear was because of the engineers habit of backing up the train before starting forward with steam engines to have draft gear slack to let the steam engine get a small running start building up tractive effort. The electric motors in the trucks of diesels had tractive effort from a dead start immediately and thus as the slack played out, would break a weak draft gear somewhere back in a sort of whiplash motion. When they stopped the backing up habit this solved the problem.
Ray------------Great Northern rules !
Neat thread!! A lot of great information here!!
Virginian, how much tonnage did those AE and Y6b typically move?
thank you for your post
I would have to look up the exact tonnages; I do know the VGN made several “world record” runs.
The N&W rated engines by division. What a Class A could drag East out of Crewe with no helpers was considerably more than one could lug up Blue Ridge, but of course they did run helpers, often 2, on Blue Ridge.
One of O. Winston Link’s recordings was of him riding a time freight West from Crewe behind 1238, and she stalled out on Blue Ridge and had to have call for a helper. That’s a really great recording.
Hey Gang,
A simple way to gauge a locomotives power; check the rear trucks. The Allegheny’s fire box was so big that it needed a six wheel truck to support it. The size of the fire box determines the amount of power the loco. will produce. It could pull a full coal drag through the Allegheny mountains, Alone. Because of that, it was given it’s name.
Later,
Bill North
Does this recording exist on the net?
Firebox does not determine power, the whole boiler does that. Otherwise NP’s 4-8-4 would have been the most powerful, but they weren’t; they had a huge firebox to deal with less than ideal coal.
That recording is not on the net. It’s about an hour long I think.
That is not exactly true Bill, many “wartime” designs used three axle trucks due to high quality steel shortage. Engineers had to use less resistant steel aloys, thus requireing more axles to distribute a same weight that could be handled by a two axle high resistance steel truck. This is the case of engines like Pennsy’s 6-4-6. The amount of drivers isn’t a way to gauge power either. Many eastern european countries had to use many drivers to distribute the weight of their engines on very low resitance rails, such case was Russia’s mythical AA20-1 2-14-4, many sections of the Trans Syberian Express weren’t even steel, but iron.
Bill–though that was sometimes the case, it wasn’t always. Take the Missabie M-3/4 for example. The original design was based upon the very powerful Baldwin-built Western Pacific 250 series 2-8-8-2’s built by Baldwin in the early '30’s. The four-wheel trailing truck wasn’t added because of increased firebox area, but to support the extended all-weather cab. Actually, the M-3/4 had a SMALLER grate area than the WP prototype (which was an oil-burner), but used the area more efficiently, due to improvements in locomotive design between 1930 and 1941. And the M-3/4 had a much smaller firebox than the original NP Yellowstone design, but that was because the NP locos needed a large firebox to burn a lower grade of coal, hence the four-wheel trailing truck in the first place. But I do agree with you about those handsome Alleghenies, the size of the firebox dictated a six-wheel trailing truck from the outset. I understand that Lima had originally thought of using a wide-spaced 4-wheel truck, however balance and strength issues made them decide on the 6-wheel instead.
Tom[:)]
Hey,
I may be wrong, but just check horse power to truck configuration. It seems to follow pretty close, for a quick figure.
Bill North
Quiz: at what RPM does a steam engine produce the highest torque?
At zero RPM you will have no pressure losses due to steam flow or movement, hence you will have the greatest pressure exerted on the pistons and the greatest torque.
Just before the drivers start to slip!
Mark
Great site…Thank you RedLeader!
Mark
I’d like to put in my 2cents worth. As a boy I saw many Big Boys pulling a string of cars up Weber Canyon in Utah. Mabe not the most powerful, but what a sight…sure beats watching the big yellow monsters that grawl by now. The only way to tell the difference is to keep track of the numbers. By the way, I had the experince of taking a ride in one of the new GM big yellow monsters last week.
BOB
SANDY SOUTHERN RAILWAY
The RPM depends on the size of the drivers.
I don’t know how to explain it in RPM and torque, but I can in MPH and Horsepower.
The larger diameter drivers allowed a locomotive to reach its maximum horsepower at a higher speed. For example, not exact-just a demonstation; a locomotive with 78" drivers would reach its max horsepower at, say, 70mph, where as a loco with 55" drivers would at maybe 48mph.
Knowing this, some steam locomotives were put to illsuited usages. Such as the Boy Boy. Looking at a line graph of horsepower to mph, the big boy reach about 5500hp at close to 45mph, I think. But the Big Boy was frequently used on drags where speed dropped below 15mph, where its horsepower was below 4000.
My 2 cents.
~[8]~ TrainFreak409 ~[8]~
I think we need to keep the fundementals of steam design in our minds gentlemen.
Rule one: Large driving wheels will gain you speed.
Rule two: Small driving wheels will gain you “Pull”
Balance these two extremes with boiler capacity, cylinder size, piston stroke, number of driving wheels, weight on the driving wheels compared to the rest of the locomotive… etc etc.
Somewhere in the middle is the sweet spot of power, but no one locomotive can be designed that can “Own” (A gamers term from the internet) all others.
Dead on! It has nothing to do with wheel size or even the presense of wheels (notice I wrote “steam engine,” not “steam locomotive.”