What's this bit I read about the restored N&W 611 being the most powerful steam locomotive ever built? Wouldn't the Union Pacific "Big Boy" rank far ahead of the 611? Or are we comparing one that is actually up & running vs. one not yet back in shape? marshallel
Some hubris, or enthusiasm whose bounds exceed the facts?
Several larger locomotives were capable of producing more horsepower than the J's. The H-8 and Q2 come to mind, probably the N&W's own Class A would be another. The Yellowstone variants.
marshallelWhat's this bit I read about the restored N&W 611 being the most powerful steam locomotive ever built? Wouldn't the Union Pacific "Big Boy" rank far ahead of the 611? Or are we comparing one that is actually up & running vs. one not yet back in shape?
There have been a number of discussions, here and elsewhere on the 'Net of a million lies, about the 'most powerful' steam locomotive. Much of the sense devolves into semantics fairly quickly. But the first thing that has to be thrown out is the mistake of thinking that starting tractive effort, or STE/TE, determines anything significant about how "powerful" a locomotive is. The proper measure of 'power' in this case (in this country at least) is horsepower, which includes time and hence speed, and quite a few imposing articulated locomotives start dramatically falling off in high-end horsepower -- one particularly attention-grabbing number being the fairly conservative speed at which a NYC Hudson begins to develop more nominal DBHP than a N&W Y-class 2-8-8-2.
Even so, I would have to wonder about calling a J, good as it was, "most powerful ever built" - that is likely true for 4-8-4s, and perhaps any eight-coupled locomotive, because the J was balanced to run 100mph and had the steam generation and 'steam circuit' to achieve that speed with a considerable train. While there are sources crediting a UP 4-8-8-4 with "80mph" top speed, that is likely to be unusual for one to reach on its typical pathetic subbituminous fuel, with typical train factor and ruling grade for best cost-effective running. So it is possible that, were NS to let the J out to its original design speed and longest practicable cutoff (trading water rate for developed cylinder horsepower), let alone to run it to the speeds achieved in the postwar testing on PRR, the developed HP would be at some 'record' level. Someone with more interest in this could easily run a range of numbers to give reasonable comparison data. But I think it would still be well short of locomotives, notably the PRR Q2, with bigger boilers and more effective machinery to use the generated mass flow for high-speed horsepower.
selector "Some hubris, or enthusiasm whose bounds exceed the facts?" Several larger locomotives were capable of producing more horsepower than the J's. The H-8 and Q2 come to mind, probably the N&W's own Class A would be another. The Yellowstone variants.
"Some hubris, or enthusiasm whose bounds exceed the facts?"
Before this 'discussion' gets too far along, someone needs to apply some bounds, and rules as to what 'measures' the respondent's are using to describe what may be their favorite 'BIG' Locomotive.
samfp1943Before this 'discussion' gets too far along, someone needs to apply some bounds, and rules as to what 'measures' the respondent's are using to describe what may be their favorite 'BIG' Locomotive.
Given the variables already mentioned, methinks it would be incumbent on a poster to specify in what way their favorite locomotive is the biggest. Sheer size, length, starting tractive effort, TE at speed, and a plethora of other factors can figure in.
I would hope that any disagreements would be of the scholarly variety - ie, "my" locomotive is a bazillion pounds on the drivers, whereas "yours" is a bazillion and one pounds total weight wet, and someone else's is a bazillion and two pounds dry...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
marshallelWhat's this bit I read about the restored N&W 611 being the most powerful steam locomotive ever built?
It wasn't, of course-- did they actually say it was?
"someone needs to apply some bounds, and rules as to what 'measures' the respondent's are using"
No need for rules-- just spell out what you're claiming. In any case, claims about power are going to remain mostly-unprovable claims-- in the US we don't have much idea what locomotives were actually capable of.
Le Massena's article ranked the NP 2-8+8-4 as #1, then the UP 4-8+8-4 was #2 -- and a D&H 2-8-0 was #3.
His criterion was simple: grate area times boiler pressure. The D&H 2-8-0 had 500 psi, so by his reckoning it ranked high.
I think that the poster meant that the N&W J class were the most powerful 4-8-4s ever built, not the most powerful steam locomotive
LeMassena's article was fascinating, and he attempted to come to an objective determination of a "big", not necessarily the "biggest" engine. He was also willing to admit that such a determination could be quite subjective and understood that he would step on some toes along the way. His rule of thumb for a "big" engine was a grate area of at least 100 square feet and a boiler pressure of at least 250 pounds. The notes at the bottom of the table explained his reasoning for using these statistics as opposed to others.
I believe LeMassena's ranking of the NP 2-8+8-4 was based on it having decent coal, not the lignite-type it was usually supplied with (as RME notes above for the UP 4-8-8-4, a "pathetic subbituminous fuel" ).
- PDN.
However based on TE alone the most powerful 4-8-4's ever produced were the ATSF's war babies. They had more TE than both the Niagra's and J's and FEF-3's ever did. They also ran long distances routinely it was nothing for one engine to run Needles to Chicago or LA to Kansas City before being changed only stopping for crew changes and water and fuel stops. They had 310 lbs of boiler pressure all roller bearing construction and cast bed frames. Why they are not considered in the elite group they burned oil so in some peoples eyes they cheated.
Shadow the Cats ownerHowever based on TE alone the most powerful 4-8-4's ever produced were the ATSF's war babies.
I think you are the victim of doctored statistics -- not to take anything away from the 2900 class or the 3776 class before it.
I do not recall any instance of a 2900 being operated at more than 300psi nominal, nor do I recall any steam pressure other than 300psi nominal being used on actual J engines in service. The critical difference is the driver diameter (80" vs. 70") which results in the J slightly exceeding the 2900s TE using the normal formulae.
Now, there would be utterly no contest between a 70"-drivered engine and a gigantic ATSF 4-8-4 for high-speed horsepower were it not for Voyce Glaze's sophisticated balancing methods, which permitted extremely high cyclic rpm (resultingin 110mph+ with train) and hence somewhat more effective power from expansion events in cylinders at that speed (i.e., more events per second) than for a 2900 at the same speed (which I have no qualms saying it, too, could reach).
Again this is a bit technical: the J was not primarily meant for long-distance high-speed service at sustained 100-mph-plus operation as opposed to 'dash' capacity, and so discussions of 'the best' and 'most powerful' are more for railfan bragging rights than operational measures. There is no question that the 2900s -- and, by extension, any 80"-drivered ATSF 4-8-4s, including the rebuilt 3751 class -- were among the most powerful 4-8-4s built, and deserve high respect as such. (And yes, I believe they, like the 3460 class, were designed to be adapted to coal burning if required ... but of course never were. Is there anyone out there who thinks the Milwaukee A class does not 'count' for high speed or power because it was oil-fired???)
This discussion kind of reminds me of the "best in show" portion of a dog show (and that's not intended to be a slam on anyone or anything).
The judge has to compare each of several breeds, each on their own merits and not compared to the other dogs, and decide which one best represents the sum of those merits, thus being "best in show."
In reality, I doubt anyone could agree on a single "best in show" amongst steam locomotives. There are simply too many variables.
Shadow the Cats ownerbased on TE alone the most powerful 4-8-4's ever produced were the ATSF
Some website says that-- it's wrong. All the later SFe 4-8-4s (3765-3776-2900 class) had big cylinders to compensate for their 60% cutoff, so if you calculate TE by the usual formula (ignoring their limited cutoff) it comes out high. No evidence their actual TE was anything special.
Quickly caught the idea that maximum continuous horsepower was the proper measure of how powerful a steam engine was. The rest is all gearing.
Actual TE and HP output as measured by a dynamometer car would be more insightful than theoretical calculations.
"One test is worth a thousand opinions." - one of EMD's noted engineers.
Paul_D_North_JrActual TE and HP output as measured by a dynamometer car would be more insightful than theoretical calculations. "One test is worth a thousand opinions." - one of EMD's noted engineers. - PDN.
And then the science deniers continue to argue.
Never too old to have a happy childhood!
BaltACD Paul_D_North_Jr Actual TE and HP output as measured by a dynamometer car would be more insightful than theoretical calculations. "One test is worth a thousand opinions." - one of EMD's noted engineers. - PDN. And then the science deniers continue to argue.
Paul_D_North_Jr Actual TE and HP output as measured by a dynamometer car would be more insightful than theoretical calculations. "One test is worth a thousand opinions." - one of EMD's noted engineers. - PDN.
To put it in scientific terms, one measurement is worth a thousand models. This is particularly true of any complex heat engine that involves phase change, radiative and conductive heat transfer and various sorts of non-linear feedback, be it steam locomotive or atmosphere.
Be very sure of exactly what is being measured and of what factors that can affect the measurement.
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