Great American articulated steam engines

[UP 4-12-2]

Do you know where the best fit curve for the Allegheny was published?

Also--steam locomotive test data is only as good as the job the crew was doing of running and firing the engine.

Though the Big Boys evidently performed well, there seems to be some evidence that the UP Challengers steamed better throughout all speed ranges--or rather that on sustained grades the Big Boys tended to slow down a bit and apparently could not produce quite enough steam.  Perhaps the variation in Big Boy numbers has something to do with the challenges posed in firing them?

John

[GP40-2]

UP 4-12-2

2. UP Big Boy 4-8-8-4.  135,000 pounds starting tractive effort, calculated.  Actual performance was measured to exceed that figure.  The last UP test with a dynamometer car yielded an astounding 6290 drawbar horsepower after starting a heavy train on a grade.

3. N&W A Class 2-6-6-4.  Very respectable starting tractive effort combined with outstanding 6300 drawbar horsepower at reasonably high speed.  Some consider it the greatest all around running articulated when speed is factored into the equation.

4. C&O H-8 2-6-6-6/Virginian 2-6-6-6.  What can I say:  7,498 drawbar horsepower.

The 6,290 HP for the Big Boy came from only one locomotive in one test. Collectively in tests, the Big Boy's were more like 5,800 DBHP engines.

To my knowledge, there is no N&W test data or documents to support the 6,300 DBHP claim for the Class A. The N&W never claimed that much HP from an A. In fact, the only people who make that claim are railfans. I have no idea where they got that figure other than out of thin air.

The Allegheny's 7,498 DBHP was from a test where the dyno readings were bouncing around like crazy. The data points were all over the place. A best fit curve shows the actual DBHP to be around 6,500 at that speed, which is still far above any other steam locomotive.

[JimValle]

Nobody's going to mention the SP's cab-forwards, AC-4 thru 12?  They were very useful and versitile, perhaps the first articulateds to be equally comfortable running in both passenger and freight service.  Not quite as heavy as some of the others mentioned, they packed a decent amount of tractive effort and you couldn't beat them for visibility.  One development of the type, the AC-9 was actually built to run the conventional way because it was originally a coal burner.  With a neat skyline casing and an all weather cab, it may have been the handsomist of all the articulated types.  And one other one - the American Railroad of Puerto Rico's Baldwin 0-6-6-0's of 1904.  Thiese engines were meter gauge and had the distinction of being the very first articulated mallets ever built in the United States.  B&O's "Old Maude" was just an upscaled version of this engine.  

[UP 4-12-2]

According to Huddleston, the USRA 2-6-6-2 was regarded, even during its era, as nearly a "failure" in comparison to the much more successful and powerful USRA heavy mallet 2-8-8-2.  Only 2 railroads bought them, and even though C&O built 10 late copies, they were primarily to replace worn-out locomotives on mine branch line service--where they were ideally suited.

Huddleston, in his book, did attempt to address Crandell's comments.  Also, he was talking about the "World's Greatest"--but he did say that all the engines in his top ten list were great engines.

The top ten engines included the Yellowstones, both DM&IR and NP versions, and the NP Challenger, along with the WP 257 Class 2-8-8-2, and I believe the B&O EM-1 Yellowstone.

The Rio Grande L-131 2-8-8-2 was left out because the list was limited to "engines built after 1930" and it was a bit too early, and not quite as powerful as the WP 2-8-8-2.

I think Huddleston's main emphasis was on Superpower ie horsepower at (more than drag freight era) speed--and engines that had all the most modern equipment--though the engines with high starting tractive effort did all rate well.

Many folks love the UP Challenger, but in this comparison it does not rate quite as highly as some other engines because WM, NP, and DRGW all had challengers that produced more tractive effort and/or more horsepower at speed.  The UP engine was certainly a fine and versatile design, and served quite admirably in just about any service they assigned it to, but Huddleston's point of view is that other Challengers, at least in terms of power output, were superior machines to the UP version.  Rio Grande most certainly preferred their own design (with 8000 pounds more starting tractive effort) over UP's.

The Y-6B was called the ultimate development of the USRA 2-8-8-2--but in reality there were so many improvements over the 30 years after the USRA engines that it is almost a completely different animal, though it looks nearly the same.

We are debating 60 years late, engines that folks like myself never even had the chance to see run (not even one of them).  There's also an awful lot of misinformation and incorrect data online.

Huddleston does make the point that few railroads actually had the kind of terrain that was ideally suited to modern Superpower steam locomotives--Union Pacific most certainly did--but Challengers operating in the east were unable to run at their full potential.  In the "Arms race of Super Steam" it might be argued that some railroads had (or were sold) outstanding locomotive designs that were just not fully suited to their particular track profile, etc.

John

[selector]

Adjectives such as "best", "most", "biggest", and "great(est)" really could do with some negotiated agreement as to their meaning.

Was not a simple Challenger great?  How about the trusty USRA 2-6-6-2 and 2-8-8-2?  Why were they not worthy of being called 'great'?  I would list the A Class as an honourable mention at the very least.

The Yellowstones were 'great' articulated engines surely.  And I would agree that the rather smallish articulated Y series from the N&W were worth inclusion on such a list.

-Crandell

[UP 4-12-2]

Valeriy--

There is a huge difference between calculated theoretical maximum tractive effort and the actual real world performance of articulated steam locomotives.

Some of the engines you listed couldn't even produce enough steam to keep the engine running down the track at a respectable speed with a train, and thus were pretty much total failures and were scrapped early.

Exceptions:

Virginian AE Class 2-10-10-2.  176,000 pounds tractive effort.  It actually did have lots of usable tractive effort, and had a long productive service career, but they just weren't very fast at all.

If you want to discuss the best of the American articulateds, I think your list would benefit from some additions or modifications.  I would suggest adding the following engines:

1. N&W Y-6B 2-8-8-2.  152,206 pounds starting tractive effort, simple, without booster.  Allegedly 170,000 pounds in the final, upgraded version with booster, but records are questionnable.  The ultimate compound articulated!  Efficient and productive.  Two of them could start a 10,000 ton train on a 2% grade in the rain!  Also produced a very serious 5500 actual drawbar horsepower at about 25 mph.

2. UP Big Boy 4-8-8-4.  135,000 pounds starting tractive effort, calculated.  Actual performance was measured to exceed that figure.  The last UP test with a dynamometer car yielded an astounding 6290 drawbar horsepower after starting a heavy train on a grade.

3. N&W A Class 2-6-6-4.  Very respectable starting tractive effort combined with outstanding 6300 drawbar horsepower at reasonably high speed.  Some consider it the greatest all around running articulated when speed is factored into the equation.

4. C&O H-8 2-6-6-6/Virginian 2-6-6-6.  What can I say:  7,498 drawbar horsepower.  Was designed and built to outperform the N&W A Class, but maybe wasn't as effectively used in service as the N&W A Class.

I just read Dr. Eugene Huddleston's World's Greatest Steam Locomotives.  Some of the engines Valeriy listed did indeed make the top 10, but they did not make the top 3.

Huddleston's top 3 were the Big Boy, A-Class, and H-8 2-6-6-6, with an "honorable mention" pretty much going to the Y-6B (he included a special tribute chapter to the ultimate compound mallet).

Respectfully submitted--

John

 

[switch7frg]

  Valeriy; maybe ~ Train Shed Cyclopedia No. 47  from Gregg would help you for the info you want.  Possibly your LHS could get this for you.

                              Respectfully, Cannonball

[Valeriy]

Erie class P-1 and Virginian class XA has unique Triplex system. P-1 has 160 000 lbs tractive effort (see p. 197 Articulated Steam Locomotives Of North America by Robert A. LeMassena, Vol.2). I think it is enough to say this is a great powerful steam engine.

Valeriy.

[CSSHEGEWISCH]

I would hardly consider the Triplexes to be "great" articulated locomotives.  Large, to be sure, but hardly great.  Both suffered from too much machinery and not enough boiler.  The Virginian XA was an unqualified failure and wound up having its running gear used for two new locomotives.

[Valeriy]

Hello!

I am interested in great american articulated steam engines such as:

2-10-10-2 Virginian class AE

2-8-8-8-2 Erie class P-1

2-8-8-8-4 Virginian class XA

2-8-8-4 NP class Z-5

2-8-8-2 D&RGW class L-131, L-132

2-8-8-2 C&O class H-7, H-7-A

What issues of Railway Mechanical Engineer (or another magazines and books) has information about this great locomotives?

 

Valeriy.