What is the largest North American tank locomotive?

It’s easy to find information about these engines for, say, British railways, but not so much for North American roads. I know we had some pretty big commuter locomotives here in the states, like the 4-6-6ts that ran out of Boston on the B&A, but were these the largest? And were there any hefty freight-oriented road tank engines here? Or were they all relegated to passenger and yard duties?

Thanks.

I can’t give you the numbers at this time, but there were some heavyweight articulated tankers used by western logging railroads here in the US.

Here’s one that survives today, and operational.

https://locomotive.fandom.com/wiki/Black_Hills_Central_No._110

I found this interesting 'site. Go to “Logging Mallet Roster” and look for the wheel arrangements that end in “T,” as in 2-6-6-2T. You’ll find some big tankers there!

http://loggingmallets.railfan.net/

I doubt you’ll find any tank locomotives bigger than those.

Black Hills Central also has 2-6-6-2T 108 that is operational. Both 108 and 110 put on a heck of a show climbing the 6% grade out of Hill City, SD. Here is a short video of 108 in action.

https://m.youtube.com/watch?v=2nx4wQUfYK8

The Boston & Albany 4-6-6t locomotives were contemporaries of the New York Central 4-6-4 Hudsons and in some ways were “squished down” versions of them. They had over 41,000 lbs of tractive effort and as such, using that barometer, could be considered the most powerful tank engines in North America used for mainline service.

https://www.railarchive.net/nyccollection/ba404.htm

Central Railroad of New Jersey had these well-proportioned 4-6-4t locomotives for commuter service that resembles the road’s 4-6-2 power.

https://www.railarchive.net/randomsteam/cnj230.htm

Thanks. I had stumbled onto this interesting piece of fanart yesterday…

https://i.imgur.com/mWccMGW.jpg

… and while I knew it was just a work of whimsy, it did get me wondering about what was out there. And, as it turns out, the answer is: not much. Heh. Oh well.

It feels like British railways did a lot more experimenting with one-off locomotives than did American railroads, the latter of which were far more interested in proven concepts and consistency.

https://www.youtube.com/watch?v=jLv3wrmXXWM

https://www.youtube.com/watch?v=BUXgmDl2gS8

Etc.

Merry Christmas.

While you are on the subject of Garratts as tank engines – Beyer Peacock attempted to peddle double-simple-articulated or ‘Mallet-Garratts’ at North American size at one point (I believe Alco had the license rights) and Trains covered this in the early '70s – including a whimsical drawing of one negotiating a double crossover…

It would not be difficult to extrapolate their design up to true North American size, of course, although you run out of real benefit with four six-coupled engines. That did not stop me from designing one with 70" eight-coupled engines and a boiler all the way out to the loading gage (there is a description on the appropriate Sam Berliner ‘apocrypha’ page) and while ‘practical’ is not a word that springs readily to mind it certainly represented a ‘next step’ beyond 2-6-6-6s for a world in which Dilworth et al. had failed to thrive…

Probably one of these:

at 1,169,750 pounds.

(Erie Triplex)

Ed

Ah, the late, unlamented, but nevertheless fascinating Erie Triplex.

The O Gauge version from MTH worked a LOT better than the original!

https://mthtrains.com/premier/spotlight/10_2015/a

Unlamented? They lasted between 13 and 19 years on the Erie. Average age of a diesel today is about 25. I have a feeling they did what they did pretty well, and did rather badly at doing something else–not exactly the Geeps of their day!

Ed

Yes, but that was just to get their money’s worth out of them. In the end all they were good for was use as pushers, that they could handle.

Still, I can’t blame Baldwin and the Erie for trying, as the saying goes "If you don’t try, you don’t do."

However, whatever it is that you perceive that they did well - they didn’t do it well enough for the design to be replicated in quantity by any of the carrieres.

All that the Triplex was supposed to be on the Erie was a pusher. Draft gear pulled out everywhere when tried differently, much as PRR would discover a bit later with Big Liz and their simple-articulated 2-8-8-0.

And the Virginian had a Triplex with one additional axle.

I decided that “largest” would best be defined by engine weight. It appears the Erie locomotives weighed 38% more than the Virginian. I think, also, the Virginian only lasted a short time, and thus were less successful. Which, of course, isn’t related to the question.

The Erie engines lasted from 13 to 19 years (again, hard to get hard numbers). U33C’s on the BN lasted about 15 years.

Ed

Not even close. Their weights were very close to each other.

Erie 2-8-8-8-2/4 “Triplex” Locomotives in the USA (steamlocomotive.com)

Virginian 2-8-8-8-2/4 “Triplex” Locomotives in the USA (steamlocomotive.com)

Also, how often did the Erie use them in daily operation over their lifespan. I seem to remember that they just sat around for long periods. I’m sure the BN got a lot more use out of their U33Cs.

Your source shows a “Total Engine and Tender Weight” of 1,169,750 for the Erie, and 842,310 for the Virginian.

1169750/ 842310 = 1.389

Weight on drivers, one would think, would be proportional to that. Approximately.

761600 / 725475 = 1.050

Not as much difference there, though the Erie is still 5% greater. The Virginian apparently had 56" drivers, the Erie 63". Another significant difference.

I do wonder at some of the numbers in the linked source.

Note that the 3 Eries weren’t all the same.

You

You can forget about “tender weight” since that would be part of “weight on drivers” since the locomotives didn’t use separate tenders. Remember, they were triplexes.

I think that we need pictures to compare the Triplex locomotives…

Douglas SElf always helps…

http://www.douglas-self.com/MUSEUM/LOCOLOCO/triplex/triplex.htm

http://www.douglas-self.com/MUSEUM/LOCOLOCO/steamtender/steamtender.htm

There are some errors and confusion. The iulllustration of the Sturrock steam tender locomotive is incorrect (both engine and tender had inside cylinders and outside frames) but the photos of the two triplexes are correctly captioned. The data could be compared with other sources…

Peter

Ah, yes. The data for the “Total Engine and Tender Weight” for the Erie’s is an incorrect entry, because the “tender” weight is used twice to get the 1,169,750 pounds.

It becomes obvious if you start looking at the weight on drivers, and…

He probably should have left out the 316,700 pound tender weight entirely, as it is confusing. The layout for the Virginian is the way to go.

So, yes, the Erie is just a snidge heavier (bigger).

Do we have any tank engines weighing more than 853,050 pounds? Anywhere?

Ed

According to Articulted Steam Locomotives of North America it was Wyerhauser’s Baldwin 2-6-6-2T #111 at 263,000 pounds 47.000 lbs tractive effort built 1929 largest of 43 logging tank locomotives of that wheel arrangement

It could be discussed whether or not a triplex was a tank engine.

One view could be that the non-running gear component must be a non-flexible unit. Thus a 2-10-2T would qualify, while the triplex would not, since there was a joint between the two elements of the latter. A two-truck Shay would then be a tank engine, while a three-truck would not.

Going the other way: the tender of a triplex and, in particular, its engine were an integral part of the machine, not a tag-along container for fuel and water. Who’s to say a tank engine can’t bend in the middle? Note that Garratt’s are considered tank engines, and they bend in TWO places.

Ed