Trains.com

What is the largest North American tank locomotive?

6552 views
23 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    August 2013
  • 88 posts
What is the largest North American tank locomotive?
Posted by Shrike Arghast on Friday, December 24, 2021 12:05 PM

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.

  • Member since
    January 2019
  • From: Henrico, VA
  • 9,690 posts
Posted by Flintlock76 on Friday, December 24, 2021 12:11 PM

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.

  • Member since
    January 2015
  • 2,673 posts
Posted by kgbw49 on Saturday, December 25, 2021 4:36 AM

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

  • Member since
    January 2015
  • 2,673 posts
Posted by kgbw49 on Saturday, December 25, 2021 4:51 AM

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

  • Member since
    August 2013
  • 88 posts
Posted by Shrike Arghast on Saturday, December 25, 2021 11:36 AM

kgbw49

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.

  • Member since
    September 2003
  • 21,606 posts
Posted by Overmod on Saturday, December 25, 2021 12:28 PM

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...

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Saturday, December 25, 2021 2:28 PM

Probably one of these:

 

 

at 1,169,750 pounds.

 

(Erie Triplex)

 

Ed

  • Member since
    January 2019
  • From: Henrico, VA
  • 9,690 posts
Posted by Flintlock76 on Saturday, December 25, 2021 4:21 PM

7j43k

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

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Saturday, December 25, 2021 5:11 PM

Flintlock76
 

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

  • Member since
    January 2019
  • From: Henrico, VA
  • 9,690 posts
Posted by Flintlock76 on Saturday, December 25, 2021 9:37 PM

7j43k
Unlamented?  They lasted between 13 and 19 years on the Erie.  

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."

  • Member since
    May 2003
  • From: US
  • 25,167 posts
Posted by BaltACD on Saturday, December 25, 2021 9:39 PM

7j43k
 
Flintlock76 

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

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.

Never too old to have a happy childhood!

              

  • Member since
    September 2003
  • 21,606 posts
Posted by Overmod on Sunday, December 26, 2021 12:29 AM

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.

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Sunday, December 26, 2021 9:43 AM

Overmod

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

  • Member since
    July 2016
  • 2,607 posts
Posted by Backshop on Sunday, December 26, 2021 12:32 PM

7j43k

I decided that "largest" would best be defined by engine weight.  It appears the Erie locomotives weighed 38% more than the Virginian.  

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.

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Sunday, December 26, 2021 1:10 PM

Backshop

 

 
7j43k

I decided that "largest" would best be defined by engine weight.  It appears the Erie locomotives weighed 38% more than the Virginian.  

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 can be sure BN got more out of the U33C's than Erie did out of the triplexes.  

I think I'd wait until some hard evidence arrived.  

I will also note that these were experimental engines, and were likely somewhat unusual in their care and feeding. The U33C's were in a family that went back to at least the U25C.

 

 

  • Member since
    July 2016
  • 2,607 posts
Posted by Backshop on Sunday, December 26, 2021 2:47 PM

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.

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Sunday, December 26, 2021 7:08 PM

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

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Sunday, December 26, 2021 7:26 PM

Backshop

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.

 

 

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

 

 

  • Member since
    May 2019
  • 1,314 posts
Posted by BEAUSABRE on Tuesday, January 4, 2022 11:32 PM

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

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Wednesday, January 5, 2022 5:07 PM

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

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 13,524 posts
Posted by CSSHEGEWISCH on Friday, January 7, 2022 10:06 AM

I would hardly consider Garratts or Shays to be tank locomotives.  Tank locomotives, since they don't have a separate tender, carry their water in a tank that straddles the boiler.  Neither Shays nor Garratts have this feature.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Friday, January 7, 2022 2:55 PM

CSSHEGEWISCH

I would hardly consider Garratts or Shays to be tank locomotives.  Tank locomotives, since they don't have a separate tender, carry their water in a tank that straddles the boiler.  Neither Shays nor Garratts have this feature.

 

 

So then this:

 

 

would not be a tank engine.

 

And this:

 

would not be a tank engine.

 

Ed

  • Member since
    September 2003
  • 21,606 posts
Posted by Overmod on Friday, January 7, 2022 3:14 PM

Nor this, either

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Friday, January 7, 2022 6:35 PM

CSSHEGEWISCH

I would hardly consider Garratts or Shays to be tank locomotives.  Tank locomotives, since they don't have a separate tender, carry their water in a tank that straddles the boiler.  Neither Shays nor Garratts have this feature.

 

Locomotives with a tank straddling the boiler are known as saddle tanks and in the UK these are sometimes identified by the suffix "ST" (as in 0-4-0ST).

Locomotives with rectangular tanks attached to the boiler are known as pannier tanks, suffix PT (as in 0-6-0PT)

Locomotives with water tanks contained within the locomotive frames are known as Well Tanks with the suffix WT (as in 2-4-0WT)

Locomotives with rectangular side tanks attached to the frames were simply called tank locomotives with just the suffix T (as in 2-6-4T).

All of these could also have a small water tank on the main frames behind the cab.

The streamlined locomotive in Overmod's post did in fact have side tanks (small ones) beside the boiler under the streamline casing. But these were supported by the frames, not by the boiler.

The generally accepted criterion is that water tanks are carried on the main frames of a tank locomotive, whether carried by the boiler or not, so both two truck Shays and Beyer Garratts meet the definition of being tank engines.

Peter

 

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

Newsletter Sign-Up

By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy