WorldRailFans

The issue of steam locomotive weights is, as I understand it, not an easy one, because the manufacturers were contracted to come in with a certain maximum on the finished loco, and as sometimes happens in an imperfect world, would often exceed this maximum. It would appear that there was considerable fudging in the "official" weights as a result.


In addition, weight of a locomotive is not in and of itself a positive factor, any more than it is with a person or a cat. That a loco would be heavy could as easily be an indicaiton of design flaw as anything else, so the Big Boy may be a better design even if it isn't as heavy as an Alleghany. The C&O and Virginian locos were odd applications, in any case, being "super power" designs used in drag freight/mineral service, where their speed and horsepower capabilities were not optimally used. The Big Boys and UP Challengers/clones were probably the one family of large articulated steam locos that was optimally used in fast freight service, along with the N&W As..


Tractive effort may be a better measure of size. I believe the GN R-2 articulateds had more tractive effort than the Big Boys.

John Oxlade from London, UK on Jan 25 1998, 10:22

responded: I know, I know, I was just kidding.!


>You are right of course, in America you had the perfect conditions to promote

>the need and use of large locos :- big trains, large loading gauge, and long

>disctances. Its hardly surprising that US locos are so big.


I think it had some other reasons too:


1./ The European standard screw coupler is rated to 65 metric tons. It would make no sense to build a loco with more traction force as it would break the coupler.


2./ In the US since the early 1910's it was obligatory to equip all medium and large locos with a Stoker. An European steamer's power was more-less limited to that level a fireman could supply. The German BR06s had two firmen.


IMO the East European (Germany included) clearences are not significantly smaller than the US ones were at the time of the steamers.


Well, the French and Italian ones are already smaller, and forget about the British ones...

C&O 2-6-6-6 Alegheney type was taller, produced more horsepower, and had a boiler that you could place the big boys boiler inside of. Also produced more tractive effort. look it up

There is a photograph of the Russian 4-14-4 mentioned by Martin Silz on January 22 at http://pavel.physics.sunysb.edu/RR/photos/landreev.jpg.

The original question was, "Who says there was an engine bigger than the Big Boy?". This is not strictly the same thing as a bigger locomotive, since an articulated locomotive can be construed to comprise more than one engine. If this is taken into consideration, the Russians may have had the biggest!

I think this goes back to something I said earlier, "How do you define BIG?". Big is too vague a word, you could mean length, weight, height, tractive effort, etc.


If you really wanted to push the subject, I reckon that you could probably find another loco that had one single feature that was BIGGER than the equivalent on a Big Boy. I do agree though that the Big Boys were some of the most successful BIG locos ever built.


John

The way that I understand it, there are quite a few steam locomotives that were larger or more powerful than the Big Boy. However, when books say that the Big Boy was the largest, they mean that they were the largest successful mainsream steam locomotive. This excludes specialty, experimental or failed designs due to grinding the turns, too small of a boiler for the cylinders etc. There are too many ways to measure steam power to say that one particular design is the largest or most powerful in all categories. For example, a Y-6 or Challenger might very well win an actual tug-of-war over a Big Boy, but in pulling a heavy time freight over a mountain pass, I know of nothing steam-powered that would beat our beloved 4-8-8-4.

I have a question for any and all of you. I don't care who thinks which engine is the largest or longest or heaviest. I would like some detailed information about the Triplex engines, specifically detailed drawings and dementions. Should anyone in this group have such information or know where I can find it, I would greatly appreciate it as I am trying replicate one at the G scale level.

Thank you,

Steve

If You want to build a "super steam loco" try to find :

Articulated steam locomotives of north America by R A LeMassena. 1979 ISBN 0-913582-26--3

To go a litte step further try to find the book: Iron horses of the Santa Fe Trail by E D Worley1965

The first book tells it all, and the second book has pictures of some very strange locos built and drawings of even stranger locos that not left the drawing board ( 2-10-10-10-10-10-2)

I suggest that you refer to www.steamlocomotive.com it has some very good information on steam locomotives and what is biggest, largest, heaviest, etc. Since you stated "engine" and not steam locomotive there were several engines bigger and more powerful. My favorite was the Virginian Jackshaft Electrics, EL-3A, these were built in 1925 and were used until 1959, scapped in 1960. These were brutes 1,282,380 pounds with a total tractive effort of 231,975, and 922,580 weight on drivers with a lenghth greater than 142 ft. They had a horsepower rating of 7125, and a top speed of 38 miles per hour. No they were not steam but the jackshafts turned drivers like steam engines. Continuous tractive rating was 135,000 at 14.2mph, and the Virginian with a long experience with big steam locomotives and many mallets, found that these locomotives could outperform any steam locomtive made, period. Thay made several tests with their biggest steam locomotives, the final and most conclusive was when they took a U.S.R.A. Mallet attached a 6000 ton train behind it and used two 2-10-10-2 behind as pushers. They tested on Clarks Gap, with a 2.07 per cent grade. They set up a 6000 ton train with the EL-3A on the same grade grade and gave the steam train a 15 minute head start. The steam train could only reach a top speed of 7 mph. the EL-3A's reached 14mph and overtook the steam train in 15 min. For good measure they stopped the electric locomotives on grade and with 3 minutes the electric juicers were back at the original pace. Clearly the steam engines had struck out. From then on until the diesel era electrics ruled Clarks Gap.


More powerful locomotives were the 2-10-10-2 AE class of the Virginian not bigger but definately more tractive effort 147,200 simple and 176,600 compound.

These were not unsucessful as they were used for 35 years before retirement, not fast they were definatly drag locomotives. The Great Northern R-2 class were more powerful with 153,000 tractive effort, The Virginian AG and C&O H-8 ( almost same identical engines ) had more horsepower and were probably the finest mallet class locomotive ever made. They were slightly shorter and heavier. The Norfolk and Western Y6c's were more powerful also with a tractive effort of 166,000. It must also be considered, that the Virginian, the N&W, and the C&O were all coal roads and they had coal a plenty, all of these engines (except the AG, H-8 classes) had by western standards small tenders, they didn't need the coal capacity in there tenders, but because the tenders weren't as big don't be fooled, the locomotives were as big as anything built, the Virginian 2-10-10-2 AE class had 48" front cylinders I don't believe any locomotive ever had larger. Other railroads with huge locomotives were the DM&IR (M-4), Northern Pacific's Z-5 ( also large were Z-7, Z-8's), B&O (EM1's), SP, (AC-12's).


Where I am leading with this is it is non productive to argrue what was the biggest, largest, etc. I believe that locomotives other than the Big Boy should be remembered and preserved. For future generations we should preserve a variety of the gone locomotives by photos, models,and technical drawings and sketches. If you do some research very few big steam locomotives survived, ( you could get a lot of nails out of a mallet ), and focusing on the Big Boy further obscures these forgotten steam locomotives.

Could some of the European railfans give details on the Crocodile class electric's? These were some of the finest mountain engines ever made, with very long careers and the specifications on these would be greatlty appreciated.

What I have thought of for years concerning the Big Boy is this. It was the most famous, thanks to Union Pacific Public Relations. From that the legend grew......

This is comment plus question. To the poster who said that Britain had nothing like big boy - quite correct, the loading guage, bridges, etc. could not handle it.


A long time ago I read that when these huge locomotives were put into service the railroads had to reinforce their bridges because the exhaust blast from the chimneys was damaging them.


Can anyone confirm this?

Someone made a list, maybe interesting?

http://www.steamlocomotive.com/misc/largest.html

Hi evryone. How'ya doing? I have had experience with rigid base

locomotives. I'v heard on the web that PRR had a 4-14-2 and a 4-14-6 expearamented with. Both wear sucsesful. Erie on the other hand, had a so-called

Greg,

the longest conventional steam locomotive is the Pennsylvania S-1.Total length 42735,5mm.Big Boy is 40485 mm,I believe.

Michael

Here we go again! I'm sure that every fan of each of these major steam engines can identify a statistic or charisteristic that was better than one (or all) of the others.

Have you ever heard of the C&O M-1? Like the Jawn henry it was a steam turbo

electric. It had a wheel arangement of 4-8-0-4-8-4 or 2-C1-B-C1-B.It was heavier

than the Bigboy. Weight of engine was 856,000lbs and engine+tender weight

was 1,233,970lbs and was 154'0" long. The hp rating was 2250kW to 5250kW or

3000 to 6000hp. It's pulling force was unknown. Another locomotive the

Y-12b or later the Y-0z 1-B-C-D-E-6 or 2-4-6-8-10-12 "Odie B. Ball".

It could produce 7800hp and 250,500lbs of tractive effort. It was

succsesful until it's 3rd test run when it came across a famous curve bridge
that "killed" many locomotives. Even articulated locomotives could not round

it. Well it turned out that the Odie B. Ball made it across, but the weight

of the heavy tender pulled the loco down into the ravene where it's boiler

exploded. It was retrieved and re-built. Dieselazation made the railway scrapp

it. Well, see'ya later. D.H.

Well, I don't want to get vacuumed into the debate about size and performance, but I have one question that I think is pertinent, considering the operating territory of Big Boy.


It is:


What is the effect of altitude on steam locomotive performance?


I've pondered this over several years without really coming to any conclusion.


But, a steam locomotive is essentially a naturally aspirated engine, in that the combustion air is sucked into the fire (by the exhaust-induced draft/draught), and not forced in by upstream blowers. So, as altitude increases, then at first glance, one might expect power output to decrease, perhaps even noticeably so at 8000 ft asl.


However, I've never seen any reference to this in the literature. Are there compensating factors that make altitude immaterial?

I'm not sure of the physics behind this, but as far as I know there is no appreciable loss of power at altitude with a steam loco (in fact I recall having heard the opposite, but I doubt this).


In the Andes, the used to use 1500hp steam locos (Baldwins I believe), and when they dieselised the line used 1500hp diesels (replace like with like). Only thing was the diesels couldn't get up the mountain because the air was so thin. So they ended up buying more powerful turbo-charged diesels. That's progress?


That is paraphrased from one of the BBC's "Great Railway Journey's of the World".

As I understand it, since the boiling point of water is lower at higher altitude, there is increased efficiency in steam locos at high altitude. But this would probably not be enough to overcome other factors, like maintenance costs.