probably old tired question but

Some say the Big Boy others say the Challenger also there were the very large experimental turbines. Would love to know which was the biggest in length not weight also.

James 

"Would love to know which was the biggest in length not weight also."  with this in mind!!         

would there have been "curve restrictions"  or places where giants like this one you put up would not be allowed?

for the 1876 Centennial Exposition in Philadelphia, Corliss built this 1400hp behemoth.  standing 70 feet tall and weighing over 650 tons, i'd say if this wasn't the biggest steam engine ever built, it was darn near close.

it ran continuously for the 6 month show and was then shipped to the Pullman factory in Chicago for the next 30 years of service before it was scrapped.

...or did you mean steam locomotive?

The 4-8-8-4 Big Boy was the longest at 132" 9" - was also one of the heaviest; next to the C&O Allegheny 2-6-6-6. Both were 600+ tons, weight may vary on water and coal load.

The S1 was the largest passenger locomotive ever constructed, with an overall length was 140 feet 2 ¹⁄₂ inches (42.74 m). At 77 feet (23 m) long and a weight of 97,600 pounds (44.3 t), the cast steel locomotive bed plate made by General Steel Castings was the largest single-piece casting ever made for a locomotive.

It seems that there are various classes of "largest".

Here is an interesting list: Railroad Locomotive Records

Depends upon what and how you want to measure it.

The N&W 2300 TE-1 was 161' 1" long and had a maximum tractive effort of 180,000#. Put into service in 1954, it was scrapped in 1957.

The C&O M1 Passenger weighed 856,000# and was 154' long. Three were built in 1947 and they were scrapped in 1948.

The C&O Alleghany had a drawbar horse power of 7498. Based upon how C&O used this engine, it's full potential was never realized.

In my book, N&W and C&O share the top honors. I will admit that UP did an excellent job of publicizing Alco's "Big Boy". I'll leave it at that.

The PRR S1 was one of many beautiful designs by Raymond Loewy. I will admit that is the probably prettiest large locomotive on the list.

Gilly

How bout the Russian AA20-1:

http://en.wikipedia.org/wiki/4-14-4

 OOPS!!!  Should have kept reading:

http://en.wikipedia.org/wiki/PRR_S1

what about curves and wt restrictions on either bridges or rail bed,  I do not remember how much the frame and stand for the Moon rocket for Apollo flights weighed but i do know the roadbed, (stone) was turned to powder to a certain depth and the road was stone and it was deep,  that thing moved a couple of inches per minute.  but what about railroad were these part of the design criteria, and  bridges "hey mr bridge guy, i need a bridge that holds an engine alone at 50 tons" not to mention the tender and the first couple of cars??

DM&IR M-4 Yellowstone with it's 140,000 lbs. tractive effort they routinely handled 19,000 ton trains 

The various answers on this thread bring us back to one thing. As an engineer (not train driver) the first step I usually do when confronted with a question is to define the success criteria. How do you define "Largest"? If it's longest, it's probably the Pennsy S-1. If it's heaviest or most traction it's something else. Are you asking for just American Locomotives? I'm not trying to be difficult but this is why we get a large amount of opinions. It also may be why this is such an interesting thread. Different people have different opinions as to what largest means. Viva la difference.

The S1, the 2300 and the C&O M1 were interesting, and BIG locomotives, but one-offs or limited production models that just did not fit well and weren't that practical and had nonexistent or very short service lifetimes.    

I think the reason people focus on the Big Boy, Allegheny, and Yellowstone is because they were the biggest locomotives that really worked out well enough to be made in volume and stay in  service a long time.  I have always respected the Big Boy most among them, because, even if it was not quite as much drawbar power as the Allegheny, etc., it was long, heavy, big, had a lot of wheels, and delivered efficiently and well exactly what it was designed to do, while using that lower-grade western coal and harder water.  It was really big AND really a good design.  

EDIT: And by the way, if we are talking one-off, and heavy, and long, the General Electric Union Pacific Coal Turbine was bigger than any of them, if you consider its two units and tender as one locomotive, which I do since it could not run without each of them in place.  It was also a really really bad idea, but that's another story entirely . . . 

"lower-grade western coal and harder water"  that is something i forgot about, hard water leaving build up on steam system!  and heat potential of different coal,  did anyone try to use kero or fuel oil to fire up one of these things.

I know that my years of sea duty i got familiar with condensation systems (somewhat) and the build up of minerals always a problem, especially with 3000 marines on the uss saipan

Except that the UP Coal Turbine (#80) was not a steam turbine, but a gas turbine modified to burn extremely fine powdered coal, which turned a large main generator, i.e. a "Gas Turbine-Electric". It worked very well when ever the Bunker C heavy oil was used, but the fly ash from the coal tended to severely erode the turbine blades.

As an addition to this discussion, the Henry Ford Museum in Dearborn, Michigan has an Allegheny on display inside.  It's the most photographed artifact in the place and gives you an idea of how large these things were.  When it was brought in, the locomotive could not fit through the doors, so the museum had to remove part of the brick work to bring it in.  The bricks weren't replaced, but the door was widened to fill in the opening.  There's a stairway to allow visitors to climb inside the cab.  Very impressive exhibit.  But it's just one of the many railroad artifacts there.  It's next to a replica of the John Bull, built from the few surviving pieces of the original.  Talk about contrast!

It is an impressive locomotive, and does indeed drive home just home big these things were.  When you are in the cab, you are so high above the ground, it really is a surprise.  I love big, big locos.  

The stationary steam engines are definite winners when it comes to power, like this one:

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

Then again, you have to hand it to the railroad engineers for ingenuity. The turbine-electric Jawn Henry was barely over 400 tons, but put out almost 200,000 lbs of tractive effort. The diesels had already proved themselves, though, and the politics of the eastern turbines would have been driven by the railroad's coal-shipping customers.

I'm just happy to stand next to a DMIR Yellowstone and say, " Yup, that's big!"

The bridges are tested\designed to support a maximum axle weight. That is, the weight or force of an axle at any given point on the bridge. It's somewhat complex, but you can let your mind go from there. Mr. Bridge guy hopes that Mr. Locomotive or Rail Car guy didn't make any modifications from the builder's specifications or at least documented them.

wow, 1905 my Great Grandfather was at that time the Commanding Officer of the "Old Soldiers Home" in Danville Ill with the rank of Colonel and this thing was built at that time.  I sure would like to see the set up that turned that crankshaft in 190whenever it was made.

wow talk about industrial revolution

when i need some information on steam locomotives, i usually turn to Wes for the answer...

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

Yep, big locomotives and engines meant big machine shops. Just to get an idea, here's one of Doxford's shop, a British marine diesel builder. (don't mean to hi-jack the thread!)

http://tinyurl.com/kyhow8g  Lathe chuck to the right.

I have a book, copyrighted 1897-1904  titled "The New Catechism of the Steam Engine/ Gas,Oil and Hot  Air Engines"  There were many, many designs and models. Some are very flat for river boats and some are as large as houses. The early ocean liners had huge boilers and steam engines. The book discusses "hot air" engines(for Congress)  and the development of the gasoline engine from steam engines.  This isn't a history book it is, for the time, current technology.

threads go where they go.  What I find fascinating is that our Grandfathers and Great Grandfathers designed and built these things with turn of the century abilities in metal working.  My Great Grand dad fought in the Civil war,  my father would sit on his knee!

that is how close I am to the Civil War.  Railroads probably were the most singular thing that built this country.  Like how did they make bridges for rail to cross the Mississippi river or the Missouri.  We all come from pretty tough stuff, people that really worked hard.  and did it for 10 bucks a week!.  That engine was to me incredible, and it ran on boiling water

or i just get impressed too easy

"Mr. Bridge guy hopes that Mr. Locomotive or Rail Car guy didn't make any modifications from the builder's specifications or at least documented them"

would this per sey be a early example of CYA?  but probably very very true

As I'm sure was stated, there was no "biggest", because that doesn't address the

"biggest in what way?" question.

I remember reading an article in Mainline Modeler (I think) once in which the guy

who drew many of the loco scale plans mentioned that he had drawn both C&O 2-6-6-6

and UP 4-8-8-4 plans recently, and realized that the boiler of the "Big Boy" would

fit inside the boiler of the Allegheny. He was referring simply to maximum diameter,

as I recall. 

The Allegheny has to be the T-Rex of US steamers, though. It just looms.

The Corliss steam engine was SHIPPED from Philly to Pullman in Chicago?  In one piece?

If you ever get a chance to visit the Henry Ford Museum in Dearborn, MI, take it. It is an amazing place and a real American treasure. Greenfield Village is next door and truly great as well -- Thomas Edison's entire laboratory brought from NJ and reconstructed there is worth the price of admission by itself!  Highly recommended.

Well, no, not cya, but engineering professionalism. The customer RR would sometimes change siderods to suit their use and that would be documented by the RR as an example.

That would change the weight of the axle load that was used in the calculations.

love to see that, all that history

I got out my 1904 book on steam engines and they have an illustration of a marine engine for a trans-Atlantic steamer that had two engines that were 47 ft tall and produced15,000 Hp EACH !!  Wonder how big the Titanics were ??

Hey, if you're in the neighborhood, contact me.   I work there and can get folks in for free.  Even so, the price of admission is WELL worth it.  Many folks make it a "destination" museum.  That goes for you other guys too.  There are a number of steam engines there because HF-1 was a big fan of machines.  The "gothic" engine is a work of art, and there's even one of the large steam power plants that used to power one of his factories.  Incredible.

i read it was something like 35 boxcars, but i can't imagine there wasn't a flat car or two somewhere in that consist.

I have to agree, if you are ever near Dearborn, MI you MUST visit 'The FORD' Museum (Greenfield Village) and get up close and personal with one of the 60 "Allegheny Locomotives" that were built.

Here is a link to give you a little idea of what you will see.

http://www.thehenryford.org/re...ghenyLocomotive.aspx

Denny

sure would be nice to see it breathing again, though.

I was at the Ford Museum years ago, in 1965-66 and remember looking at the locomotives. Have some pictures somewhere of them. Great place, would like to go back.

Those engine would have been close to the Titanic's. She had two triple expansion steam engines that exhausted into a low pressure turbine. The whole works put out 15,000 + 15,000 + 16,000 hp. 

Speaking of the 15,000 hp range, there have been proposed rail projects out there that were mainly for nationalistic posturing and political stature, the Soviets and WW2 Germany being the main proponents, of course.