Which of the old steam engines had the widest diameter (not length) boiler? I read the big boy was roughly 94" and Allegheny was roughly 95" and the 2-10-10-2 I could not find a diameter... The challenger models seemed to be slightly less than big boy... Question does anyone know definitively the boiler diameters of these top 4 or 5 big steamers? And, which is the biggest in Diameter, not length, weight, pulling, etc. JUST diameter of these big guns! Thanks!
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According to The Locomotives that Baldwin Built by Fred Westing, the Alco Big Boy's boiler was 95" in diameter. The Western Pacific had some 2-8-8-2's and the DM&IR had some 2-8-8-4's that each had boilers 104" in diameter.
I have seen claims that the Virginian 2-10-10-2's had the largest boiler diameter (Wikipedia says 119"), but I don't know of a published reference to verify this.
Would the other 2-10-10-2 have the same size boiler or did it get changed up?
For what its worth, the diameter of the boiler on ANY steam locomotive does NOT equate to the "pulling power" of the locomotive!
@Hot Water posted:For what its worth, the diameter of the boiler on ANY steam locomotive does NOT equate to the "pulling power" of the locomotive!
It doesn't equate to the hat size of the engineer either, but nobody's asking about power just boiler diameter.
@Hp289 posted:Would the other 2-10-10-2 have the same size boiler or did it get changed up?
The Santa Fe 2-10-10-2's were very much smaller than the Virginian locomotives.
@Hp289 posted:Would the other 2-10-10-2 have the same size boiler or did it get changed up?
The Santa Fe 2-10-10-2 boilers were 89"and 7/8's" just before the firebox, reduced to 78" and 7/8's" (essentially 90" and 79") the rest of the length. (source: Santa Fe Locomotive Diagram - Iron Horses of the Santa Fe Trail.)
Rusty
FWIW, there is a diagram the book "Allegheny, C&O's Finest" that shows how the boiler of the Big Boy would fit inside the boiler of the Allegheny.
Wasn't there a C level C&O meeting held inside of the H-8 firebox?
So, it appears the Allegheny has the widest boiler?
The November 1918 edition of the Railway Mechanical Engineer, starting from page 600, discusses the Virginian AE 2-10-10-2 class and has specs on the boiler among other things. Try this link. https://archive.org/details/ra...wy/page/602/mode/2up
Just curious; why are you so concerned with steam locomotive boiler diameters?
@Hot Water posted:Just curious; why are you so concerned with steam locomotive boiler diameters?
Maybe he's not so much "concerned" as perhaps just..."curious"? 🙂
Mark in Oregon 🎄
Go to STEAMLOCOMOTIVE.COM.
Everything you ever wanted to know about steam locomotives is there.
@Rich Melvin posted:Go to STEAMLOCOMOTIVE.COM.
Everything you ever wanted to know about steam locomotives is there.
Maybe everything but boiler diameters.
@Bob posted:Maybe everything but boiler diameters.
Except,,,,,,,,,,,,,boiler diameters don't really mean much. What is much more important is the maximum working boiler pressure and the size/capacity of the furnace system, i.e. firebox and grate square footage, which is the ability to produce enormous volumes of high pressure, superheated steam, under all load conditions.
Maybe he just wants to know the answer to the question that he asked.
Yes, just the question I asked, thanks Arthur and to those that tried to help me out. I'm just doing some wondering and I didn't find everything I was looking for. I'm only concerned about the large locomotives, big boy, Allegheny, Santa Fe 2-10-10-2, challenger, and Yellowstone. Are their other big ones like that? Just trying to figure out the widest boiler and by how much for these big engines. Thank you! Based on what you guys said and what I also found, it seems the Allegheny and Virginian 2-10-10-2 are the biggest?
@Hp289 posted:Yes, just the question I asked, thanks Arthur and to those that tried to help me out. I'm just doing some wondering and I didn't find everything I was looking for. I'm only concerned about the large locomotives, big boy, Allegheny, Santa Fe 2-10-10-2, challenger, and Yellowstone. Are their other big ones like that? Just trying to figure out the widest boiler and by how much for these big engines. Thank you! Based on what you guys said and what I also found, it seems the Allegheny and Virginian 2-10-10-2 are the biggest?
Without doing any research, but from memory, the Northern Pacific had some really large 2-8-8-4 and 4-6-6-4 steam locomotives. Then there were the Santa Fe 5011 class 2-10-4s, and Southern Pacific 2-8-8-4 and 4-8-8-2 cab forwards. Lets not forget the PRR various duplex steam locomotives (6-4-4-6, 4-4-4-4, 4-4-6-4, etc).
thanks, but which were the largest diameter boilers?
@Hp289 posted:thanks, but which were the largest diameter boilers?
Don't know, and don't care, as boiler diameter means nothing when comparing horsepower and performance.
@Hp289 posted:thanks, but which were the largest diameter boilers?
The 5011 Class 2-10-4' boilers were 100" and change at their widest.
Rusty
HP289,
Boiler diameter measurements depend on where they are measured, usually getting wider the farther back from the front of the smokebox you go. Using data from the 1947 locomotive Cyclopedia, measurements of the first ring or smokebox show the DM&IR M-3 2-8-8-4 with 102 1/2" dia., PRR Q2 with a 97 15/16" dia., the B&O EM-1 & NYC S-1a with a 96 1/8" dia., the ATSF 2-10-4 with a 95 1/4" dia., C&O 2-6-6-6 with 90 25/32" dia., UP Big Boy with 90" dia.
I hope this pretty much answers your question.
And per the November 1918 Edition of The “Railway Mechanical Engineer”, page 602, the first course for the Virginian 2-10-10-2 is 105 1/2” and the largest course is 112 7/8”.
So, it actually generally appears the DM&IR M-3 2-8-8-4 with 102 1/2" dia is second and The Virginian AE 2-10-10-2 at around 118+ is the widest boiler on these large engines.
Hp289
I have some data here, most from Train shed Cyclopedia. Some of the values are shown on the diagrams and some are measured by myself( Max. boiler dia. w/jacket and some of smokebox dia.)
VGN VGN DM&IR WP D&RGW NP C&O SP GN PRR
AE AD M-3/4 #251 L-131 Z-5 H-8 AC-9 R-2 J-1
Max. boiler dia. 118.5 112 108.6875 108.6875 113 110.25 109 109.125 111.125 106
Max. boiler dia. 126 118.2 117.5 112 118 114.6 117 113.5
w/jacket
Boiler dia. 1st ring 105.5 100 104 104 104 103.25 102.06 97.84 100
(ID)
Smokebox dia. 106.75 101.25 109.5 106.5 104.37 107.62 104 99.06 101
(W/jacket) (W/jacket)
Very interesting discussion.
Thanks for asking the question as it allowed for the discovery of some interesting little known facts.
@Hot Water posted:Don't know, and don't care, as boiler diameter means nothing when comparing horsepower and performance.
I don't understand this type of response...🤔 Maybe the OP is building a model and would like that information.
If the question was about "horsepower and performance", that's one thing; if you "don't care", then why bother responding at all?
Mark in Oregon
For the historical record, in response to Tom Tee's question, it was a dinner party held in the firebox of the Northern Pacific's 2-8-8-4 at time of construction. Fortunately the attendees did not have to squeeze through the firebox door, but rather the boiler was on stanchions and was not attached to the frame. The NP Yellowstone had the largest firebox ever employed in a steam locomotive.....182 square feet.
@Strummer posted:I don't understand this type of response...🤔 Maybe the OP is building a model and would like that information.
But,,,,,,,he asked the question here on the Real Trains Forum, instead of one of the modeling forums.
If the question was about "horsepower and performance", that's one thing; if you "don't care", then why bother responding at all?
Mark in Oregon
True enough... maybe it's just one of those "musing" type questions; kinda like what gets asked a lot in the "3 rail traditional toy trains" section. You know, like "baseball and toy trains"; "favorite post-war accessory", or "favorite train song" type of thing... 🙄 🙂
Mark in Oregon
What about those huge South African locomotives? Did any of them exceed American ones in diameter? ISTR that they were pretty big, and unencumbered by close clearances, having worked in the wide-open spaces of the continent.
FWIW, the Virginian AE 2-10-10-2s had tremendous tractive effort at 176,600 lbf in simple mode and 147,200 lbf in compound. That's more than the Big Boys, Alleghenies, or even the DM&IR Yellowstones -- and remember, this is a 1918, pre-"Super Power" design, unlike most of the other big articulateds that were mentioned above. That huge boiler diameter was what provided enough steam to make a monster like the AE work while the Santa Fe 2-10-10-2 and the Triplexes with their smaller boiler volumes couldn't keep up. The AEs were slow, but they could sure push and pull!
While the tractive effort numbers for the Virginian 2-10-10-2s are very impressive, you have to understand that there is a huge difference between “tractive effort” and “horsepower.”
Those old locomotives could produce tremendous amounts of pulling power at slow speeds, but their boilers - even the BIG ones - could not produce enough steam to meet the demands of the cylinders at higher speeds. That was the very principle upon which “Super Power” was based…horsepower at speed. A Lima-designed Super Power steam locomotive boiler could produce approximately 15% more steam than the cylinders could consume when working at maximum horsepower output, even on the Allegheny.
@Arthur P. Bloom posted:What about those huge South African locomotives? Did any of them exceed American ones in diameter? ISTR that they were pretty big, and unencumbered by close clearances, having worked in the wide-open spaces of the continent.
South African Railways steam locomotives where NOT "huge", since their railway was not even standard gauge. The SAR used "Cape Gauge", which was/is just a wee bit wider than meeter gauge (maybe three foot six, or there about). Although the SAR did have beautiful 4-8-4s and various sizes of articulated Garrett locomotives, there axle loading limitations precluded ANY steam locomotive as large as what was used on the North American Continent.
@Rich Melvin posted:While the tractive effort numbers for the Virginian 2-10-10-2s are very impressive, you have to understand that there is a huge difference between “tractive effort” and “horsepower.”
Those old locomotives could produce tremendous amounts of pulling power at slow speeds, but their boilers - even the BIG ones - could not produce enough steam to meet the demands of the cylinders at higher speeds. That was the very principle upon which “Super Power” was based…horsepower at speed. A Lima-designed Super Power steam locomotive boiler could produce approximately 15% more steam than the cylinders could consume when working at maximum horsepower output, even on the Allegheny.
Of course. As I said, this was 1918 and BEFORE Lima pioneered the Super Power concept, which to me makes it that much more impressive. Alco maxed out the very limits of what that technology could produce. A single AE could pull over 100 of VGN's famous battleship gondolas loaded with coal all by itself, over the mountains and all the way to the ocean -- albeit at about 8 mph. This led the Virginian to electrify west of Roanoke in the mid-1920s, even though Super Power had been invented at that point. Not even that cutting edge steam could match the performance of the old squareheads on that route, and later the EL-2Bs and rectifiers. For as much horsepower as they had, the Alleghenies were wasted on the Virginian and run exclusively on the flats east of Roanoke.
BTW, the last surviving AE (#805) wasn't scrapped until 1958 -- that's 40 years of service!
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