More from the article: "Neither company [C&O or DM&IR] seemed to recognize that the high-capacity steam locomotive delivered the most ton-miles per train-hour at speeds close to that corresponding with maximum power output. This may have made little difference to the captive DM&IR, but understanding the C&O's attitude is difficult. DM&IR dragged immense loads of iron ore from the mines to the docks, while the C&O used its massive 2-6-6-6's in coal-drag service well below their maximum abilities." Le Massena clearly thinks C&O was stupid to get a fleet of 2-6+6-6s-- what isn't clear is what he thinks they should have done with them, given that they had saddled themselves with such unsuitable engines. What C&O did was pair them on 11500-ton coal trains up the 0.57% to Alleghany; does Le Massena think they would have saved money by pairing 2-6+6-6s on, say, 8000-ton trains instead? Hard to see why they would-- but apparently that's what he thinks about DM&IR, so maybe he thinks it about C&O too. In any case he thinks the C&O would have been better off with a fleet of 16-driver engines, or maybe 20-driver. (I can't tell whether any design of simple Mallet would have satisfied him-- likely not.) The obvious question: why did they choose fewer drivers, anyway? To us fans it is puzzling, and it's going to remain so. An engine with 150,000 lb nominal TE will pull more cars up a given grade than an engine with 110,000 lb-- we know that for sure, and presumably C&O did too. To get 150,000 lb TE we need 16 drivers or more-- C&O knew that too. I'd say we fans can't come up with any relevant fact that wasn't equally obvious to the C&O-- yet they bought 2-6+6-6s, which makes no sense to us. Far as we can tell from the article Le Massena never gave this puzzle a thought-- a glaring omission, if true. Probably most readers give him the benefit of the doubt, figuring he must have come up with some reasonable explanation that he didn't want to bore them with. Maybe it's even true-- hard to see how he could be that serenely oblivious. But the explanation is hard to reconstruct.
GP40-2The B&O also did a lot of experimenting with water tube boiler locomotives. While it is possible to have a large direct heating area and run higher pressure than a fire tube boiler, the B&O mechanical engineers found that water tube boilers where just too fragile in the railroad world. What everybody realized by the mid 1940's was that the fire tubes simply did not add as much to steam production as originally expected. Boiler design changed to emphasize direct heating area, while the shorter fire tubes pretty much served as "exhaust pipes" to get the spent gasses out to the stack as quickly as possible.
The June 1967 article on the D&H high pressure experimentals ended up with a comment that every time one of them went out on the road, the machine shop had to follow it. OTOH, the watertube concept did show up in a lot of locomotive designs in the form of thermic siphons.
I can think of a couple of ways that the extended combustion chamber helped. The first in that the large volume of gas would be radiating heat like crazy (direct heating surface) - radiative heat transfer is proportional to the 4th power of the temperature compared with linear for convection - I would imagine that there were copious amounts of incandescent carbon particles in the combustion chamber. The second is that the combustion chamber would give those carbon particles at least a few more milli-seconds to burn before they're shot up the stack.
- Erik
Firebox (or direct) heating surface was one of the considerations that went into the formulas I described in my December 24 reply. (You can see a concise explanation at Wes Barris's steamlocomotive.com.) Here are the components of the formula:
(Direct heating surface+ (superheating surface*1.5)+((tube+flue heating surface)/6)*driver diameter)/HP cylinder volume). I multiply HP cylinder volume by 100 just to keep the final number in bounds). Both the 1.5 multiplier for the SHS and the division by 6 of the tube & flue is based on railroad practice.
Key point - this formula is an attempt to present available steam at speed and does NOT take into account tractive power. Multiplying the total heating surface area (direct, superheater, and tube&flue) by the driver diameter takes into account the number of times per mile the cylinders will be refilled. You could substitute RPM and achieve the same comparative result.
Notice that with compounds, I'm only taking the live steam after starting.
Just as a sample of the interesting results, go to Steamlocomotive.com, find the Lima-built H-10 2-8-2 that set the tone for superpower on the New York Central (Locobase 9696) and a Missouri Pacific Mike that was rebuilt with thermic syphons in the firebox (Locobase 24 - MP 1426-1570). Both come from the same era, had the same driver diameter and boiler pressure. The H-10 had a bigger grate, not quite 10% more firebox area, and more superheater area. Its SPR (the "SuperPower Rating") is 21,661 compared to the MP's 15,053 (a 43% difference).
I'd love to see any comments on this reasoning.
Also (and this may start another, much smaller thread), I'm looking for information on when and where the Central of Georgia's two 2-6-4Ts ran. Did they perform similar duties to those of the Tennessee Coal Iron & Railroad's 4-6-4 30.9.3s, which delivered miners to coal mines? (Locobase 7310)?
erikemGP40-2It had a lot to do with the direct heating surface available, more so than the total heating surface. A common "end of steam" design was to use shorter, larger diameter fire tubes and lengthen the combustion chamber. In addition, larger arch tubes and multiple thermic syphons would often be employed to increase the direct heating surface. One of the things that struck me in the article on the D&H high pressure experimentals (June 1967 Trains) was the discussion of how much more effective heating area was in the firebox as opposed to the flues. The D&H high pressure locomotives traded off a lot of flue area in favor of heating surface in the firebox - somewhat easy to do with watertube boilers. Took me thirty to realize the difference was radiant (direct) heat transfer in the firebox versus convective heat transfer in the flues.- ErikP.S. There's a nice picture of the boiler for D&H 1400 on Doug Self's "Loco Locomotives" website.
GP40-2It had a lot to do with the direct heating surface available, more so than the total heating surface. A common "end of steam" design was to use shorter, larger diameter fire tubes and lengthen the combustion chamber. In addition, larger arch tubes and multiple thermic syphons would often be employed to increase the direct heating surface.
It had a lot to do with the direct heating surface available, more so than the total heating surface. A common "end of steam" design was to use shorter, larger diameter fire tubes and lengthen the combustion chamber. In addition, larger arch tubes and multiple thermic syphons would often be employed to increase the direct heating surface.
One of the things that struck me in the article on the D&H high pressure experimentals (June 1967 Trains) was the discussion of how much more effective heating area was in the firebox as opposed to the flues. The D&H high pressure locomotives traded off a lot of flue area in favor of heating surface in the firebox - somewhat easy to do with watertube boilers. Took me thirty to realize the difference was radiant (direct) heat transfer in the firebox versus convective heat transfer in the flues.
P.S. There's a nice picture of the boiler for D&H 1400 on Doug Self's "Loco Locomotives" website.
here is an example, of how boiler and smokeboxes grew. Though the angle of the photo is twisted, the back of the caps is in one line - Bullmoose, Y3a, 9000, Heavy. Chall., BB:
Actually, the early 3900class is missing here, the boiler and firebox-length of the late3900 class Challenger grew in length a portion in comp. with a 9000, the Y3a has a longer boiler and bigger firebox than the Bull Moose, but has shorter smoke box
-hope, you enjoy!
lars
Lars Loco Using shorter, larger diameter fire tubes would actually lower the total heating surface available, but had great benefits. The larger diameter fire tubes would allow a free flowing exhaust, and the shorter length allowed a longer combustion chamber design. The result was a boiler that on paper looked "smaller" than an older design with a higher number of longer, smaller fire tubes, but was more powerful. Excellent explanation here of boiler design. Does Le Massena's "formula" takes concern of that?
Using shorter, larger diameter fire tubes would actually lower the total heating surface available, but had great benefits. The larger diameter fire tubes would allow a free flowing exhaust, and the shorter length allowed a longer combustion chamber design. The result was a boiler that on paper looked "smaller" than an older design with a higher number of longer, smaller fire tubes, but was more powerful.
Excellent explanation here of boiler design. Does Le Massena's "formula" takes concern of that?
Lars--
I had always read that NKP turned their Berkshires quickly, as did N&W their big steam power--in both cases routinely under 2 hours.
However, Kratville and Bush in the UP Type Vol. 2 book indicate that during hurry periods Union Pacific actually turned engines in as little as 25 minutes (obviously without the washdown but with a quick inspection over the drop pit). Since this included turning 4-12-2's in 25 minutes, it is quite obvious that the middle cylinder would not always have received the maintenance it needed.
Big Boy boiler was considered free steaming according to Kratville, and had the ability to raise large amounts of steam quickly...tested on Alco's plant, they raised the boiler from cold start to 300psi within 45min. In hurry seasons turnarounds were performed within 2 hours, blown down 40 min., 40 min washing, 40 min for steam and fire up.
When treated this way, I think it must be almost visible to see how the boiler grow in length while becoming hot :-)
Cheers
UP 4-12-2 I suspect that being "free steaming" had more to due with the amount of available heating surface, the length of the boiler tubes, the draft, and the relative open-ness or backpressure of the exhaust. John
I suspect that being "free steaming" had more to due with the amount of available heating surface, the length of the boiler tubes, the draft, and the relative open-ness or backpressure of the exhaust.
John
Examples of this design included the 4-8-4 NYC Niagara and C&O J3a. The 2-8-8-4 B&O EM1 of 1945 was a very good example of a big engine using this design. The EM1 had very short, large diameter fire tubes, but had a large firebox and combustion chamber, large arch tubes, and 5 thermic syphons which gave it the same direct heating surface as the H8 Allegheny.
Those 3 engines mentioned were considered very "free steaming" and had the ability to produce high horsepower at high speeds.
Actually, the UP 4-12-2 had a rather large, long boiler and a rather large firebox. So long, in fact, they had to use a "Gaines Wall" (a low wall toward the front of the firebox) to help direct the heat where they wanted it and to have the exposed heating surface they needed (I don't fully understand the theory). It also had rather long boiler tubes. In fact--the 4-12-2 boiler is actually longer and larger than the boiler used for many articulateds (not the last designs, but many others.) The boiler was designed to stay within clearance limitations on the Union Pacific in 1926--and to stay at or near 59000 pounds axle loading--which was the UP limit at that time. A 10-drivered engine--even a larger three cylinder 4-10-2--was rejected because it could not produce the power and speed they wanted. (Note: they already had 3-cylinder 4-10-2's that did not produce enough power and speed). I think Kratville and Bush state they even considered but rejected a 4-10-4.
I'm a dumb civil engineer who designs things that don't move, but I seriously doubt that being "free steaming" had anything to do with whether an engine was articulated or not--but much more to do with the design of the boiler, firebox, superheater tubes--and yes--the smokebox--where they knew that proper installation of the deflectors had an impact on how free steaming an engine would be.
Also--the UP 4-12-2 was considered for rebuilding into a 4-6-6-2 simple articulated--which would have been built in very early 1940--but ultimately, they decided to build a 4-8-8-4 instead.
According to Kratville and Bush, installation of roller bearings on all axles would have made the 4-12-2 the "near equal" of the first group of UP challengers in actual performance. As it was, tonnage ratings on the railroad between the two classes were very similar.
I suspect that being "free steaming" had more to due with the amount of available heating surface, the length of the boiler tubes, the draft, and the relative open-ness or backpressure of the exhaust. The challengers and big boys were considered to be very "free steaming" engines.
John, Paul, et. al.,
I wonder how much of the "free steaming" ability of the 4-12-2 was due to it not being an articulated? Instead of running through long pipes with flexible joints, the supply steam would only eed s short run from the superheater output to the cylinders and conversely the exhaust steam would have had a short path from the cylinders to the nozzles underneath the stack.
With a single axle trailing truck, the UP type would have not had the firebox geometry possible with the Texas type.
Paul--
UP's studies did indicate that "freer" steaming locomotives did perform better--ie more horsepower at higher speed. They did indeed have a better draft--but that isn't all. So many of their engines were fitted with larger diameter smokestacks--or even dual stacks. Jabelman was nearly obsessed with free steaming engines and reduced backpressure. The emphasis in the west was on speed--and Santa Fe had the edge with a shorter route and higher speeds. Trains magazine, or Classic Trains, had an article about the UP 800's within the last year or two that discussed the concept of "free steaming" engines in excellent detail--better than I can.
Some boilers--like the 4-12-2's--were designed to produce copious amounts of steam--because they knew they needed it to move heavier tonnage trains faster. So they did have a reputation as very easy steaming engines--easier to get going than other types--easier to produce plenty of steam and heat. There are stories about just how easy it was to get them moving...When used in passenger service, the 4-12-2's did not have the top speed of some passenger power but they were easily able to accelerate trains rapidly out of the station stops--faster than the passenger power--and therefore were actually able to maintain passenger train schedules when called upon to do so. They were capable of speeds above 65 mph when needed.
I hope this helps some.
Respectfully submitted--
and had actually slashed operating costs (and dramatically increased average train speeds) because they steamed so much better than anything that came before them.
What does this mean that a locomotive "steamed well" or "steamed better" or was "free steaming" than some other locomotive. I have seem this term in accounts of operating and firing locomotives, but the term seems rather subjective.
Does it mean that the locomotive had high combustion efficiency, that a small amount of coal raised a lot of steam? Or does it mean that a locomotive had an effective draft system, that you could stoke the fire with a large quantity of coal to produce a lot of steam without clinkering up or choking the fire?
Was there any systematic study of designs and why a locomotive was "free steaming" and why another one wasn't?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Ooops,
UP4-12-2,
my bad, I did not read your mail carefully enough.
I understand Jabelman did not like roller-bearings. That he did not favor the 9000 is plausible, and valid, in my humble opinion, proved by the latter designs.
The boiler and firebox of the 3900's in fact does not diifer so much from the 9000's, though the shape became different.
They were big improvements over the elderly "Moose's" , however. Otherwise, it was up to Lima und C&O to prove, 2 cyl. and 2 rods are up to such kind of piston forces, making the third cyl. somewhat obsolete.
I meant of course 6000 indicated HP for the T1 (or 5400DBHP, if this is acceptable).
Cheers,
-edit-
BTW,
If you can think "Popular Mechanics" is a reliable source, I read there modern UP-engines had an expected life-time cycle of 3million miles or 30 years.
Jabelman decided he hated the 9000's, not roller bearings. The U.S. government was willing to pay, prior to WWII, for the upgrading of ANY steam locomotives that needed it, knowing that a big increase in rail traffic was coming. The 88 4-12-2's at that time were still the largest fleet of mainline motive power on the railroad, and had actually slashed operating costs (and dramatically increased average train speeds) because they steamed so much better than anything that came before them. The government was willing to pay for roller bearings on all axles and other improvements that would have fixed the principal maintenance issues of the 4-12-2's, but Jabelman only wanted brand new power and would not hear of upgrading older power.
I just received the book by Willian Kratville and John Bush, The Union Pacific Type, Volume 2. They did extensive, meticulously detailed interviews with actual Union Pacific employees in both the engineering and operations sections of the railroad, over a 30 year period of time, while some of the men involved in the original design and operations of the 4-12-2 were still living. These loyal Union Pacific employees made it crystal clear that Jabelman was not in favor of upgrading ANY older locomotives--but that he always believed in total replacement as being, in his opinion, more justifiable. So whenever UP management requested estimates to do this or that to improve older power, he made absolutely certain the estimates were inflated--because he wanted to build or buy new power instead.
The UP engineering department actually prepared a sketch plan to rebuild the 4-12-2's into 4-6-6-2 simple articulateds while retaining the boiler--and an estimate outside the UP engineering department was prepared. Based on that estimate, the UP management actually accepted the idea and said--"let's build the 4-6-6-2" before Jabelman stepped in and argued his case to build brand new simple articulateds instead. The sketch plan is included in the Kratville/Bush book. Ultimately, UP chose to build the Big Boys to get over 6000 horsepower instead of 4900+/- out of a 4-6-6-2.
Authors Kratville and Bush contend that if it were not for Jabelman, and the easily foreseen in 1939 coming diesel revolution, it is highly likely the 4-12-2's would have received roller bearings on all axles and some other easily doable improvements that would have upgraded them into truly first class high speed freight engines while reducing the main operational headaches. Even as it was, the UP was operating them at sustained speeds of 60 mph and above--which was hard on the frames for the ones not originally built with one-piece cast frames.
I agree the C&O 2-10-4 was a great engine, but so was the 4-12-2, and the C&O 2-10-4 did not produce 5900 horsepower--that's big simple articulated territory. So far as I'm aware the highest horsepower out of a 2-10-4 is about 5600 peak horsepower in the case of the Santa Fe 5001/5011 classes.
The 4-12-2's are recalled by those who operated them to have steamed as well or better than most engines UP ever owned, and that is why they lasted until very nearly the end of steam. Although there were maintenance issues with valve gear, they had remarkably few issues with the boilers. Even as late as 1952, after Jabelman was gone, the UP had a plan that called for keeping the last 25 4-12-2's through 1965, along with the 3900's and 4000's.
UP 4-12-2 Also--UP's 4-12-2's were never modernized with roller bearings (other than on the Gresley gear of some) becaue Otto Jabelman decided he absolutely hated them, and spent much of his career trying to get rid of them or replace them--even basically ignored potential U.S. government war-era funding for roller bearings which would have dramatically upgraded their performance and especially their durability.
Also--UP's 4-12-2's were never modernized with roller bearings (other than on the Gresley gear of some) becaue Otto Jabelman decided he absolutely hated them, and spent much of his career trying to get rid of them or replace them--even basically ignored potential U.S. government war-era funding for roller bearings which would have dramatically upgraded their performance and especially their durability.
I never read Jabelman was against roller-bearings, huh? Something mixed here with tales from Southern Pacific?
UP 4-12-2 Because they never received some "modern" improvements, we'll never know what the real potential of those engines might have been. As engine 9000 was tested in 1926, peak horsepower was 4917 indicated at the cylinders at 37 mph (reported in UP Type, Vol. I) and later improved versions most certainly did better--but there's no data regarding how much better the later versions performed. What a shame. John
Because they never received some "modern" improvements, we'll never know what the real potential of those engines might have been. As engine 9000 was tested in 1926, peak horsepower was 4917 indicated at the cylinders at 37 mph (reported in UP Type, Vol. I) and later improved versions most certainly did better--but there's no data regarding how much better the later versions performed. What a shame.
A real improvement was the T1-Texas. One Cyl. less, but a good 1000hp more than the 9000-class,
The UP got finally rid of all this 3-cyl.-maintance-horror by designing the Chally.
CSSHEGEWISCHLe Massena's problem was he often passed his uninformed opinions off as facts to the railfan community.
I was under the impression that LeMassena was more accurate and/or better informed than Lloyd Stagner. Regarding inaccuracies in printed articles and books, I became very frustrated with Lloyd Stagner's works many years ago--and refuse to buy anything that has his name on it. Why? Well, at least where Santa Fe steam is concerned, he likes to quote lots of numbers, and either his writing or the editing on the part of Morning Sun Books was shoddy. Where Stagner quotes Santa Fe steam data, especially in The Santa Fe in Color book series, there appear to be several mis-quotes. This does not become fully apparent until you read the cited sources (S. Kip Farrington's The Santa Fe's Big Three, which included many actual Santa Fe loco test reports). Always go back to the original data source and be wary of locomotive horsepower and/or tractive effort ratings in print. Recent Classic Trains Steam special issues have also included articles that appear to conflict with each other where locomotive data is concerned.
This thread makes very interesting reading, especially for someone like myself who has read LeMassena's Articulated Steam Locomotives of North America books...
Regarding great, or potentially great engines, or relatively unsung engines:
The Santa Fe hudsons were known for beinq quite slippery, and in that regard are not as fondly remembered by most SF fans as the 4-8-4's.
The 5001 and 5011-class Santa Fe 2-10-4's were marvelous engines producing very high horsepower (if I recall correctly, well above 5000 horsepower for a 30 mph band of usable speed according to the actual test data published in S. Kip Farrington's The Santa Fe's Big Three.) but because they toiled mostly in the New Mexico desert, they are largely forgotten. In the curvy areas of Arizona, the 2-10-2's apparently performed better--so I think many folks forget about or vastly under-rate the 2-10-4's.
Also--UP's 4-12-2's were never modernized with roller bearings (other than on the Gresley gear of some) becaue Otto Jabelman decided he absolutely hated them, and spent much of his career trying to get rid of them or replace them--even basically ignored potential U.S. government war-era funding for roller bearings which would have dramatically upgraded their performance and especially their durability. Because they never received some "modern" improvements, we'll never know what the real potential of those engines might have been. As engine 9000 was tested in 1926, peak horsepower was 4917 indicated at the cylinders at 37 mph (reported in UP Type, Vol. I) and later improved versions most certainly did better--but there's no data regarding how much better the later versions performed. What a shame.
I wish to defend both the Lima A-1 2-8-4's on the Boston and Albany and their near cousins with Coffeen fedwater heaters ("the John L. Lewis look") on the nearby B&N. Both did their jobs, Both crossings of the Birkshire Moutains were early candidates for dieselization, but not because of any problems with the Birkshires. The B&A's did see further use on the NYC system and were seen later in Michigan, Ohio, Illinois, and Indiana, often with larger tenders. And obviously the AT&SF thought enough of the B&M's to buy some.
That does not prevent from admiring the NKP-PM-W&LE-C&O design even more.
GP40-2CSSHEGEWISCHWhile Le Massena concedes that the design of NP's power took consideration of the low-grade coal that was available, he implied that even better performance would have been possible with good coal. Better performance would have been possible with better coal AND a complete redesign of the combustion area. It is not as simple as just using better grade coal in the existing design. Railroads that had the best steam coal in their backyard such as the N&W, C&O, and B&O had their boilers, specifically the firebox/combustion chamber area specifically designed to maximize the potential of such coal. Same with powerplant design. You can't take a plant that was designed to used Powder River coal, and start using fast burning/high BTU Pittsburgh Grade coal. The entire combustion area would need to be redesigned. Le Massena problem was he often passed his uninformed opinions off as facts to the railfan community.
CSSHEGEWISCHWhile Le Massena concedes that the design of NP's power took consideration of the low-grade coal that was available, he implied that even better performance would have been possible with good coal.
While Le Massena concedes that the design of NP's power took consideration of the low-grade coal that was available, he implied that even better performance would have been possible with good coal.
To start with, is there a point where a large grate with high-BTU coal might melt the crown sheet?
Would the flues be sufficient to carry off the hot gases from the firebox-combustion chamber?
Would superheaters be large enough for adequate steam flow?
Would the firebox-combustion chamber and flues absorb that heat for steam production efficiently?
Finally, would these improvements reach peak output at 40 mph, about the limit for 63" drivers; or would the engines be considered "slippery!"
The Red Lodge mines were gassy. The geology wasn't very fun, either.
RWM
Railway ManColstrip was a very advanced mechanized mine for its time, and of great interest just for its very low mining costs.
Colstrip was a very advanced mechanized mine for its time, and of great interest just for its very low mining costs.
The 9 cu. yd. dragline that was part of the original opening of the mine ca 1923, was still in use in 1971 along with the "small" electric shovel (ISTR also about 9 cu. yd.).
Prior to opening the mine in Colstrip, the NP was getting its coal from the mines around Red Lodge. The Red Lodge mines were underground and thus labor intensive, which was particularly important after the wage inflation due to WW1. Another issue was safety, the worst mining disaster in Montana history was happened in Bear Creek (a very few miles east of Red Lodge) during WW2.
CZ:
The source of coal for the NP Yellowstones (as well as many other NP steam engines in the Rocky Mountain area) was the company's open-cast mine near the town of Colstrip, Montana. Popularly referred to at the time (and in railfan legend) as lignite, this is in fact a sub-bituminous coal of about 8,300 BTU. Today, we call this "Northern Powder River Basin" coal and it is mined from the exact same seam for large mine-mouth power plants owned by Colstrip Energy and Pacific Power & Light, and for numerous northern plains and Midwestern utilities such as Detroit Edison.
NP's coal supply west of the Rocky Mountains was the company mines at Roslyn, Washington.
Most railways that served major coal-producing regions owned their own coal mines and sourced as much coal as possible from their captive mines. Some of these coal companies bore the same name as the railroad (e.g., Union Pacific Coal Company) and some did not (e.g., Utah Fuel Co. of the D&RGW; Clearfield Coal Co. of the NYC).
The NP's use of the very large firebox on the Yellowstone was an attempt to gain better efficiency from the low-value coal it had close at hand in Montana, as opposed to higher heating value coal from Roslyn, the Illinois Basin, or "Lake Coal" via Duluth, which was considerably more expensive due to transportation costs to carry it to Montana to put into a locomotive tender. Both Railway Age and Coal Age covered the NP's effort extensively as it was of great interest to both the railway and coal industries, the former hopeful that it would be technically possible to burn such poor-quality coal and still generate adequate transportation without high maintenance and locomotive failure expense; the latter hopeful that it would create a market for otherwise worthless coal in an era when oil and natural gas were rapidly encroaching on the railway, domestic, and industrial heating and process market. Colstrip was a very advanced mechanized mine for its time, and of great interest just for its very low mining costs.
feltonhill The NP 2-8-8-4's grate area was initially 182 SF, but it was later reduced to 161.4 SF because of drafting/combustion problems.
The NP 2-8-8-4's grate area was initially 182 SF, but it was later reduced to 161.4 SF because of drafting/combustion problems.
The grate size was to burn the (Rosebud) coal, which was a very poor but cheap grade of coal. The Z5 was not a high capacity type of locomotive and was used in pusher service almost entirely after the Z6, Z7 and Z8's were running. The Z5 was very large at the time it was built, but a very slow locomotive compared to the Z8's or the Big Boys. I am not sure about the exact name of the coal, but it was cheap and so the NP engines grate size had to be much larger to get proper amount of heat out of it.
CZ
feltonhillThe best I have is that it weighted 405,600 lbs, excluding tender.
IC #1 was 388000 lbs, excluding tender. It was the only attempt at a freight Hudson, but was too slippery.
C&NW, CA&E, MILW, CGW and IC fan
I was underwhelmed when I first read about this method of power ranking, and the more I thought about it, the more exceptions I could find, even when I held the caloric value of coal constant. (This thread's discussion of BTU values has been very useful to explore a different area of disagreement.)
A central problem was the dismissal of the boiler. Same grate, same pressure and I was pretty sure you'd have different results with different-sized boilers.
Then I wondered about the effect of superheating the steam that's produced? So I used the "equivalent heating surface" calculation of 1.5 x the superheater's sq footage divided into the total heating surface. That brings the boiler into play and, as I'll show in a moment, takes a long step toward making this a useful way to compare locomotives.
But then I thought of oil-fired locomotives - they don't have "grates" in the sense of spreading the fuel out over a single surface. They burn their fuel in a volume bounded by the firebox. So I substituted firebox heating surface for grate area, which I think allows for an apples-to-apples comparison of oil burners with coal burners.
And, I thought, if grate area is your only measure, then clearly Wootten anthracite-burning fireboxes take the palm. Their grates are relatively huge - at least twice the area and often more compared to an equivalent narrow-firebox design. What I discovered is that these fireboxes usually had very similar direct heating surface areas, so soft-draft, thin-fire apparatuses such as these can be compared.
After tinkering some more, I came up with a formula that takes into account the superheater's contribution as outlined above,
the higher rates of evaporation per square foot of heating surface for fireboxes compared to tubes (about 6 to 1),
driver diameter (fewer RPM means fewer "lungfuls" per minute or per mile).
It was a lot of fun and the resulting number works pretty well for all kinds of steam locomotives. But along the way, I became satisfied that using firebox (or direct) heating surface area (this includes syphons, arch tubes, combustion chambers...) times the boiler pressure times the superheater ratio(x 1.5) can give a shorthand comparison.
Steve Llanso, Locobase.
More quotes from the article--
"The [CB&Q] 2-10-4 was operated at speeds well below that for peak power (about 20 mph)...The Burlington 2-10-4's big boiler, 107-square-foot grate, and 250-pound pressure, thus misapplied, were more ornamental than useful in the production of ton-miles at minimum cost."
CB&Q got the 2-10-4s to haul 8000-ton coal trains out of southern Illinois; ruling grade against the loads may have been 0.3%, which would indeed slow them to 20 mph or so-- when they were on that grade. But most of the time they wouldn't be on that grade, so most of the time they'd be making better speed, maybe even good enough to satisfy Le Massena. No doubt he'd prefer that they reduce the assigned tonnage, but he still makes no attempt to explain how that would lower costs."When the [SP] cab-forwards were used in passenger service over difficult profiles at high speeds, their performance was magnificent; yet their primary use was in low-speed freight service, three or four to a train, operating well below the ultimate capacity of boiler and machinery."
In the 1940s SP rated its newest 4-8+8-2s at 1450 tons eastward over Donner Pass, with which they could apparently make 15 mph or better on the steepest part of the climb. Not good enough for Le Massena-- one wonders what tonnage rating he would have approved. Note that if they cut trailing tonnage by, say, 40%, they'd only be cutting total tonnage by 30%, so the increase in ton-miles per hour won't be that great.
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