BigJim Conductor_Carl Well, imma learn you up! https://archive.org/details/sim_railway-age_1936-09-26_101_13/page/435/mode/1up "Riddle me this Batman", according to the article, it lists the starting tractive effort at 104,500 lbs. Yet, the graph shows it to be about 118,000 lbs. Where did this figure come from? Did the N&W possibly turn the screws up to 300 psi on said test?
Conductor_Carl Well, imma learn you up! https://archive.org/details/sim_railway-age_1936-09-26_101_13/page/435/mode/1up
"Riddle me this Batman", according to the article, it lists the starting tractive effort at 104,500 lbs. Yet, the graph shows it to be about 118,000 lbs. Where did this figure come from? Did the N&W possibly turn the screws up to 300 psi on said test?
Great discussion. In my opinion, it's not outside the realm of possibility that an A could develop 6,300hp as the graph shows. I have looked at this before and based on calculated boiler capacity and machinery friction of its 6-coupled configuration that had lower weight on drivers than the 8-coupled articulated Big Boy or the Allegheny 6,300 seems reasonable (although possibly at firing/steaming rates in excess of how the locomotives were used in service).
I have never found the claim from the 1936 Railway Age article that an A could "attain a speed of 64 m.p.h. with a 7,500-ton train" to be remotely believable, unless on a downgrade or with decreasing speed. Using Davis equation estimates, a 7,500 ton train of 85 ton cars would have about 8 lb/ton of resistance, requiring 60,000lbs of DB pull at 64mph. Based on the Railway Age DB pull graph, a single A could develop approximately half that much at 64mph, or a still respectable 5,100 DBHP. Taking the 7,500 tons at 64mph at face value implies over 10,000 DBHP!
timz Conductor_Carl My instinct would have been to ... try and get comparative costs ... Try how? Where would you look?
Conductor_Carl My instinct would have been to ... try and get comparative costs ...
Try how? Where would you look?
The L&N historical society has a book coming out on the M-1. I would hope that it has test data to determine fuel costs, and costs of each order (which I think I can already get). But it probably won't have maintenance costs so I wouldn't be able to compare it to a hypothetical L&N articulated (not to mention costs of updating infrastructure to accommodate said hypothetical articulated) so won't bother trying to find this out.
The Emmas were 2-8-4s instead of 4-8-4s because of short tables and lack of wye facilities. What would make someone think an articulated -- even one with six-coupled engines -- would be any shorter?
The instructive thing to learn about N&W practice is in Ed King's book on the A (which I regrettably don't have to hand). Study the calculations involved in 15,000T with a single A from Williamson to the Scioto River (Kenova) bridge. There is a picture there of an A arriving with very little coal left in that tender...
Conductor_CarlMy instinct would have been to ... try and get comparative costs ...
Conductor_CarlWhat am I learning now? That I dont know anything and it is worthless to try and learn anything new ...
He's on the Empire Builder in 1937, in the cab of the 2588.
"We thus arrived at Fort Browning. The station stop lasted 1 min but an additional 2.5 min elapsed before the train was moving again. The start took place on a 1/100 gradient. Heavy trains such as ours were started on mountain gradients by what was known as the 'compression method'. The train was held on the gradient by the air-brake with all the slack stretched out. The reverse lever was placed in full forward gear, the throttle 'cracked' and the air released. The train slowly dropped back about a quarter-turn of the driving wheels and then, as it was brought to a standstill by the compression of the steam in the cylinder, the throttle was pulled wide open and the train started as a unit with all the draft gear stretched and without jerking. To start a 1260-[metric]-ton train on a 1/100 gradient without slipping, with a two-cylinder locomotive having 6 ft 8 in driving wheels, is quite a feat."
He rode a MILW 4-4-2 on a nine-car Hiawatha in 1937
"The locomotive rode remarkably well. At 96 mph I wrote my notes conveniently standing up and not leaning against anything. At 106 mph I took them quite comfortably, sitting down."
timz Try this. N&W pulled 10,300-ton coal trains to the Allegheny divide with two 2-8+8-2s, climbing 5+ miles of just under 1%. L&N pulled 8300-ton coal trains up 7 miles of just under 1% Ford to Patio with three 2-8-4s. Who was smarter?
Try this. N&W pulled 10,300-ton coal trains to the Allegheny divide with two 2-8+8-2s, climbing 5+ miles of just under 1%. L&N pulled 8300-ton coal trains up 7 miles of just under 1% Ford to Patio with three 2-8-4s. Who was smarter?
I dont think that I will.
Earlier in this thread I was learning things. I learned about compensated HP. Neat! Q2 testing was posted. Really cool!
What am I learning now? That I dont know anything and it is worthless to try and learn anything new because it is not possible to evaluate if someone made a good choice or not because I will never have as much information as them. Wahoo.
My instinct would have been to look at the L&N, try and determine how often they would haul those sort of trains (many times a day?), try and determine what infrastructure changes would be required to accommodate a more powerful articulated, try and determine if the route favors high tractive effort or high horsepower to color what theoretical engine they could get, try and get comparative costs so I could figure how many M-1's you would lose out on if you replaced part of the order with the hypothetical articulated and capital required to support it, and then see if that makes more sense than just triple heading M-1's. If I did that I would learn all kinds of stuff about the L&N. Their operating practices, their routes, the M-1 and its usage, its infrastructure, and why they made the choice to buy the most expensive berkshire.
But I wouldn't know as much as the L&N did when they were making those decisions, so I would be wrong. and that would take a decent amount of money and time to learn this crap just to get to that wrong conclusion, and it really doesn't matter, so I think I won't bother.
Infrastructure did have a lot to do with locomotive choices on some roads.
When UP bought the Big Boys, they installed longer turntables at several critical terminals and had enginehouse stalls extended at several places. They also did some curve work to ensure horizontal clearances on curves.
Not all railroads could afford to do that. So they rolled with the biggest power that fit the railroad.
It's worth talking about -- no one said different. We just have to keep in mind how ignorant we are. Too bad so many fans don't do that.
Try this. N&W pulled 10,300-ton coal trains to the Allegheny divide with two 2-8+8-2s, climbing 5+ miles of just under 1%. L&N pulled 8300-ton coal trains up 7 miles of just under 1% Ford to Patio with three 2-8-4s. Who was smarter? Safe bet most fans will vote for N&W. So: should talking ensue? Sure. Will much of the talk be dumb? Sure. Are we worse off after the talking? No.
Supposedly L&N couldn't handle articulateds in its shops, or something like that. Easy to imagine fans sneering at L&N: "Jeez! That's the reason you don't use the right engines? Build a proper shop, fer crissakes!" As usual, the fans think they know something L&N didn't.
timz I feel kind of silly, repeatedly stating the obvious: if you don't know about costs, you can't judge anything -- you don't have the evidence needed to judge. Why isn't that obvious to you?
I feel kind of silly, repeatedly stating the obvious: if you don't know about costs, you can't judge anything -- you don't have the evidence needed to judge. Why isn't that obvious to you?
Maybe it is as you insinuated repeatedly, and I just kept taking the high road on. I'm just stupid. You convinced me. None of this is worth talking about.
Conductor_CarlSo are you able to say if, for example, Big Boy was good or not.
Conductor_Carl ... looking at what a railroad set as its design criteria and what it intends to accomplish, what their design could and did accomplish, and then making a judgement ...
My comment about too-few-drivers referred to the WM 4-6+6-4 (Pennypacker agreed with you about them, by the way) but more to the C&O 2-6+6-6. You weren't around for the forum fights about them. Don't worry, you didn't miss anything. It was all Keystone Kops.
timz Conductor_Carl "... you can't actually determine if it was good or not." Exactly -- you can't "determine" it. And since you can't, it's silly to sneer at 1940 railroaders for not doing what looks smart to you. (Especially when what looks smart to you is an engine with lots more drivers.)
Conductor_Carl "... you can't actually determine if it was good or not."
Exactly -- you can't "determine" it. And since you can't, it's silly to sneer at 1940 railroaders for not doing what looks smart to you. (Especially when what looks smart to you is an engine with lots more drivers.)
Interesting. So are you able to say if, for example, Big Boy was good or not. Or the PRR Q2? Or the ACL R-1? or any locomotive really?
A bit of the interest of history is looking at a event and proposing what you consider to be plausable counterfactuals, and this allows you to investigate those events and get a better understanding of what happened in actuality (for example, the Battle of Midway and how that would go differently if one guy decided to turn his plane around instead of keep looking for the japanese, a plausable counterfactual). In train terms, this translates into looking at what a railroad set as its design criteria and what it intends to accomplish, what their design could and did accomplish, and then making a judgement on if their criteria was well matched to their goals and if their design was well suited to the goals and criteria. Sometimes the criteria is bad (IMO the PRR Q2), sometimes the criteria is good but the design has issues (IMO the ACL R-1), and sometimes you just nail it (Something like the N&W Y6).
As far as that last statement of yours ("what looks smart to you is a engine with lots more drivers") I think you are still talking about my critique of the WM M-2 (which I drew way back). considering that the B&O had EM-1 Yellowstones heading into Cumberland and had a route paralleling the WM's tracks that the M-2 would have been on, you can get a decent comparison between the two and see what had more over the road success. I'm still gathering sources on this but it is a entertaining enough excercise.
Conductor_CarlI asked why the N&W would keep the A at 275 PSI if in the initial tests they ran them at 300, per BigJims theory based on the high starting pull recorded.
Conductor_Carl"... you can't actually determine if it was good or not."
timz In that case: how much coal did an N&W A with 275 psi burn, pulling 11000 tons from Portsmouth to Columbus, and how much coal did an A with 300 psi burn pulling 12000 tons? How much did the coal cost, and how much more did the 300-psi engine cost in repairs?
In that case: how much coal did an N&W A with 275 psi burn, pulling 11000 tons from Portsmouth to Columbus, and how much coal did an A with 300 psi burn pulling 12000 tons? How much did the coal cost, and how much more did the 300-psi engine cost in repairs?
a mostly different question that what makes a boiler above 250 PSI unsatisfactory and one that does not need to be answered. If your point is that we do not and cannot know as much as the railroads back in the day did then its pretty clear that the N&W (with all the data they had from the 275 PSI A in terms of consumption, maintenance and over the road performance) determined that the 300 PSI engine was superior seeing as how they uprated all of the engines and built every new engine after the first 300 PSI batch in 1943 to the same pressure.
Conductor_CarlI think that we can come up with these sort of answers.
Conductor_Carl as far as if 300 PSI boilers were worth it ...
Conductor_Carlif your thought is that ... we can't calculate performance or determine why choices were made the way they were, then what's the point of talking about this stuff?
And to not suppose we know which engine was better, when we know nothing about what they cost to operate. You'd think that would be obvious to everyone, but apparently it's not obvious enough.
timz What none of us knows anything about is what "unsatisfactory" means -- how much more does a 300-psi boiler cost, considering everything? If a 300-psi engine performs better, is it worth the cost? Apparently some RRs thought so, some of the time.
What none of us knows anything about is what "unsatisfactory" means -- how much more does a 300-psi boiler cost, considering everything? If a 300-psi engine performs better, is it worth the cost? Apparently some RRs thought so, some of the time.
Well, can't we figure out what unsatisfactory means?
In this day and age we have unprecedented access to so much information instantly and freely, and a lot more for relatively low cost, that I think that we can come up with these sort of answers.
With regards to the boilers, in this case judging by the article and what is now known about those alloy boilers, boiler over 250 psi being 'unsatisfactory' probably had less to do with the pressure than it did the material (as the N&W and UP experience with 300 PSI non alloy boilers was issue free in comparison to the great boiler scrapping that other railroads had to do of their alloy boilers).
And as far as if 300 PSI boilers were worth it, all you have to do is look at repeat orders. If a railroad thought that a design was worth ordering again with no modification, it was worth it to them. Therefore the UP thought 300 PSI boilers were worth it when they did a repeat order of the Big Boys, and the N&W thought the A's and Y6's were worth it when they did their repeat orders. And that is before you look into the specific aims of a engine and evaluate if it met those goals. Returning to Big Boy, the goal was to eliminate double heading over the Wasatch. They did that and increased the allowable tonnage, so it is a success.
Finally, if your thought is that we don't know what is acceptable in locomotive design or why railroads did what they did, and we can't calculate performance or determine why choices were made the way they were, then what's the point of talking about this stuff? At that point trains become just big smoky movey things that are old and loud, as opposed to things that can be quantified and understood.
BaltACDFeature that the biggest difference is that one is stationary and the other exists in a continual state of railroad beating and banging - start/stop/coupling/slack action.
A far more important difference is not the banging and bumping, but the starting and stopping and standing that characterize most real-world railroad service. One apparent assumption of Woodard's in designing early Super-Power fireboxes was that both the radiant heat distribution and the heat uptake would be relatively continuous -- the same assumption Porta made for the Dona Cristina 2-10-2s and his 'cyclonic' combustion boiler, and PRR made when they designed the boiler and draft system for the S2 turbine. As we know, that is not even a particularly good working assumption.
The ability of a 'standard' riveted convection section to handle expansion and contraction is a much more important concern than vibration and road shock (at least in my opinion). My understanding of the 'waist seam' leakage on the Q2s was that the boiler was overconstrained against expansion and swelling, not that there was mechanical shock transferred at the rear cylinder saddle.
It is not there, but in the sheeted structure in the firebox, that the greatest issues with changing firing conditions show up. I confess I was surprised to learn that 500psi wagon-top stationary boilers were commonplace in the oilfields, and certainly a lack of vibration would contribute to their suitability, but I do not know how continuous their load and firing would have been -- they would have been oil-fired, most probably, and that is the most strenuous kind of firing for a Stephenson boiler unless very, very carefully designed and regulated.
Overmod... Keep in mind that most of the 'trouble' of higher pressure is not in the pressure in the convection shell at all. There were 'locomotive-type' boilers in oilfield service that routinely (and reasonably safely) ran 500psi for extended time. The two things that caused issues were the staybolted construction of large-area water legs, and thermal cycling of diffrent parts of the boiler. B&O reasonably happily got 350psi out of the Emerson watertube firebox, although I don't think they had an engine that could make proper use out of that steam pressure with single expansion.
Keep in mind that most of the 'trouble' of higher pressure is not in the pressure in the convection shell at all. There were 'locomotive-type' boilers in oilfield service that routinely (and reasonably safely) ran 500psi for extended time. The two things that caused issues were the staybolted construction of large-area water legs, and thermal cycling of diffrent parts of the boiler. B&O reasonably happily got 350psi out of the Emerson watertube firebox, although I don't think they had an engine that could make proper use out of that steam pressure with single expansion.
Feature that the biggest difference is that one is stationary and the other exists in a continual state of railroad beating and banging - start/stop/coupling/slack action.
Never too old to have a happy childhood!
The point is that many railroads found that 300psi for 'better thermodynamics' did not translate into either 'better availability' or 'lowest operating cost'.
Something I didn't mention is that, with the advent of 'obligatory' water treatment for modern alloy boilers, there was an increased importance on water rate, both in terms of avoiding blowdowns and conserving generated steam. The former is where some of the continuous-blowdown scam comes in; the latter accounts for putting air horns on steam locomotives.
"Conventional wisdom" -- reading between the lines -- was that any pressure higher than 300psi was rapidly noneconomical. If I recall correctly the KCS 2-10-4s ran 310psi in a comparatively lightweight boiler... but not for very many years. N&W had their experiments with up to 315psi, but even with efficient 'boosted' compounding that never (at least to my knowledge) became standard.
I just tried the link again -- works fine, in Chrome anyway.
timzit says riveted boilers are "not satisfactory" above 250 psi. What does that mean? Another thing us fans know nothing about.
To make this easier on readers, the correct page number in the magazine is 450, and the page in the Hathitrust file is 590, nowhere near where the link provided dumps you. That wouldn't be too bad except that it takes forever and a day to scroll to that page (I had to switch to thumbnail view to do it at all) and then when I get there, the page crashes when I have read only a little and I have to do it all over again.
It is not rocket science to figure out that in December 1942 there was still emerging trouble with silicomanganese and nickel steel -- possibly relating to improperly reamed and tapered rivet holes in the 'thinner' plate that gave the design weight reduction.
For fun, see if you can deduce the 'railroad' from which the accompanying table was taken. There were two railroads with 300psi 4-6-4s, but what about 4-4-2s...
Amusingly, this is also the issue of RME that has coverage of the 5-year trial of the D&H experimental welded boiler (p.258) and a CMStP&P adoption of the method (p.250) and a discussion of the 3776 class 4-8-4s (p.367).
To put the cracking observations in perspective, remember the colossal amount of 'reboilering' required for engines with clever boiler alloys in the period after 1945. The Niagaras, for example, were designed (and tested) at 290, and 'railfan sources' note that they were derated to run at no more than 265... after every locomotive in the S1 class had to have its boiler completely replaced. I never went through and made a comprehensive list of railroads that had to do this -- or that scrapped their "modern" locomotives in favor of other motive power when they began observing the practical maintenance concerns -- but it may be that someone has (perhaps at steamlocomotive.com).
There were other concerns with high-pressure construction -- see the issue reported with cracking knuckles in throat sheets on p.113, for example. The woeful ATSF 3460 class, when it got its 'reboilering', had chamber syphons put in. The only part of that I have documented is that you see them as a kind of 'palimpsest' on Santa Fe diagrams, where they were drawn in and (probably not too much later) erased. Brashear has a note that they didn't perform as expected -- I suspect the situation was more complicated, and considerably more concerning.
The boiler problem was so advanced that it induced Alco to build a whole vertical annealing facility for welded boilers by 1947... just in time for the mass abandonment of any new reciprocating locomotives. (They would then expediently scrap this, only a few years before it would have become invaluable in Alco's attempt to rebrand itself as a nuclear-technology company!)
A point to remember is that the boilers were 'unsatisfactory' as commodity items, repaired and serviced to a price, and not given the full 'attention to detail' in fabrication and finishing than, for example, modern 'replicas' have.
In that connection, Balt's comment about changing boiler design from riveted to welded construction has some 'teeth'. The folks doing the Tornado Peppercorn Pacific replica didn't pay careful attention to a couple of key components when they went from 'riveted' dimensions to welded -- and had cracks in the mud ring and a part of the boiler where two different sheet thicknesses were juxtaposed, requiring carefully-underreported cost to 'rework'...
Meanwhile, a fairly large part of the issue around boiler pressure of '300psi' or higher was that much greater economical gains in operation could be achieved by reducing exhaust back pressure than in increasing steam-chest pressure with an overly restrictive exhaust. This was exacerbated by increased issues with compression at required high-speed cutoff with the higher pressures, something that was only imperfectly beginning to be addressed by Okadee et al. when the market of concern collapsed.
Conductor_CarlIt means that higher pressure boilers are going to be harder to build and maintain. All those bolt holes for the rivets and such are just more points for wear and failure and are going to require patching. The article looks to be looking forward to welded boilers, as most engines at the end of the age of steam were still all riveted (A, Allegheny, Big Boy, Y6B, Yellowstones).
And welded high pressure boilers have their own set of issues. The higher the pressures the more critical the construction methods as failures are more catastrophic as the pressures increase.
It means that higher pressure boilers are going to be harder to build and maintain. All those bolt holes for the rivets and such are just more points for wear and failure and are going to require patching. The article looks to be looking forward to welded boilers, as most engines at the end of the age of steam were still all riveted (A, Allegheny, Big Boy, Y6B, Yellowstones).
Conductor_Carlif you tested your engine at 300 and you know you built the boiler for 300 why not start at that?
https://babel.hathitrust.org/cgi/pt?id=mdp.39015013029783&seq=593
it says riveted boilers are "not satisfactory" above 250 psi. What does that mean? Another thing us fans know nothing about.
BigJim "Riddle me this Batman", according to the article, it lists the starting tractive effort at 104,500 lbs. Yet, the graph shows it to be about 118,000 lbs. Where did this figure come from? Did the N&W possibly turn the screws up to 300 psi on said test?
So the easy thing for me to do here is just say "I think the HP is crap so why wouldn't I think the drawbar pull is crap" and call it a day, but that is boring.
Typically engines toward the end of the 1930s were able to put a bit more power down than the tractive effort calc would imply because they had a greater actual Mean Effective Pressure than the formula stated (usually mean effective pressure is that .85 which is just matched to the common 85% cutoff). Allegheny could beat its numerical tractive effort because its mean effective pressure was .94 of the total as opposed to .85. and while they didn't show the Cylinder pressures for Big Boy their actual vs calculated drawbar pull curve has the Big Boy outpulling what the calculation says it should.So the A having a mean effective pressure of something like .87 instead of the number they used in the calc (.77?) Isn't out of the question, its just impressive.
I further do not think that they bumped it up to 300 for the tests because the later drawbar pull/speed curve has the A pulling around 124,000 pounds ish, so beating this test. Finally, if you tested your engine at 300 and you know you built the boiler for 300 why not start at that? Why putz around for 6 years with 275 PSI when you have proven how capable it is at 300?.
Not necessarily that there were too few drivers, but it appears that the goal was to increase the overall productivity over the big ol' 2-10-0's with a higher horsepower engine (as said ol' 2-10-0's had higher tractive effort). However, on tests the challengers where only about 10% faster. When the max HP recorded is over a thousand below what baldwin ballparks it should be its pretty apperant that the routes it was put on never allowed it to really get up speed and put all those horses to work.
But you are right, the people at the WM railway knew about all of the little idiosyncrasies of their line and perhaps they went with this high HP engine as opposed to one that had greater tractive effort because the passing sidings put a hard cap on train length, or something to that effect. If that is the case then a challenger is probably the next logical step up from a 2-10-0 if the line is too curvy for rigid frame locomotives like a 2-10-4, and the WM was just taking the next logical increment up. I just don't know the line well enough to know if a lower HP Yellowstone would have been better suited or if the only way to improve was with HP.
The 104,500 lb calculated TE at 275 psi was a fairly conservative guess. The A was somewhat limited cutoff (75% as I recall) so N&W assumed less than the usual 85% MEP.
But yeah, 118000 lb drawbar pull does sound pretty impossible with 275 psi.
Conductor_CarlWell, imma learn you up! https://archive.org/details/sim_railway-age_1936-09-26_101_13/page/435/mode/1up
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All kinds of infrastructure factors also went into steam locomotive purchases.
Turntable size, lateral clearances for cylinders on double track or past sidings, or through passenger stations, track radius in engine terminals, etc, etc.
Tender size for operating distance coupled with turntable size might also be another factor impacting the length of the actual locomotive.
Driver size - is fast freight capability needed in addition to coal drag capability? Is a wheelbase of four 56-inch drivers the way to go or three 69-inch drivers the better solution for intended needs while still fitting engine and tender on existing turntables?
Lots of factors in addition to 16 drivers versus 12 drivers.
https://www.steamlocomotive.com/locobase.php?country=USA&wheel=4-6-6-4&railroad=wm#342
Interesting discussion at the attached link.
Conductor_CarlI'm just pointing out a ready example of a engine that seems to be fundamentally ill suited to the [WM] road it was on
Fans like to say, why did they buy 12-driver engines when 16-driver engines can pull more tonnage? Like the railroaders didn't know that. We have no idea why they did what they did -- all we know is, we don't know anything that they didn't know.
By the way -- when BigJim said he didn't know how the 6300 dbhp figure got started, he probably meant he didn't know what test Pond was basing his 1936 statement on. Unlikely anyone else can answer that.
Excellent discussion, thanks
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