Hi Overmod!
More turbines on the N&W? Yes, I suppose it's possible. The bugs in the "Jawn Henry" (and there were some) could have been worked out had the developemental work continued. But as I understand it ol' "JH" cost more to build than a Class "Y" and didn't do the job any better, so the experiment wasn't repeated.
One positive thing about N&W's slow dieselization process, they avoided the mistakes other 'roads made and went straight to "Geeps". Any other diesel units they aqquired came from 'roads they merged with or purchased.
Still, when Saunders pushed the dieselization process as I'm sure you know he put the N&W in the red for the first time in it's history. Luckily for him the N&W being a "coal pipeline" that couldn't help but make money it recovered pretty quickly. Then ol' Stu went on to other adventures.
Wayne
I know it is off topic, but I have to join you in a brief Saunders excoriation fiesta.
We know what N&W would have come up with -- more turbines. For the low end of the picture.
As noted, I'd have adapted the Y class with better compounding balance, which wouldn't have taken much more than applying the proportional injection in slightly larger interstage receivers, doing full dynamic balancing on the running gear, and adjusting the truck centering and compliance for stability at the higher speed. That would have made them 50 mph locomotives with most of their weight on drivers ... but with their low-speed coal-hauling economy essentially unchanged.
Then change the A to make better water rate for given DBHP, and adjust the train factor as appropriate. Use the booster-on-the-A-tank approach if you want to preserve starting on some portion of the peak grade profile. (If diesels come, use them as convenient 'slug mothers' for motors under the tanks...)
RME
Well, had steam lasted longer on the N&W you certainly would have seen welded boilers, no doubt about it. Since N&W wasn't in any rush to dieselize, and some speculate N&W steam might have lasted to 1965 or possibly 1970 who knows what they might have come up with?
And then Stuart "Junk-em-All!" Saunders came along and ruined all the fun! Fie upon him!
Firelock76 Hi Overmod! Maybe N&W felt "Class A" was good enough for their 2-6-6-4 because, at least in the old days, "Class A" meant the best, as in "A Number One!" They were certainly proud of that locomotive.
Maybe N&W felt "Class A" was good enough for their 2-6-6-4 because, at least in the old days, "Class A" meant the best, as in "A Number One!" They were certainly proud of that locomotive.
Ed King certai ly thought so.
Let me remind everyone that one of the Big Things that was a possibility for the A class was to replace their boilers -- excellent, but still mid-Thirties construction -- with a modified version of the boiler from the PRR Q2, which of course was good for upward of 7900 ihp on the test plant. That would have clocked the Allegheny right there, to be honest, in about the only respect where an Allegheny was actually 'better' than an A (even with the fancy forward support arrangement and the 'streamlined' nest-o-snakes steam-circuit arrangement).
Now throw welded construction into the mix (this is speculation, but not at all particularly extravagant speculation, as I think that the Q2s themselves would have received new welded boilers had they remained in service just a couple more years -- and been reboilered, as the NYC Niagaras had to be a bit earlier... just earlier enough, I think, to miss benefiting from Alco's shiny normalizing furnace for welded boilers ... because of the nickel-steel-boiler cracking problem. The riveted boiler in the Q2 had some sealing problems in the waist, I believe because of the center cylinder saddle; this would NOT have been a problem on a reboilered A even without welded construction.
Dave Stephenson will probably know how far the proposal actually got. But that one thing alone -- a Q2-size boiler on the roller-bearing-rod version of the A chassis, with the improvements in leading truck design -- constitutes a perfectly good model for a 'standard' simple articulated with both power and speed adequate for any service that would be practically run behind a locomotive of such high capacity.
I do confess to being a bit enamored of the N&W approach to motive power, seen with the A, J, and improved Y classes, and of the quality and ability of the men who designed them. (As distinctly opposed to the job done with the K3 design a decade earlier!)
Maybe N&W felt "Class A" was good enough for their 2-6-6-4 because, at least in the old days, "Class A" meant the best, as in "A Number One!"
They were certainly proud of that locomotive. There was very little an "A" couldn't do, and do well. I rode behind 1218 on excursions several times and it's amazing how much power was packed into such a small package. When I say small I mean it's small for an articulated compared to a "Big Boy" whose size alone will take your breath away. Small compared to an "Allegheny" as well.
Firelock76Why'd they [C&O] call their 2-8-4's "Kanawhas" instead of "Berkshire's"? Who knows? "Kanawha" is kind of a cool-sounding name at any rate.
I used to joke that this was a 'turnabout-is-fair-play' sort of thing. C&O originated the 'Mountain' type as commonly used in the USA, but NYC called their engines of that arrangement 'Mohawks'. So why would C&O use a Central-affiliate's name for the wheel arrangement? They had their own river name to make the point...
As a peripheral point: the 2-6-6-4 never got a name. Didn't really need one when a letter would do so well... ;-}
NorthWest I have very little engineering experience, (and even less steam design experience)...
I have very little engineering experience, (and even less steam design experience)...
Remember, we all had to start somewhere.
Otto Kuhler, the streamlining designer, said once that he was embarrassed by his earliest attempts. When I was in my early teens I sent him a few 'fledgling' designs ... and I am embarrassed thinking about them...
The important thing is to keep thinking, and remember in general (as with any design work) what all your stakeholders actually need...
... but is the problem with the 2-10-6 that the firebox would create more steam than the cylinders could use?
I will let Juniatha herself answer this first.
What other wheel arrangements do you see as working well? My possible idea- please critique: A 2-12-4 reverse Union Pacific?
My possible idea- please critique:
A 2-12-4 reverse Union Pacific?
Not a good idea imho. The long rigid wheelbase concerns alone would make the locomotive restricted in service. You would need multiple cylinders to take advantage of the potential adhesion. Three cylinders is likely no more a good idea for American practice than it turned out to be as tried in the '20s, and four cylinders poses even more issues unless outside... in which case you'd have to put 'em at the back end a la the George Emerson or PRR Q1 duplexes. And that was not a very good idea for a variety of reasons... even before you get into the doubled main rod mass and all that.
Both Juniatha and I would advise that you use some form of divided drive on something that size ... either a duplex-drive or an articulated. If you need a better demonstration of that, consider UP's own development path after 1926, and tell me how many 'improved' rigid-frame 12-coupled locomotives they built. Compared to how many Challengers...
Other than that, and your 2-8-8-6, I don't see many other possible wheel arrangements that would work well, besides possibly a 4-10-4 for heavy passenger trains at speed.
The 2-6-6-4 is a sweet spot for contemporary freight-train lengths where there is no perceived need for peak performance over the 'ruling' spots in a grade profile without helpers. I think Juniatha is right that you'd need the larger firebox-end arrangements for a double eight-coupled engine with a deep firebox. While I can argue that the Allegheny could have been done as a 2-6-6-4 with appropriate thermodynamic and structural improvements, I think an eight-coupled variant would clearly be in six-wheel territory.
I have been working on various ways in which a large locomotive could reliably carry reduced-firing arrangements, in part to facilitate sliding-pressure firing with retention of high superheat as a means of controlling fuel (and consequently water) rate to match actual HP requirements more closely. Almost any such arrangement (chain grates, extended syphons or waterwalls, co-firing with liquid fuel for peaks) would involve more weight at the rear, rather than less.
So, would the future of steam, if developed in the 1950s, just be improvements like SCOA-P wheels and Aluminum cabs? Sort of like reliability improvements that seem to be the near future of diesels?
There would certainly be a tendency to be conservative in some respects (absent the existence of diesels). However, the search for application of internal-combustion engines in railroad service is reminiscent of the application of the discovery of X-rays, particularly to dentistry: there were so many people working on the idea, in so many different contexts, that eventually the technology would have evolved into a practical replacement for steam -- with most of the conclusions that were noted about the end of steam. Elsewhere in the world, where EMD (or NOHAB or Electroputere) penetration was comparatively slight, steam remained only as long as it took for diesel replacement to be possible. We can argue that some if this was motivated only for idiotic political reasons (as in China or, to a lesser extent, Russia) but it nonetheless did happen, and mere rearranging of the sheet metal or the wheel construction is akin to the famous old metaphor of rearranging the deck chairs on the Titanic in that context.
We also know there was quite a bit of active interest in alternative approaches to steam power in the period of interest ... even if we dismiss all the research and experimentation into effective locomotive diesel engines (at Baldwin definitely, at Alco after the 'hiccup' of the DL-109; at Lima as what seemed to be a panicked afterthought, regardless of how well and elegantly designed the actual diesel end product was). You can laugh at Baldwin for its approach to turbines (outsourcing to Westinghouse) but that was a shrewd decision in my opinion; this was before the great leverage military gas turbines made to design of small power turbines in general after WWII (which brings up the issue of whether we count a coal-burning bottoming-combined-cycle gas turbine as 'steam' for purposes of this discussion).
As I have commented elsewhere, I think the 'future' as seen by Hamilton, and then Lima-Hamilton, and then Baldwin-Lima-Hamilton, was in free-piston gas=generation as the 'future' of railroad power... in the postwar age where railroads had built up enough creditworthiness to pay for large motive-power capital improvements. In the absence of that 'incentive' I find it doubtful there would have been a Baldwin-Lima merger, although there is some evidence that the Lima-Hamilton merger was optimal for reasons not connected with locomotives.
An aspect of steam 'evolution' in the Forties that I think is very important is the rebuilding of older power to more modern standards. Whether or not this was driven by artificial tax policy is no more relevant to the discussilon than noting that equipment trusts preferred diesels as being more easily resold in the event of default -- the situation with having to effectively write off things like the whole T1 and Q2 fleet early probably being extraordinarily traumatic.
I have an example of this near me -- a thoroughly 'modern' 2-8-2 built out of a 1912 Consolidation. Has all the late-'40s toys: FWH, booster, Bailey Foam-Meter... There is also the Reading example of the T1 4-8-4s being rebuilt from smaller engines. I thought of this as being due to quirks in the tax laws... but they may also be a way of re-using older power that would otherwise be scrapped, or reducing the investment in 'new' power with greater capabilities. The question then becomes: what do you put into such projects, and what is the marginal return from each of them.
Regarding starting TE, I mentioned a possible solution in Extreeem Steeam, but with 40s tech it would be all but impossible, see Overmod's tweaks...
This refers to providing traction motors on some of the truck wheels, the tender, and attached auxiliary tanks, and then providing a battery bank so that current from the TMs could be stored regeneratively (as a partial alternative to, and presumably field excitation for, using grids or resistors as in dynamic braking.
In the absence of a large, established population of older diesel-electrics, the traction motors and other components would be very expensive. They would also need some sort of proper sealing against casual water and other contaminants, just as electric motors under steam-electrics would.
I started at one point to see whether useful power could be run through expanded Spicer axle drives -- not as full TMs, but at useful aggregate booster power, with smaller motors similar to what might be adapted to passenger cars. The initial battery would probably be derived from the cell banks in WWII submarines... but once these were gone, new replacements might be (prohibitively) more expensive for the benefits to be gained.
There may be more logical approaches to providing practical boosting with "typical" levels of technology and control systems for the period. More thoughts are welcome.
Were turbines the only real practical way to increase steam performance?
Turbines are more efficient at higher shaft speed. They develop good torque at starting -- but use comparatively extravagant amounts of steam mass at starting and very low speed to produce that torque, as in a turbine the exhaust has to clear the blade pairs to continue to produce torque in the stage. So they shine in long-distance passenger service -- and do relatively poorly on trains with many stops, or that require high starting effort.
One problem with the PRR S2, reading between the lines, is that its train length was sized to its high-speed running capacity. Engineers unfamiliar with the care and handling of a turbine would be tempted to throttle out to get positive acceleration, and the resulting combination of very high draft and 'settled' fire would result in massive thermal changes in the firebox structure (the drop in pressure probably NOT contributing to the effort, but the static high pressure aggravating the stresses.) Unsurprisingly this would produce a popping staybolt fiesta in the wrong hands ... or if repeated high stress fatigued the staybolts or holes ... or if the wrong sort of nickel-steel alloy was used in the boiler sheets. The material in the Hagley indicates that this was considered fixable in production locomotives... up until some time in 1946. After that you see crawfishing references to the locomotive as an 'experiment' and not intended as an actual design for road service... and later still, of course, (perhaps, uncharitably, around the time the cost of the engine had to be amortized early with the bankers) it was made out to be a dog.
The probably 'correct' way to start the turbine would be to accelerate more slowly, and take more of a mass-flow loss, in order to keep heat rise and stresses minimized. I am not sure, as I've said before, how much properly-welded boiler structure would have helped the problem ... but it would not have actively hurt things unless the welded boiler were designed with riveted-boiler thicknesses, transitions, and features. (See Tornado's foundation ring for a modern example of the kind of problem that can develop if designers don't get the point right!)
There are advantages to using a positive-displacement expander (which is what a reciprocating steam locomotive is) when you are going to be running at part load much of the time, or going to varying load (for example, running over a hill-and-dale track profile with a train that has slack action). So I would expect a considerable continued place for piston engines vs. turbines (although much of that place might well have gone to motor locomotives of one sort or another). Why American practice did not go to double valves is still a bit of a mystery to me; deepened when you consider that separating exhaust from inlet events becomes facilitated with a dual-valve configuration...
Hi Dave!
The C&O called their 4-6-4's "Hudsons", they didn't have a problem with that. However, they called their 4-8-4's "Greenbriers" because there was NO WAY a southern 'road like the C&O was going to call it a "Northern"! They could only bend just so much!
Why'd they call their 2-8-4's "Kanawhas" instead of "Berkshire's"? Who knows? "Kanawha" is kind of a cool-sounding name at any rate.
And of course there was no way a 'road one of whos founders was a Confederate general like the N&W was going to use the term "Northern" either! Class J had to do.
And then there's the RF&P. "Generals" and "Statesmen" for their 4-8-4s, certainly not "Northern"!
First, you are an excellent teacher and know more about the threory of steam locomotive development and application that I probably ever will know. Despite havinig lived 64 years in the USA, minus perhaps about a total of three years in trips overseas before moving to Jerusalem in 1996. (I do not count time in Canada as time in a foreign country railroadwise. Indeed, I think my last trip behind steam in a regularly scheduled standard gauge North American train probably was in Canada.) So, if you wish to call simple articulateds Mallets, please do so. I used to do all the time. Someone I thought more knowlegable than me "corrected" me, and I took his word.
I have a question, relating to this sort of side issue. The C&O called 2-6-6-6's Alleghanies, the 4-8-4's Greenbriars, and the 2-8-4's Kenawas. What did they call their 4-6-4's? Batics or Hudsons or what?
I'v learned that the most popular steamer (among drivers) in Israel was the North British 2-8-0. But the largest number were the 4-6-0 variation of the Stanier Black-5. And 2-8-0's were used in passenger service.
Juniatha In pondering how steam's performance could have been advanced , you jump to concluding : "More output - how ? by more input ! more coal per hour - i.e. larger grate , i.e. more carrying wheels below .
In pondering how steam's performance could have been advanced , you jump to concluding : "More output - how ? by more input ! more coal per hour - i.e. larger grate , i.e. more carrying wheels below .
No, that is not what the larger grate is intended to do, and you know it.
If you want more lb/hr fuel combustion, you'll go to better plume geometry (for example, some form of Velox burner) and better firebox arrangements to handle the increased radiant release.
Most, if not all, the improvements being made to steam in the late '40s involved increasing the efficiency with which the heat was to be used, not the amount of heat that was produced. That is why there was interest in air preheat, better feedwater heat, fewer losses in the steam circuit including steam and condensate leakage at seals, etc.
I would like to think that we have abandoned Brobdingnagian ideas for single fireboxes... Triplexes, for instance... in favor of more flexible designs that actually move real '40s or '50s consists in real railroad practice.
A 2-10-6 would have been an unbalanced enough design in proportions of firebox to front end - a 2-8-6 would have done little if anything a 2-8-4 didn't do and that in a speed range most railroads never ran their freight trains in steam times . Both w/a would not have helped the one wanting point of classic steam in competition with diesels : starting t.e. !
I almost don't know where to begin correcting these misconceptions. The front end is adjusted to suit the firing conditions -- its "variable" is gas mass ejection, and it is comparatively easy, as so many modern efforts have shown, to improve it far beyond any 'resistance' or whatever that might be imposed by a larger radiant surface.
I have bent over backward to indicate that six-wheeled trailing trucks would only be necessary on very large power... or in cases with wartime restrictions on materials giving increased weight. The Allegheny is a special case, although for it to be used 'as intended', you can treat its increased GA is being appropriate to 'one and a half Berks' (and hence appropriate to having a 3/2 increase in the number of carrying axles under that grate area). In practice, with proper methods of Rankine implementation, I think a high-speed 2-6-6-4 would do most of what an Allegheny could do. The weight benefits of welding are probably more in the convection section, but even so equalization could be made to distribute weight -- perhaps backward as well as forward.
But I'm not second-guessing the Lima people when they start specifying a 4-8-6 for a high-speed locomotive with a double Belpaire, even though I think it is excessive. They must have thought something. A 2-8-6 would give the same performance improvement (over its four-wheel-trailer-limited 'equivalent')as a 4-8-6 (the smokebox length, of course, not constituting a 'limit' on a Master-Mechanic-style-plated front end gas path) and in my opinion it is silly to bring that point up in such a way.
Part of the reasoning behind colossal grate area (and increased 'firing rate' is to get a reliable heat-release rate when using substandard coal or operating under suboptimal conditions (for example, partial impairment of FGA in the tubes, or clinkering/ashing
To think that starting TE was the greatest advantage of diesels is... well... in my opinion somewhat naive. The actual stated benefits that made the most difference were in areas like maintenance and range extension. Or the advantages of dynamic braking. Or in the ability to tailor power size to fit particular trains. Or to repair part of the nominal HP of a "locomotive" without putting the whole thing in the shop. Or in having to expend fuel to heat it up, and when sitting idle... the list is longer than you make out.
I don't want to play down the idea that starting TE from many effectively-constant-torque motors, driving most of the axles on a locomotive, was not significant -- it was just not nearly as significant in practice as it was on EMD letterhead. For one thing, '40s-'50s era traction motors have to be derated under about 11 mph. For another thing, slip control was primitive and relatively slow to react. Much of this hasn't come to light prominently because fan enthusiasm for early diesels is mostly in catching rarities rather than studying operation.
Meanwhile, an asynchronous compound driving small TMs in series easily produces similar effective 'starting TE' at vastly reduced locomotive cost (you don't need transition, for instance; you're treating the motoring like a large, indirectly-powered booster).
(As a side note contravening our premise in this thread, In a world shared with diesels you would easily be able to run the diesels for starting power and then throttle them back to most cost-effective operating power. Instead of using diesels like helpers, you would adjust their HP to give maximal advantage at starting and during periods of low-speed acceleration, and under these conditions, relatively low diesel-engine HP gets the job done as effectively as higher hp (if you never get to the point on the curve where motor instantaneous/hourly crosses horsepower). This would also provide peak 'overpower' for starting or acceleration from unexpected 'checks' enroute.
The much higher effective acceleration of an 'equivalent' steam locomotive over about 25 mph may make up some of the advantage of diesel power... at least it did to Kiefer in 1947, and he was no fool when it came to analyzing motive power on a working railroad. I will get to some of the 'train handling speed' issues later on.
I have forgotten some stuff, but am prepared to continue if anyone cares.
Ok , Overmod in his very own words calls for less high specific firing rates , although I would not exactly want a lazy fire ("Hey ,we're about to get a highball , now get up and make steam !" "Ooohh-uhm-argh , right now ? are you sure ? what about if we have to wait another 20 minutes ? I'm soo lazy now , I guess I just keep laying back again , you shut the firedoor , will you , it's getting cold !") Well , sorry ..
You seem to forget I said "lazy" fire, not lazy fireMAN. Or cold fire, for that matter. Or about things like pops lifting and wasting water and heat...
At the instant the throttle is opened, rated pressure in the cylinders is rated pressure, so effective short-termTE will be unchanged regardless of the state of the fire. The large mass of overcritical water in the boiler means that this pressure will not sag very quickly even if the fire is not whipped to a frenzy. And with a light fire on large grates, even small changes in effective draft will -- relatively calmly and reliably -- get the heat balance where it needs to be to maintain pressure with steam generation.
Lazy also implies that you get the desired heat release, both radiant in the plume and then as a volume of combustion gas sufficient for proper convective transfer, without lifting the fire, tearing holes in it, making the plume move so fast combustion isn't completed by the time the gas gets to the tubeplates... etc.
Where you want the 'fast' motion is in the tubes and flues, to minimize the thickness of the laminar layer adjacent to the metal. So Besler tubes are your friends .. but not so much if unburnt fuel or ash-carryover slagging impedes or plugs the smaller passages...
"Lazy" goes double for GPCS, of course, where even the underfire steam/air is purposefully restricted to keep the bed in net-reducing conditions. But let me guess, if I asked you, you would not have done heat balance for the GPCS reactions in a large firebox, or be able (or perhaps willing is a better word in the context of a general Forum post) to tell me where the secondary air ought to be introduced. I gently suggest that a mocking tone is not appropriate in such circumstances.
A somewhat less hefty draught per sq.ft of grate would have helped to reduce unburnt losses, no question . For a complete solution of this problem you would have had to turn to gas producer firing as proposed and in cases realized by Porta and Wardale.
There are other approaches that are capable, too, fluidized-bed and chain-grate firing being two of them. I have very substantial doubts that GPCS will reliably scale to large installatilons, particularly with unanticipable output-rate changes -- any more than other gaseous-fuel combustion experiments with or without producer gas would. (And I would include many of the pulverized-coal combustion schemes in that general category, too, as much of the combustion and flame-plume physics is at least similar.)
However , this is not without special delicacies of its own . it would make output of a steam locomotive even less flexible to substantial fluctuations in output demands...
You're starting to deflate your own arguments. Might be better to avoid this sophisticated, and limiting, an approach for regular working power under typical American conditions.
There is, in fact, some interesting historical context. Railroad people were fascinated by both the characteristics of producer gas and the efficiency with which it could be used in internal-comvustion motors very early. If you look at back issues of Railway Age or similar publications, you can see many potential applications to locomotive practice, specifically including running a sealed firebox 'pot' to generate producer gas and then combusting it ... sometimes in a firebox, to make steam, which had fewer construction difficulties or limitations than early industrial-gas-engine technology. Producer gas is a bit like Stirling engines -- the power DENSITY is low even though efficiency is high. I believe special care will need to be taken with making the available 'bed area' on a GPCS locomotive larger than Wardale et al. claim, and use windbox control to manage the amount of gas produced rather than ramp the whole firing rate up and down with dampers.
it would be best suited for long distance constant running .
For which turbines would be infinitely better than reciprocating locomotives in the first place. Weren't you the one who was complaining that well-advanced designs like the V1 turbine and the B&O W-1 were too 'extreem' for a discussion of practical steam locomotive evolution after the late '40s?
By the way , if it works out ( who knows ?) I put up an overlay of the C&O H-7 on my 2-8-8-6 , lined up at cab ends for comparison ( you could ask why not at front wheels and I could reply why not on firbox front plate or on drive sets ? the point is , as long as the locos are not identical in dimensions , there are always parts that overlap better and those that run astray)
I don't understand what this is supposed to be saying. Why you would compare anything modern with an H-7 is a mystery in the first place. The point of operating comparison is from the effective center of the driving wheelbase. If measuring either rigid or overall wheelbase... use common sense. LOA (for roundhouse stall length, and siding clearance) is similarly easy and straightforward. Determining things like effective guiding isn't exactly rocket science, alhough it does involve some careful understanding of geometry and progressive loading/weight transfer.
Things like effective Cooper rating, or debating the efficacy of tapered loading on equalized locomotives, have a bit more leeway in how they can be conducted for comparison.
The most notable thing about the comparison you illustrate is just how much more capable that boiler is. Some of the comparison is specious in the way comparing a N&W A to a Y would be specious: the one has a deep box with good circulation, and much more effective radiant surface. A similar example (although at a smaller scale) would be the improvement of Woodard's 2-8-4 over the MC 8000 Mikado (which itself was a vast and significant improvement in the effective design of steam power).
What is going to be interesting is the service you'd use such a large locomotive on. Fast freight is going to hit siding length and yard capacity long before you use the full developed power of the locomotive. Negotiating some of the classic 'hills' of American railroading at higher effective speed is a big, and exciting, prospect... but the size of the engine is effectively wasted the rest of the time it's running, unless you propose to use it at comparatively high speed when not using HP for grade climbing. (And believe me, that's exactly how I'd want to use one of those things, as it would be ideally suited for such service if balanced to run that fast!) The question I'd ask is how you'd pay for the much more intensive amount of trackwork needed in a world of stick rail and wood ties, and the state of improvement that might be necessary to interchanged rolling stock, to operate that way.
You're certainly not going to run the thing on typical mineral trains. C&O had problems using a lesser design optimized for (comparatively) high-speed horsepower (the H-8) in that service; they'd have been better off with a dedicated mountain locomotive. (Which the Grizzly ain't in my respectful opinion).
Also , at first I didn’t care but then I found checking out Lionel Wiener’s brought some light to the matter of using the term Mallet : In his book offering a substantial survey on types and specifications of all kinds of articulated locomotives worldwide he has devoted a large chapter to the Mallet type; While in his introduction to this chapter he writes that compounding was a part of the original Mallet concept and mentiones its – alledged – wheel slip self-stopping function, in his summary of essential marks of the American Mallet as it had – in more recent years at the time of his writing – developed he does *not* mention compounding as a sine-qua-non of the Mallet type and on page 320 explicitly mentiones the PRR 2-8-8-0 as a Mallet having four HP cylinders . So , in practice , Lionel Wiener has in fact used the term Mallet much as I did in my humble posting.
While in his introduction to this chapter he writes that compounding was a part of the original Mallet concept and mentiones its – alledged – wheel slip self-stopping function, in his summary of essential marks of the American Mallet as it had – in more recent years at the time of his writing – developed he does *not* mention compounding as a sine-qua-non of the Mallet type and on page 320 explicitly mentiones the PRR 2-8-8-0 as a Mallet having four HP cylinders .
So , in practice , Lionel Wiener has in fact used the term Mallet much as I did in my humble posting.
You seem to be of the opinion we didn't validate your choice of terminology.
Hi Juniatha!
I have very little engineering experience, (and even less steam design experience), but is the problem with the 2-10-6 that the firebox would create more steam than the cylinders could use?
What other wheel arrangements do you see as working well?
Yes, the diagram is showing up and is readable, thanks.
This has been the best learning experience for months, keep it up! Thank you (Juniatha and Overmod) for taking time out of your day to answer my sometimes less than educated questions. It means much to me.
Thanks,
NW
Hi Juniatha! I KNEW I sent that book to the one person who would give it the best home it could wish for!
I'm so glad you're finding it useful! And the hunt goes on...
Hi Northwest , hi Overmod
A somewhat less hefty draught per sqft of grate would have helped to reduce unburnt losses , no question . For a complete solution of this problem you would have had to turn to gas producer firing as proposed and in cases realized by Porta and Wardale . However , this is not without special delicacies of its own . it would make output of a steam locomotive even less flexible to substantial fluctuations in output demands - it would be best suited for lang distance constant running .
By the way , if it works out ( who knows ?) I put up an overlay of the C&O H-7 on my 2-8-8-6 , lined up at cab ends for comparison ( you could ask why not at front wheels and I could reply why not on firbox front plate or on drive sets ? the point is , as long as the locos are not identical in dimensions , there are always parts that overlap better and those that run astray )
Also , at first I didn’t care but then I found checking out Lionel Wiener’s brought some light to the matter of using the term Mallet : In his book offering a substantial survey on types and specifications of all kinds of articulated locomotives worldwide he has devoted a large chapter to the Mallet type;
So , in practice , Lionel Wiener has in fact used the term Mallet much as I did in my humble posting .
Choo-choo- and keep on steaming
Juniatha
2-10-6 update-
Going with 63" wheels, to enable higher speeds, and Giesl Ejector,
Next question:
To Belpaire, or not to Belpaire?
Sounds thoroughly workable -- now for the next round of the process...
Dimensions!
Okay- to stay on Juniatha's original topic, here is my idea of a locomotive that could have been built in the late 50s...
A 2-10-6, with major changes including-
-A welded boiler,
-British Caprotti valve gear,
-Aluminum cab, running boards,
-Roller bearings, (yes, I know many locomotives had them)
-Boiler jacket not made of asbestos, (suggestions for material? I know that asbestos was still legal then, but it would need to be eliminated eventually...)
-SCOA-P Wheels
Any other suggestions?
We're starting to drift a bit off Juniatha's stated topic -- so we should probably revive one of the older 'modern steam' threads to discuss modern tech and alternatives, if they are not logical extensions of or alternatives to late '40s to mid-'50s technology.
That being said...
NorthWestGoing back to the coal chute idea, this wouldn't work under catenary, (http://www.youtube.com/watch?v=IlqJiYKxLRo), but if you kept engines going at 1-2 MPH, I agree that a time faster than 2-3 minutes is possible.
All you would need to accommodate catenary (this being a straight stretch, and no particular speed or even constant-tension being really required) would be chutes approaching from either side. A little ridge or hollow at the centerline of the pile wouldn't be troublesome. And yes, I think the forward speed could be considerably greater than what Bailey uses, given that the rate of forward progress during loading need not be constant. The only substantial drawback to such an approach is that parallel tracks would have to be spaced comparatively far apart (compare the 8- and 10-track coaling towers that had minimum space or structure between tracks to save space) -- but consider that the very short effective dwell time for coaling might make multiple-track coaling facilities redundant except for accommodating traffic in opposite directions.
For loading water, the SpillX system being adapted for diesel locomotives could work. They advertise 600 GPM. http://spillxfueling.com/.
I like the idea. You'd probably want faster throughput, but you could get that fairly easily by hooking up multiple parallel lines (I believe the couplings are OTS aircraft-style, so no point in going to larger diameter 'specialty' hoses absent a greater market than "faster watering" would probably justify.)
I would consider gas pressurization of the water supply, instead of mechanical transfer pumping. You could use a fairly small pump to build up considerable effective pressure, or use locomotive brake air in a pinch without worrying about air motor maintenance.
Regarding under pressure displaced air, some could be diverted to reservoirs, to later charge air brake cylinders, or just be vented straight up. Yes, it would be quite a blast...
You would not recover the vented air -- it will be saturated with water, and probably more than a little boiler-treatment chemistry. You would need some sort of muffling arrangement, especially at higher fill speeds (hearing PPE for the workers might get around some of this, but by no means all -- have you ever heard an Alco with an air starter?) and you would want some kind of positive deflection for the overflow spray. This won't have the amazing water, water everywhere characteristic of 80 mph scooping -- but there will be a considerable amount of foaming toward the end of the fill that would have to be "accommodated" -- perhaps by directing it into fixed troughs, a bit like track pans in reverse. Then filter the overflow at leisure, arrange to deoxygenate it if needed, etc.
Building on Kylchap blastpipes, am I correct in thinking that they weren't used in the US?
For the record, it's "Kylchap" -- the original idea coming from Kylala (sorry, I'm on a Mac and alt-codes for the umlauts don't work) and the detail design 'improved' by Chapelon, hence the name. (The same thing goes for things like the "Lempor" configuration (Lemaitre improved by Porta), Kylpor, etc.)
I don't know of any American locomotive built with a Kylchap, probably more due to circumstance than any perceived disdain for the design, but there's a lot of material and careful fabrication in one of these, and they are not 'fire and forget' solutions. The American solution usually involved multiple stacks, as you indicate, with multiple nozzles and without the fancy multiple-vane diffuser system.
Also , would a double stack approach be helpful? The only example I've seen in the US is on UP's ALCO FEFs.
There are scads of double stacks out there, although some of them may be hidden, or have the last stage 'siamesed' into what looks like a larger oval stack. (There were simple articulateds built early,but that doesn't truly count in this sense.)
Interestingly enough, I can think of two American designs that had FOUR stacks ... the PRR S2 and the UP FEF-4. My opinion is that the idea is silly -- it works great at very high speeds, but maintaining proportionality during slips is... well, ask H.T.Cover about staybolts...
Finally, condensing tenders. This has already been discussed, but I wish to address partial condensation. This would involve venting some (if not most) of the steam out the stack to maintain draft, but siphoning some steam back into the tender, relying on the mass of the water to condense it.
This has been tried for almost as long as there have been steam engines. The problem, paradoxically, is that the heat recovery is just too great. One pound of saturated steam at atmospheric pressure will bring six gallons of water just to the boiling point -- at which temperature it will not work in most injectors. So only a comparatively small amount of steam mass flow can be run into the tender before... no more heat can go in.
I had the bright idea many years ago of pressurizing the tender. Not very bright, was it, and I trust you will see why with a little thinking...
This also could help serve as a feedwater heater.
Naaah -- normal FWHs, open and closed, do a far better job. Remember the FWH has to heat up to SATURATION temperature for boiler pressure -- hundreds of degrees higher than atmospheric. Best to do that 'as needed' and minimize boiloff and vapor losses...
Once water in the tender fell below a certain level, it would be necessary to have a condenser shut-off in the cab, you can imagine what would happen if just steam was pulled into the boiler...
PULLED???
No amount of steam in the tender would ever go spontaneously into a boiler. Not that the injector physics would allow it at all in the first place.
And the water source is piped below tank level both for the injector feeds and the cold-water FWH pump. Much like auto gas tanks have a little 'well' at the sock location which acts like a tiny tank so you can get that last drop... So if you start pulling steam... better be right with God because you'll be seeing him soon as you pass him...
This would help ease the problems with the SAR Class 25s, such as maintenance of the turbines, and would be more practical than the 25's tenders for larger locomotives, particularly if large centipede tenders were used. So, maybe not 8X the range, but a meaningful increase?
For a consideration of condensing, see the ACE 3000 patent. (And see how far you can read before you realize where the problems are going to be!)
The problem again is that for anything approximating USA-style mass flow, a steam-to-air tender needs to have ginormous surface area, and positive ventilation of that area. And then you have to arrange to move the condensate out of the condensing circuits promptly.
One solution, of sorts, is to use 'greywater' or other impure water to trickle over the pipes in the condenser. Makes it work MUCH more efficiently, for relatively small water mass, and deposits on the outside of the tubes are easier to clean.
A better solution -- in line with what you are saying, but for somewhat different reasons -- is to use the Holcroft-Anderson 'recompression' scheme. This does 'condensing' heat exchange on exhaust steam until it is right down where the phase change/latent heat of condensation keeps the temperature stabilized for a given back pressure. Then use a mass of exhaust steam, as in an exhaust-steam injector, to velocity-pressurize some of the cooled steam -- it will phase change back to water, at the elevated sentient pressure, saving a considerable amount of heat in the process. This was a hard thing to do in the Twenties. It is much easier now.
Water rate reduction is a major point to be achieved, and was becoming significant even in the '40s as a defining limit on locomotive size. The V1 was more thermally efficient than the Q2 at most speeds, but even so, its over-the-road range was no greater than about 115-130 miles. In the days when that distance was considered a day's run for a crew, that was not a major constraining influence on schedules. But as soon as PRR saw that F units could run across a couple of divisions without stopping... Katy bar the door.
Overmod, thanks for the pictures, they are the same. What a good idea!
Going back to the coal chute idea, this wouldn't work under catenary, (http://www.youtube.com/watch?v=IlqJiYKxLRo), but if you kept engines going at 1-2 MPH, I agree that a time faster than 2-3 minutes is possible.
For loading water, the SpillX system being adapted for diesel locomotives could work. They advertise 600 GPM. http://spillxfueling.com/. Regarding under pressure displaced air, some could be diverted to reservoirs, to later charge air brake cylinders, or just be vented straight up. Yes, it would be quite a blast...
Regarding 7100, it seems odd that a Klychap blastpipe wasn't fitted...and that other details were changed during building...
Building on Klychap blastpipes, am I correct in thinking that they weren't used in the US?
Finally, condensing tenders. This has already been discussed, but I wish to address partial condensation. This would involve venting some (if not most) of the steam out the stack to maintain draft, but siphoning some steam back into the tender, relying on the mass of the water to condense it. This also could help serve as a feedwater heater. Once water in the tender fell below a certain level, it would be necessary to have a condenser shut-off in the cab, you can imagine what would happen if just steam was pulled into the boiler... This would help ease the problems with the SAR Class 25s, such as maintenance of the turbines, and would be more practical than the 25's tenders for larger locomotives, particularly if large centipede tenders were used. So, maybe not 8X the range, but a meaningful increase?
Your thoughts?
NorthWest On page 80 of my "The Spirit of Steam", there is a picture of N&W's Shaffers Crossing engine terminal in Roanoke, VA. There are brick sheds, about as long as a long articulated. Are these the lubritoria? They sound like a great way to streamline enginehouse operations. If you could load the tender at the same time...
On page 80 of my "The Spirit of Steam", there is a picture of N&W's Shaffers Crossing engine terminal in Roanoke, VA. There are brick sheds, about as long as a long articulated. Are these the lubritoria? They sound like a great way to streamline enginehouse operations. If you could load the tender at the same time...
I think you're right -- the definition matches. Here are some NWHS pictures 'on the ground'.
Personally, I would keep both fueling and watering strictly away from lubrication operations, as you'd need another set of people to oversee the simultaneous fueling. Better to have the fueling under one of the typical multiple-track plants, with the whole skip-car transfer system optimized in one place.
Lo these many years ago, I first read about the Milwaukee's 'coal shoots' that were built for high-speed refueling of the F7 Hudsons. As I recall, at the time these were described as being able to fill a tender in 2-3 minutes without appreciably increasing the fines -- how this was done, I can't tell you, and Ms. Google is essentially worthless because too many people can't or won't spell 'coal chute' correctly.
I did develop my own approach to this that was angled so it would fit 'under' catenary. I used an articulated chute that could change its positions hydraulically to minimize the shock to the coal, and indexing arrangements to move the locomotive forward at controlled speed to get the right loading rate. I suspect that the equipment that fills PRB coal-train hoppers is perfectly capable of adaptation to fast coal-fired locomotive filling if desired.
I leave it up to planners to decide if they want to handle ashes anywhere near coal fueling points -- I myself would never, never, never do this even if I had a full water 'frit pit' to drop and transfer the ashes. (Remember that a modern locomotive will have some kind of ashaveyor system to minimize 'dwell' of much of the ash under the grate, for extended range and EPA compliance... so the amount of ash actually dumped may be substantial, and its physical position at the time of dumping may vary from class to class relative to where the coaling is done. I would continue to have ashing done on the entrance track, and fueling somewhere in the departure queue, as engines otherwise going to service with fires dumped will need their 'ashes hauled' but NOT more fuel...)
There is some fun to be had speculating about how to take water fast. Naturally this equipment will be at MANY more places on a railroad than at service points, but the equipment at a service point would need a particularly fast and robust method. The obvious approach is the same basic principle NASCAR uses: a combination of gravity head and pressurization to get a euphemistically-named 'high mass flow' perhaps at multiple ports. The tenders will need something analogous to the venting system on NYC PT tenders if this is done -- the water has considerable inertia, and considerable air will be vented at high speed, preferably in directions where it won't blow people off or otherwise cause 'issues' around the facility. An alternative is to have some kind of low-level locking hose arrangement for fast filling, but this implies a certain amount of added complexity and maintenance with the hose alignment, locking fittings, etc. -- and just as with gas pumps, it's 'too easy' for one forgetful person to drive off with the hose still stuck in the filler... causing delay to all the following engines that would be lined up to take it on.
What is your opinion on Caprotti valve gear? (The improved British version).The people who run Duke of Gloucester seem happy with it, per their website.
Remember to call this "British Caprotti" as a technical term; it's a very different thing from what Caprotti himself developed (and Baldwin tried to push in the late Twenties). It's certainly a good and robust system, well-engineered, and in my opinion as designed for maintainability as any alternative poppet-valve or Reidinger-style drive. Note that the company, like Franklin, looked at using full variable shaped cams with continuous "spherical-faced" roller followers, and gave them up in favor of a few fixed profiles.
Here is Franklin type B,
here is the Franklin 'long compression' patent
so you can see how a couple of the alternatives were supposed to work.[/url]
The British Caprotti system is said to give reliable cutoff as low as 3 to 5% -- what is not always mentioned is that practical cutoff in a reciprocating locomotive at speed is probably running into the law of diminshing returns by about 14-15%, and you then start having to flirt with things like variable superheating to be able to make use of very short cutoff and long expansion practically.
I do have to think that the Franklin type D approach (documented here) may be 'as good' as a variable system needs to be, although there are a couple of hair-raising assumptions there with respect to using wire-drawing for effective pressure modulation!
I believe the Skinner Engine Company came up with the right approach to make poppet-vave seats reliable at the required speeds and pressures, although you'd need some care and testing to figure out how to use that design on a locomotive.
The problem with rotary valve drives in general is that they involve a great deal of cost, and a wide variety of intricate and expensive parts, to do something that Walschaerts/Heusinger or Baker do with a few relativeluy-simple rods and joints. Baker in particular can be equipped with needle bearings (cf. Multirol on N&W) which makes them very low-maintenance, and you can drive OC poppets perfectly happily off Baker gear right up to the inertia limits of the valve drive itself. (As a digression that may have some meaning: the N&W Baker gear as applied to the A class had a tendency to unravel' when wound out 'in the corner' at high speed -- but I do not know the extent to which this involved piston-valve resistance rather than rod inertia. The high-speed testing of the J class on PRR certainly seemed to be limited by piston-valve issues, not by inherent limitation in the Baker gear)
I for one am a strong believer in conspiracy theories regarding 71000 Duke of Gloucester. There were too many things done wrong, always in the wrong direction, to make that locomotive look bad as built. I cannot overstate what a wonderful job the people who restored that locomotive and then 'debugged' it have done, and what they have provided with respect to British Caprotti documentation and understanding in the process. (And yes, it makes me grit my teeth when someone mentions '1361'... ;-} )
When looking at valve gear, always keep Cossart in mind, as it has quite a few theoretical advantages, even if it looks a bit strange to American eyes. I believe the Berry Accelerator Gear uses some of the same idea with regard to inertial force compensation.
David Wardale certainly seems to think that doubled piston valves (with proper detail design) are a 'better' approach than a British Caprotti approach, particularly when looking at the cost of making a relatively few examples and then keeping them running on a general 'enthusiast' level of budgeting.
NOTE: Valve gears do two things: they physically move the valve arrangement, and they control things like timing and cutoff of the valve arrangement. I have seen some complaint about my periodic use of 'valve drive' instead of 'valve gear' with what appears to be a tacit assumption that I am using those terms as synonyms. I am making the distinction between the DRIVE (which physically moves the pieces) and the GEAR (which is the whole setup, including whatever arrangements are made for phase, timing, duration, etc.)
A somewhat extreme example of the differentiation can be seen in Bulleid's original sleeve-valve gear as used on Hartland Point and on the Leader class. The special drive he used to rotate the sleeves while moving them longitudinally -- this not being done to get quicker effective port opening, but to prevent mechanical seizing, so the precision of the rotary motion was not nearly as significant as that of the longitudinal -- was taken off a sprocket on the leading coupled axle. This kind of drive could also be adapted for the longitudinal drive without introducing the chain drive problems encountered on the Merchant Navies if the chain merely provided the power to drive the valves, but a separate trip or reverser arrangement controlled the actual 'valve-gear' timing and duration functions.
Another way to look at this is with some of the flavors of trip (cf. Corliss) or complex-mechanism valve gears, like the motor-wound spring drive I used on some of my early high-speed 4-8-4 designs, where the actual power that moves the valves can be ridiculously imprecise, and only the actual control system needs to be precise. In my opinion you can get into sloppy thinking more quickly, and with less warning, if you forget that the drive and control are two very different things in a valve gear.
Overmod daveklepper At 81, my eyesight, even with bifocals, may not be sufficient, but the previous photo's "tank" looks like a 2-6-4T to me and not a 2-6-6T! I think everyone who's ever seen a picture of one of these 3/4 view says that -- as the thread I got the picture from says, 'count the journal boxes instead of looking at the wheels'. Here's a faded picture of the slightly older class NYC used, which shows the lids a bit better:
daveklepper At 81, my eyesight, even with bifocals, may not be sufficient, but the previous photo's "tank" looks like a 2-6-4T to me and not a 2-6-6T!
At 81, my eyesight, even with bifocals, may not be sufficient, but the previous photo's "tank" looks like a 2-6-4T to me and not a 2-6-6T!
I think everyone who's ever seen a picture of one of these 3/4 view says that -- as the thread I got the picture from says, 'count the journal boxes instead of looking at the wheels'. Here's a faded picture of the slightly older class NYC used, which shows the lids a bit better:
Hmmm...I would say Dave has pretty good eyes!
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SCOA-P are good wheels, in my opinion. I think they were developed after big steam was moribund here, they came from Australia, and perhaps had license fees (you may recall this was one reason stated for their nonexistence in United States practice). I would want to price-compare Web-Spoke (in our historical time period) as those wheels fixed the rim issue..
Just to jump from the '40s to current practice for a moment, modern driver centers would probably have to be forged or rolled in one piece (according to Federal regulations) but it's intriguing to consider what could be done with modern lost-foam methods and metallurgy, for a cast wheel. Laser keyhole welding largely eliminates any concerns with welded fabrication or assembly of castings -- and perhaps with differential heating or tempering if desired. The essential thing is to have a very strong, stiff structure between the axle and the pin.
I am of the opinion that there is potential for an FRA exemption for certain kinds of driver constructilon on 'new' reciprocating locomotives, if a good fabrication protocol backed up by proper NDT and other testing were demonstrated.
There were in fact several systems for flange lubrication (at least one that worked the same way a Hennessy lubricator does) and I agree these are significant on steam locomotives that have substantial flange contact. The problem is that you have a fillet from the flange to the tread, and the tendency is for flange lubricant to run down onto the tread when centrifugal force isn't keeping it slung off. I think that using Porta's HAWP (high-adhesion wheel profile), complete with its little step for slinging rod lube off before it contacts the tread, is a good idea... but there also has to be a similar feature for flange lube. One that does not weaken the flange root. Be thinking of good ways to do this. About the best way I know is to use the 'stick' style of on-locomotive lubricator (Trains had at least one article discussing these) which uses solid lube to effectively eliminate any wicking or transfer issue. No reason why this approach couldn't have been used with 1940s technology.
The bad news is that most of the deleterious wheel wear isn't flange wear; it's tread wear. Due to things like microslipping, the tread takes on a decidedly noncircular profile rather quickly, especially when sand is used extensively. The Harnischpfeger-style frequent on-locomotive lathing that Porta discussed (it's in the ACE 3000 patent discussion somewhere) is intended to mitigate this problem. If you can't arrange a drop table arrangement for machining tire profile, there's always some flavor of 'Lidgerwooding' (where the cutter(s) are attached to the locomotive, and a cable winch pulls it on its wheels as the truing is done... There are ways to address the problem before lathing or other severe response is necessary -- but there are many issues involved. I recommend this to your attention.
Associated with this is the control of sand used for adhesion. You want it metered properly, only to the location where it does good (and NOT sticking in the flange lubricant! and then removed as soon as it is no longer needed. The catch here is that the sand needs to be heated, but you want to use as little steam mass as possible -- whether directly or used in making compressed air -- to keep your operating water rate optimized.
I am a very firm believer in TOR (top-of-rail lubrication) applied immediately after the traction wheels have passed, Again, this is not a modern idea, but it works MUCH better on long CWR than it does on 33' stick rail....
It is surprising what happens to train resistance when this system is used.
The thing about 'grease' (by which I take it you mean Alemite) is that it does so well at what it does... but it requires substantial air pressure to force the lubricant in. I do not think the Alemite reservoirs are required to be any bigger than they are considering the length of sustained running a locomotive would do in the '40s... and how quickly the greased joints can be Alemited with a portable gun during a stop...
The modern 'grease'lubricated' roller bearing (using, for example, chemical superfinishing and AAR M-942-spec grease) is a relatively recent addition to bearing technology. It is hard to beat a system that can hold up for 300,000 miles or more without disassembly. And yes, you can arrange circulation for M-942 grease in lines, so that if you wanted to centralize flushing or periodic renewal in the wet, abrasive environment of working steam power it wouldn't take much.
Yes, self-lubrication works on a great many things on a locomotive -- and you would certainly use it. This was the great thing brought in by mechanical lubricators, which could easily work as positive-pressure lubrication up to sensible hydrodynamic pressures as found in IC engine tribology (although I don't think many, if any.,locomotives of the '40s used pressure anywhere near that high).
Modern steam almost certainly can't be 'total loss', meaning that all closed bearings will have to have return lines and good seals, and open areas -- firebox slides and Walschaerts die blocks being two particularly important ones -- will either need to be made of inherently-lubricated material or be given biodegradable lubricant. The good news is that it shouldn't be difficult to cross-drill bearings and pivots so that lines in the rods (for example, small hardlines mounted in the webs with elastomer supports) and other rotating parts can get reliable pressure lube. There is a reference to this in the Encyclopedia of World Railway Locomotives, but I have never been able to find the exact class of engine that used it.
A good place to start looking at 'modern' practice in lubrication is to study how N&W did it. I won't go extensively, and boringly, into the different kinds of lubricant needed on a conventional locomotive, but having special service facilities with all the needed materials and supplies in one place, the 'lubritoria' in N&W's practice, is a tremendous advantage -- and it wasn't lost on me that a complete lube rig could easily be built on a truck chassis... or one of the oilfield lube-service trucks, which have multiple compartments and pumps for different materials, could be bought used and converted for effective 'portable' use to make PM more practical.
Keep going -- this is better and better.
A couple quick ideas:
What about the SCOA-P drivers? I think these could ease maintenance.
Also, flange lubrication systems could help with wheel wear.
It takes effort (and time) to grease a locomotive. Would self lubrication systems work?
Thank you for your detailed responses.
In order:
Gölsdorf will not help the particular axle problem I was seeing (which is of the leading axle of the rigidly-attached rear engine) because there is no way the parallel linkage can be set up to work right. (This is essentially the same situation as in the Krauss-Helmholtz arrangement I was describing earlier).
Taking draft power through the linkage is also probably a Bad Idea.
What might work would be a system of horizontal or angled levers, like a skewed version of the Miller Traction Increaser, which would provide some lateral guiding force across the pivot from the hinged engine back to the 'right' point on the rigid engine's frame. That would let a lateral-motion device on the rigid engine's leading pair take relatively free lateral position, while its effective angle is restrained.
You would want the Alco style of chassis hinging (where there is no vertical allowance in the articulation joint, and all the vertical accommodation is handled in the suspension equalization) -- but I am thinking that nine axles is beginning to push things, especially with the added length for the cylinder block added in there...
Whatever arrangement of levers you used, it would likely cost a lot less, both in first cost and in upkeep, than a Franklin booster, and almost certainly a lot less than a Lewty booster. It helps that the lateral-motion device, which would constitute the really expensive part of the linkage, is already in the fundamental design of your Mallet.
We should remember, though, that additional driver axles do NOT provide the same kind of benefit a booster does. The idea of the booster is to provide something that can use available boiler steam at very low track speed, where a conventional two-cylinder quartered setup would provide only very peaky torque (and hence have high propensity to slip) if given enough steam. If you want to approximate the starting TE of something like a diesel-electric, you have to use gears, too.
It may bear mentioning that very clever people thought 'if one geared booster axle is nifty, why not put cranks and rods on more than one' -- hence, the Bethlehem Auxiliary Engine. Turned out that every one that was built pounded the track mercilessly. I am not sure what could be done to solve that problem. But that idea did take a weird bounce in the mid-Sixties, when there was an apparently-sincere proposal to ameliorate axle slipping on an Alco FA by installing outside cranks and rods. (That was a response to the whole diesel-hydraulic fad at the time.)
Reversing guidance is provided by the pushed-forward tender truck, and use of a modified version of the Franklin radial buffer. All that is required is proportional steering moment applied to the rear of the frame -- same as the levers and centering devices on a second-generation Delta truck do. You don't have the long lever-arm moment that you do with a four- or six-wheel trailer, but it is certainly as adequate as any Mallet with two-wheel end trucks...
The thing that has to be watched with Cardan shafts is that the force the train can momentarily exert, usually in buff when slack runs in, can be many times the peak TE force. When I was in college, I heard a story about a high-school engineering wannabe who learned all about torque. He 'borrowed' his dad's diesel Mercedes to test a hypothesis: that with all the torque available, revving the diesel engine in neutral and popping the trans into gear would produce very quick acceleration off the line. Apparently, when he tried the idea, he totalled the car -- exploded the engine, cracked the transmission case, even torqued the frame and body to where the doors wouldn't open. And that's orders of magnitude less than the force that might be applied across the journals in the Cardan shaft... with rotational inertia as well as effective adhesion friction keeping things from rotating and relieving the stress via slip.
That is one reason I have a Ferguson clutch in the Deem-style duplex conjugation gear I designed (which uses what are essentially Spicer drives on the axles adjacent to the rear cylinder block, and has a Cardan-shaft arrangement between them). I may still experience some brinelling of the races in the U-joint bearings -- but they will not come apart.
In principle, there is a pretty good reason you wouldn't want to drive the truck axles from the rear drivers. That reason is differential tire wear. Steam drivers require fairly frequent machining (for reasons I have discussed in other posts) while the truck wheels would be relatively less worn. That leaves the truck wheels at effectively larger radius than the gear ratio is spec'd for. You can guess the likely result...
Now, the principle of the Lewty booster (ignoring the triple-expansion part of it) is that you have a hydraulic fluid-power pump driven by the booster 'motor' (whatever it is) and the power is neatly carried by armored flexible hose ... OTS spec for hydraulic construction equipment, perhaps ... to one or more hydraulic motors on the truck axles. Note the extent to which these motors can be nose-suspended or frame mounted, and how all the complex engine pieces so easily damaged or disturbed on a Franklin booster can now be carried neatly anywhere you find 'em convenient.
Should be able to drive more than one axle, with proportionally-exact torque and speed, by simple control means, and without compromising suspension performance (or balance, even up to high speed, when 'unenergized'.
Now, one of the people involved in modern steam-turbine-electric design did some studies on the use of belt drive, on pulleys external to the truck frame, to get multiple axles to be driven off one booster-powered shaft, outboard of where the ashpan arrangements and blowdown would be on a trailing truck. He went so far as to calculate the maximum power that could be sent through a Gates poly-V belt with a Weller roller tensioner. It was 'adequate' (as the old RR-Bentley line went...) This had the rather obvious advantage that NO amount of whacking the train would cause damage to any part of the drive. But belt tension, friction, and other effects are NOT scalable from familiar levels of belt drive thrust.
I remember getting probably the last look at the inside of an ex-PRSL Baldwin road switcher (I think RS-12) in the late Seventies. Something that made a very great impression was that the water-pump drive on the engine was done with ordinary V-belts, like fan belts -- about twenty of them, it seemed, in a row. (And that was just for circulating coolant load, not traction power!)
It should not be lost on you that the Lewty booster can drive a coupled axle just as effectively as it does an idler -- in fact, I believe this is what Porta was proposing on the 2-10-0. You would then be able to derate MEP difference in the main cylinders at low speed ranges, making up the thrust with the booster-engine power applied smoothly regardless of angle and with reasonably continuous torque...
All good thinking on your part -- keep it up!.
Overmod, thank you for the detailed reply. I am not an expert, but I think I understood most of that...
The advantage over a 2-8-8-6 with booster engine is that it eliminates the complication and expense of a booster engine.
Could the flange wear problems be mitigated by using the Gölsdorf axle system? (Although this would likely negate the cost advantages of doing away with the booster engine).
The only issue I can see with a 2-8-10-0 is reversing, such as in helper service.
Going back to the booster engine idea, could the rear truck of a locomotive be driven from a Cardan Shaft from the rear driver axle (through gearing)?
That's an interesting idea. But, out of curiosity, what does it add that a 2-8-8-6 with a booster couldn't do better?
I would have to worry a bit about where you would put the articulation pivot between the engines. A 10-coupled rigid wheelbase on the rear of a Mallet would already have lateral motion devices at least front and rear, and the pivot in the chassis needs to be positioned where the 'hinged engine' has the center of its rigid wheelbase 'tangent' to a continuous curve when the center of the 10-coupled wheelbase is. Leading coupled wheels should NOT be used to engage curves if that can be avoided! Your flange wear will suffer even if your stability doesn't...
The 2-6-8-0 isn't as 'unconventional' as it might seem; consider it as an 0-8-8-0 that has had one of its forward-engine drivers fitted with a pony truck for better guiding in the same length, but that does not require a reverse truck to run stably. (The PRR HC-1, Big Liz's husband, was a 2-8-8-0 and not a 2-8-8-2 for similar kinds of reasons).
I am firmly of the opinion that simple articulateds (SE Mallets in Juniatha's terminology) should never have more than eight coupled wheels in an engine unit -- but that is scarcely a 'law of nature' or even a necessitated design principle. Remember that a deep-firebox locomotive is almost by definition intended to produce maximum HP at higher speed -- something that requires care on a 10-coupled wheelbase, but can certainly be done (following, for example, the methods described for T&P 610). You are wise, however, to resist the temptation to 10-couple the leading engine...
I don't think it would require *all* that much more steam than a 2-8-8-6, especially if you size the cylinders appropriately for higher-speed horsepower (use the Lima formula of high MEP, comparatively narrow bore, and long stroke with lightweight rodwork). In particular, the UP 4-8-8-4 is NOT an example comparable to a deep-firebox locomotive -- it has the shallow extended grate characteristic of the later Alco articulateds, and it burned remarkably poor 'coal' much of which was yanked out the stack long before efficient combustion. (Many sources have noted that much of the stoked fuel never touched the grates...) The whole reason for the big firebox requiring three carrying axles is that you can have a big, lazy fire that is also bright, for good radiant release over a large effective surface area. Lots of draftmass flow, without extensive points of high velocity through the grate ...
At lower speed, you don't need the high prompt uptake, so you could put the large, lazy fire up over the coupled wheels, where Porta's 2-10-0 and the N&W Y class have it. Now instead of a 2-8-8-2 arrangement you use your 2-8-10-0 chassis and steer the after end as I was suggesting to Juniatha: push the tender lead truck forward to the optimal Bissel 'swivel point' (as some German locomotives did) and give it some controlled lateral with progressive compliance...
Fits at least one extra car into siding length, eliminates at least two carrying axles, uses its adhesive weight more effectively, and cuts a WHOLE lot of mass off the schedule that determines its engine crew's compensation...
OK all you others: what do you think?
Okay- here's my attempt to add to the discussion:
What about a 2-8-10-6? Yes, it is an unconventional wheel arrangement, but with small drivers, it would fit in about the same space as a UP 4-8-8-4. It would need lots of fuel, to maintain steam, but a large firebox over a 6 wheel truck would allow this. This arrangement is probably best suited to a drag locomotive. Differing numbers of drivers have been tried before, such as the GN M-1 2-6-8-0s.
What are your thoughts? (I am in no way a steam locomotive expert)
Just as a quick note (before dropping it) du Bousquet's locomotive design predates the T18 by at least a year...
Juniatha Personally , my view is of Lima going sideways a bit - the 4-8-6 as a beefed up 'da capo' of the formerly successful idea of going from 2-8-2 to a 2-8-4 and offering more steaming capacity to get trains of existing tonnage rolling faster ( only to see RRs to load up Berkshires to the limit until they moved no faster or nearly than the Mikes had done if with a somewhat longer load )...
Personally , my view is of Lima going sideways a bit - the 4-8-6 as a beefed up 'da capo' of the formerly successful idea of going from 2-8-2 to a 2-8-4 and offering more steaming capacity to get trains of existing tonnage rolling faster ( only to see RRs to load up Berkshires to the limit until they moved no faster or nearly than the Mikes had done if with a somewhat longer load )...
There is a very, very important change that occurred in here, somewhere between the mid-Twenties and 1938 (as both ends of the spectrum are firmly pinned at that range). That is the practical development of stable two-wheel leading trucks (that were not some Krauss-Helmholtz variant).
Many railroads (Nickel Plate and Erie being two that immediately come to mind, and L&N being a probable) knew EXACTLY how to use a 2-8-4 to do most if not all of what a 4-8-4 would do. I think this comes in part out of the AMC and part out of Baldwin's (yes, Baldwin; every blind squirrel gets at least some nuts) experimenting with high-speed articulateds in 1930 that led to the 2-6-6-4 as a practical 'Berk-and-a-half' to run at higher speed.
By the time of the A, there was no question that a practical high-speed locomotive could be built with a two-wheel Bissel. Not much later, we see the improvement programs for better BALANCE -- not just 'reduced augment at low speeds' -- for locomotives like T&P 610.
In my opinion, this trend would have continued -- certainly at Lima, which had considerable interest -- developing a three-axis stabilized 2-wheel lead truck for ANY engine not explicitly designed for dual service at very high peak speed. And an early consequence of this would be -- in my opinion -- greater use of something like a 2-8-6 rather than a 4-8-6 of equivalent developed horsepower.
I have not run the numbers on weight distribution to see how this would have affected practical design of the Double Belpaire as Lima was proposing to use it. But I see little reason for railroads not to 'standardize' on lightweight mains of common length between their 6-coupled and 8-coupled engines, for instance -- which the 2-8-6 would give you (driving on the third coupled axle, of course)
This, I think, would push the evolution of the 4-8-x very firmly toward the higher-speed end of design optimization. And this is precisely the niche that disappeared so compellingly at (or perhaps by) the end of the Forties, although in the absence of diesels for passenger work this decline would not have been nearly so marked.
I treat the conjugated duplex as a 4-8-x for these purposes, with the advantage chiefly being greater potential sustainable high speed at minimum augment. Had the anticipated great 'streamliner' speed-up of postwar passenger service come to occur with steam power, that sort of design would have been necessary (although I repeat that the mechanical turbine with Bowes drive was a compellingly better, better, better, alternative.)
We have to do some guessing about Alco, since there is such a division of opinion about the A2a design (including whether or not the two-wheel lead truck was merely a compromise, or whether the low spoked drivers were a kludge or (as I prefer to believe) recognition of the value of lightweight rods and proper design in normalizing augment for reasonable fast-freight speed). This is complicated because Alco so determinedly shucked its whole steam-design effort after 1947, and in all probability much of its design thinking in the critical years after the Niagara were essentially lost. I would expect, based on the Challenger precedent, that Alco would continue with the four-wheel guide truck, and standardize running gear for drive on the second coupled axle, although this would give them a decidedly schizophrenic attitude toward firebox fabrication and combustion efficiency (rigid-frame vs. articulated).
Baldwin -- who the heck knows? They'd build whatever someone said they wanted ... to a price, with their ineffable cost-cutting approach to less-than-one-sigma quality. They were learning the hard way about this by the end (I think; Trostel has a different take on that). They bought their enhanced valve systems from Franklin in the '40s, just as they bought the Caprotti rights in the late '20s (and I may be uncharitable, but I think the one would have gone about the way of the other, in the absence of design refinements that Baldwin was ill-suited to investigate.
- uhm - that toungue-in-cheek answer to the diesel challenge didn't work because it was an answer to a question nobody had asked , while with its burnt offering the builder looked stunned , their speechlessness vividly bespeaking their cluelessness what to do about the new situation.
I have no idea what this means.
The massive overload C&O came very near to rejecting in the H-8 2-6-6-6 design was not exactly promoting trust in Lima's competence with this size of steam - maybe these locomotives really were nearer than we think to the very technological limit the steam builders were then able to handle.
As noted, there is more to this story that meets the eye. (Compare this with Brasher's description of what Lanning et al. at ATSF were trying to get Baldwin to do in the early '20s: massively overweight and essentially unbuildable, and then whining when Baldwin did the detail for fabrication...)
The great controversy over the weight was not that the engines were heavy -- it was that the builders lied, and the railroad winked, in order to avoid HIGHER LABOR CHARGES that were tied to the weight of steam locomotives. (Do you find it surprising that C&O was shocked, really shocked, I mean we had NO IDEA how heavy those things were in its 'public' response, and that Lima got scapegoated after the fact? (Remember whose 'fault' it was that the weight overage came to light?)
C&O ordered them knowing that its ROW and civil were capable of handling engines of that size. In any case, with the end of wartime materials restrictions, further six-wheel-trailer articulateds would have 'made weight' -- even before we look at the savings inherent in welded boilers at that scale.
Baldwin still was pretty deep in the 'dark age' as concerns superheating , steam distribution , cylinder efficiency and mechanical balancing of drive and running gear.
I think the situation is not quite that bleak -- Baldwin could get the job done perfectly well, they just had minimal reason to innovate 'on their own dime' (and were distracted by the promise of innovative non-steam power in where they put their innovation). My favorite example of the Baldwin 'way' would be the C&O M-1 turbine project (which was run through in great haste, and no little secrecy, to beat PRR to the turbine-locomotive punch). Look at all the little places the failures turned out to be. Then look at the Centipedes... or any of the truck-mounted diesels... and all the little places there where the failures turned out to be. Completely in keeping with the Baldwin that delivered the first of the ATSF 3460 class with holes in the wrong place...
ALCO in my view was looking best .
Must be that Schenectady vibe, like GE. I'd certainly agree they were doing the best overall mix of design and build quality. I almost wish the turbocharger hadn't been invented so rapidly -- or had been perfected for heavy application a little quicker... ;-}
I do still wish Alco had recognized the need to have its own electrical manufacturer -- perhaps if they hadn't been located in Schenectady, they might have done differently! (And why not acquire the Westinghouse tooling and IP when that company shucked its rail efforts? Isn't 20/20 hindsight a wonderful thing?)
( "Oh-yeah , there she goes again , what else would you have expected of her!" )
Nothing but the finest.
(BTW: when I PM on a Forum topic, it's because the reply involves issues that I think would be of relatively low, or no, interest to Forum members or to the topic under discussion. The issue with cab-forward stability falls partly into that category, as does Henderson triplex design.
On the other hand, since I have no objection to anyone re-posting my PM content either directly or in other threads -- I'm perfectly happy in this case to put everything directly 'out there' as I see it. (So all you folks seeing the firehose swinging your way... SHE did it! "See what she made me do!" ;-}
Hi folks
On the issue Baltic :
The Baltic Sea ; the 'fish pond' ( shallow water , about 600 - 700 ft ) between Germany and Sweden ; from Kiel , German city NE of Hamburg , towards the East , the South coast has Mecklenburg with Rostock and Stralsund , former home of the oil fired three cylinder Pacifics 03-10 class , then Poland with Gdansk ( formerly Danzig ) with Stocnia Gdanska , the shipyard where Lech Walesa once worked and which later built the new deep sea three mast square rigger sail ships ) and then the coast swings around and up along former Eastern Prussia with former Koenigsberg , home city of Emanuel Kant , now Kaliningrad , Russia , followed by the Baltic States ( Estnia , Lithuania , Latvia ) , then Russia again with Leningrad , in the summer partying the 'white nights' since it already is far enough up North to have northern lights , and finally goes up around the Eastern end : you come to Finland and turning West again at the Northern coast is Sweden , coming into Stockholm , pretty soon you can go to Danmark all via sea bridges and come back to Kiel , Germany , take an express by DB for rushing south and you may arrive in Munich just in time for the Octoberfest to have a few gallons of beer before entering your USAir Transatlantic flight ...
Since the Prussian KPEV T18 class 4-6-4 tank engines were built by builders on the South coast of the Baltic Sea and meant to run the lines across the great flatland of Eastern Prussia , the w/a was designated Baltic .
So the Baltic is one of but a few names designated explicitly to a tank engine .
But let me propose we'd close that thing I unintentionally ignited by making that side remark as an example for a more relaxed approch , not for a new quarrel .
And yes , I'd appreciate returning to the original question - steam development in the decade that didn't realize because with diesels coming steam got aborted .
Personally , my view is of Lima going sideways a bit - the 4-8-6 as a beefed up 'da capo' of the formerly successful idea of going from 2-8-2 to a 2-8-4 and offering more steaming capacity to get trains of existing tonnage rolling faster ( only to see RRs to load up Berkshires to the limit until they moved no faster or nearly than the Mikes had done if with a somewhat longer load ) - uhm - that toungue-in-cheek answer to the diesel challenge didn't work because it was an answer to a question nobody had asked , while with its burnt offering the builder looked stunned , their speechlessness vividly bespeaking their cluelessness what to do about the new situation . The massive overload C&O came very near to rejecting in the H-8 2-6-6-6 design was not exactly promoting trust in Lima's competence with this size of steam - maybe these locomotives really were nearer than we think to the very technological limit the steam builders were then able to handle .
Baldwin still was pretty deep in the 'dark age' as concerns superheating , steam distribution , cylinder efficiency and mechanical balancing of drive and running gear .
But it's true ,
that's what I think
*gee*
It's Summer in the City
hot summer in the city ...
so keep it cool , guys
have a Coke ,
relax and be wise .
regards
Oh , Overmod :
you have partly posted , party sent pm ; please do not go double track .
I definitely prefer *all* of topics steam to be posted and discussed in this forum , so I leave it to you to
post points in your pm once again here in this thread for answering . Sorry .
Northwest -- you are welcome in here, particularly if you post something with respect to the actual topic Juniatha started the thread for... from which we keep drifting. My objection, such as it was, was only that you had restated something that was already a distraction which should have been placed in its own thread days ago*; the whole reason 'Baltic' came up at all was in the context of NYC's not being the first-designed 4-6-4, or even the first American 'super-power' 4-6-4 design. And that, to strengthen the connection, the MILW did in fact refer to their class as 'Baltics'. (I repeat the distinction: if there are pin-guided trucks at both ends, call it a Baltic; if there is a radial at the back end, call it a Hudson, remember the example of the 4-8-4 when discussing if there is a 'one true name' for some of these classes...;- ] )
(I was also disappointed, I guess, because there was 'new blood' showing up to add further viewpoints to the topic of steam development, and then none were there... So please come back and give some!
I don't have the photos, but the last time I saw one of the B&A "tanks," I was quite sure it was a 4-6-4T pulling some freight cars on the Grand Junction across Main Street near Vassar Street in Cambridge in the late Spring of 1950 (or 1951?), after the suburban service had been dieselized.
We HAVE to figure out what this could have been. I am not a NYC older-power specialist and so have to defer to Internet or secondary sources, and NYC enthusiasts. If someone can point me to a B&A 4-6-4T, I would be delighted. I see no way Mr. Klepper could possibly have mistaken either the 2-6-6 rebuilds or the 4-6-6s for a 4-6-4... so what did he see?
If we want to discuss this stuff any further, we should put it in its own thread. I want to get baclk to the 'alternate history' and the technology.
*To forestall any potential drift: I am perfectly aware of Mr. Strunk's misguided opinions on the distinction of those two words, so don't distract from topic further by mentioning that subject... ;-}
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