Overmod
>> E pur si muove. Publication is not demonstration of correctness. <<
It does prove regular use of the word or term or form of plural in the case of “Duplex” – word used as a noun , a special naming defining a locomotive type and therefore needing to appear in plural if said locomotives `duplicate` .
>> Making fun of Fowler does not dismiss him merely because it suits your ego. <<
O-M-G , I will not answer this , full stop .
>> I have six years of Latin and no need to consult Wikipedia references on the subject as my sole justification.<<
However you seem to have a need to criticize for the sake of criticizing , disregarding reasonable discussion of a topic .
>> Period. End of diversion (I hope). <<
Ok , now that things turn out not so well for you in that off-topic issue of blaming me for using incorrect forms of words – issue raised in reply of my having mentioned my wondering about your particularly not writing proper technical term but using instead some words in a very special way , stretching their regular meaning , to put it this way – now you want to drop the subject .
The same way as with the issue about my allegedly oh-so-wrong use of the term "simple expansion Mallet" : strangely , as soon as I had posted that scan of Wiener`s book showing his using the term much the same way .. there was silence , everyone had just dropped the subject silently . None of those having criticized me stood up to criticize Wiener !
Oh , I can see why ! No , not so easy , sorry , you have asked for it and now after having taken the bashing patiently yet in vain for so long , I feel it`s enough :
Concerning some of the words in focus , I have here some scans of pages in Locomotive Cyclopedia 41 with page explaining meaning of “auxiliaries ..” and also page where alphabetically a word “ancillaries” should have appeared but doesn`t , further Webster`s dictionary , Langenscheid`s for mech E , Schöffler-Weiß .. see following :
As by definition in Webster`s “ancillary” in view of machinery has a wider and more general meaning about “being of subsidiary rank” while “auxiliaries” has a more defined meaning of “helping” – in that way a booster engine maybe regarded an “ancillary” engine while a feed pump is certainly an “auxiliary”. Since my use of the technical term of “auxiliary” was aimed at pumps and generator and the whole usual bunch of “appurtenances” spread on the boiler , usually , it was the correct word to use while “ancillaries” is not regarded a technical term at all . Also interesting is the definition of "conjugated" - used instead of "linked" , "coupled" , "connected" ..
To note : there is no plural form of “duplex” found , so there is no “duplexes” neither .
The word coining “flavor of” so extensively used standing for “design of” , “type of”, “variation of ” , “form of” ( the point being while one may guess what it`s meant to stand for , one can never be sure about a more accurate definition ) is not mentioned anywhere’s in any context just vaguely near the meaning you use it for .
To be sure : *I* for one have always been tolerant and good willing in view of individual use of words and coining of sentences with other writers , including user Overmod , I have simply tried to understand as best possible what a writer wants to convey - not trying to find fault and "derailing" wilfully at a "switch" not fully true to gauge and rail profile contours .
However , I decently expect same attitude towards my postings , too . I am aware that I tend to build sentences as American railroads build freight trains and a readers mind may in cases encounter the same challenge as a car driver at a level RR crossing while the cars rumble by . If someone feels he looses track , he may write to me and I will answer correspondingly .
To try and find alleged flaws and deficiencies , concentrating on nitpicking in the absence of something more substantial is *not* helpful and does not lead anywhere .
I`m not writing here for quarrelling or having issues . Unfortunately I have to reply and after giving way for so long , hoping in vain for things to shape up I have decided to fight back .
Sorry , if this effectively takes time off any addressing the topic – which by now is about dead anyways .
My regards and thanks to all of those who have contributed their inputs with best intentions .
Juniatha
WOW! GOOD FOR YOU GIRL!!!
Let this be a lesson, never EVER mess with a granddaughter of a square-rigger skipper! One uses real brass knuckles, the other uses figuratives. It's in the blood. It took some doing to get those ships 'round the Horn, and various ways of persuasion of men and ship.
Keep on sluggin', slugger!
Wayne
PS: Lady Firestorm's an ally of Juniatha. DON'T make Lady Firestorm mad! Don't make her get on this Forum in a bad mood!
I'm going to say one thing more, not addressed to anyone in particular, but "if the shoe fits, wear it."
Several months ago when Juniatha was off the "screen" a number of you were crying "Where's Juniatha? Where'd she go?" Tells me she was missed, and missed badly.
The question is, did some of you want her back for her insights and expertise, or did you want her back so you could practice one-upmanship? Or to show off your own knowledge? O what a genius you were? About everything?
You see, at this point I've got sort of a proprietary interest in this young lady. We've corresponded, exchanged thoughts on things, and become as close as electronics will let us. So let me tell you that as a childless couple if Lady Firestorm and I could choose a daughter, Juniatha would be the one. Make of that what you will. This young woman WILL be treated with respect. Do you read me? Good.
That's all I have to say. Next posting I'll be back to my usual irreverant wise-ass self.
Departing the frequency. Out.
Firelock76 Several months ago when Juniatha was off the "screen" a number of you were crying "Where's Juniatha? Where'd she go?" Tells me she was missed, and missed badly. The question is, did some of you want her back for her insights and expertise, or did you want her back so you could practice one-upmanship? Or to show off your own knowledge? O what a genius you were? About everything?
The interesting thing is that I felt exactly the same way, then and all this time up to now: I was looking forward to trade ideas with someone genuinely interested in modern steam design who was willing to talk about it on an open forum. So yes, insights and expertise, and hopefully friendship too. That the person involved was female only added more delight: just to know that there was such a person in the world was enough. (And I also confess that, since my own daughter decided it was uncool for a girl to like trains (yet), and my son is 'in the autism spectrum' I thought it was an opportunity to share some of the work I have done over a comparatively long period of time in steam design with someone who would 'run with the ball' after I am no longer involved.
Now, I am from New York, where (as you know) we are prone to speak frankly, use sarcasm as terms of endearment and 'bust chops', and occasionally provide drinks of water from firehoses to people we accept as at least our peers, part of the same confraternity. It works, or should work, just the same in specialty engineering as it does in, say, the theatre, or the exercise-equipment design community. It most certainly does NOT mean that I have any intent of being a small tin god of an internet forum someplace, far less that I enjoy showing people up like the trolls and flamers on /. or one of the old chat groups, blessedly now only alive in memory. I will make no further comments about disrespect except to state that I am now being VERY careful to avoid giving any sense, or for that matter 'responding in kind' any more.
This has certainly gone in directions I did not intend, perhaps substantially through misunderstanding -- one very severe, which appears to involve some breach in a confidence that I cannot imagine committing. But that is a private matter, and I would not even mention it here except that you have no provision for PM on the Forum at this point so I cannot discuss things in private. I do not believe I have said anything conveying either disrespect or disdain for the young lady in question, and I now repeat that I have no such intention.
I am no longer responding in any kind of adversarial sense in this, or any other, thread of Juniatha's; as I said, this misunderstanding has gone far enough, and if it requires that I eat crow for nonobjective reasons, or in fact any reasons, I will not hesitate to do so. If anyone has further comment or opinion on the matter, I invite correspondence via PM (where it is appropriate) and not via distractions to the threads.
NOW can we have Juniatha's discussion about three-cylinder implementation?
RME
Overmod NOW can we have Juniatha's discussion about three-cylinder implementation? RME
As a hopeless romantic about steam, whether it could have stayed around longer, made some kind of comeback during the "Oil Crisis", or may return in some shape or form, please, please, tell me more about the Algerian Garratt, the Cossart Valve Gear, and the "salmon" rods.
Are the salmon rods on that 180-deg eccentric crank a solution to 2-cylinder dynamic balance and dynamic augment problems, that we don't need 3-cylinder machines, the Pennsy S-2/LMS Turbomotive turbine, the conjugated duplex, or some manner of high-speed Heisler geared drive to power bogies?
Where can I get more information on the Cossart valve gear -- separate piston valves for exhaust and admission? Hollingsworth talked about the Cossart system being "electrically actuated" -- is this true or the result of a misunderstanding. If the Cossart system doesn't require a 90-deg offset drive from the crosshead, does that mean the valves could be driven from the crosshead, and the only purpose of the "salmon rod" is driver balancing?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Paul Milenkovic As a hopeless romantic about steam, whether it could have stayed around longer, made some kind of comeback during the "Oil Crisis", or may return in some shape or form, please, please, tell me more about the Algerian Garratt, the Cossart Valve Gear, and the "salmon" rods. Are the salmon rods on that 180-deg eccentric crank a solution to 2-cylinder dynamic balance and dynamic augment problems, that we don't need 3-cylinder machines, the Pennsy S-2/LMS Turbomotive turbine, the conjugated duplex, or some manner of high-speed Heisler geared drive to power bogies? Where can I get more information on the Cossart valve gear -- separate piston valves for exhaust and admission? Hollingsworth talked about the Cossart system being "electrically actuated" -- is this true or the result of a misunderstanding. If the Cossart system doesn't require a 90-deg offset drive from the crosshead, does that mean the valves could be driven from the crosshead, and the only purpose of the "salmon rod" is driver balancing?
It is a little misleading to refer to Cossart valves as piston valves, although they certainly are that by definition.
This description is based on my memory of a second generation photocopy of an article in “Locomotive Railway Carriage and Wagon Review” for (if I recall correctly) 1931. Although I have quite extensive literature on French steam, I haven’t found a French description of the system. Certainly my translation of Chapelon’s “Locomotive a Vapeur” doesn’t give it more than a cursory description (probably because it was only applied to simple rather than compound locomotives).
The valve gear layout is very similar to contemporary Caprotti installations, with two valves, one inlet and one exhaust side by side at each end of the cylinder, both with their valve stems vertical. The cam is arranged transversely and operates the valves through rocker arms similar to those in a single overhead camshaft automobile.
The valve liners are flared at the bottom, like a locomotive exhaust over the blast pipe, and the valve when open drops into the flared area, giving a very free flow of steam either in exhaust or admission.
These could be best considered as a form of poppet valve that doesn’t ever have to seal against a valve seat and removes the impact forces and replaces intermittent movement of poppet valves by a continuous movement, like conventional piston valves. The valve does of course still have to seal against the valve liner, and the form of the piston rings used in this application (where they effectively leave and re-enter the valve liner) is not something I can easily imagine.
I believe the actuation of the valves was completely mechanical, from the “salmon rod” through a rocking arm. I don’t know if the camshaft rocked or rotated but either is possible.
However, the adjustment of the cam to control the cut-off was through an electric servo system, which is presumably what Brian Hollingsworth was referring to.
A comment I have heard was that all four valves were dropped clear of the liners when the locomotive was drifting, giving an effective reduction in resistance, and the Algerian Garratt was able to coast for long distances during trials in France.
Apart from the Algerian Garratts, all of which used Cossart gear, the main application was on Nord 2-8-2T tank locomotives used in Paris commuter service, although at least one Nord “Super Pacific” was fitted in the early 1930s. This Pacific was displayed in Paris with the British LNER 2-8-2 “Cock o’ the North” in 1934(?).
The tank locomotives were used from the early 1930s until the mid 1950s in heavy suburban service and none was ever converted to conventional piston valves, so the system must have worked well enough in the hands of maintainers familiar with the system.
No further Pacifics were converted, however. The loco concerned had been a one off with Caprotti gear on a four cylinder compound layout, and I believe it was fitted with a standard set of 2-8-2T cylinders, so that might have been regarded as an economical way out from an even more complex system.
Certainly, the “salmon rod” helped balance reciprocating forces, and may have helped in the longitudinal plane particularly. This would be important for a large tank locomotive, since longitudinal oscillation is often taken up by tuning the engine-tender coupling springs, something not present on a tank engine.
Off the top of my head, the “salmon rod” I think was used on the three cylinder simple De Caso 4-6-4s (I can never remember whether these were 232R or 232S) in conjunction with poppet valves, but not on the post war 232U, of course.
M636C
I think the discussion of Cossart is not 'off-topic' because the gear might have been adopted for some postwar American applications.
M636C Paul MilenkovicAs a hopeless romantic about steam, whether it could have stayed around longer, made some kind of comeback during the "Oil Crisis", or may return in some shape or form, please, please, tell me more about the Algerian Garratt, the Cossart Valve Gear, and the "salmon" rods. It is a little misleading to refer to Cossart valves as piston valves, although they certainly are that by definition. This description is based on my memory of a second generation photocopy of an article in “Locomotive Railway Carriage and Wagon Review” for (if I recall correctly) 1931....
Paul MilenkovicAs a hopeless romantic about steam, whether it could have stayed around longer, made some kind of comeback during the "Oil Crisis", or may return in some shape or form, please, please, tell me more about the Algerian Garratt, the Cossart Valve Gear, and the "salmon" rods.
This description is based on my memory of a second generation photocopy of an article in “Locomotive Railway Carriage and Wagon Review” for (if I recall correctly) 1931....
A reasonably full description is here, Cossart's American patent application (of 1932) for the system. Uncharitably, but with some historical precedent for the ways patent-protected devices came to be adopted by 'cash-strapped' railroads, I would note that this gear would have been coming out of patent protection at just the time America abandoned new steam construction; the likely marketer (Franklin) was already heavily invested in poppet valves...
I had thought this is why they were called 'drop valves' -- not just because of the vertical motion.
Thanks, Peter -- good show.
First of all I want to thank Firelock for his making aim accurate and it seems we are all heading to resume matters steam at an envisaged extra lease of life through the 1950s - which isn’t exactly ‘modern steam’ which might be interesting to discuss in another thread I may open if there are users interested .
@ Paul M M636C Overmod
As concerns the question on Cossart poppet valve gear , Overmod had again stepped in - or jumped forward - whatever - so I don't have to cover that , other than by a personal remark .
I think , Cossart poppet valve gear was not really on the list of the American builders , they fiddled with the Franklins , however : for peace let's assume someone in some office had at one bright day shouted "Cossart ! WoW ! Yeah ! Cossart , that's it !" And then they would have rebuilt the Franklin engines with their too small valves into Cossart with too small valves and made test runs , found trifle differences , started discussing them and ..
found it inconclusive ...
Because : Franklin , Cossart , Lenz or what have you : without adequate cross sections and a minimum of inner streamlining the one would not help any better than the other .
And , btw , the drawings show what small lifts the valves offer - a piston valve actuated by Walschaerts was not really inferior because at the point of opening a port it was already travelling at speed and in - then - 'modern' layouts of long lap valve gear the valve over travelled the ports width and by the travelling speed involved in this , it already gave quite rapid port opening .
However , I feel the discussion will now circle around poppet valve gear and their relative virtues and that is but a side aspect of what types of steam the builders might have turned out had the railways bought steam for another couple of years .
My personal thinking is , non of all these fancier ideas here ventilated could realistically have had a chance to be considered - the builders were way too conservative to do that and although ALCO seems to have been prepared to try some inputs offered by Chapelon at his 1938 visit , Kiefer of the NYC had turned it all down and ALCO certainly was not to build a J-3a featuring 'French Frills' when Kiefer didn't want it . And since in 1945 the visit had been 'long since passed' I wonder if anyone would have turned up old files and propose something then ventilated even if it should have passed beyond mere consideration back then . After all , Prof Giesl's efforts came to nothing , they all had their own specialists for draughting and all were firm believers of the very way they were doing things - whether successful by objective standards or just 'good enough' by 'home made' standards .
So , frankly , while you may feel free to ventilate the impact of Cossart valve gear , I guess it would simply not have happened and if so it would not have gone beyond the stage of an arguably disproportioned test engine remaining indifferent as concerns performance and thermodynamic efficiency of cylinders . Which would , in the end have ended steams extra lease of life with a couple of loco classes we haven't seen but without sensational technological break through and thus it would have petered out in 1955 .. 57 like it did in 1945 ..47. Only , we might have seen a Lima 4-8-6 , maybe an ALCO 4-10-4 or 4-10-6 , a couple more Baldwin very heavy 2-8-8-4 and 2-10-4 and extra-super heavy 4-8-4 and maybe another high speed 4-6-4 by ALCO or other and possibly a Duplex class by ALCO for the NYC , carefully avoiding the observed shortcomings in the PRR T1 yet surprising with *still* some unpredicted specialties , although performing tolerably well all-in-all as long as Alfred Perlman although ante portas was not yet in chair ( we must bend known history here to keep Alfred off for a couple more years and must pretend previous management had listened to Kiefer's 'A Practical Evaluation ..' - we don't want to assume an Alfred Perlman reformed into a pro steam loco man , I believe that would over-charge just about anyone's imagination )
Regards
special note
Overmod : >> That the person involved was female only added more delight: <<
No-no , absolutely not !
I'm writing here solely for discussing steam locomotives . It was a mistake maybe , not to have done as many other users do and log in as a # locomotive or the like . On the other hand some of you then might have wondered at times about that user's way of thinking . As by my way , I wanted to be open , our angle of view differs from that of men sometimes and I feel that’s ok .
Other than that , just forget any non-railroad aspects and see me as just another steam loco enthusiast and we’ll get along fine .
= J =
I think you are very correct about how American designers would proportion Cossart valves, if used -- wrongly. I do wonder whether the Cossart gear would have found a trial here when the gear came out of patent protection.;; assuming no diesel alternative. (Whether or not that trial would have used the drop valves, or used the balancing arrangement to drive OC or RC poppets, is another issue ;-})
I do think there would have been more recognition of Chapelon post-1945 had there been no diesels. And I suspect Al Perlman would have been level-headed about workable steam had there been no 'better' diesels...
What do you see supplanting reciprocating steam if it had petered out in the latter '50s, and there were no practical diesel-electrics? (That's a straight question -- for example, would it have been motor locomotives, or turbines of some kind? Something would have to be replacing recip steam in fairly large numbers, and I'm not sure what the 'best' answer would be.)
Meself, I couldn't see anything realistically supplanting steam in the late 50's with no practical diesels around. The only alternative would have been mainline electrification on a massive scale with it's heart-stopping expense. The Pennsy only completed its New York to Washington electrification with financing by a New Deal government loan. I doubt any similar loans would have been forthcoming in the 50's.
Remember this is long before the era of "too big to fail." Personally I think if you're too big to fail you're too *** big for your own or anyone elses good, but that's another story.
Dittos to your supposition about Al Perman and steam. "Alfred the Great" was a practical man, whatever got the trains over the road would have been fine with him.
Overmod A reasonably full description is here, Cossart's American patent application (of 1932) for the system. Uncharitably, but with some historical precedent for the ways patent-protected devices came to be adopted by 'cash-strapped' railroads, I would note that this gear would have been coming out of patent protection at just the time America abandoned new steam construction; the likely marketer (Franklin) was already heavily invested in poppet valves... A comment I have heard was that all four valves were dropped clear of the liners when the locomotive was drifting, giving an effective reduction in resistance, and the Algerian Garratt was able to coast for long distances during trials in France. I had thought this is why they were called 'drop valves' -- not just because of the vertical motion. Thanks, Peter -- good show.
Seeing a clear view of the drawings (for the first time) I see that my description was wrong in that the liners were not flared, but that conventional liners sat inside a flared casting. At least that solves my concern about the piston rings and a few other misconceptions from the poor quality copy of the article.
I downloaded the PDF straight away....
Hi folks -
The point with the valve shape was the valves and seats were relieved of steam pressure load and thus the valves could be freely actuated – same as btw was the case with piston valves . Except for transient pressure differences on exhaust sides where the chamber with exhaust lead just opening has a higher pressure than the opposite side and this pre-loads the actuating rod system , i.e. valve gear , enhancing development of bearing play . At lower speeds in contrast to expected shortening of travel due to movement lost in play , this had an effect perhaps surprising at first glance : it served to *enlarge* valve piston travel in the presence of play in valve gear using the summation of bearing play to maximize valve travel and do so at maximum lead . At higher rpm speeds , mass inertia tended to cause over-travel due to summation of bearing play .
For me , the Cossart has had a funny déjà vú effect in that left and right hand drives interact – about the same way as a type of valve gear did I had inadvertently invented when first becoming interested in ( trying to ) understand the way the Walschaerts worked . Since the steam loco model I had for inspecting was pretty vague and sloppy as concerned replicating valve gear and – in hindsight – likely had suffered from rough handling to have its return crank pointing approximately 180 ° against crank pin , I was quite a bit mislead in tracing what does what . Accepting return crank was to oppose crank pin lead me to assume there must be some interaction rh to lh sides that was just left off in the model . I tried for some time to figure out the geometry of this ‘missing link’ until I came up with a solution involving telescoped hollow lateral shafts and with a bit of further thinking the device could be advanced into a great tool to amplify piston valve travel and that did make the ( actually falsely proportioned ) combination link look just right . With ironing out some bugs , I had back then simply ‘dealt’ with a teen’s casual “oh-uwwh-mm-to-be-done-by-some-shibbly-shucks-what-ever” , my ‘modified W’ could easily provide a 12 in valve travel – some 50 % larger than in a regular decently good Walschaerts .
On the NORD 141.TC 2-8-2 suburban tank engines the Cossart was quite successful – however it was not in the mentioned sole two cylinder rebuilt of a NORD 3.1200 séries ‘Super Pacific’ – de Caso’s original intention to make compounding superfluous by a valve gear providing low throttling losses and enabling shorter cut-offs than usual did not work out – and it couldn’t because viewing advantage of compounding solely in larger expansion without usual increase of throttling effect through inadequate port opening at short cut-off was incomplete . So , preferably perhaps we should consider the 141.TC *having Cossart valve gear* to have been very successful in practice – the 141.TC series having been good engines of considerable power for their service mass , simply withstanding replacement for a long time . As concerns the Cossart poppet valve gear it was perhaps an example of success by full series application , making all the difference in contrast to a one-off application , although a decently good shed shop and servicing sure had their part in it .
The opposed return crank setting encouraged using an intentionally front-heavy ‘salmon’ rod providing opposed motion to main rod in order to balance reciprocating part of masses to a larger degree , however that sort of balancing could not be complete since the motion of the ‘salmon’ rod differs from that of the main rod and because it added yet more reciprocating mass having to be stopped at dead center and then re-accelerated and thus causing more vibration in revolving sense than without it and it’s longitudinal reciprocating mass balancing . For application in very much larger and much heavier American Super Power it would pretty soon have found it’s practical limitations .
My old saying : nothing is for free in engineering
The Cossart valve gear – if generously proportioned with large ports and careful inner streamlining – *could* have advanced ihp output at same boiler output of many American Super Power types – what the impact of inherently sharper exhaust beats might have been on draughting would have depended on applying or not an adequately advanced exhaust steam conduct and draughting arrangement . Had the old narrow round chimney and simple round nozzle been continued with , then a large part of the thermodynamic advancements and extra output gained with a Cossart of good design would simply have gone ‘up in smoke’ .
A word on diesels :
As you may have noted when reading my introduction and again my introduction to my drafts ( meanwhile deleted ) I did not simply ‘extract’ diesels from the scenario . If we were to do that , question arises if the diesel engines should be considered not yet invented and that immediately would raise question as to what about the gasoline engine ? If both were to be excluded that would take away something like 95 % or better of road traffic . Now , you might exclaim “ Why , that’s railroad heaven !” – still may I say this would be a pretty arbitrary assumption : after all the oil was / is there , the technology was there and physical laws allow for these engines . So , I prefer a picture closer to reality , just tweaking *success* of the diesel engine in railroad application and that could be assumed had the known very successful groups not come together and interacted to make the diesel the success it did become . Arguably , there might be a surprisingly simple tweak – although I have to ask forbearance by the followers of Baldwin and their mighty steam power such as the admirable Santa Fe final classes and other – you name them . Ok , that said , let’s propose early on ( about the time in actual history EMD was fledging ) someone at the Baldwin design office had come up with the idea of transplanting ships diesels to railroad vehicles to make a new power – ‘The Diesel-Electric Locomotive’ – and a patent document was written to be registered for the Baldwin Locomotive Works . The effect might have been along these lines : Baldwin would have seen diesel success partly as an in-door competition and thus interest would have been decidedly less pressing than it actually had been with EMD where diesel meant do or die and nothing in between . Further , sorry folks , I just feel at Baldwin development of the diesel engine as a traction tool marketable to railroads would have taken – uhm – let’s say *longer* than it did at EMD and the results might have been just that trifle bit less revolutionary , enough to lack sensation and compelling surge for railroad management . Diesels – just think of the ‘Centipedes’ might have become a type of locomotive you *could* use aside or instead of steam and would enjoy some success on arid area mainlines , heavily graded mountain lines and other - yet few people would really get crazy about them .
That scenario would have had an immediate implementation on the steam loco manufacturers : there would not have been a dramatically new and threatening situation – business after cooling down from war production level would have continued just placidly somewhat like it did , say , in the 1930s when it slowly restarted under the policy of ‘New Deal’ . Since the post-war automobile craze would still rise as it did and together with air travel would compete with passenger trains , we might have seen some railroads turning as they did towards light weight diesel trains like the Zephir , or light weight diesel streamliners – on the other hand we might have seen more new high wheeled Atlantic and Pacific types heading new passenger stock before it all went the way vividly described by the song about the ‘City of NewOrleans’ ( .. good morning , America , how are you – say , don’t you know me I’m your native son ..)
Imho , the interesting point about steam traction to have continued for some extra 10 – 20 years could be : how would the RRs have dealt with trains as heavy or nearly as they occasionally are now with what looks like a complete production batch of diesels up front and then dispersed along the train – or would they simply have stayed with the loads seen in steam’s late hour and run more trains faster over the mainlines as better suiting steam’s character of performance , making at least equivalent totals of ton-miles of commerce ?
The simplest way of delaying the advent of the diesel locomotive was to have crude oil to be priced a few times higher than it was in the period of 1920 - 1950. FWIW, there was quite a bit of concern about the oil supply in the US in the early 20's, overcome by the discovery of oil in west Texas.
If you look at the detailed drawings in the US Patent, in particular Figures 10a and 10b the piston valves and their liners are quite clear. I must admit the the explanatory diagram figure 6 shows poppet valves and I can't explain that other than that that diagram was showing the cam operation and the type of valve was irrelevant.
Is that important? it might be conceptually easier to increase the diameter and the stroke of the piston valve to allow for larger steam flow in large US locomotives.
Was the Cossart fitted Nord Pacific not a success? It was a pretty simple conversion, using 141TC cylinders and valves, and it lasted as long as the other (compound) Pacifics. It didn't demonstrate the lower steam consumption that was hoped for but it must have cost less to maintain than the compounds.
The considered opinion in France was that four cylinder compounds (like the 141P) were "better" than the simples (like the 141R) but the 141Rs stayed in service longer and worked more traffic, presumably at lower cost per tonne-kilometre.
Having looked closely at some of the diagrams in Chapelon's "Locomotive a Vapeur" , the characteristics of German locomotives seem to differ from those of French locomotives they are being compared with. They match the German diagrams the data is drawn from, but I wonder whether enough of the conditions affecting the results were standardised to allow the results to be compared.
While Chapelon did good work, I sometimes wonder if his results were as impartial as might be expected.
erikemThe simplest way of delaying the advent of the diesel locomotive was to have crude oil to be priced a few times higher than it was in the period of 1920 - 1950. FWIW, there was quite a bit of concern about the oil supply in the US in the early 20's, overcome by the discovery of oil in west Texas.
Since this is more than peripherally germane to this thread's 'assumptions':
There was more than a little concern about the oil supply in the '20s, and not just in the early '20s. It's generally forgotten that the Fischer-Tropsch patents on syngas and fuel synthesis were licensed at GREAT expense in the latter half of the '20s, since it was assumed that future increases in expected demand (mostly from automobile traffic) would have to be filled via coal conversion. I don't think it's safe to establish a 'blanket' low price for oil products from "1920 to 1950" as that leaves out some 'transient spikes' in price that were only kept from persisting by sometimes-fortuitous events. (Much the same as the situation when the Carter administration was pushing syngas and other projects in the '70s in the wake of the OPEC embargo)
Even so, Clessie Cummins noted that PRR had an ongoing interest in improved forms of internal-combustion power (i.e. better than gas-electrics) as late as 1927 (when he notes that a key proponent died, and the inherent conservatism of the replacement killed development). That strongly indicated to me that there were significant economies even at high fuel price, and these in part could be attributed to the greater fuel efficiency of compression ignition.
BTW: Baldwin seems to be coming in for some badmouthing regarding diesel development. That company was concerned very early with research into diesels, with reasonable results as early as 1927; the principal difficulty they seem to have encountered -- and it was a serious one -- was that they treated diesel-electrics as electric locomotives with on-board power generation at first; the existing designs of motor simply did not produce the power density necessary to match what simpler steam locomotives could achieve. When they got around that with the 'modular' locomotives (with the 412 and later 408 engines) the reason for not marketing them extensively was high first cost, not any particular disasters with the technology (there may have been problems with the V-12, but apparently not with the V-8). Had Baldwin understood the importance of capital financing as well as Sloan at GM did, it might not have mattered if EMD's locomotive design (lightweight construction, MU capacity, etc.) had not come to be -- you'd have had efficient single-unit diesels at 'normal' large steam horsepower, and it would be difficult to find a practical consist in the '40s that two 6000-peak-hp locomotives in air MU could not have handled... not to mention that even with crude startup and shutdown of individual motors, the fuel burn could be easily modulated in 15 steps to suit the particular train or running conditions.
So our 'special conditions' about later diesel acceptance might be stated as follows: we assume that oil prices remain as they would have been if the West Texas and Aramco efforts had not occurred; we can presume that GM did not get involved with systems design of motor-electrics; we can presume that the rush to dieselize only involved practical considerations of operation and not special financing (or perhaps not-so-veiled threats to re-route automobile delivery traffic via other roads). Automobile and truck traffic remain at levels determined by factor prices in that environment, as does the expansion of refinery capability and technology optimized toward eight-carbon fuels (perhaps made easier by synthesis methods, which require more rather than less processing to get to 'diesel' fuel and 'gas oil').
To me, this produces a timetable just as Juniatha indicated: you have 'modern steam' continuing to be developed past 1948, but ultimately being supplanted by compression-ignition power over the next decade or two (perhaps mirroring dieselization in other areas of the world).
We then get into considerations external to locomotive detail design -- most notably the great increases in wage cost in the late '40s, including wages and supply stability in coal mining. My opinion is that this was a much greater reason for rapid dieselization than operational cost saving (which, as has been pointed out repeatedly, was not all that great comparing first-generation diesels to contemporary best-practices steam). Stalling off the postwar 'gains' made by labor for a few years would also add to the survival of steam a bit longer, but it would still be likely that Juniatha's window would be appropriate.
Relative loss of passenger traffic would be seen in that model as well, as restrictions on automobile adoption would be relatively minimally reduced by higher fuel price (vs. rationing or supply caps at regulated low price). So many of the great applications for large modern steam -- certainly the ones most notable in Kiefer's motive-power study -- would be collapsing at much the same rate as historically observed. That leads to some interesting possibilities regarding where new steam development would occur...
Some more comments on the salmon rods are here (article from 2012). Much of this confirms what Juniatha was saying.
As noted, only with substantial reduction of the reciprocating component of main-rod mass is this system workable at all, and VERY careful detail design of the main pins, particular at their outer ends, is required. (The specific form of crank attachment I used involved a smooth fillet at the inner transition from pin to crank stem, and use of multiple curved engagement 'splines', similar to a Torx or star bit, rather than a crude square or Woodruff-like locking key, precisely to prevent the combination of lateral stress at the root of the pin and torsional stress at the end from inducing fatigue. I also expected that the construction methods that came to be adopted for axles (including the very late development of centrifugal casting) would come to be used for main pins...)*
I have already mentioned Langer's 'balancer X' (patent here but there is an Alco development of 'greater antiquity' here (scanned on surely one of Google's poorest OCR days! Both these systems accomplish the longitudinal balancing along the centerline, with heavy gears and no linear-SHM problems with mass reversal. What I'd like to point out, in connection with an earlier discussion, is that no one appears to have actually built a locomotive in America that used these systems, and (reading between the lines of the PRR Q2 testing) even the most severe surge problems could be addressed by using large tender mass and/or tuning the spring resonances in the radial buffer. The severe longitudinal problems observed with the Q2 on the test plant (where the tender mass was not present) only occurred below about 35 mph indicated, which to me argues strongly that it was predominantly thrust forces, rather than inertial forces, that were causing the behavior, and the observed 'phasing' behavior (which did not seem to differ between sync- and antiphasing) would further confirm that hypothesis. No purely rotating balancer would account correctly for this, although it might be used as a partial 'correction' for the vertical component of rod thrust at high speed.
I am still awaiting specific information from Voyce Glaze's balancing book for the J class to determine the magnitude of the yaw forces that had to be overcome to permit zero reciprocating overbalance.
*(I did preserve methods for fine adjustment of eccentric crank lead and angle; PM me if you want details)
Hi –
What I commented on the Cossart valve gear was my own view of it , the text linked was interesting for the curious variations of these rods on deCaso 232.R three cylinder and .S four cylinder compound where the author asks what they were really needed for . As concerns mentioning the 160.A.1 also having had these rods t the outside drives I have also wondered what they were meant for with an engine having six cylinders - although two were set at 180 degrees . Naturally , the outside man rods were the longest and heaviest of all and thus maybe the object was to provide perfect balancing of reciprocating masses by using these rods ..
Here are some more interesting articles on that site :
http://myweb.tiscali.co.uk/peclegg/sncf/articles/article_2009_05.html
Was there a conspiracy ? (author Carpenter on the question if there had been opponents effectively keeping André Chapelon from realizing much of anything on SNCF in the first few post war years so critical for steam traction ( have read quickly but will not comment here )
http://myweb.tiscali.co.uk/peclegg/sncf/articles/article_2007_01.html
the Garratts of Algeria ( haven’t read , yet the 4-6-2__2-6-4 did look awesome , didn’t it – it might have looked even mightier if the cylindirical forms of boiler and supplies had been trued by their center lines and outer overall diameters )
http://myweb.tiscali.co.uk/peclegg/sncf/articles/article_2006_08.html
big wheels for high speeds (haven’t read , yet saw the Thuile engine , that incredible 4-4-6 , saw mentioning it had a flangeless second driven axle – which immediately would indicate that three axle rear truck was a pivoting bogie – maybe I *should* put up a 4-4-6 *Super-Limalized* Atlantic ?)
http://myweb.tiscali.co.uk/peclegg/sncf/articles/article_2006_06.html
A Portuguese inspector rides the footplate of a NORD Super Pacific ( haven’t yet - must still read )
http://myweb.tiscali.co.uk/peclegg/sncf/articles/article_2012_02.html
Les Trains de M Hulot ( interesting analysis of the role trains play when (rarely ) appearing in a film by Jaques Tati and how the author found out which train station it was where the scene was filmed of the crowd of passengers trying to get to the right platform according to incomprehensible announcements by the loudspeaker – have read but won’t tell which station it was – read by yourself *gee*)
Overmod : >> I am still awaiting specific information from Voyce Glaze's balancing book for the J class to determine the magnitude of the yaw forces that had to be overcome to permit zero reciprocating overbalance. <<
In view of those lingering words of 115 mph *plus* exploit , *that one* I'd also like to see ! As I look at the wheels with their counterweights I would like to see calculation showing this to be 'zero overbalancing' - i.e. zero reciprocating mass balancing .
So , looking forward to see the calculation method and results , complete with masses of rods , bearings and pins , wheels mass distribution and masses of piston , piston shaft and cross head , too . Don't forget calculation and results of for&aft oscillation movement resulting from this 'zero overbalancing' .
.. and what was to be the point in it when even the diesel and electric locomotives of that period with their axle-hung massive motors caused substantial dynamic peaks on top of static axle load , in the vicinity of some 50 - 70 % of the static value at rail joints - amount largely depending on geometrical exactitude or wear of joints , dynamic augments no less than those of steam loco main driving axle - however on *all* driven axles then !
add.:
Overmod >> The specific form of crank attachment I used .. <<
Where did you use it , i.e. on which locomotive ( design or realized ) would you mind posting drawing / photo of it ?
Overmod >> here << http://www.google.com/patents/US2432907
Trouble with that one is , it would only work if the drive axle was vertically fixed in frame and not ride freely up and down within guiding plates to stand on the rails and have all dynamic vertical forces *not* attacking frames but rails as defining its vertical position , or in other words : vertical position of a conventional drive axle was not defined by frame structure of engine unit itself , instead it was defined by means outside the engine unit , i.e. by riding the surface of the rails . The vectors given in the patent drawing for the drive axle ignore this fact and are therefore not! representing real conditions in a steam locomotive main drive axle and frame work , but a theoretical arrangement as described above which was not! practically viable because of indispensability of suspension of frame work on axles and thus indispensability of free vertical travel of axles in guides .
If this fundamental system of spring loaded axles is being retained , any additional balancing system running *within* the frame structure will inevitably *upset* the vertical riding of the engine unit because its! vertical dynamic forces act upon the framework of the engine system – while those transmitted by the wheels! Act upon the rails . Thus , there is a fatal miss in linking these dynamic forces which causes the whole additional balancing system to fail - a glaring fallacy !
One must understand the fundamental difference in working and distribution of dynamic mass forces in a classic direct drive steam locomotive and any type of piston & rod motor , the latter having a crank shaft of *fixed* rotational position within its motor block while the former is more complex having a ‘crank shaft’ ( main drive axle ) allowed to shift vertically or in general : at right angle to piston forces . Ok , I can hear one remarking upon locos having cylinders at angled position and thus horn guides not at right angle to piston force vector – yes , it could be done .. it had a price , though : suspenstion had to be made pretty stiff or else such engines would get into ‘waddling’ when starting under high t.e. – i.e. teeter from side to side under the influence of propping up by vertical vector of piston force – I’m sure this should have been present in some British small drivered 2-8-0 and 2-10-0 engines some with cylinders quite substantially canted to the horizontal – clearly this was done because of prescription of loading gauge limitation , not by free choice . It was something different again when in four cylinder compounds the outboard cylinder were lightly slanted in view of inevitable slanting of inside cylinders .
A similar mistake in thinking has been published in the Pennsylvania magazine in connection with a proposal for solving the T1 trouble with slipping .
But that’s another story …
Do you use any particular 'historical' method of balancing? I've been using Ralph Johnson's 'The Steam Locomotive (1945 printing), and there is a copy available here in online format. (If you have access to one of the Hathi Trust partner organizations, you can download a .pdf copy). His chapter on counterbalancing (XVI) begins on p.252.
There's a useful table (LXI) on p.268 that shows the overbalance amounts and percentage for several classes of locomotive. Note in particular the figures given for the NYC J3a; this almost certainly was derived from one of the engines with the Timken lightweight roller rods -- note the difference between its numbers and those of the much lighter and nominally faster Milwaukee class A.
Johnson makes an interesting statement on p.269: he feels that on a modern locomotive only a minimum of overbalance weight (he appears to advocate about 100lb at most, regardless of locomotive weight) should be placed in the mains. He says instead that the remaining overbalance weight should be evenly distributed in the other drivers. In light of the AAR recommendations on dynamic counterbalancing of wheels driven by tandem rods, I think it would be appropriate to put only a 'fraction' of overbalance in such wheels. So the result is a bit like doing the opposite of tapered loading!
It is only a small step from this to zero overbalance on the mains, where the vertical component is most critical. Now, I would argue that it also becomes critical at a higher speed on the leading coupled axle, to prevent unloading that might lead to guiding failure, but that is a point yet to be determined.
As an additional item to notice, he uses the term 'longitudinal shake' for the motion I learned as 'surge' -- at least, I think they mean the same. He hints at the effect of long chassis and high relative polar moment of inertia on 'modern heavy locomotives' (bottom of p.266) but he does not compare this with the last two recommendations made by Eksergian in 1928 (p.264 nos. 4 and 5) where bringing the rodwork as close in as possible benefits the nosing or hunting tendency.
This gets us within sight of eliminating overbalance weighting in the most critical wheels. I look forward to seeing what was actually done and tested on N&W. (Fringe benefit, as I mentioned earlier:
this book of Glaze's also contains design information on the Y7 design...)
I'd like to address the last question: I think the great problem with dynamic augment in steam power was not so much the inertia of the rotating forces directly -- significant as that was -- as it was resonance effects, often associated with the suspension 'period' or spring rates, which could produce sudden-onset instability upon very slight increase in rotational speed. Diesel-electric nose suspension did not produce this effect dependent on rotational speed (although Alco had an interesting experience with the Hi-Ad trucks and roll resonance at a critical speed of around 15 mph on standard jointed rail with typical poorly-maintained low joints). So the force involved in diesel suspension shock (in the critical vertical plane) acts like higher unsprung mass (which is essentially what it is). That is not to say it isn't substantial or significant! Only that it is not self-resonant in the vertical plane to the same extent that steam is...
Where the diesels REALLY cause the woe is in lateral accelerations (the yaw component of hunting, for example). The mass of the motors down low very effectively transfers lateral shock to the flanges and if that shock reflects back enough from the railhead, you can get very effective effects both in 'shear' and in overturning moment -- to say nothing of 'hammer'-like effect on the head and upper web due to the heavy metal-to-metal contact and the somewhat 'deadblow'-like effect of the isolation mounts on the motors.
Obviously I have not built a full or even scale model of a locomotive with the Nord salmon-rod drive. But I should have drawings of the detail design of the main pins... somewhere. If not I may be able to re-create them
Overmod So our 'special conditions' about later diesel acceptance might be stated as follows: we assume that oil prices remain as they would have been if the West Texas and Aramco efforts had not occurred; we can presume that GM did not get involved with systems design of motor-electrics; we can presume that the rush to dieselize only involved practical considerations of operation and not special financing (or perhaps not-so-veiled threats to re-route automobile delivery traffic via other roads). Automobile and truck traffic remain at levels determined by factor prices in that environment, as does the expansion of refinery capability and technology optimized toward eight-carbon fuels (perhaps made easier by synthesis methods, which require more rather than less processing to get to 'diesel' fuel and 'gas oil'). To me, this produces a timetable just as Juniatha indicated: you have 'modern steam' continuing to be developed past 1948, but ultimately being supplanted by compression-ignition power over the next decade or two (perhaps mirroring dieselization in other areas of the world). We then get into considerations external to locomotive detail design -- most notably the great increases in wage cost in the late '40s, including wages and supply stability in coal mining. My opinion is that this was a much greater reason for rapid dieselization than operational cost saving (which, as has been pointed out repeatedly, was not all that great comparing first-generation diesels to contemporary best-practices steam). Stalling off the postwar 'gains' made by labor for a few years would also add to the survival of steam a bit longer, but it would still be likely that Juniatha's window would be appropriate. Relative loss of passenger traffic would be seen in that model as well, as restrictions on automobile adoption would be relatively minimally reduced by higher fuel price (vs. rationing or supply caps at regulated low price). So many of the great applications for large modern steam -- certainly the ones most notable in Kiefer's motive-power study -- would be collapsing at much the same rate as historically observed. That leads to some interesting possibilities regarding where new steam development would occur...
IMHO, higher oil prices would have substantially reduced long distance auto and truck travel, how much would have depended on how high the price. One possibility is that auto traffic would have resembled the situation in the city of Avalon on Catalina Island, where the standard "car" is a four seater golf cart (along with golf cart based tow trucks). Similarly, air travel would have developed more slowly as fewer people could afford to fly. Both aspects would have kept up demand for high speed long distance passenger trains, thus making the likes of Lima's 4-8-6 more attractive to the railroads. The reduced competition from long distance trucking would have allowed the RR's to continue investing in line improvements that would have allowed for high speed operation.
OTOH, higher oil prices would have worked against the roads operating oil fired steam locomotives. Not sure if this would have pushed the roads to coal or diesels, but the Espee would have been more likely to electrify the Donner Pass line, for which the cab-forwards were designed (the main advantage is that the firebox is in front of the smokebox - think CO reduction).
There was substantial progress prior to WW2 on reducing maintenance, locomotive runs on the order of 1,000 miles were done on a daily basis.
Speaking of WW2, another big "if" was WW2 as the war effort led to improvements in the design of the 567, aircraft, aircraft engines and mass production methods.Steam locomotive development took a back seat to production for the duration, and new designs such as the PRR's T-1 weren't fully debugged prior to production.
- Erik
Juniatha .. and what was to be the point in it when even the diesel and electric locomotives of that period with their axle-hung massive motors caused substantial dynamic peaks on top of static axle load , in the vicinity of some 50 - 70 % of the static value at rail joints - amount largely depending on geometrical exactitude or wear of joints , dynamic augments no less than those of steam loco main driving axle - however on *all* driven axles then !
Probably one of the worst offenders would have been the original GE locomotives for the Milwaukee electrification as the motors weighed about 15,000 lb each. Mitigating circumstances were that the passenger geared locomotives were almost never run above 60 MPH ad that they were equipped with 52" wheel on the driven axles. On the other hand, the quill driven electric locomotives had only the weight of the wheelsets to contribute to dynamic augment.
I am curious if dynamic augment was a potential problem with side-rod electrics such as the PRR DD1.
Actually the Pennsy developed the DD1 as a direct result of a series of tests performed on the West Jersey and Seashore near Franklinville. These tests measured force exerted on the track structure by three different designs of electric locomotives an E2 atlantic and a D16. Two of the experimental electrics had relatively low drivers in a B-B wheel arrangement with truck mounted motors. The third was a 4-4-0 wheel with quill drive on the two axles of the large diameter drivers (68"?). The high wheeled example was found to have far superior tracking characteristics compared to low drivered motors. The side rod arrangement was the most practical means of transmitting the energy from a huge electric motor to two sets of drivers while maintaining a desired high center of gravity. By all accounts I've read, the DD1 rode and performed extremely well.
I've rad about the the testing that led to the DD1, the PRR did a nice job on this, though they had to re-learn some lessons with the GG1. I am curious if the reciprocating motion of the side-rod drive would lead to the same dynamic augment as with a steam locomotive, though the critical speed for may have above the top running speed of the DD1.
The high center of gravity is also achievable with a geared quill drive.
I guess my last post wasn't an actual answer to you question. My guess is that the DD1 would have the same dynamic augment characteristics as a conventional steam 4-4-0. I'm sure the PRR went with the side rod arrangement as a practical wheel slip control. Coupled drivers could hold the rail much better than individually powered wheel sets lacking sophisticated wheel slip control. The 4-4-0 wheel arrangement was a known steady rider. The pilot truck was seen as a necessary evil to ensure good tracking and to overcome nosing/hunting forces of a siderod powered unit.
From what I've read the side rod or jackshaft arrangement on the DD-1 was strictly a matter of practicality. The axle mounted traction motor hadn't been invented yet, or at least one powerful enough for a mainline locomotive hadn't been invented yet. They were being used on trolley cars of course but that's another application. The electric motors had to be mounted on the frames.
The Virginian used jackshafts on their first big electrics as well. The Virginian wasn't concerned about dymanic augment as the fastest those locomotives would go was 28 miles an hour.
Quote M636C
>> Was the Cossart fitted Nord Pacific not a success? It was a pretty simple conversion, using 141TC cylinders and valves, and it lasted as long as the other (compound) Pacifics. It didn't demonstrate the lower steam consumption that was hoped for but it must have cost less to maintain than the compounds.<<
Obviously it wasn’t because cost conscious NORD railway would have rebuilt all their Pacifics to that scheme if had been a success . Likely the engine , besides not showing up as economical in coal consumption as hoped for , it was a rough rider with but two heavy drive lines instead of – self balancing – four and may have caused *higher* maintenance costs because of the substantially higher mechanical vibration and mass forces caused by the two cylinder unit causing much faster working loose of the many bolted joints in these old-style fabricated plate frame construction . A likewise actual maintenance cost record had been found by DRG when they analyzed statistics on profoundness and complexity of maintenance work done by H4 large overhaul of 01 and 03 class two cylinder standard Pacifics as compared with that of S3/6 and S10-1 four cylinder compound Pacific and 4-6-0 . In contrast to prevailing ideas , the four cylinder compound engines did *not* show more costly because their mechanical wear was much lighter and consequently much less heavy replacement and re-machining work had to be done – and that although the older and very lightly built S10-1 4-6-0s were by then run very hard on loads and schedules put up in view of the larger and newer 03 class Pacifics which nominally was some 10 % more powerful . As with the larger Baden IVh Pacifics , DR 18-3 class , Th Duering later described in his books on German Pacifics how these engines shaped up once properly put in order and run and maintained correctly – again combining lower coal consumption per 1000 tkm and doing so at lower maintenance costs as compared with 01 Pacifics in comparably heavy service .
>> The considered opinion in France was that four cylinder compounds (like the 141P) were "better" than the simples (like the 141R) but the 141Rs stayed in service longer and worked more traffic, presumably at lower cost per tonne-kilometre.<<
( “Worked more traffic” – well , little wonder with 1323 141.R as compared to 318 141.P …)
This argument has been used ‚until the hammer wears out on the anvil’ – yet it is wrong and for the following important factors :
1.) As on most railway systems , on the SNCF steam had to give way to electric traction on the most important mainlines first . The ‚Ligne Imperiale’ – mainline of the former PLM , railway that had insisted on their old 141.F to become SNCF standard in a modernized form – was largely electrified in the early 1950s , so early in fact that some of the last delivered batch of 141.P never saw their proposed roaming ground but were sent to depots of secondary importance right away . Still , many 141.P continued in heavy express and dual purpose service , running consists of up to 20 coaches and freight trains of some 2000 tons – which is about as heavy as freight trains would get in Europe during the post war steam era , with exceptions up to 2800 .. 3000 tons for heavy Decapod classes both in Germany and in France .
I should make it quite clear that the quality of running and the level of performance demanded in these services the 141.P were then being used was way beyond the capacity of 141.R engines – both in speed , power in upper speeds and in maximum output . The 141.P could rise to 4000 ihp and somewhat over when equipped with double Kylchap . I have seen the speed / output curves established on the Vitry test bank for an early version of the class and they are nothing short of awesome .
As this demanding kind of service fell to electric traction , the 141.P engines were sent wandering to various smaller depots , being put to work on lighter trains , secondary lines , allocations now changing at random , some engines at reserve , some on miscellaneous duties ... Since at the same time the SNCF – again as usual practice towards the end of steam traction – was seeking to simplify and reduce their steam fleet for the remaining , mostly lesser , operation , it were the more sophisticated high performance engine classes that were to go first .
2.) To compare the 141.P – a modernized version of a 1920s conservative design with bolted plate framework – with the 141.R – a 1940s downsized design , initial batches incorporating some major features that made American steam as robust and enduring as it had become , the later batches almost fully equipped with these features , namely one piece cast engine bed , box pok wheels , Franklin auto wedges and many more – is to compare a Citroen with a Chevy or Beaujolais with Pepsi or what have you – what I want to say : each had virtues of its own – yet are they comparable ?
To be sure : André Chapelon had opposed construction of a standard Mikado based on that old PLM class – however old patronage won over technical ratio . Chapelon’s plan for a standard engine of this category was a four cylinder compound 2-8-4 of 5000 ihp , incorporating all the modern design features he had seen at his 1938 visit to American railroads , these engines would therefore have been a totally different proposition to the 141.P , based on 1920s design to be improved in steam circuit and some mechanical details by Chapelon .
3.) The 141.R flooded post war SNCF by an unprecedented number of engines , 1323 all together . That sheer number made the class first choice to keep as final steam power in view of planning for an ever simplified and more unified remaining steam fleet to fade out steam traction .
For a degraded dwindling fleet of steam in miscellaneous secondary work the simple and reliable 141.R with its more modern mechanical design , built more robust , was of course better suited than any of the elder classes lacking all those features developed to make engines lasting and enduring .
4.) Btw , as steam was being ‚knocked down’ another engine class that had to go early was – the DR 44 , SNCF series 150.X . Although crews much appreciated them in heavy freight service on the hilly lines of Alsace-Lorraine , they , too , were replaced by 141.R . A driver commented : „When ascending the long ramps with a 150.X I could rely on her surefooted pulling through at a steady pace – then , with the 141.R , I always had to be prepared to jump at the throttle if the engine slipped and would spin up rapidly and tear up the fire if I didn’t stop her quickly .“
So , surviving last didn’t always prove best . Basically , the two cylinder simple engine unit is the one delivering a defined output value by working on the highest internal mechanical forces of all types practically possible ; it has the highest piston forces per defined output value of all types ; it offers no self-balancing what so ever , causes the largest balancing problem of all types , inevitably has comparatively high throttling losses because of large individual cylinder volume , offers low degree of expansion if running of engine is not to be too hard – its specific advantage was focused on having all moving parts easily accessible on the outside , that was a deciding advantage as long as all these parts had to be constantly serviced and maintained . While other branches on engine design – btw the diesel engine – aimed at self-supporting no-maintenance design , steam locomotive development fatalistically accepted rapid and substantial wear and perpetual need for attending to engine parts . This path was only left with the last developments , notably roller bearings and mechanical lubrication , to some extent with Franklin auto wedges . Had the steam loco engine unit been developed to maintenance freeness as had become self-understood with contemporary diesel engines , it would not have made much of a difference how many cylinders a locomotive would have had , designers would have been more free in choosing the optimum number and configuration of the steam engine unit for suiting thermodynamic and traffic performance demands .
>> Having looked closely at some of the diagrams in Chaperon’s "Locomotive a Viper" , the characteristics of German locomotives seem to differ from those of French locomotives they are being compared with. They match the German diagrams the data is drawn from, but I wonder whether enough of the conditions affecting the results were standardised to allow the results to be compared.<<
There is something in it – I had also been wondering and actually have found some aspects differing . However , spare me going into that or else I’d have to go on for pages on end while I want to keep it concise .
>> While Chapelon did good work, I sometimes wonder if his results were as impartial as might be expected. <<
Not sure what this is supposed to mean . Viewed impartial by others ? Presented impartial to other designs by him ?
The former : certainly not if you come to think of what happened to the proposed very advanced family of high performance steam ( shelved to the 12th of never while old PLM designs were being pressed through to become standard engines in somewhat modernized variations )
The latter : certainly so , André Chapelon as from all that can be said has always been prepared to appreciate a colleague’s achievements .
Sorry , have to quit ...
>> Having looked closely at some of the diagrams in Chaperon’s "Locomotive a Vapeur" , the characteristics of German locomotives seem to differ from those of French locomotives they are being compared with. They match the German diagrams the data is drawn from, but I wonder whether enough of the conditions affecting the results were standardised to allow the results to be compared.<< >There is something in it – I had also been wondering and actually have found some aspects differing . However , spare me going into that or else I’d have to go on for pages on end while I want to keep it concise.<
>> Having looked closely at some of the diagrams in Chaperon’s "Locomotive a Vapeur" , the characteristics of German locomotives seem to differ from those of French locomotives they are being compared with. They match the German diagrams the data is drawn from, but I wonder whether enough of the conditions affecting the results were standardised to allow the results to be compared.<<
>There is something in it – I had also been wondering and actually have found some aspects differing . However , spare me going into that or else I’d have to go on for pages on end while I want to keep it concise.<
Please, put this in its own thread. And then DON'T keep it concise! ;-}
BTW, the drop valves are not in a 'proper form' in Cossart's patent drawings; I think the patent concentrates on the drive to the valves, and not the valve design explicitly (which makes some sense). If he has a patent on the detail design of the 'drop-valve' itself, it was probably not also filed in the United States, at least not under his name. You will note that the valves as shown in the patent are "patently" unworkable (couldn't resist the pun) -- would that ring area actually seal properly? and where are the bridges? I had thought the valves as illustrated are diagrammatic stand-ins for a modern-in-the-early-Thirties valve system.
It's necessary to go to a later reference to see the detail design of the drop valves -- I have some, but I can't post them here. [EDIT: some material posted below.]
Overmod >> Please, put this in its own thread. And then DON'T keep it concise! ;-}<<
O-M-G ! noo-oh ! I quick fetch my bike and get out - just leave it alone , 'twas a mess and reflected the difference in attitude between French (dynamic behavior of locomotives ) and German ( continuous constant running of locomotives ) approaches - just the relative importance of constant cut-off against constant evaporation or the basis of evaluation of boiler nominal output on grate / total evaporative surface and so on and so on . Well , in a nutshell they can be re-calculated to be comparable and - alas ! - horse power or cheval vapeur - the physical unit was the same ( actually slightly surprising for times before the European Union ) and has since become amalgamated in SI unit kW . Oh , but boiler pressure wasn't quite ... for instance - *gee* .
Crossing Cossart once again - ok , so we will have to search and check to find a *real drawing* of these pist-o-pop drop valves .
Juniatha ... we will have to search and check to find a *real drawing* of these pist-o-pop drop valves .
Try this (I believe it is from an older edition of Yoder's "Locomotive Valves and Valve Gears" (note the page headings):
Here is the rest of the section at smaller size (I can provide larger if this is not easily readable):
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