Quentin
Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.
M636CNo, there were a small number of other locomotives fitted with Franklin Type B rotary cam poppet valve gear. Santa Fe 4-8-4 No 3752, Pennsylvania K4s 4-6-2 No 3847 and T1 4-4-4-4 No 5500 and US Army 2-8-0 No 611 were all fitted with Franklin Type B valve gear. All these locomotives were rebuilds, and the C&O 4-8-4s may have been the only locomotives built new with Franklin Type B valve gear. The statement has been made that T-1 No 5500 was the best of its class after rebuilding with Type B gear, so it is likely that the C&O locomotives were similarly better than conventional locomotives. Peter
Correction: That's 4-6-4, not 4-8-4.
I never knew that this was the only locomotive to be built originally with Franklin poppet valves. This is mind-blowing, considering Watt used poppet valves in his steam engines almost two centuries prior!
GT_MillsI never knew that this was the only locomotive to be built originally with Franklin poppet valves.
As I understood it, the RC arrangement on the L2b did not provide substantial 'enough' improvement over the 14" piston-valved version as C&O used these (extremely heavy) locomotives. I have lost the technical material (some of which may be in the '47 Cyc along with the description of continuous-contour shifting-cam RC) on precisely what the Franklin installation on the late Hudsons was; if continuous contour it would have suffered from the line-contact issues; if multiple fixed cams it would have had inferior intermediate cutoff control to the engines with Baker gear...
I don't recall if the cracking problem (with heavier 'return' springs for expedient debouncing of the poppet valves at speed) extended to the L2b valves; some of the 1948 planned improvements to the PRR T1s, specifically including better metallurgy and centrifugal casting for the valve spools, might have been incorporated on them considering their relatively late build date.
M636CWallyworld, I've checked Vernon Smith's book, and PRR 6110 was tested at Altoona in 1944. One table shows 6666 Indicated HP at 100 MPH, and another table shows 6000 Drawbar HP at 70 MPH. Remember that that required three E-7s which must have cost a lot more to buy! I have Wardale's book, which is pretty good. I also have the translation of Chapelon's "La Locomotive A Vapeur" (the title wasn't translated), which is very interesting. There are a number of good books in German, which I can (just about) read. A couple of English books by E.S.Cox, particularly "World Steam in the Twentieth Century" are worth reading. Cox was largely responsible for the British Railways Standard Steam locomotives, and there's a good book on them too! They were extensively tested both on the road and on a static plant. My personal interest is in China, and some day I'll finish rewriting a new edition of my book "Locomotives in China". (published in 1984). The development of the QJ is a particular interest of mine. It was basically assembled from standard Russian parts, and is apparently the work of Lebedyanski, who was responsible for the Russian L and LV classes. I actually have a photo of the QJ that Wardale was working on, but before any changes were made to it. It was stored complete at Datong in 1985. A friend visited Datong, and had a couple of meals with David Wardale while he was working there. Much of the frustration Wardale experienced was made clear at that time. However, I didn't think that the standard QJs were quite as rough and ready as Wardale indicates. They do look and sound good in service. A couple of 4-6-4s were rebuilt to Wardale's principles for limited service out of Melbourne, Australia. They've had some problems with the valves - the tighter tolerances to reduce steam consumption caused some overheating problems. Lubrication problems with superheated steam have been around for at least a century. I don't think the angled stacks (like the "Red Devil" ) look very good, and they might not improve performance that much. Peter
Tell me about La Locomotive a Vapeur. Not that I will be able to get my hands on either the French language version or the English translation, but how does it compare with, say, Wardale's The Red Devil?
I had thought the Red Devil would have much more technical information than it does, but it is largely Wardale complaining about what a hard time he had, first in South Africa, then in the US and finally in China. Three separate attempts to "bring back steam", three failures reflecting differences in the engineering culture in the three countries at that time.
The Red Devil is replete with graphs meant to show performance improvements, but it is lacking in a lot of other detail. To me, its biggest failing is that it starts out claiming that the Gas Producer Combustion System is the answer to the carbon-carryover problem and part of the answer, along with Chapelon-style improved exhaust and reduced steam-circuit pressure drops. Wardale makes some outsized claims of the improvements in water and coal economy, but as you get deeper in the book, the improvement of the Red Devil is shown to be more incremental when data is collected in actual service. Little explanation is offered to show why apart from blaming crews that they "lacked enthusiasm" to operate the GPCS properly.
Can you give me a sense of what La Locomotive a Vapeur is like? Does Chapelon show economy and power improvements and give detail as to where they are coming from and under what service conditions?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
The translation is by Carpenter. It does not redraw the French graphs and exhibits, much as the Wasatch translation of 'Rear Boiler Knowledge' from Glasers Annalen does not. Among other things it contains Chapelon's useful Sherlock Holmes deduction on how Timken thin-section rods can possibly work with roller bearings.
All the calculations were to be in 'part 2' of LLAV, which was never reprinted after the original edition (in French) and as I recall much of it was never printed at all. Discussion of this on steam_tech was extensive but now 'lost to science' with the collapse of Yahoo Groups; it remains to be seen if the archives or collateral are restored on groups.io. I recommend that you review anything remaining on the Web by Thierry Stora or Claude Bersano before it, too, gets taken down...
I was sent a page scan of the 1938 edition to do a full translation of the 'missing' part ... and should get back on it!
GPCS is in part founded on a mistaken understanding of heat transfer in a locomotive boiler; it resembles some of the misunderstanding of the thermodynamics of Besler tubes. Effective heat release is only part of the concern; it must then be taken up effectively and then communicated to water in ways that facilitate generation of suitable 'power steam'.
Products of combustion transparent across a wide portion of the emission spectrum are not as effective at radiant heat transfer as the luminous flame from vaporized (but unoxidized) carbon. Uptake from transparent gas is likewise peaky in the tubes; hence heating of a blackbody followed by re-radiation nearly normal to a (similarly black) tube wall has enhanced heat transfer benefits in addition to increased convective transfer in an annular restriction. In a boiler where there is no practical effort to recover the heat from the (transparent) H2O in the gas stream -- in GPCS this deriving not only from combustion but the 'process steam' introduced in the cellular windbox -- still more Rankine efficiency is thrown away.
Wardale acknowledged at one point that GPCS was a chemical reaction, not a firing method. Just as chemical reactions benefit from intricate process control, and often go haywire without it, so we can reasonably expect large-scale GPCS in tight packaging to be; if we now expect it to follow what is already a complex load-following steam demand it may become clear that no human fireman can consistently make all the various often interrelated adjustments in realtime... or perhaps better stated, shouldn't be expected to.
This isn't to say that some of the ideas of GPCS are mistaken. The idea can be adapted to produce a luminous primary plume with the addition of preheated primary air in addition to process steam, and to preclude clinkering and other ash-glassing problems (it would be nice to have cyclone firing on a locomotive but there are considerable issues!). Part of the reason for a cellular windbox is to permit different parts of the bed to be selectively 'blown' at different times and at different rates.
The angled stacks are not 'new' to Wardale and Girdlestone; N&W famously used them in a considerable range of power, although offhand I can only remember Porta using one purely to increase the effective accelerating entrainment length in the front end purely for loading-gage reasons (the others usually being to clear parts of the feedwater heater, as with the Australian Hudsons) Note that American use of stack extensions, particularly on ATSF, accomplishes the 'same thing' where loading gage permits.
Fascinating in a way that I get all the way here without mentioning the Franklin System at all, let alone the flavors of RC actuation. Note that one of the issues with OC Franklin, as with Lentz/Lenz before it, involved a certain amount of scam. The premise was that radial valve gear could be used to drive the System's poppet valves just like piston valves, with shorter cutoff producing different mass flow to the cylinders but with timing precision. The problem is that with poppet valves, opening them incompletely or slowly doesn't produce good effects; a poppet valve needs to lift cleanly and return sharply without bounce or float, and no SHM valve gear provides this unless the actuating cams are cut with steep profile (in which the necessary modified-trapezoid cam profile is difficult to achieve) and this in turn introduces nightmare-box complexity into the drive mechanism to work.
Meanwhile the RC system can only approximate the continuous cutoff control of Walschaerts or Baker if it uses a continuous-contour cam (which uses spherical followers) and in more sophisticated variants variable actuation or 'variable geometry' on the cam-follower linkage. To my knowledge no system of fixed cams was particularly successful in practice, and the best of the 'workarounds' was an almost-appalling-to-purists dodge (actually patented!) which used 'wiredrawing' intentionally to give "cutoff" effect with increasing speed ... this was fine for War Department 2-8-0s that could be driven by inexperienced soldiers, but not so good for railroads concerned with best efficiency...
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