# 388
( B-t-w : Could we agree on each poster putting his number to his post all by himself ? .. and quote number of post your reply refers to )
As for the G5 ( five , to be sure ) , in my view this was a versatile engine for the purpose it was built for and for sure as economic as a smaller one since with the boiler working at moderate combustion rate lbs per sqft hour combustion efficiency and heat transfer efficiency is higher than at higher specific output of a smaller boiler to achieve the same hourly evaporation . ' A small train needs a small engine of small output ' was an old misconception that prevailed thougout the steam age for fear of burning excessive amount of coal - note , the same railroads that scorned thermodynamic efficiency claiming it was't worth the effort to save a few lbs of coal per hour , they shrinked of using powerful engines beause they might use a few more lbs of coal per hour , completely forgetting about the extra power offered and enabling more attractive schedules to be put up for these trains ... funny .
Regards
= J =
# 387
Remember that the Pennsy was big on extra-heavy rail. Presumably, when they went to 152 lb rail on the main lines, they had plenty of 110-132 to recycle on branch lines, and did so. And they did keep D-16's running through WWII and after. But many of their branches did have rail heavy enough for the G5 (pardon my memory slipto G6. Must have been thinkiing of the obiquitous B6 0-6-0 switcher. When the K-4 and E-6 were modern, the G-5 was also modern.
# 386
Overmod
I must agree with you on your analyses of the G5s. They were ideal for the service as a heavy commuter engine in the greater Pittsburgh area, but the entire fleet could not be utilized there. As a former South Jerseyan (ite?) it struck me as a misapplication to use them on the Atlantic District on short trains easily handled by light Atlantics and D16sb's. How much the PRR had to spend to upgrade the Atlantic district as well as other lightly used lines to accommodate G5s is interesting to ponder. Also got to wonder how much fuel was wasted using big power on small trains.
Perhaps Pennsy was figuring on enough growth to justify the big engines. I'm guessing by the early 1930's, the G5s and the last 100 K4s were starting to look like poor investments
That's not to say I won't be ecstatic to see a G5s back in steam!
# 385
Dave, do you have information on the G6? I don't know anything about it.
If you meant the G5 (as now being restored at Strasburg) -- in my opinion it's about the antithesis of a practical branchline engine -- heavy weight, big boiler, HIGH center of gravity, optimized for things like commuter service on main lines, not for operation on light or poorly-maintained track.... but that is just an opinion, and quite possibly an unjustified one...
There are some examples of rebuilding older power in the States, but I think most of them owe far more to tax law concerns than to a serious desire to improve performance of older power. As was noted, it was economical up to the Depression to use older road power for many secondary services, and during the Depression itself there was precious little available capital for things producing smaller revenue. Add to this the adoption of gas and diesel power for many jobs the 'improved' locomotives would do, well, not quite better enough for the money spent...
One of Dilworth's design considerations in the early years of EMD locomotives was to produce units of a size that would work easily on many branch lines, and combine those into locomotives of large road power. I suspect it would not be difficult to count the number of branch lines where single MUable units could not go (and those were often served by such light, ancient locomotives that practical 'thermodynamic' or mechanical improvement wouldn't be net cost-effective).
On the other hand, in Britain and Europe a great deal of very practical work was done. Chapelon provides many examples in La Locomotive a Vapeur, to mention just one source.
# 384
The Boston and Maine was a major railroad is using older power for branch lines and commuter service. I would guess that during WWII, during which they bought some 4-6-2's second-hand from the DL&W, fairly modern ones, the largest class of locomotives was the Mogul, 2-6-0. But of course they shopped these acient devices, replacing Stvenson wtih Walshearts, slide valves with piston valves, adding superheating in some cases, etc. Some lasted until the end of steam. Did not other railroads also rebuild older power for greater efficiency?
The PRR G6 4-6-0 was designed as a modern branchline locomotive.
# 383
The upgrading of secondary lines and sidings is more often because of the need to support heavier freight cars. There has been much discussion over the need to be able to handle 315,000 LB freight cars, especially on granger branch lines.
# 382
NW
Yes, think fuel economy is a big factor. Feedwater heaters definitely increase the efficiency of the boiler and therefore should decrease fuel consumption. Increasing the boiler pressure should also make for a more efficient engine, as well as an increase of superheat (not as a result of increased pressure), though I understand if the superheat is to high, 1940's cylinder lubrication doesn't hold up. Increased boiler pressure should translate into smaller cylinder diameter to produce similar tractive effort while consuming less steam. Roller bearings should help, some. But I think they would have a greater impact on maintenance costs.
Assigning right sized, modern, efficient power to appropriate service would have to be better than dumping oversized, downgraded, well worn large locomotives into secondary service. It's always amazed me what pains railroads will go to, upgrading secondary lines and sidings to accommodate larger power, rather than upgrading their small engine fleets. They still do it!
#381
Going back to my apparent fascination with odd SE Mallets, any thoughts on a 2-8-10-2?
(I'm not sure why I like different driver numbers. But it seems more plausible than a double 10.)
This was posted a while back, and I think we should return to it. Big steam isn't everything.
rfpjohn #369 I really think that the railroads would have had to address the problem of branchline/mainline local power. Pretty much everything being used in such service, post WW2, was at least 25 years old and quite worn out. Locomotives built from the mid 20's on for mainline service were too big for secondary use. The Reading's G3 Pacifics and the rebuilt G1sb and G2s come to mind as a positive step in this direction. The Canadian Pacific also built some neat Pacifics during the late 40's, but other than being new, I don't think the Canadian engines incorporated anything not seen 30 years previous. I like the idea of modernized, mid sized Pacifics and Mikados. Such power would incorporate cast steel frames, welded boilers, improved draft arrangements, feedwater heaters (too many mid size US engines lacked them) and roller bearings on all axles. I believe piston valves would be a natural choice. Poppets just didn't seem to hold up under US style maintenance cycles and I'm guessing that when used in service, not demanding peak output, Poppets don't really improve performance/economy that much. We've already kicked around yard power. (Pun just noticed) From the discussions, I'm sold on conventional rod power for the yard. I think that improvements would have to be in boiler efficiency and attention to steam flow. Hope this is close enough to topic. I'm just kind of a small engine guy! John
#369
I really think that the railroads would have had to address the problem of branchline/mainline local power. Pretty much everything being used in such service, post WW2, was at least 25 years old and quite worn out. Locomotives built from the mid 20's on for mainline service were too big for secondary use.
The Reading's G3 Pacifics and the rebuilt G1sb and G2s come to mind as a positive step in this direction. The Canadian Pacific also built some neat Pacifics during the late 40's, but other than being new, I don't think the Canadian engines incorporated anything not seen 30 years previous.
I like the idea of modernized, mid sized Pacifics and Mikados. Such power would incorporate cast steel frames, welded boilers, improved draft arrangements, feedwater heaters (too many mid size US engines lacked them) and roller bearings on all axles. I believe piston valves would be a natural choice. Poppets just didn't seem to hold up under US style maintenance cycles and I'm guessing that when used in service, not demanding peak output, Poppets don't really improve performance/economy that much.
We've already kicked around yard power. (Pun just noticed) From the discussions, I'm sold on conventional rod power for the yard. I think that improvements would have to be in boiler efficiency and attention to steam flow.
Hope this is close enough to topic. I'm just kind of a small engine guy!
John
I think that fuel economy would also be a big factor-any thoughts?
# 380
Hi NorthWest
Body overhang in curves : no greater than in a regular 2-6-6-2 , say . Mind the main frame unit is the *center* one - point is to have radially displacing units both ends to universally run forwards / backwards at same quality of vehicle guiding . ( I would ***not*** suggest to 'mallet-link' another unit in front of the already 'malleting' unit ) So , in UIC formula it would be a tank (1'C) C (C 4') where the members in brackets are the slewing or swivelling units ( UIC counts axles rather than wheels ) . Mind , with two swivelling units - one at each end - you would have to really take care about tuning centering forces and preferably would have to add a lateral dampening , too - something which was used in steam but in rudimentary form by surface friction - not a very reliable and finely adjustable way of having lateral displacement dampened .
Juniatha
#379
Juniatha,
Dominator and Super Boy?
Hello everyone,
Sorry for that confusion, I should have explained in my first post the intended goal. Yes, if there were more than 50 made, I would be surprised. The tank engine concept is a good one, interesting that they made the 12-coupled work.
A quick question about this:
JuniathaA double ender derivate of the Mallet principle might – among many possible configurations - have been realized as a 2‑6‑6‑6‑8 or 2‑8-8‑8‑6 .
How much body overhang on curves do you think?
Oh, and Juniatha, I think your post counts are slipping backwards...I think I am back at one again...
# 378
Prof Overmod did strike again
.. and completed what I had left wanting in my easiness ( meticulousness other cases notwithstanding ) - nice illustration and about the ‘dropped Schwartzkopff’ ( sic , spelling correct with 'tz' and 'ff' and they used an according facial side portrait , too ) I simply tend to abbreviate things , you know that by now .
NorthWest ,
your suggestions should have been logical developments from Chally and BB - at least for that second w/a the 4‑8‑8‑6 one name would present itself : the ( even ) BiggerBoy , or simply : BigBoss ( sorry , my being witty again ) Now if a 4-6-6-4 was a Challenger then a 4‑6‑6‑6 might have been called a Winner ? At least within the range of steam power competition .
In view of the above mentioned combination trucks of Helmholtz and Eckhardt , a Helmholtz truck could replace the conventional front bogie , especially since already it was a point to put enough mass on front engine unit in any concept Mallet locomotive . That way , I come back on my preference of having two identical sets with interchangeable drive parts all over .
2-10-10-2 or -4 : As a specialized ramp pusher power a double ten coupled might have made sense , only my recognition prefers to keep it to double eight coupled for overall length and balance of power boiler to cylinders .
What has not yet been considered in this context are tank engines : if the distance to travel in a pushing stint was short enough , a tank engine could do – yet one of formidable proportions never realized so far . The biggest of tank engines in Europe had been the Hanomag / Schwartzkopff built 2-12-4 two / three cylinder tank engines of the BDŽ ( Bulgarian State Rys ) . A double ender derivate of the Mallet principle might – among many possible configurations - have been realized as a 2‑6‑6‑6‑8 or 2‑8-8‑8‑6 . ( why did I change the rear bogie ? do you really want to know ? *g* well , what’s your idea about it ? ) Of course you might comment : then , why not a tank 2-10-10-6 ? not impossible at all – yet lacking when in reverse , that slewing action of the then leading unit that allows for soft curve entering with low lateral flange forces for turning the locomotive mass .
Sure , the Garratt fans would then exclaim : now wait a minute , that’s the case for the Garratt with each a Mallet config power bogie , such as a [2-6-8-2]_____[2-8-6-2] or other oddities . However , if for no other reason it would have been turned down for being too far off the mark in development of steam in America .
#377
JuniathaWhile an Eckhardt bogie might have been applied comprising leading and first and second coupled axles , to provide for more than a minimum of lateral displacement in coupled axles behind con rods always had to be seen as a compromise between engine curve passing flexibility and a desire to keep lateral distance between cylinders to a minimum - i.e. have con rods as close to wheels as possible
General audience: don't miss the importance of this point in Northwest's original context.
Most North Americans are likely to be unfamiliar with what is more commonly referred to as a 'Schwartzkopff-Eckhardt' bogie -- Juniatha is referring to it just by its inventor's name*.
Here is a diagram of the arrangement:
It might be thought of as a refinement of the Krauss-Helmholtz, with a Beugniot-lever arrangement to move two driver pairs rather than just one. I see no reason why this could not be adapted to a locomotive with roller bearings in cannon boxes.
To repeat, with slightly different emphasis, the point Juniatha made: to provide the necessary lateral outside clearance for this arrangement to work, the rods have to be spaced away from the faces of the drivers further than would be required merely for American-style lateral motion devices. That means that the moments causing hammer blow will be magnified, just as they are in a conventional locomotive which carries its rods further away from locomotive centerline.
I have not done the calculations for the actual increased magnitude of hammer-blow forces for a 50"-drivered locomotive running no faster than Northwest was originally proposing for his locomotive, but with the rotating and reciprocating masses minimized via modern construction. It would also be interesting to see if the advantages from the S-E bogie would outweigh its additional capital and maintenance costs.
* (Before anyone starts bringing up nomenclature again, this is no different from calling a "Beyer-Garratt" just a Garratt, Schwartzkopff being the locomotive builder's name associated with using Eckhardt's bogie design. However, to be consistent, we'd then have to refer to what in the USA is commonly recognized as a 'Krauss-Helmholtz' bogie as just 'Helmholtz' as a similar situation is involved there. My own opinion is that when a company does extensive work on the detail or implementation of a design idea, they are entitled to 'co-billing' in the name, but I have no idea whether Schwartzkopff is entitled to that kind of credit (or Krauss, for that matter..._. Juniatha knows far more than I do about the history involved with this, probably both with respect to Krauss and Helmholtz and to Schwartzkopff and Eckhardt, so I do not argue with her choice.)
#376
All right, so general consensus is a 2-10-10-2 remake probably isn't a good idea. And a 2 axle rear truck suits no purpose but making curves even harder. My thoughts for it would be a >15MPH machine, being used exclusively for helper service/heavy drag freights (coal), like the VGN used theirs. Have a smaller engine on the front, and a double ten on the back...sort of like DPU power, increase the unit train size, but keep draft gear and coupler forces acceptable by putting more power on the back... Yes, it would be a very specialized machine.
Okay, scratch that...
But, what are your thoughts on the 4-6-6-6, and 4-8-8-6?
P.S. Juniatha, thanks for that link!
# 375
Coming back on Karen Parker's pixel magic , I just saw some interesting illustrations of the - mentioned before - Lima 4-8-6 , Ohio type as by Karen , and a suggestion for a 2-10-6 again all based on the universally adaptable Allegheny type . The 2-10-6 would be quite interesting as for boiler proportions - yet would be a borderline case as concerns vehicle and axles lateral / radial displacement arrangements . While an Eckhardt bogie might have been applied comprising leading and first and second coupled axles , to provide for more than a minimum of lateral displacement in coupled axles behind con rods always had to be seen as a compromise between engine curve passing flexibility and a desire to keep lateral distance between cylinders to a minimum - i.e. have con rods as close to wheels as possible .
See : http://www.karenparker.net/PixelMagic/pm_cnoj4.htm
# 374
2-10-10-2 or 2-10-10-4 wouldn't make such a big difference since in both cases firebox would have had to extend over rear drivers ; longitudinal development of boiler would have been the problem and with given classic boiler concept as used in big SE Mallets such as BigBoy or Allegheny further increase of steaming capacity would have come to a limit , thus again limiting power output development of larger than 2 x 8 coupled w/a ; improving ssc ( specific steam consumption ) would have offered a not too small margin for higher outputs - yet again this would have applied more to upper speed ranges than to starting effort .
Same goes for a pixel magic suggestion by Karen Parker for a 2-6-6-6-6 she derived from the Lima Allegheny type .
Btw - there also is a pixel magic picture of a '2-8-8-6' derived from the Allegheny , so you can see what enormous development in length boilers would have needed to take to make full use of such large w/a - this would not have been without some substantial rethinking . In my own draft of a 2-8-8-6 I have applied my own type of tubes and boiler drum arrangement to enlarge boiler sufficiently .
Using very small drivers would have been a question of designing a sturdy enough drive with shorter stroke and smaller big end of con rod - certainly not promoting roller bearings , still challenging with plain bearings - should not have been impossible back than , yet certainly asking for high quality design and best quality high tensile steels to be used , maybe having to go for a completely revised method of building main wheel set with its axle , wheels and pins ..
#373
Adding to my giant locomotives post above, I'm wondering if we would see a return of the 2-10-10-2?
Or maybe even a 2-10-10-4? Maybe around Big Boy boiler size, but with 50" drivers. For really heavy drag service...
#372
(Originally posted yesterday on this topic at some length; that post seems to have disappeared, or been removed somehow...)
JuniathaWould you mind to explain why you should have to lift the *boiler* ?? ... how could you *not* access the rear cylinder of cast engine bed Q1 and for instance take off the cylinder head and pull the piston without having to lift the boiler .? Ok , you might have had to pull it to the cross head side and that will have involved more dismantling work than usual , the firebox foundation ring was placed inwards close yet above the rearward facing cylinders and what may have come in the way was the Delta truck , yet again it looks like there was space enough to take off the rearward facing cylinder head to access the cylinder [etc.]
You are absolutely right. I can't even plead 'thinking of the George Emerson 4-4-4-4' -- that one didn't have firebox/cylinder interference, either... strange how you can look at something so many years and not see key details.
To replace the 'missing' Q1 picture: here is one (I believe it is from the Jack Pearson collection, via Wikipedia):
This is at fairly high resolution (1111 x 471), so you should be able to zoom in on the rear cylinder area.
Also: Here is a view of the locomotive under construction; this is from Bill Burket's collection of Pennsylvania photos.
There is a good side view of the 6130 without shrouding in Staufer's original Pennsy Power (1962) on p.232. This is small, as printed, but has very good contrast; since it is an 'official' PRR picture, I suspect large versions exist.
Note by the way the position of the anti-vacuum valve for the rear cylinder, and the reasons why it might be 'up there'.
I tried to find a good 3/4 view from the rear, showing the potential interference between the trailing-truck frame and the rear cylinder head, with no success -- but it does look as if the cylinder was hung 'far enough' out to make it easy to pull either head without removing much more than some piping. Yes, it might be necessary to back the trailing truck off a bit ... but I rather suspect not...
Something I would like to see is the way the ashpan and chamber were arranged around the rear cylinder saddle assembly... the detail views I can find do not show this clearly.
BTW: the comments on the Meyer were left in inadvertently, as I originally misunderstood what was being discussed. Shows you the problems inherent in not scrolling to check before posting! (It was a bit too serious for 'conditions', wasn't it??? ;-} )
# 371
(answering # 370 ) - boiler lift needed to access rear cylinders ?
Hi Overmod
Would you mind to explain why you should have to lift the *boiler* ?? if the pictures of PRR Q1 6130 show up : how could you *not* access the rear cylinder of cast engine bed Q1 and for instance take off the cylinder head and pull the piston without having to lift the boiler .? Ok , you might have had to pull it to the cross head side and that will have involved more dismantling work than usual , the firebox foundation ring was placed inwards close yet above the rearward facing cylinders and what may have come in the way was the Delta truck , yet again it looks like there was space enough to take off the rearward facing cylinder head to access the cylinder ; if it was possible to pull the piston towards the rear may have just been possible - since it was without tail rod as usual US practice - yet I wouldn't want to decide on that for sure ; in any case , it would still have been possible to pull piston to the cross head side , maybe demanding some further parts to be dismantled before , yet no difficulty ( quite in contrast to modern jet engines for example , well I guess these would have been clearly beyond average Crestline rapair shop work quality - *g* )
PRR Duplex Q1 6130 with cast steel engine bed new at Baldwin
Ok , the sail ship did show up , the dubious Duplex doesn't - I'll leave it to everyone to type PRR Q1 6130 into the google search mask and take a look at photos that show up for information on position and accessibility of rearward facing cylinders .
BTW : That turning of the Meyer bogie : my , that was just a joke – don’t be so implacably earnest , if *I* wouldn’t have taken certain of your words with good humor I would not answer anymore .
#370
My apologies for mistaking the point about cylinders forward -- I conflated the description of the Meyer at the beginning of #358 with some of the points made elsewhere in the thread, and did not pay enough attention to the rather pointed quote of the relevant line in #361.
Juniatha >> But I doubt the situation would be any more complicated than what was used on an Allegheny; .. << That would mean comparing grapes with watermelons ... (on an Allegheny , allegedly the second set of cylinders never was anywhere near the firebox throat plate , if I’m not totally mistaken)
>> But I doubt the situation would be any more complicated than what was used on an Allegheny; .. <<
That would mean comparing grapes with watermelons ... (on an Allegheny , allegedly the second set of cylinders never was anywhere near the firebox throat plate , if I’m not totally mistaken)
I was referring, of course, to the steampipe layout as used on the Allegheny, of which the Alco designers were (so rightly) proud. Still with the assumption that cylinders to which those pipes were directed were immediately adjacent to throat. I apologize if this was not adequately clear.
>> So there is little or no issue with accessing the 'front' cylinder heads, extracting pistons, etc. as there is when the rear cylinders are part of a cast bed. <<
?? why should 'that* be so ? ‘cause on the Meyer you could swing a cylinder out with the bogie and have it readily accessible on your work stand? well , in a model locomotive maybe the bogie can be spun 360 degrees around and around - *g* - yet , I would be taken by surprise if a real Meyer could come anywhere near *this* sort of Hatha Yoga for locomotives .
I think it would be preferable just to use a crane, or a jack, and lift the main frame clear of the bogie when you need to service the 'front' of the cylinder block on the bogie. The equivalent operation on the 'rear' cylinders with a cast bed would involve (among other things) disconnecting and lifting the boiler, a much more involved, and probably delicate, operation.
I spoze you could swing the bogie on the pivot, using some sort of combo drop table/turntable, but you'd almost certainly have to take some or all of the steam piping out, rather than just disconnecting joints, to rotate it 'far enough' to get full access to one side's cylinder block ... and then repeat the procedure 'the other way round' for the other side. Whereas lifting the frame lets you roll the bogie out, to where it can be lifted, swung, accessed easily, quickly replaced with a spare, etc.
john
#368
Hi Juniatha, yes, I will get back on topic...
On the UP, would we have seen a:
4-8-8-6 "Super Boy"?
or a
4-6-6-6 "Wasatch?
Or, a successor to the FEF (Four Eight Four), a
FTF 4-10-4?
Interesting ideas, indeed...
And would DMIR like Juniatha's 2-8-8-6?
Some deep thoughts...
#367
Hi Juniatha! Interesting you bring up the idea of the New York Central using duplexes. According to George Drury the NYC kicked around the idea of doing just that around the time the Niagaras were coming into service, but never pursued it.
And then it being lunch break time, they went back to kicking around a football.
Wayne
# 366
However , what this thread keeps missing are posts concerned with the topic : what types of - classic reciprocating ! - Super Power steam locomotives might have appeared on which RR had diesels not taken over the way and when they did .
Would PRR have sorted out the problems of the duplexi , would NYC had to have one , too ( and then what would the Alcohaulics at Schenectady have made of the concept ?) - would the N&W have shocked compound Mallet fans by deserting the concept and build a SE Mallet Y-7 ? What larger than an Allegheny could have been built at all ( I had offered a proposition of my own for that )
.. and so on .. that's what's been touched but left all too quickly here .
Failies and their more or less fairly assorted cylinders may fare fair enough - yet I believe they were not on the agenda when Union Pacific considered how to improve lifting 4000-plus tonnes over the Wasatch range .
So may I dare to propose if perhaps we could consider to think about contemplating to possibly take a look at
Steam we haven't seen ?
Hope is last to die .
# 365
( sorry I didn't want to bother anyone with even doubling my text , even if we talk doube ender locomotives and such - sorted it out , mea culpa !)
Buenos dias , profesor Overmod
>> Juniatha has already recognized that merely having the cylinders under the front end, while that's a good idea for shortest exhaust tract on a rigid-frame engine, is not necessarily good for an articulated <<
???
le ruego me perdone , mas :
If you quote me , would you kindly mind to quote me correctly ? I don't see where I should have written *that* ? On the contrary , I would *always* recommend to have cylinder blocks in front of their respective drive units - Mallet , SE Mallet or Duplexi - you may remember my voting for ideally *identical* drive sets in these engines .
It's a logical arrangement with the steam locomotive , especially when equipped with a tender , being principally forwards running oriented . It's different with special concepts *explicitly* designed for unidirectional running - such as the Meyer or all the geared bogie supported concepts ( Shay etc ) for smaller engines or Garratt for larger power on roads abounding with curves and tight curves , too , or tank engines having symmetrical w/a as they were used on pull / push commuter traffic in Europe .
Dealing with the - not too significant , not worth an extra wheel set anyways - extra driven wheel base spreading caused by intermediate position of cylinders of the second drive set would be another topic ; for this-here let me just summarize it's not a hindrance if you properly arrange for lateral displacement(s) and centering device(s) and their lateral thrust(s) .
That would mean comparing grapes with water melons .. ( on an Allegheny , allegedly the second set of cylinders never was anywhere near the firebox throat plate , if I’m not totally mistaken )
?? why should 'that* be so ? ‘cause on the Meyer you could swing a cylinder out with the bogie and have it readily accessible on your work stand ? well , in a model locomotive maybe the bogie can be spun 360 degrees around and around - *g* - yet , I would be taken by surprise if a real Meyer could come anywhere near *this* sort of Hatha Yoga for locomotives .
Bueno . Saludas , compañeros ,
# 364
# 361 >> Does this place the second set of cylinders beneath the firebox? <<
Jesus ! There are ways to avoid *that* , my goodness , I'm not as goofy as *that* , if you beg my pardon . Simply stretch or compress to suit .. uhm , boiler and / or frames I mean .
And [my] opinion on Fairlie locomotives?
O-M-G
sincerely
#363
Thanks Overmod, for clearing up my misconceptions.
Juniatha, your thoughts on Fairlies?
#362
NorthWest Does this place the second set of cylinders beneath the firebox? I believe doing that killed the PRR Q1 and B&O N-1, but I could be wrong.
Does this place the second set of cylinders beneath the firebox? I believe doing that killed the PRR Q1 and B&O N-1, but I could be wrong.
The situation is a bit different here, as the engine is modular, and can easily be taken out from under the boiler for maintenance. So there is little or no issue with accessing the 'front' cylinder heads, extracting pistons, etc. as there is when the rear cylinders are part of a cast bed. You would not want continuous blowdown near the cylinders, or utilize 'open' snifting or relief around the ashpan, etc., but those are detail design issues.
There is also no particular issue with the effective chassis length being increased by the rear cylinders, which is another issue common to opposed-cylinder duplexes (and the Withuhn conjugated duplex family).
Steamlines will be up close to the throat, which poses a problem if you want to do preheat, or FGR, or front-mounted oil firing, in that area. But I doubt the situation would be any more complicated than what was used on an Allegheny; there might be some restriction on boiler course size adjacent to the throat with restricted overhead loading gage, but I doubt this would be serious enough in most cases to condemn the idea. I'd presume all-welded firebox and boiler construction, so the need to get in there for inspection or maintenance would be minimal.
I think I like the cylinders facing the ends of the locomotive...like the first picture, only reversed.
When you do that, you greatly increase the length of the rear-engine steam lines, and also the return exhaust tracting. Juniatha has already recognized that merely having the cylinders under the front end, while that's a good idea for shortest exhaust tract on a rigid-frame engine, is not necessarily good for an articulated (where you already need to allow length for the flexible steam and exhaust tracting).
Personally, I don't care for Fairlies, but de gustibus aut bene, aut nihil...
#361
Hello,
JuniathaI would actually prefer cylinders of both bogies point forwards , that is : to smokebox end of locomotive .
I think I like the cylinders facing the ends of the locomotive...like the first picture, only reversed. Your thoughts?
And opinion on Fairlie locomotives?
Sincerely,
NorthWest
# 360
Hi RFP John
The Golwé looking good ? .... Upfhmm-ark .. [ swallow , breathe ] .. ok ..
What system to deliver steam to cylinders ?
Well , as far as I heard people talk , they usually had it beamed down and out by Scotty , no ? Seriously : much the same as in any articulated : flexible pipes - with a little more or less steam leaking , depending on maintenance , condition of driving . line curvature , steam pressure and your local weather report ...
Thank you for the illustrations. The Golwe' loco was more the picture in my head. You must admit, it's pretty cool looking! After digging into Mr. Wiener's book, I realized my concept was a bit off.
In the 0-4-4-0t Meyers, what sort of system do they employ to deliver steam to and exhaust from the cylinders?
#359 rfpjon
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