# 421
In reference to #418: The PRR tested several locomotive designs prior to the opening of Penn Station and the DD-1 showed significantly lower impact forces than the other designs. Reasons given for this were the asymmetric wheel arrangement and high center of gravity. The DD1 wasn't that early of a design as it was contemporary with the BA&P locomotives. While the ca mounting of the motor was unusual, it did allow for less compromise in the proportioning of the motor than with nose suspended motors.
One reason that this isn't completely off-topic is that the PRR testing showed high center of gravity can be a good thing in locomotive design.
- Erik
# 422
In order to get this thread back to the original topic, while browsing Will Davis' blog, I came across this. Since Juniatha mentioned a possible Alco 2-12-6, I found this interesting. Perhaps Will Davis will explain more?
# 423
I read the Will Davis blog, it's interesting to say the least. Mention was made of clearances, very wise since the line drawing reminds me of a pregnant sperm whale! What I'd be concerned with is track curvatures, it would seem to me a 2-12-6 wheel arrangement would be very limited as to where it could go.
Remember there were places, quite a few, where the UP's 4-12-2's couldn't go.
# 424
Hi folks
I had seen a sketch of this locomotive before , unfortunately it did not show anything about this special cylinder / frame connection or the rods arrangement ; what it did show was this awkward position of cylinders overhanging the front end and the rudimentary pony truck , a drawback to times long since gone by when - much-much smaller engines ! - had shown inadequate tracking because of insufficient guiding of the leading axle . Further , drive to the second of six axles must inevitably cause larger than necessary forces in intermediate coupling rods , an hitherto unseen extended sequence of coupling rods causing increased wear and summation of bearing play , increased chance for misalignment of axle and rods gauges .. and more .
I should add as to the story I had read , this had been a proposal for C&O when they had asked for an engine above their 2-10-4 ; the proposal was rejected and in the following design was changed into the known Allegheny SE Mallet type . All in all a single twelve coupled with but two large cylinders certainly would not have been an edifying design and a double six coupled engine having four cylinders was the right choice back then .
In my view a twelve coupled engine would have been practical - yet *only* in combination with a three cylinder layout , further developed from the level attained with UP Nines where namely the inside drive arrangement was not fully up to demands and conjugated Gresley gear caused high forces in outside Walschaerts and with play - the usual dirt abrasion theme which so plagued steam - produced awful valve events in middle cylinder .
Increasing cylinder volume was one thing - what mattered was piston force and longest possible stroke in relation to wheel diameter to produce maximum torque at wheel rim . In that respect the ATSF 5000 class Baldwin 2-10-4 did already exploit then technical limit pretty closely - and did so with a balanced center drive , too .
All in all this 2-12-6 proposal was aiming at an awkward design , with all signs of compromised 'tongue in cheek' or 'last resort' solutions where it intended to reach beyond established size and capacity of Berkshires and Texas types . As the known 4-8-6 this is another hint Lima steam design was virtually void of ideas for possible steam answers to the diesel challenge . To me this sadly feels like a subsequent justification for starting dieselization when it did .
Regards
Juniatha
( edited by inserting some extra remarks )
# 425
1. Did the UP 9000's, their 4-12-2's last until the end of UP steam? (The Challengers did, I believe.)
2, If the 9000's had been completely successful, would the Challengers and Big Boys have been built?
# *426*
Dave -
1. - yes , pretty much so ; it was understood elder engines were withdrawn earlier than later power of the same capacity , yet the Nines had longer working life than many other engines , namely the BigBoys . If so , you might conclude they had been more successful as they accumulated more miles in longer service life - yet that would be misleading since life span of BigBoys was largely determined by advancing dieselization .
2. - you cannot conclude on degree of UP Nines' success by the fact BigBoys were built , nor UP switched to SE Mallet instead of straight frame three cylinder power . An engine concept incorporating four outside cylinders was potentially offering a wider scope for development of power than a straight three cylinder type . However , more aspects played their obvious or obscure roles in making decisions . I already hinted the Nines had been quite successful - especially in view of gross neglect and still remaining in service for years on end - however they had not been as complete a success as they could have been without ailings namely of Gresley conjugated gear , built-up framework ( only the last batch had cast steel engine beds ) and various other minor flaws . To be fair , this class of locomotives had been sort of an 'intermediate' as development went from conventional power of the times up to the 1920s to later high performance power . You can see more evidence of progress advancing by design changes incorporated in series of Challengers as they continued to be built . BigBoy on the other hand clearly was a loco class of larger power capacity than the Nines - early Challies were not , as I had asked for discussion in my earlier thread about the Nines / Challengers .
And yes , even if the Nines had been *completely* successful time would have passed them by and larger locos would have been built - and would have been built as SE Mallets , simply since a single frame type extended into a 4-16-4 would have been impossible .
And , please mind we want to have each post numbered here - thank you for doing it all by yourself .
# "427"
Did the 9's with cast steel beds stay in service longer than fabricared beds? Were any 9's with fabricated beds rebult with cast steel? When was the very last major steam locomotive in North America built with a fabricated engine bed? (Approximately if no one has the exact answer)
# 428
Trying to answer your questions Dave :
1. No , I think not ; afaik Union Pacific joined the bandwagon with other railways never to care much about sorting out individual engines of earlier batches and seeing to keep the last / best ones of a class . For one reason , decisions on keeping / ending service of steam locomotives often were based on local service or district line running , that is : engines of one class could be laid aside at one engine facility while others of the same class continued at another shed handling traction on another line . Since engine swopping between sheds had always been a never ending activity , hardly one shed could assemble a group consisting but of one best suitable / latest built batch - regardless of any progress realized when building these various batches . For instance , on DB the last shed maintaining 01 class Pacifics - Hof , Franken , near the former border to the Eastern Block - never had a roster consisting but of reboilered 01 , neither had they rejected reboilered engines to keep but the original ( Wagner- ) 01 - each which way would have had its pro and contra part / part since imho DB Witte reboilering of 50 engines 01 class should be considered but partly successful , having shown drawbacks of its own . DR was more to the point by concentrating their last Wagner-01 engines in Dresden-Altstadt while sheds of Erfurt , Magdeburg and Berlin-East had but 01.5 engines , i e 01 rebuilt with high capacity boilers . Ironically , during the very final years last survivors of both variations of 01 engines were re-united at Saalfeld shed - a typical expression of late hour steam traction when hitherto valued advances in performance or maintenance upkeep had become meaningless since the remaining engines were handling but easy enough services without having to be fully extended .
Same with last of UP steam .
2. Not that I have read about it and again it would be just typical of railroads : if at all they cared for batch-to-batch improvements as did the UP , they hardly ever went as far as rebuilding earlier engines to later standards - again DR rebuilt *some* of their earlier 01 engines with larger front bogie wheels and double action brakes on drive wheels both introduced with later batches , *naturally* not all of them .
So not having rebuilt earlier engines to later standards did not indicate degree of success of design changes .
3. Quite simple : dunno ( and , frankly , I don't care )
#429
The first thing I noticed when looking at this locomotive was that there would need to be quite a bit of play in the driving axles to let it negotiate any type of curve. Maybe even swiveling them like the first driver set of a SE Mallet and having a rigid front truck?
# 430
quote # 429
>> Maybe even swiveling them like the first driver set of a SE Mallet and having a rigid front truck? <<
Oooopset ?
How's **that** supposed to be ?
Puzzled ragazza
Juniazza
No , really I don't see why major well-proven set-ups would have to be up-set only because there is another drive axle introduced . 2-12-4 types - if as tank engine , yet that doesn't make a difference as concerns length of coupled wheel base and overall w/b - worked in Bulgaria and did so on mountain division abounding with sharp curves : *they* didn't need to carry their leading truck 'swallowed' - see description and small picture at
http://www.thefullwiki.org/2-12-4
All you needed was ..
flexibility !
More lateral displacement loaded by well balanced centering forces and according rods & pin arrangements ...
#431
I was thinking...Mason Bogie...yet improved...but apparently not.
But yes, having flangeless drivers and lots of flexibility is needed.
Thanks for the tank link.. been studying the Harz 2-10-2s, and their special driver play. Applicable here?
# "432"
The two Bulgarian 2-12-4T's: "Preserved." Preserved in operating condition? Used occasionally?
# 432
NorthWest
Design of lateral motion has to be specially adapted to w/a - yet the idea is pretty much the same as in the Harz 2-10-2 negotiating 50 m radius curves !
With a mainline 2-12-4 no flangeless drive wheel set should be necessary , UP found that out in their Nines .
BDZ 46 class preserved in running order or cold ?
Dunno - I guess preserved engines vary between warm and cold from time to time - not only but also in Bulgaria.
= J =
#434
Sorry for my rather disjointed post above, I was in a hurry.
No flangeless drivers? I guess so, but it depends on the route. UP's 9000s lived on relatively straight (for mountains) track.
#435
daveklepperThe two Bulgarian 2-12-4T's: "Preserved." Preserved in operating condition? Used occasionally?
According to Rob Dickinson, they are in the strategic reserve at Asenovo, not operating but under cover.
The leading axle on Woodard's 2-12-6 is positioned where it is to shorten the wheelbase to permit shorter turntables. I wish Mr. Davis would post the whole text of Woodard's presentation, as it makes many things clear that are not well recognized from just looking at the plan and elevation.
This design comes at a very interesting time in design history, when the 'correct' design paradigms for large high-efficiency locomotives were not as well recognized as they were even by 1931, or even the practice of the AMC in its Berkshire and Texas designs. Lima itself would come to find that driving on the third axle, with longer stroke, would be a preferable approach to the 'unitary machinery support' approach with large cylinders set close together ... and I think it pays to consider why.
One amusing note is that the proposed locomotive retains the articulated trailing truck, which might explain some of why Woodard drives with high angularity on the second coupled axle -- the first Berkshires with this truck were notorious for bad riding, as the articulated design did not correct nosing nearly as well as the later "bissel" Delta trailers would. This behavior would have been well recognized by 1928, and here we see Woodard either calculating or assuming that the nosing moments would be so reduced as to make the much greater piston thrust ... and lower resistance to nosing moment given by the 'inside' lead truck ... not pose a major issue.
Interesting to note that essentially the entire history of high-speed articulated locomotives lay years in advance at that time, so the superiority of a "SE Mallet" with an effective version of divided-drive was not obvious. (Of course, almost the same thing can be said about Lionel Wiener's book -- look at how many high-speed simple articulateds existed at that time.)
I am still tinkering with how you construct the equivalent of an Eckhardt bogie at the rear of a 12-coupled chassis -- and what kind of lateral you need in the trailing-truck axles to get the result to guide correctly... Oddly enough, I think Stroudley already figured out the optimal way to thin the flanges and profile the tread on the middle drivers. It's at least a well-thought-out start...
# 436
I hope I get to see one of the 2-12-4T's some day. Sort of the European equivalent of the USA Big Boy or Alleghainy
# 437
Dave ,
Uah-well , you'd be slightly disappointed , I presume , if you went there with expectations as big as that ( but then again USAir might ask you to pay for extra luggage when you want to board with *that* huge a cloud of imagination looming about you - *gg*
It was a tank engine on second glimpse featuring a somewhat astounding number of powered wheels in a row - but then again not *so* astonishing that it would make you dizzy or only look twice . On the contrary , it gets pretty normal looking in a short time . How do I know ? I haven't seen one in reality but I have enough photos of them and in relation with photos of the various Decapods that were roaming the Bulgarian Railways and so closing eyes I can just imagine .. and there they are - somewhat longer than a T20 DR 2-10-2 ramp tank engine , somewhat less well proportioned , always the question which one to prefer : the two cylinder version with inside frame rear bogie - the outside frame bogie three cylinder version ? the boiler full size of that of a Decapod - no they weren't without power and bulk of their own - and in this strange , remote landscape , in these very blackish steam sheds where green Decapods with red wheels stood off the general air of black soot and cinders ..
Only , what was the exhaust ? I don't know , except for I can guess it was pretty rough , although originally the type of draughting pretty much was that of the DR standard types of steam it had long since become 'bulgarized' considerably - all railways of the South East of Europe tended to sharpen draughting plus they tended to add strangely primitive nets on or in the chimney to fight spark throwing ...
http://www.youtube.com/watch?v=XyFZfx5y6mk
BDZ 05.01 spins wheels
http://www.youtube.com/watch?v=d97pJ2vdED4
ex DR 01 509 and 533 on June 11 2011 – soft sounding exhaust
http://www.youtube.com/watch?v=3eHVa6tzmx4
typical 01.5 sound when climbing – although still going pretty easy
http://www.youtube.com/watch?v=HqspH2u4qMM
05.01 three cylinder Bulgarian Pacific fresh from restoration in the snow
http://www.youtube.com/watch?v=HJ5xyYlR_7M
BDZ 52 class ex German Decapod , serviced in station
http://www.youtube.com/watch?v=OhprH2oXfFU
BDZ three cylinder 4-8-2 03.12 preserved engine : run by , serviced , another run by coasting whistling
http://www.youtube.com/watch?v=4dXTmMy9g6g
01.23 Mikado runs over viaduct in background – nice typical village setting
http://www.youtube.com/watch?v=XNgem6NwZCs
BDZ 16.01 ex German 42 class heavy austerity Decapod , preserved
http://www.youtube.com/watch?v=BwtoGwMFX1U
in cab of 03.12 three cylinder 4-8-2 while switching
Rgards
#438
I had forgotten how different the exhaust of a three-cylinder locomotive is from what we consider nromal. This reminded and presented some wonderful experiences.
# 439
The discussion of the PRR S1 on another thread makes me wonder, what about a duplex class for the SP&S? They had a pretty straight and flat line, and had big 4-8-4s. Also, they had extremely poor Cascades coal. So, what about a 4-4-4-6? Or would a 4-8-6 be better?
# **440**
makes sense to me, dual service too.
# 441
If you have 'extremely poor coal' - then an x-x-6 type of w/a might have made sense - there was a discussion about the Lima 4-8-6 offered as an 'answer' ( or not ) to the diesel invasion and I had posted my view it had presented an answer to a question no one had really asked . However , for really poor coal .. problem with poor coal was it was actually unsuited for locomotives in many ways and presented all kinds of troubles , including lots of cinders and clinkers even increased corrosion in boilers for high sulphur contents , dependiong on its actual consitence .
Duplex or single drive set - that depends if you want a purely ( not poorly ) express engine or dual purpose . Since most US RR in the end never allowed any motive power to escape the dual torture service , a 4-8-6 would probably apply . If you want a flatland racer it's the Duplex you might prefer ..
#442
The SP&S went to oil-their late steam burned it, including their Challengers, which were copies of NP designs that burned coal. The Washington coal was just so poor. Since the SP&S' passenger trains were mostly just forwarded NP and GN trains, I think the 4-8-6 is more likely, even if the duplex is more fun! But it would have been fun to see blasting along the Columbia.
#443
How about a firebox design similar to what Mr. LaPorta used on those 750mm 2-10-2s in Argentina? They had a diet of poor grade coal which clinkered easily. His solution of a gas producer firebox setup with steam fed up through the grates resulted in practically eliminating clinkers and with 70% of the primary air for combustion coming in above the firebed, there was very little solid abrasive material carried through the flues and out the stack. Really neat, efficient, little hogs! So maybe SP&S could burn some of that local real estate without wearing out the boiler and burning up the countryside in one of those handsome 4-8-6s.
# 4-4-4 (*g*)
on # 442 and 443 :
Gas Producer Combustion System , he called it , GPCS . I’d think this would have made sense if it would have been available back then - I believe Porta only developed it in steps through the 1950s or even the sixties . It is not without its challenges - if you read Wardale's "Red Devil and other tales .." you get an impression although at points I feel you have to read somewhat between the lines to get the real McCoy . One thing , it seems to work best when a locomotive can settle down on a pretty constant pace for an extended time – which would have made it look good for freight train service on many of the long mainlines across the United States . The logics in his theory of reducing temperature of the fire bed to obtain fine , non-clogging ashes look good . I’m less happy with having air holes in firebox walls and obstructing thermal expansion of the sheets . Some of what Porta allegedly has reported of upkeep of his fireboxes tends towards the ‘story-like’ – without having seen hard evidence of maintenance and ton-miles service sheets I’m not fully convinced .
One point is GPCS would ask for a larger firebox volume and grate surface – a case for that six-wheel Delta truck .
However – with all that upheaval why not go for ten coupled , making it a 4-10-6 ? There you have tolerably all the guts you want to ask of an American Super Power steam locomotive !
Chooooo-wah !
#445
JuniathaHowever – with all that upheaval why not go for ten coupled , making it a 4-10-6 ?
I mentioned a SP&S 2-10-6 much earlier in this thread, but a 4-10-6 makes more sense, especially for dual service. Maybe also a Dominator 4-6-6-6?
GPSC sounds interesting, I'll have to do some research!
# 4-4-6 - *g*
>> # 445 : >>Maybe also a Dominator 4-6-6-6?<<
Oh , that would be another story .. how to get a 2 x 6 coupled Duplex through curves .
It could be done yet it would take some scrutinizing design effort to go into a well balanced arrangement of
lateral displacement , centering forces and springing characteristics .
#447
The 4-6-6-6 would be an articulated, an expansion of SP&S' Challengers. Looking at satellite photos, a 2X6 Duplex wouldn't like the curves on this line....
#448
Juniatha,
A kind of late reply to #4-4-4 (Baltic?).
I dug up some figures on Porta's 2-10-2s from an online article;
Superheater elements, no replacements after 310686 miles of service.
10% of the tubes were replaced during the first 248548 miles of service, all failures were attributed to longitudinal cracks caused by overexpansion during initial assembly.
No boiler shell or firebox sheet repairs during the first 12 years of service.
These engines averaged 7456 miles per month, average train was in the 1500-1700 ton range. And, yes I believe you are right in saying the GPSC was developed gradually through the 1950's.
So, maybe if we invent a steam powered time machine..............
# 449
A steam-powered time machine? The "steampunks" are working on it. Let's give 'em some time and see how it works out.
#450
And if I had a steam powered time machine, I would go back to post #448 and replace "Baltic" with "Jubilee" or "Reading"!
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