Before any other comment is necessary – do you have a stray 26MB storage available and a good monitor or printer?
Download this from Google Books (PDF format).. It will answer just about any question you might immediately have.
There are some other references, like Condit’s book in 1977, but they’re not so easily and cheaply accessed.
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.
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?
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 cl
2, If the 9000’s had been completely successful, would the Challengers and Big Boys have been built?
# 426
Dave -
And yes , even if the Nines had been completely successful time would have passed them by and larger locos would have
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 :
Same with last of UP steam .
#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
#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?
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
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
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
#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.