Union Pacific 4-10-4

[Paul Milenkovic]

Overmod

Russia sent a team over to study best American practice circa 1928, the right time for early Super-Power but a tad early for the better improvements to the idea.  The great fruit of that trip was the IS class 2-8-4, which was successful; I think the 4-14-4 would have worked fine on its intended service -- heavy trains on obligate light rail, ridiculously light rail by our standards.  What it would NOT do was traverse light track not nicely lined and surfaced... or any kind of diverging switch or yard trackage.  Alas! this includes most wye trackage to turn the engine around, including the reverse leg.

 

The Russian 4-14-4 was said to have a 33-foot "rigid" wheel base whereas I looked up that the Union Pacific 4-12-2 type "only" had 30-feet 8-inches?

I read, was it in Kratville and Bush, The Union Pacific Type, that those locomotives were restricted in where they could go.  There was something written about getting a retired Union Pacific type to California for display in a city park was a close thing getting it there?

The Russian locomotive used a combination of lateral motion on end drivers and blind drivers in the middle, so perhaps its wrecking the track was a combination of a badly designed equalizer rigging, badly constructed track, overenthusiasm for bragging rights and just bad decisions on where to operate it?

[Overmod]

Paul Milenkovic

The Russian locomotive used a combination of lateral motion on end drivers and blind drivers in the middle, so perhaps its wrecking the track was a combination of a badly designed equalizer rigging, badly constructed track, overenthusiasm for bragging rights and just bad decisions on where to operate it?

The Russian engineers were not idiots, although far too many would die as if they were; I think the design assumption for what was basically a massive mineral hauler was similar to Porta's at Dona Cristina: long trains on main lines at near-constant speed, with a maximum of adhesive weight.

That it would not negotiate track in yards could be predicted.  That it would not like anything but veeeeerrry long crossovers might be equally predictable.  What might not have been as clear was the need to turn engines with that rigid wheelbase on wyes (or loop tracks) to set up for loading and unloading.

The thing other than straightening switch trackwork would be rolling rail, and on much of the track at that period I'd expect even a 14-odd ton axle load to be oprimistic science fiction much of the time...

[7j43k]

Paul Milenkovic

A large part of the fascination with steam locomotives is the many design tradeoffs and how no single design is suited for all railroad services.

There are also numerous design rules that end up getting violated, too, making for more variation, along with arguments in the enthusiast community.

We a discussion on another thread as to whether a large-firebox 2-8-4 could be replaced by a 2-8-2 wheel arrangement by rigging the equalizers to redistribute weight? 

I presume the GN O-8 was included in the discussion.

Grate area  98.5 sq ft

Weight on lead axle 30340 lbs

Weight on drivers  325000 (4 x 81250) lbs

Weight on trailing axle 70200 lbs

Driver diameter  69"

T. P. at 83.5% Working Press.   75900 obs  (Working Pressure 250 lbs)

Wardale thought a 4-8-4 could be turned into a 4-8-2 by such a change to take weight from the trailing truck and transfer it to the drivers?

Another rule is that a 4-wheel leading truck is required for a locomotive in high-speed service.  Maybe a 2-wheel leading truck was never used in applications exceeding 80 MPH, but 2-wheel trucked locomotives have been used on passenger trains?

GN used 2-6-2's on passenger trains, along with a multitude of 4-6-0's.  The Prairies had a higher weight per driver axle than any of the Ten Wheelers.  Driver diameter was 69", while the 4-6-0's had a large range of diameters, with a max of 73".  I imagine the 2-6-2's would have been the better choice for slower speeds and frequent stops.

The LS&MS was very much into high speed.  And 2-6-2's.

Here's one pulling the 20th Century:

 

Grate area of their 2-6-2's exceeded that of their 4-6-0's.  And so did their maximum driver diameter--81" for the Prairies, 80" for the Ten Wheelers.  So they took them very seriously.  

And then came the Pacific.  

Overmod pointed out that a minimum weight needs to be placed on a lead truck to allow the amount of horizontal resistance needed to obtain stable guiding, but there are cases where the required boiler makes the locomotive so heavy that the non-driving carrying wheels are at the axle-load limit.  The 2-6-6-6 Allegheny comes to mind along with the Pennsy 6-8-6 S-1 and S-2 locomotives?

 

 

Yes, though my recollection is that the 2-6-6-6 suffered from "unfortunate weight gain" during the design/build process.  Possibly the other two did, also.

 

 

 

 

Ed

[daveklepper]

Liked this so much that I positively had to:

[Overmod]

The interesting thing is that the big Prairies actually seemed to work as high-speed locomotives on the LS&MS, although not elsewhere:  I am actually unable to tell what the actual truth was.

It gets worse in the wake of the problems with the Wilgus electrics, which were designed with the same general guiding principle and were branded as such a disaster after the initial runs that they had four-wheel trucks shoehorned in -- without consulting Wilgus who quit as a result.  'New York' then took over  motive power design, and sent orders to rebuild the Prairies as rather inferior Pacifics ... or so the story went.

I am pretty sure that a leading Bissel in that era was grossly incapable of the necessary high-speed accommodation if this engine were to encounter a critical augment resonance at the upper speed range it could most probably reach... in other respects it was a better engine for high speed than either an Atlantic in the same 'form factor' or a typical Pacific of its era.

[SD70Dude]

Overmod

The interesting thing is that the big Prairies actually seemed to work as high-speed locomotives on the LS&MS, although not elsewhere:  I am actually unable to tell what the actual truth was.

I'd wager that track quality had a lot to do with it.  

Think of all the British locomotives with 2-wheel leading trucks, or their road freight engines without lead trucks.

[charlie hebdo]

daveklepper

Liked this s much that iI positively had to:

 

Glad you did. The height of elegance! 

[Flintlock76]

SD70Dude

I'd wager that track quality had a lot to do with it.  

It did.

British railroads were built by industrialists who had plenty of money, and they didn't have to travel the distances American trains did, add in relatively cheap labor and they could build those tracks with superb quality.

The downside was, when the Americans started competing with the British for overseas markets the American locomotives handled less-than-perfect track than the British locomotives did, so the American builders started getting most of the business.  The Brits build darn near perfect locomotives, but they needed darn near perfect tracks to run on.

[charlie hebdo]

SD70Dude

 

 

Overmod

The interesting thing is that the big Prairies actually seemed to work as high-speed locomotives on the LS&MS, although not elsewhere:  I am actually unable to tell what the actual truth was.

 

 

 

I'd wager that track quality had a lot to do with it.  

Think of all the British locomotives with 2-wheel leading trucks, or their road freight engines without lead trucks.

 

I think the Burlington used 2-6-2s in commuter service at one time. 

[Overmod]

charlie hebdo

Glad you did. The height of elegance! 

In a way, it never did get any better.  Consider that the torch would be passed, further east, to something not quite as splendidly pared-to-the-bone greyhound lithe but just as carefully machined and driven for high speed.  Never mind that much of the rest of the railroad might be slowed to suit the best financial interest of the stockholders -- 'The Twentieth Century must go through! ... let her fly, and with such wings!

[charlie hebdo]

Flintlock76

 

 

SD70Dude

I'd wager that track quality had a lot to do with it.  

 

 

It did.

British railroads were built by industrialists who had plenty of money, and they didn't have to travel the distances American trains did, add in relatively cheap labor and they could build those tracks with superb quality.

The downside was, when the Americans started competing with the British for overseas markets the American locomotives handled less-than-perfect track than the British locomotives did, so the American builders started getting most of the business.  The Brits build darn near perfect locomotives, but they needed darn near perfect tracks to run on.

 

When most of the pre-grouping British mainlineswere constructed in the 19th C,  labor was probably cheaper here. There, an Act of Parliament was required to build a line and lines were built with quality to last more than a decade with lower grades,  broader curves and protected crossings. 

[Overmod]

charlie hebdo

There, an Act of Parliament was required to build a line and lines were built with quality to last more than a decade with lower grades,  broader curves and protected crossings.

But here, an act of the Legislature was just as required to build most early lines.  And the British built with expensive quality to last more tha a decade ... with durable stone blocks holding fishbelly rails, hundreds of parsimonious little tunnels, loading-gage restrictions and a constant dominance of right-of-way people over operating men.  So they were expensively locked into the 1830s forever.  At least we figured out how to get to house size incrementally, and could make use of the few broad-gauge properties that were built out... and, in time, we came to our own understanding of how to build railroads to 100mph or higher standards.

[Erik_Mag]

The point that James Vance made in his "The North American Railroad" was that conditions in the U.S demanded a very way of building railroads. One consequence of the nearly level British railroads was that British locomotive makers didn't have to design for high tractive effort, whereas once the US railroads figured out that a locomotive could pull a money making train up a practical grade, the emphasis turned to building to a much less expensive engineering standard.

As OM pointed out, the UK is stuck with 1830's loading gauge. Ironically, the canal system in the UK also has very tight loading gauges, with maxium beam between 6 and 7 feet, height above waterline maybe 7 feet. The height limit in canal tunnels was to allow boatmen to propel the boats by laying down on top of the boats and using their legs to push against the top of the tunnels.

[Overmod]

Erik_Mag

once the US railroads figured out that a locomotive could pull a money making train up a practical grade, the emphasis turned to building to a much less expensive engineering standard.

I don't think this was necessarily the case at all; the first engine to exploit practical adhesion on substantial grade was the Gowan and Marx, and the track that locomotive ran on was heavy enough to carry the many loaded cars it could pull.

The real take-home message about 'cheap' came with Stevens' "temporary track expedient" in 1827.  Up until then I think there was sort of the same idea as in England that good track was damn permanent -- heavy chunks of carefully-laid granite for piers, with stout fishbelly girders for rail between them.  Unsurprisingly both the ride and the line and surface of such a thing was ridiculous, and the expedient American alternative of longitudinal wooden girders with strap rail was not much better.  When Stevens used multiple 'sleeper' crossties to give a resilient ride, not requiring careful initial roadbed preparation and relatively easy to "keep" lined and surfaced, he was onto something we still use today; there are better fixed systems but they are very expensive both to build and maintain.

Keelboat 'modularity' was often remarked on in practice during the American canal era, to the extent that boats built to fit the canal 'gauge' could be knocked down for portage and reassembled, and taken apart for their lumber 'downriver' to solve the problem of how to make upriver trips before cost-effective steam was possible at other than steamboat-line size.

The real thing that was missed right at the beginning of railways was the Rainhill condition that all locomotives 'consume their own smoke'.  Had this been made a rigid condition ... perhaps even to the requirement to sequester any visible or olfactory product of the locomotive, as at least one science-fiction alternate-history story has suggested ... we might have had an impetus to clean coal, both on the railroads and in parallel on steam road carriages, and the history of power transportation including optimized alternatives to steam might have been interestingly different...

[SHKarlson]

Trainman2941

From what I understand, Russia built a 4-12-4, when they still had steam.

Soviets conceived of 2-14-4, later the engine truck got two axles.  It was NOT an attempt to upstage Union Pacific (all the Cold War era one-upping came after the War); rather it was a way to get more tractive effort (enough to break link couplers, oops) whilst keeping the axle loadings low (the number, AA20-1 honors the Railway Commissar, Comrade Andreyev, and the intended twenty metric ton axle loading, see also the FD20 and OR23) as five year plan did not include steel for strengthening bridges, and Soviet railways were world's widest dirt-track lines.

The discussion on leading trucks is instructive, I'm going to use some of that to get the model I'm building to track properly.

[Fr.Al]

I thought I read somewhere that a 4-10-6 type was proposed. It might have been the UP or even the Pennsy. Or was I dreaming?

[Overmod]

Fr.Al

I thought I read somewhere that a 4-10-6 type was proposed. It might have been the UP or even the Pennsy. Or was I dreaming?

There is a pencil drawing of a 4-10-6 with RC poppet valves in the Casey Jones Museum's collection in Jackson, TN.  This followed a sketch in what I recall to be a '70s issue of Trains; I don't now remember if the 'original' was Townsend's 4-8-6 with the additional driver pair 'imagineered' in; it would certainly seem to make better sense to do a 2-10-6 but this might be a consequence of the heavier weight of all the RC valve-gear components in the area of the cylinder block.