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Alleghenies

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Posted by timz on Wednesday, December 14, 2022 4:42 PM

Overmod
As a 'fact', I have on my desk a copy of [the drawbar-pull-vs-speed graph for the 2-6+6-6]...

Which shows X pounds at one speed and Y pounds at another -- it's about the same graph as we've seen elsewhere?

So say it shows 97000 lb at 20 mph and 70000 lb at 35 mph. What does that tell us about the cost to operate the engine?

Overmod
the actual cost of fuel and water to operate the locomotive is at a minimum at the peak of the effective horsepower curve

Guess you're saying the fuel/water cost per ton-mile is minimum at 35-45 mph. Need facts to support that. You recall that on test the 2-6+6-6 had about 5.9% drawbar thermal efficiency on a full tonnage train Hinton to Alleghany?

Overmod
...a comparable locomotive design optimized ...

A 16-driver engine, you mean? Preferably compound? Which C&O unaccountably didn't want. Too bad you weren't there to tell them about the optimum design.

Only way you're going to get a horsepower peak at 15-25 mph is to have 16 drivers, or more. You know that, and C&O knew that. So when are we going to hear a fact that you know and they didn't?

Overmod
The [PRR] Q2, a rigid-frame design with one fewer driver pair, develops higher drawbar TE than the Allegheny at any speed

That's test-plant "drawbar pull", isn't it? Where "drawbar" means the rear of a stationary locomotive, ahead of the tender?

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Posted by Backshop on Wednesday, December 14, 2022 5:05 PM

How many of us operate our cars for the majority of the time in stop-and-go traffic in the city and only occasionally use it at its most efficient speed on the highway?  

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Posted by Pneudyne on Wednesday, December 14, 2022 5:36 PM
Given that comparison has been made with the Big Boy, it may be noted that the its original mission can be viewed as having had two facets.  Firstly, it was required to take 3600 tons up the 1.14% Wasatch grade, and then run through to Green River, over mostly moderately graded track.  At Green River, the trains were to be handed over to Challengers for movement eastwards.  Evidently UP thought that the Ogden to Green River run would provide for better locomotive utilization than the Wasatch grade alone.  The inclusion of the Wasatch to Green River part of the route effectively meant that the Big Boy would need to have similar speed capability to the Challenger type, hence the 68 inch drivers.  One may speculate that for the Wasatch alone, a 63 inch 2-8-8-4, such as the DM&IR design (albeit with slightly lower axle loading and improved suspension) would have been a reasonable match.
 
Clearly UP was concerned about vertical railhead stresses, hence its fairly tight axle loading limit despite using 131 lb/yard rail.  One may deduce that it was also equally concerned about lateral railhead forces.  The Big Boy was equipped with the full Alco/Blunt “Lever System” of graduated lateral controls, with in particular six of its driving axles having lateral cushioning devices.  UP had first deployed the Alco/Blunt system of the FEF2 4-8-4, which had a somewhat longer wheelbase than was typical for 80 inch 4-8-4s.  It could have been that the Big Boy did not give away much in nimbleness as compared with x-6-6-s articulateds.
 
On excess power/excess haulage capacity, sometimes its provision was seen as contributing to economy, rather than being a diseconomy.  At least, that is the impression may gain from the writings of P.W. Kiefer of the NYC, in respect of the Niagara 4-8-4, about which he said:
 
A basic principle in this development was the incorporation of capacity in excess of that required for current work to be performed, in order to obtain the greatest possible continuity of operation, reduced time and expense for maintenance, and possible shortening of schedules.  That this principle was correct has already been demonstrated by the performance obtained since the engines were placed in regular service beginning in October, 1945.

 

Mileage between tire turnings has averaged about 190,000 with individual engines running as high as 235,000 compared with about 100,000 miles heretofore.  This high mileage is attributed to the high factor of adhesion, together with the design of spring equalization system which uses coil springs at the connection with the frame, the lower initial resistance in trucks and the use of lateral-motion devices on front and intermediate driving axles, all of which increase the flexibility of the driving machinery and permit automatic adjustment against variations due to accumulative wear.

 
The Niagara had not quite the full 'Lever Principle' set of lateral controls.  But it is clear that Kiefer saw graduated lateral controls as a key feature.  The Niagara 4-8-4 was of a size that the Western roads would have deployed on mountain grades, so might have been seen as “overkill” for what was basically a flat route.  But that was not misdesign or misapplication, rather it was Kiefer’s intent, apparently justified by his QED.
 
Steam locomotive power vs. speed curves tend to take the form of an inverted and somewhat skewed approximation to a parabola, sometimes with the initial downslope above the peak being shallower than the corresponding upslope before the peak.  For a given basic design, improvements made in the air-gas-steam cycle to obtain more power and/or greater efficiency not only cause the power peak to move upwards, but also higher in the speed range.  There is usually a lesser corresponding change in the upslope, particularly in its lower reaches.  The upward and outward movement of the power peak might be an objective in itself, or it might be more a byproduct of making general improvements, in which case specific utilization of the new peak might not be a priority objective.
 
 
Cheers,
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Posted by ATLANTIC CENTRAL on Wednesday, December 14, 2022 6:07 PM

Backshop

How many of us operate our cars for the majority of the time in stop-and-go traffic in the city and only occasionally use it at its most efficient speed on the highway?  

 

Very true, however my 7600 lb FORD F250 sees no measureable change in fuel economy from stop and go traffic to highway use at 80 mph on I95.

It's fuel consumption also does not seem to be effected by the work it is doing, that is loaded with construction tools and materials, or pulling my 1600 lb dual wheel trailer with my 1600 lb GRAVELY garden tractor on board, or running light with just me.

The activity of the onboard fuel economy metering suggests it is always getting about 12 mpg.

Suggesting that the available torque and hp from the 6.2 liter gasoline V8 with 385 hp/405 lb-ft torque @ 4500 rpm, is more power than I have yet been able to find a way to use in a way that would fall below its simple hourly fuel consumption rate.

So maybe, an Allegheny was bound to use a similar amount of coal and water slugging a coal train up a hill, or flying down the tracks with a hot shot freight?

But again, I could be wrong,

Sheldon

    

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Posted by Overmod on Thursday, December 15, 2022 8:15 AM

Gradual and proportional lateral compliance, particularly on the lead driver pair of a given engine on an articulated, is an essential component of high-speed stability (this is a fact, but I'm not going to substantiate it with citations).  This is different in effect from lateral-motion devices strictly intended to relieve flange forces or permit tighter curve negotiation (also factual, but I'll spare the railfans the MEGO detail)

One specific issue (which I do not know) is whether C&O ran its coal trains at high speed on downgrades or flatter sections, perhaps approximating how D&H post-'38 moved to be more of a one-speed railroad at a higher 'one-speed'.  If that in fact were a consideration, it is comparable to the way the Union Pacific used the Big Boys as pneudyne has laid out, and the use of a higher-speed-capable design might be more justifiable.

On the other hand, by 1941 (and definitively by 1948) chassis and balancing sophistication had reached the point that eight-coupled engines with comparatively small drivers and better steam distribution could perform at high speed.  There was nothing 'special' about the balancing technique on the British Rail 9F 2-10-0s that could not be easily adapted to American practice -- and those locomotives were reputedly capable of 97mph road speed on what I recall to be 56" wheels.  We have been treated to a number of articles in Trains and Classic Trains, and discussion in patent literature, about how lower drivers could be used with correct dynamic balancing, better weight distribution in cast driver centers, the use of Withuhn conjugated duplexing, etc., and of course there is all the discussion about how fast N&W could get Y-class compounds to run.

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Posted by sgriggs on Friday, December 16, 2022 4:12 PM

ATLANTIC CENTRAL

 

 
sgriggs

 

 
ATLANTIC CENTRAL

 

 
kgbw49

In an alternate universe it would have been interesting to see how an Allegheny would have fared over Sherman Hill and the Wasatch Range.

I know, I know, different fuel, different builder allegiance, 110,000 lbs tractive effort instead of the Big Boy's 135,000 lbs tractive effort, 12 drivers instead of 16 drivers.

But 13% more tractive effort than a Challenger.

I am just saying it would have been interesting to see an Allegheny give Sherman Hill and the Wasatch Range a go where there was more fast freight opportuniity and a rugged test.

In an alternate universe.

 

 

 

I think an Allegheny could have replaced a Big Boy or Challenger out west with acceptable results.

But neither a Big Boy or an ALCO Challenger could have replaced the Allegheny, or the N&W Class A, in the east.

The Big Boy is not "nimble" enough for Appalachia, and as you point out, the Challenger lacks the power.

I think the C&O/LIMA and the N&W understood the "nimble" issue when staying with 12 drivers, and that is born out by the B&O experiances with EM-1's at higher speeds.

Sheldon

 

 

 

 

I don't agree with this at all.  The Alleghenies were terribly overweight and wouldn't have even been allowed on UP property with their 86,000lbs axle loadings (UP axle load limits during the late steam era were 68,000lbs).  In spite of their axle loadings, the Alleghenies were much less capable than the UP Big Boys in the service these locomotives were intended for.  On their railroads' respective 1.14% ruling grades, the Alleghenies were only rated for 2950 tons, whereas the Big Boys were initially rated for 3600 tons (later increased to as much as 4450 tons).  People like to focus on the maximum horsepower capabilities, but overlook the important performance differences in the speed range where these locomotives operated more frequently.  The Allegheny had 35,000lbs less weight on drivers, smaller cylinders, and lower boiler pressure, all of which are significant drawbacks for a locomotive intended to haul heavy trains on mountain grades.  As a result, the Big Boys developed more horsepower than the Allegheny up to 25mph, allowing faster acceleration from stops, and offsetting some of the Allegheny's horsepower advantage at higher speeds.

With respect to whether the Big Boy would have been nimble enough to handle mainline coal trains in C&O territory, they could negotiate 20 degree curves and were shorter in overall height than the Allegheny.  The only question would be whether clearances to adjacent tracks on the C&O mainline would permit their operation, however let's not forget that the Allegheny was itself a very large machine.

 

 

 

Well, you make a good point about the axle loading, east coast roads in general where built with heavier trackage.

As for the nimble thing, I am aware of the abilities of the BigBoy on curves, but locos with longer engine wheel bases cannot maintain higher speeds around sharper curves, loose TE faster on sharper curves, etc.

An over all examination of eastern power vs western powers shows this difference. 

Western roads had/have great "straight a ways" where their tall drivers locos could stretch their legs. And if they had to slow down for some curves in some mountains that was ok.

But in the east straight a ways are rare, every line, level or in the mountains, is one curve after another winding thru the soft hills of the piedmont or around other pre-existing or natural obstacles (Bays, rivers, existing cities, not to mention our smaller, but in some ways more challenging mountains).

So smaller drivers and shorter rigid wheel bases allow moderate speeds on more milage.

The B&O learned this lesson with their 2-10-2's. After dumping one over on the old mainline, they stayed on the straighter Pittsburgh route. The old mainline required the articulated locos, draging coal or cruising along with general merchandise.

The Big Boy was built for a job, it did it well. The Allegheny was built to be more versitile (because that is what LIMA was selling with "Super Power"), and its "supposed" mis-use possibly proves how versitile.

But I could be wrong.....

Sheldon 

 

Sheldon,

When you use the term 'engine wheel base' you seem to be referring to the rigid wheelbase of the each coupled driver set.  And while there is no disputing that a 6-coupled engine like the Allegheny or the class A has a shorter rigid wheelbase on each of the articulated engines than an 8-coupled engine like a Big Boy or Yellowstone, I don't know that such a difference has a meaningful effect on the locomotive's ability to maintain speeds or tractive effort on Eastern U.S. mountain railroad mainlines.  There are certainly examples of 8-coupled non-articulated locomotives that were successfully operated on mountainous mainlines in the Eastern U.S.  For example, the N&W J, the C&O Greenbriar, and the AMC 2-8-4 Berkshires all have rigid wheelbases roughly equal to the UP Big Boy, and none of them were considered poor performers in the mountains.  The B&O EM-1 was as close to a UP Big Boy as there was in the East, and they were very successful in all service assignments, including their initial work on the demanding Cumberland division hauling coal and fast freights. 

So I don't quite understand how a UP Big Boy would have been unable to put its low speed advantages to work on the C&O mainline, and outperform the Allegheny hauling coal its own rails.  I also don't see how the Allegheny could do a Big Boy's job on the Wahsatch, or Sherman Hill, since it lacked the starting TE to handle the Big Boy's tonnage ratings.  That is not my definition of being more versatile.

To my mind, the Allegheny was over-boilered for all but the heaviest fast freights, and its design was not suited for C&O's needs, which were hauling heavy coal trains over the Alleghany summit.  This should surprise no one, because the Allegheny wheel arrangement and primary design parameters were selected by the railroad parent company's Advisory Mechanical Committee, with little to no input from the C&O's traffic or mechanical departments.  This is documented in multiple books by Huddleston and Withuhn.  

Scott

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Posted by ATLANTIC CENTRAL on Friday, December 16, 2022 4:37 PM

sgriggs

 

 
ATLANTIC CENTRAL

 

 
sgriggs

 

 
ATLANTIC CENTRAL

 

 
kgbw49

In an alternate universe it would have been interesting to see how an Allegheny would have fared over Sherman Hill and the Wasatch Range.

I know, I know, different fuel, different builder allegiance, 110,000 lbs tractive effort instead of the Big Boy's 135,000 lbs tractive effort, 12 drivers instead of 16 drivers.

But 13% more tractive effort than a Challenger.

I am just saying it would have been interesting to see an Allegheny give Sherman Hill and the Wasatch Range a go where there was more fast freight opportuniity and a rugged test.

In an alternate universe.

 

 

 

I think an Allegheny could have replaced a Big Boy or Challenger out west with acceptable results.

But neither a Big Boy or an ALCO Challenger could have replaced the Allegheny, or the N&W Class A, in the east.

The Big Boy is not "nimble" enough for Appalachia, and as you point out, the Challenger lacks the power.

I think the C&O/LIMA and the N&W understood the "nimble" issue when staying with 12 drivers, and that is born out by the B&O experiances with EM-1's at higher speeds.

Sheldon

 

 

 

 

I don't agree with this at all.  The Alleghenies were terribly overweight and wouldn't have even been allowed on UP property with their 86,000lbs axle loadings (UP axle load limits during the late steam era were 68,000lbs).  In spite of their axle loadings, the Alleghenies were much less capable than the UP Big Boys in the service these locomotives were intended for.  On their railroads' respective 1.14% ruling grades, the Alleghenies were only rated for 2950 tons, whereas the Big Boys were initially rated for 3600 tons (later increased to as much as 4450 tons).  People like to focus on the maximum horsepower capabilities, but overlook the important performance differences in the speed range where these locomotives operated more frequently.  The Allegheny had 35,000lbs less weight on drivers, smaller cylinders, and lower boiler pressure, all of which are significant drawbacks for a locomotive intended to haul heavy trains on mountain grades.  As a result, the Big Boys developed more horsepower than the Allegheny up to 25mph, allowing faster acceleration from stops, and offsetting some of the Allegheny's horsepower advantage at higher speeds.

With respect to whether the Big Boy would have been nimble enough to handle mainline coal trains in C&O territory, they could negotiate 20 degree curves and were shorter in overall height than the Allegheny.  The only question would be whether clearances to adjacent tracks on the C&O mainline would permit their operation, however let's not forget that the Allegheny was itself a very large machine.

 

 

 

Well, you make a good point about the axle loading, east coast roads in general where built with heavier trackage.

As for the nimble thing, I am aware of the abilities of the BigBoy on curves, but locos with longer engine wheel bases cannot maintain higher speeds around sharper curves, loose TE faster on sharper curves, etc.

An over all examination of eastern power vs western powers shows this difference. 

Western roads had/have great "straight a ways" where their tall drivers locos could stretch their legs. And if they had to slow down for some curves in some mountains that was ok.

But in the east straight a ways are rare, every line, level or in the mountains, is one curve after another winding thru the soft hills of the piedmont or around other pre-existing or natural obstacles (Bays, rivers, existing cities, not to mention our smaller, but in some ways more challenging mountains).

So smaller drivers and shorter rigid wheel bases allow moderate speeds on more milage.

The B&O learned this lesson with their 2-10-2's. After dumping one over on the old mainline, they stayed on the straighter Pittsburgh route. The old mainline required the articulated locos, draging coal or cruising along with general merchandise.

The Big Boy was built for a job, it did it well. The Allegheny was built to be more versitile (because that is what LIMA was selling with "Super Power"), and its "supposed" mis-use possibly proves how versitile.

But I could be wrong.....

Sheldon 

 

 

 

Sheldon,

When you use the term 'engine wheel base' you seem to be referring to the rigid wheelbase of the each coupled driver set.  And while there is no disputing that a 6-coupled engine like the Allegheny or the class A has a shorter rigid wheelbase on each of the articulated engines than an 8-coupled engine like a Big Boy or Yellowstone, I don't know that such a difference has a meaningful effect on the locomotive's ability to maintain speeds or tractive effort on Eastern U.S. mountain railroad mainlines.  There are certainly examples of 8-coupled non-articulated locomotives that were successfully operated on mountainous mainlines in the Eastern U.S.  For example, the N&W J, the C&O Greenbriar, and the AMC 2-8-4 Berkshires all have rigid wheelbases roughly equal to the UP Big Boy, and none of them were considered poor performers in the mountains.  The B&O EM-1 was as close to a UP Big Boy as there was in the East, and they were very successful in all service assignments, including their initial work on the demanding Cumberland division hauling coal and fast freights. 

So I don't quite understand how a UP Big Boy would have been unable to put its low speed advantages to work on the C&O mainline, and outperform the Allegheny hauling coal its own rails.  I also don't see how the Allegheny could do a Big Boy's job on the Wahsatch, or Sherman Hill, since it lacked the starting TE to handle the Big Boy's tonnage ratings.  That is not my definition of being more versatile.

To my mind, the Allegheny was over-boilered for all but the heaviest fast freights, and its design was not suited for C&O's needs, which were hauling heavy coal trains over the Alleghany summit.  This should surprise no one, because the Allegheny wheel arrangement and primary design parameters were selected by the railroad parent company's Advisory Mechanical Committee, with little to no input from the C&O's traffic or mechanical departments.  This is documented in multiple books by Huddleston and Withuhn.  

Scott

 

OK

    

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Posted by kgbw49 on Friday, December 16, 2022 8:22 PM

Atlantic Central and sgriggs, great discussion!

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