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What's so special about Big Boys?

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Posted by BigJim on Wednesday, December 7, 2005 2:10 AM
As I said Mr. Parks,
You show me something REAL, that means in Black & White from a UP Employee Timetable, not some fantasy in your own mind, and only THEN can we start to actually compare locos of different roads.

As for any single steam engine starting a 5 1/2 mile long train (on level track), and with all friction bearings ('cause remember that's what most of them were back in those days), never happen.

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Posted by Anonymous on Tuesday, December 6, 2005 11:17 PM
In the Kalmbach book "Steam Glory" there is a story about N&W's Y6 which includes comparison tables with Lima's 2-6-6-6s and UPs 4-8-8-4s.

There are numerous books out about N&W locomotives. Arguably the best is "N&W - Giant of Steam" by Col. Lewis I. Jeffries which is about to be reissued in a much expanded version by the N&W HS. Those interested can also be enlightened by volumes 2, 3 and 4 of Louis Newton's "Rails Remembered". Newton had a hands-on relationship with N&W steam matched by few, today. There is a book out on the class A which, I understand, is being expanded for a second edition which will be published by the N&W HS.

A new thread about the Y6 will not plow any new ground for N&W enthusiasts and will irritate steam fans of other railroads.

Where N&W excelled was designing locomotives to develop their maximum horsepower in the speed range where the locomotive was expected to spend most of its time. The Y6 maxed out at 25 MPH; when you're hauling heavy tonnage uphill, that maximum is ideal, and neither Big Boy or the Allegheny would be comfortable - or economical - doing it (even if they could handle N&W's curvature). To this add in the fact that both the Big Boy and the Allegheny outweighed the Y6 by about 140 or 150 thousand pounds, and were both more expensive, and you can appreciate the Y6 better. As far as Gross Ton Miles per Train Hour per Dollar, neither can touch the Y6 in any service.

The weight differential between the Big Boy and the Allegheny and N&W's 2-6-6-4 is even more atrocious, being in the neighborhood of a flat 100 tons (573,000 pounds for the A against an average of about 770,000 pounds for the Alleghenies and Big Boys). The Alleghenies averaged (for all 60 Alleghenies versus the 43 As) costing $100,000 more per engine and tender than the As. The cost figures used for the As - the first ten built in 1936-7 - were only slightly less than the first 4-6-6-4s Alco built for UP in 1936-7, so N&W's cost figures were not out of line.

When you want to compare anybody else's engines with N&W's, you might feel pretty good about it until you start to factor in weights and dollars. Then you lose.

N&W designed tenders better than most other folks, too, figured on the basis of empty weight to loaded weight.

The A would handle a 16,000 ton train of coal from Williamson to Portsmouth, 112 miles, nonstop in about 4 hours, turning in around 500,000 gross ton miles per train hour. If the A had to stop and start his train twice due to operating conditions (detouring around track work, or setting out a bad order car, or something), he'd still make it on a tender of coal (the A [auxiliary] tank increased water supply so that was no problem). I don't doubt that the Big Boy could make that run on a tank of coal, but if it had to stop and start the train twice (and starting and accelerating is where you burn it up) I'm not sure he could make it. I'm not sure the 2-6-6-6 could make it anyway, because his AMC designed tender didn't carry as much coal as did the A (figuring an A tank for both engines, just to keep water from being a factor). The Yellowstones? I don't think they could have made it on a tank of coal - not reliably. Cylinders too big, drivers too small, boiler pressure too low, which also militates against the 2-6-6-6.

Volume three of Newton's "Rails Remembered" contains records of test runs on N&W's Pocahontas Division with Y6bs with tonnage trains, which include fuel and water consumption figures, as well as GTM/TH. The value of compounding comes to light full force. He also has records of As on the Scioto Divison between Williamson and Portsmouth that may be enlightning. He was present for these tests and kept his own records.

To answer the question "what made N&W steam superior" the answer is that their power was designed by their own designers for the jobs at hand, without having any undesirable outside influence (need for an outside builder to try to sell more locomotives than actually needed to move the business, for instance) or any pet theories that wouldn't actually contribute to maximizing the profitability of the design. N&W made some mistakes in locomotive design early on, but was determined not to repeat them.

Remember - Alco and Baldwin and Lima were in the business of making money by selling locomotives, and if they could sell 25 69-inch drivered 4-6-6-4s to a mountain railroad that could actually move the business with, say, 18 or 20 lower-drivered 2-8-8-2s, they'd try their darnedest to sell the 25 Challengers. And they did, in cases like the Clinchfield, which bought 60 MPH Challengers for a railroad that only had about one stretch of track good for more than about 45 or 50. The Western Maryland is another example.

N&W was not in the business of making money building locomotives. They were in the business of economically building locomotives that would help them to make the most money running a railroad. Carrying gross income over to net was the name of the game, and paying dividends to the stockholders.

Go back to the years between the end of WWII and dieselization, and tell the forum how many railroads consistently beat them at those two items.

Allegheny fans - I'll give you a clue. C&O didn't even come close. Don't try to rationalize stuff like passenger losses and time freight losses; your arguments don't hold water. In an era where a railroad's potential profitability could be measured by the amount of coal business it had, C&O had more coal to haul than N&W and an easier railroad to haul it over; they had roundhouses full of the most fashionable steam motive power ever conceived by the mind and built by the hand of man; on the western haul they handled their coal all the way to Lake Erie while N&W (of that era) had to deliver its west coal to connections at Columbus. And with all that, they were never in the profit-making league with N&W.

That's what counts. Always did. Always will.

Oh, and trainjunky29 - your weight figures include tender, and last I heard the tender didn't contribute to tractive effort. And Y6's tractive effort figures in its final form were 166,000 pounds simple, 132,000 compound.

Old Timer
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Posted by Anonymous on Tuesday, December 6, 2005 8:46 PM
QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by oltmannd

QUOTE: Originally posted by feltonhill

The grade from Portsmouth to Williamson on the N&W is descending westbound at about -0.016% for the first 100 miles (range - level to -0.058%), upgrade 0.30% at Kenova over the Ohio River and -0.012% for the last 30 miles or so into Portsmouth.

Train weight varied depending on the mix of 50-ton and 70-ton cars. At a train length of 160 cars, trailing weight would be about 12,000 to 15,000 tons. Ultimately, a single A was expected to haul 180 cars over the division, a trailing weight of up to 17,000 tons.

According to GP40-2's figures, a CW44AC could develop 4,305 DBHP. To match the A's performance, it would need between 5,300 and 5,400 DBHP, so it would not match a single A's performance overall. The GE's operating economy would obviously be much better.

Again according to GP40-2's figures, a CW60AC would have about 5,895 DBHP. This is beyond the range of an A in daily service.

I've found no data for an FEF-3 above 75 mph, so I don't know what it would do with any certainty. Existing information indicates that they were very capable performers in regular service and could reach their design speed (100-110mph) easily. However, they were not record-breakers in the DBHP department according to the small amount of test info available. Don't know why.

GP40-2's figures for the P42 indicate that it would develop 3,850 DBHP at 100 mph. This would be pretty rarified atmosphere for steam and is likely well beyond the range of an FEF-3. My guess is that an FEF-3 would develop about 2,500 to maybe 2,700 DBHP at 100.

Since I don't have access to much diesel information, I find the relatively high percentage of rated HP making it to drawbar HP unusual. I didn't think they were that efficient from prime mover to rear coupler.


I think the diesel numbers being thrown around are net traction HP which is elec power out of the main gen headed for the traction motors. You'd have to factor in losses in the traction motor and gear set plus some allowance for HP to move the loco itself.

My recollection is that the overall eff. from engine shaft into generator (traction HP) to drawbar is about 80%.


Try in the neighborhood of 93% to 96% of the actual crankshaft horsepower for the latest designs. Even the orginal EMD FT's were 82% to 84% efficient, and that was with using unsophiscated DC generators/ DC traction motors.

Nominal Horsepower rating is the minimum HP available to the alternator. This is a conservative number, and actual crankshaft HP into the alternator is usually several hundred HP higher than the Nominal rating.

Currently I am not a liberty to discuss the latest tests on the new ES44DC's, but they have eye popping efficiency from crankshift to drawbar, especially for DC traction motors.


Of course, to compare this to a steamer you would have to take into account the efficiency of the prime mover--"chemical horsepower" in vs. drawbar horsepower out.

Internal combustion engines are much better than boilers, but they have never been great.

Sincerely,
Daniel Parks
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Posted by Anonymous on Tuesday, December 6, 2005 8:40 PM
Okay, this is rapidly going to break down about Big Boy vs. Y6b. I noticed that Mr. Jim the Big lives in Roanoke, Virgina (small home town bias perhaps???).

I suspect we are seeing Western railfans vs. Eastern railfans here [:)].

In defense of the Big Boys, a Y6b wouldn't be much good at hauling express reefer blocks, but a Big Boy could do a respectable job of hauling N&W coal trains.

Dear Mr. Jim the Big,
When your car/truck/SUV/Hummer gets hit at the crossing by a Big Boy at 50 mph, I think you'll agree that it's a big engine [:)].

To compare cold hard numbers:
A Big Boy weighed nearly 1.2 million pounds; a Y6b weighed 961,500,

A Big Boy put out 135,375 lbs. of tractive effort, a Y6b put out 152,206 lbs. simple, but was quickly reduced to 126,838 lbs. compound,

A Big Boy was 132' 10" long, a Y6b was 114' 10.5" long.

Given the choice for largest, I'll go with the Big Boy. Best is of course debatable.

Y6b information from http://spec.lib.vt.edu/testdata/nw/locomotives/nw18.html

Sincerely,
Daniel Parks
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Posted by GP40-2 on Tuesday, December 6, 2005 8:33 PM
QUOTE: Originally posted by oltmannd

QUOTE: Originally posted by feltonhill

The grade from Portsmouth to Williamson on the N&W is descending westbound at about -0.016% for the first 100 miles (range - level to -0.058%), upgrade 0.30% at Kenova over the Ohio River and -0.012% for the last 30 miles or so into Portsmouth.

Train weight varied depending on the mix of 50-ton and 70-ton cars. At a train length of 160 cars, trailing weight would be about 12,000 to 15,000 tons. Ultimately, a single A was expected to haul 180 cars over the division, a trailing weight of up to 17,000 tons.

According to GP40-2's figures, a CW44AC could develop 4,305 DBHP. To match the A's performance, it would need between 5,300 and 5,400 DBHP, so it would not match a single A's performance overall. The GE's operating economy would obviously be much better.

Again according to GP40-2's figures, a CW60AC would have about 5,895 DBHP. This is beyond the range of an A in daily service.

I've found no data for an FEF-3 above 75 mph, so I don't know what it would do with any certainty. Existing information indicates that they were very capable performers in regular service and could reach their design speed (100-110mph) easily. However, they were not record-breakers in the DBHP department according to the small amount of test info available. Don't know why.

GP40-2's figures for the P42 indicate that it would develop 3,850 DBHP at 100 mph. This would be pretty rarified atmosphere for steam and is likely well beyond the range of an FEF-3. My guess is that an FEF-3 would develop about 2,500 to maybe 2,700 DBHP at 100.

Since I don't have access to much diesel information, I find the relatively high percentage of rated HP making it to drawbar HP unusual. I didn't think they were that efficient from prime mover to rear coupler.


I think the diesel numbers being thrown around are net traction HP which is elec power out of the main gen headed for the traction motors. You'd have to factor in losses in the traction motor and gear set plus some allowance for HP to move the loco itself.

My recollection is that the overall eff. from engine shaft into generator (traction HP) to drawbar is about 80%.


Try in the neighborhood of 93% to 96% of the actual crankshaft horsepower for the latest designs. Even the orginal EMD FT's were 82% to 84% efficient, and that was with using unsophiscated DC generators/ DC traction motors.

Nominal Horsepower rating is the minimum HP available to the alternator. This is a conservative number, and actual crankshaft HP into the alternator is usually several hundred HP higher than the Nominal rating.

Currently I am not a liberty to discuss the latest tests on the new ES44DC's, but they have eye popping efficiency from crankshift to drawbar, especially for DC traction motors.
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Posted by BigJim on Tuesday, December 6, 2005 5:53 PM
How about you so called "Big Boy" junkies cough up some ACTUAL tonnage ratings and track speed limits from "Employee Timetables", and some gradients from track charts and then we can get down to some REAL comparisons and I bet you will find your precious little "Big Boy" wasn't so big after all.
Y6 Forever

.

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Posted by feltonhill on Tuesday, December 6, 2005 5:41 PM
N&W's eastbound grades were 1.4% compensated North Fork to Elkhorn Tunnel after the line relocation ca 1950, 1.00% compensated Walton to Christiansburg, and 1.2% not compensated on Blue Ridge. These figures are from track charts.

Re: BB actually moving a 5.5 or 6-mile train, see Old Timer's post 28 Nov 05 at 00:11:48 and my post 28 Nov 05 at 21:40:19. No sense plowing old ground.

As far as discussing N&W's steam power, Y6's or otherwise, how about someone starting a separate thread.
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Posted by jkubajakiii on Tuesday, December 6, 2005 3:11 PM
It's always the sheer size it. From what I heard, The Union Pacifc wanted a locomotive that can pull like a 2-8-8-4 Yellowstone, but can run fast like their own 4-6-6-4 Challengers. 25 of these new 4-8-8-4 locomotives were built just before the attack on Pearl Harbor. An American Locomotive Company employee chalk the name "Big Boy" on the side of No. 4000's tender, so the name stuck. The UP was so impressed with the design that additional Challengers to the roster were build to simular specs, abit 4 feet shorter. UP's own No. 3985 is an example of the latter part of the Challenger fleet.
The Big Boys were outnumbered by the entire Challenger fleet by more than 4 to 1. (The UP had 109 Challengers, I think.) But in the end, the Big Boys had the last laugh. Only one other Challenger still exist in a park/museum in North Platte, Newbraska. (The oil tank in No. 3977's tender is currently being used by 3985 after she's converted to burn oil.) 8 Big Boys are on display across the country, including Scranton, PA. (Steamtown) and one they tried to rebuild into operating condition in Dallas, Texas (Age of Steam Museum) for a movie, but it fell through.
Sure the N&W's 2-8-8-2 Y-6 class had more traction effort and more drawbar pull than the Big Boy, but these are drag locomotives. Their driver wheels have a smaller diamiter than the Big Boy. Plus the Norfork And Western is more of a mountain railroad the the Union Pacific ever was. The N&W drags all needed helpers becaue they have THREE summits between Norfork and the Ohio River Valley. All of which are in the 2.2% graden range. The UP Overland Route from Omaha, Newbraska and Ogden, Utah is the flattest railroad to the west! Sherman Hill may get a lot of attention, but it is hardly a speed bump! The Wasach Range on the Wyoming/Utah boarder has steeper grades, but they are well below 2%.
That's why the Big Boys (as well as the Challengers) can really haul! In fact, it been said if the Big Boy was used in the Midwest, like Illinois Central's Mainline Of Mid-America, at top speed could haul a train SIX MILES LONG! But I doubt we'll ever find out.
[{(-_-)}]
James Lawrence Kubajak III
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Posted by tree68 on Tuesday, December 6, 2005 3:07 PM
QUOTE: Originally posted by electro-ortcele

QUOTE: Originally posted by electro-ortcele

In what way was N&W's steam superior?
I've heard that UP used low quality coal, but other than that, Big Boy was built by alco, why would alco make intentionally inferior-quality locomotives for UP when they could make good ones for others?

Can someone answer this question for me? I'm not trying to make a discussion out of it, I just haven't heard this before, so I'd like to know what it's about

The history of the railroads (and a lot of other things, for that matter) is full of locomotives that were ill-designed for their intended use, just as other locomotives filled the bill perfectly. I can't cite examples, but if you read some accounts of specific locomotives, you'll find them. Sometimes it was a case of ego or keeping up with the Joneses, sometimes it was just a case of poor planning or circumstance, sometimes it was a case of a subsidiary RR getting hand-me-downs from its parent. Even within a given railroad the same locomotive would work great in some areas and not in others.

I have no doubt that the locomotives of ALCo, Baldwin, etc, etc, were all of the highest quality (or some of them wouldn't still be around). As nanaimo73 said - it's a matter of whether the locomotives they built for the railroads would do the job the railroads wanted them to.

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Posted by nanaimo73 on Tuesday, December 6, 2005 1:27 PM
QUOTE: Originally posted by electro-ortcele

Big Boy was built by Alco, why would Alco make intentionally inferior-quality locomotives for UP when they could make good ones for others?


Alco did not "make intentionally inferior-quality locomotives for UP", it was the design and not the construction that was the problem. N&W did a better job of designing their locomotives to do the jobs they wanted done.

If Old Timer has the time, I would enjoy reading his thoughts about the uses of the A class locomotives during the 1950s, and how the Big Boys would have made out on those runs using eastern coal.
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Posted by Anonymous on Tuesday, December 6, 2005 11:19 AM
QUOTE: Originally posted by electro-ortcele

In what way was N&W's steam superior?
I've heard that UP used low quality coal, but other than that, Big Boy was built by alco, why would alco make intentionally inferior-quality locomotives for UP when they could make good ones for others?


Can someone answer this question for me? I'm not trying to make a discussion out of it, I just haven't heard this before, so I'd like to know what it's about
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Posted by Anonymous on Tuesday, December 6, 2005 11:16 AM
Traction effort is a physical value, so it can only be attributed to actual mechanical parts of the locomotive. You can't calculate tractive effort for the generator output, because electricity is not a mechanical force (at least not on the marco level).
Power on the other hand can be attributed to electricity. And usually the power used in calculations is prime mover power multiplied with efficiency of the entire locomotive (traction motor power loss included), so the figures of tractive effort are accurate if the right efficiency percentage is used.

Starting tractive effort is calculated from locomotive weight and adhesion, while the
continuous tractive effort is calculated from the maximum electrical flow that motors can tolerate (which gives you a certain minimum speed at full throtle).

So, the motors can tolerate a certain amount of electricity, which means they have to turn at least so much while full generator output is being fed into them.
That minimum turning speed gives minimum train rolling speed, which
combined with HP and efficiency gives a certain maximum continuous tractive effort.







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Posted by oltmannd on Tuesday, December 6, 2005 10:29 AM
QUOTE: Originally posted by feltonhill

The grade from Portsmouth to Williamson on the N&W is descending westbound at about -0.016% for the first 100 miles (range - level to -0.058%), upgrade 0.30% at Kenova over the Ohio River and -0.012% for the last 30 miles or so into Portsmouth.

Train weight varied depending on the mix of 50-ton and 70-ton cars. At a train length of 160 cars, trailing weight would be about 12,000 to 15,000 tons. Ultimately, a single A was expected to haul 180 cars over the division, a trailing weight of up to 17,000 tons.

According to GP40-2's figures, a CW44AC could develop 4,305 DBHP. To match the A's performance, it would need between 5,300 and 5,400 DBHP, so it would not match a single A's performance overall. The GE's operating economy would obviously be much better.

Again according to GP40-2's figures, a CW60AC would have about 5,895 DBHP. This is beyond the range of an A in daily service.

I've found no data for an FEF-3 above 75 mph, so I don't know what it would do with any certainty. Existing information indicates that they were very capable performers in regular service and could reach their design speed (100-110mph) easily. However, they were not record-breakers in the DBHP department according to the small amount of test info available. Don't know why.

GP40-2's figures for the P42 indicate that it would develop 3,850 DBHP at 100 mph. This would be pretty rarified atmosphere for steam and is likely well beyond the range of an FEF-3. My guess is that an FEF-3 would develop about 2,500 to maybe 2,700 DBHP at 100.

Since I don't have access to much diesel information, I find the relatively high percentage of rated HP making it to drawbar HP unusual. I didn't think they were that efficient from prime mover to rear coupler.


I think the diesel numbers being thrown around are net traction HP which is elec power out of the main gen headed for the traction motors. You'd have to factor in losses in the traction motor and gear set plus some allowance for HP to move the loco itself.

My recollection is that the overall eff. from engine shaft into generator (traction HP) to drawbar is about 80%.

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by Anonymous on Monday, December 5, 2005 5:41 PM
In the words of numerious persons that have heard all this before. "There comes a time to let it rest." I remain respectfully yours to all members and readers, -----Piouslion
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Posted by Anonymous on Monday, December 5, 2005 5:18 PM
Uhh-ohh: here we go again [:)][:D]!
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Posted by Anonymous on Monday, December 5, 2005 4:01 PM
In what way was N&W's steam superior?
I've heard that UP used low quality coal, but other than that, Big Boy was built by alco, why would alco make intentionally inferior-quality locomotives for UP when they could make good ones for others?
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Posted by Anonymous on Monday, December 5, 2005 2:10 PM
QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by Old Timer

Anybody know how to get this back on topic?

All I see is a couple of guys trying to out-brain each other. I don't see either one making any particular points on it.

Old Timer


Exactly, that's why I done dealing with the Trainjunky on this subject. Besides, Oldtimer, everybody who knows anything about steam knows that the N&W's steam was far superior to anything the Union Pacific ran anyway.

Anybody want to start a Y6b thread???[:D]


Mathematics and theory aside, the BigBoys are pretty cool. And what makes it even more interesting is the fact that 8 survive.

And there's always someone talking about the possibity of restoring one. And even though its extremely unlikely and will probably never happen. Just the thought of it can get you excited about them again. Or is it just me?

GP40-2

A N&W thread sounds good, The J, A and Y5 to Y6b were excellent.
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Posted by Anonymous on Sunday, December 4, 2005 10:40 PM
GP40-2 asketh:

"Anybody want to start a Y6b thread???"

What was so special about the Y6b? N&W had seventy other locomotives in classes Y5, Y6 and Y6a that were the equals of the Y6b in performance. The Y6bs were just the newest.

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Posted by tree68 on Sunday, December 4, 2005 10:11 PM
I just looked up "Torque Curves" on google, and while the sites I checked had to do with autos and electric motors, all the curves marked "torque" on graphs looked more or less bell-shaped.

In answer to the original question - nothing. It's a big steam locomotive. As in the case of many things - people have their preferences. I happen to be fond of Berkshires. Does that make them more special than anything else? Probably not, but I still like them.

IIRC - the consensus seems to be that the Big Boys were built for a specific purpose, and they mostly fulfilled that need. They would not have performed well in another application because they weren't built for that application. Could another locomotive have done a better job? Maybe. But UP bought the Big Boys, and you can bet they weren't cheap. So even if they turned out to be less than perfect, unless they were a total bust, it made sense to run them until they didn't make sense any more.

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Posted by timz on Sunday, December 4, 2005 6:39 PM
QUOTE: Originally posted by GP40-2
A steam locomotive's power curve is exponential in nature...

I mean that a steam locomotive's power curve follows the classic Gaussian Distribution Curve (i.e "the Bell Shaped Curve")....

...torque curves are gaussian in nature. Therefore, it is impossible for a steam locomotives power curve NOT to be gaussian in nature....

If you deny that torque curves are gaussian in nature, then your don't fundamentally understand torque.



What do you think, guys? Is he pulling our legs? After the first two I thought he had to be, but now I dunno.
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Posted by Anonymous on Sunday, December 4, 2005 12:05 PM
QUOTE: Originally posted by GP40-2
Man, you just don't give up even when you are wrong!

I bet you drive your parents crazy.

If you deny that torque curves are gaussian in nature, then your don't fundamentally understand torque. Since you don't have a true fundamental understanding of this stuff, many of your assumptions are wrong from that point forward.

The difference between an man and a kid is that a kid whines and cries even when he is wrong. A man, on the other hand, admits his mistakes, learns from the experience, and moves on. Trainjunky, stop being a whiny kid, and learn to be a man.


Dear GP40-2,
I see this degrading into mudslinging again. I my defense, I see a difference between whining and using a little math.

Sincerely yours,
Daniel Parks
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Posted by GP40-2 on Sunday, December 4, 2005 9:03 AM
QUOTE: Originally posted by Old Timer

Anybody know how to get this back on topic?

All I see is a couple of guys trying to out-brain each other. I don't see either one making any particular points on it.

Old Timer


Exactly, that's why I done dealing with the Trainjunky on this subject. Besides, Oldtimer, everybody who knows anything about steam knows that the N&W's steam was far superior to anything the Union Pacific ran anyway.

Anybody want to start a Y6b thread???[:D]
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Posted by GP40-2 on Sunday, December 4, 2005 8:48 AM
QUOTE: Originally posted by trainjunky29

QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by trainjunky29

Dear GP40-2, maybe you have established it, but wait one minute:
If torque vs. rpm is Gaussian, wouldn't that mean that at 0 rpm's, you would have no torque? And if you have no torque when stopped, then how does a steam locomotive get things moving? Quite the contrary, a steamer's torque is at a maximum at speeds near 0, and only goes down from there. I admit that I may not have the benefit of college mechanical engineering classes, but I can still read a graph.

Secondly, wikipedia is an open source document. That makes it MORE reliable--any malicious or ignorant falacies on the sight would soon be corrected by others either well-meaning or more knowledgeable. If you don't want to use wikipedia, then be my guest to pick some other reference. Without a reference, we could very easily end up arguing over two completely different subjects.

Finally, why are we dealing with the largest of the large in terms of random numbers? You can model the Big Boy in Monte Carlo routines if you so desire. I personally prefer brass [:)]! And has anybody noticed that we are arguing about stuff completely different than what this topic started about [8D]?

Sincerely,
Daniel Parks


Torque always has to start at zero. You just can't instantly have say 10,000 lbs ft torque out of no where-it has to start somewhere-and that starting point is zero. Now, we are getting into the idea of limits. If you graph the starting torque of any locomotive in small enough increments you will see a ramp up from a zero starting point, a maximum, and a fall back to zero.

Second, as you are aware, power is torque X speed. It is possible to have a large torque reading while having zero power. Example: You are pressing hard on a wrench to remove a stuck bolt. When you first place the wrench on the bolt, you don't instantly have maximum force. Your force starts at zero, then your muscles apply all the force they have. If you are applying all your strength, and the bolt still is not turning, you have created maximum torque BUT zero power. Now, the bolt slowly starts to free itself and turn. The torque reading on the wrench will go down, but the power you have produced will go up.

Anyway, we were talking about a locomotives power at certain speeds, not it's tractive effort.. I said to graph the Big Boy's Power vs. Speed. I never said for you to graph a locomotives tractive effort curve (which is nothing more than a linear reading of the torque produced by the locomotive's wheels).

P.S. Here's a tip for the future: You can say what you want about the Wikipedia, but I guarantee you if you use that thing for a college level paper you will get a nice big fat F on it.


I agree with most of this post. I do not, however, agree with your earlier post. Here's why:
You said that torque vs. rpm was Gaussian. Certainly torque cannot go from 0 to whatever instantaneously. However, using your bolt example, you could put on, say, 150 foot-pounds, and the bolt would still be stuck. You would have 0 rpm's, but plenty of torque (not Gaussian).

Similarly, with a Big Boy, you could have full steam pressure in the cylinders, with full torque, but not be moving (say the train you're coupled to has the hand-brakes applied, and you are on a "cog Big Boy" so the wheel's won't slip) (not Gaussian).

Additionally, you said,
"Trainjunky, we already established that the locomotive's job is to apply torque to the rails, and torque curves are gaussian in nature. Therefore, it is impossible for a steam locomotives power curve NOT to be gaussian in nature."

There are three things here I hold issue with:
1.) A locomotive's job is to apply a force through the coupler to the train. Torque really isn't the issue here, it's the mechanical advantage between the crankpin and the tire on the locomotive's driving wheels (wheel and axle, so to speak) (Galileo once described the wheel as the "perpetual lever"). Then of course you have to figure in the friction between the wheel and the rail. Basically, torque isn't as important as force--the piston puts a linear force on the main rod, which creates torque, which is made into a "rectified" linear force by the wheels.

2.) We've already gotten into torque vs. rpm (or speed) curves, but just to summarize my argument: At zero rpm's (or zero mph), torque can vary from zero to whatever maximum the locomotive can produce. A gaussian torque vs. rpm curve would mean no or practically now torque at 0 rpm's.

3.) You assert that since torque curves are Gaussian in nature, horsepower curves are by default. I deny that torque curves are Gaussian in nature, but let's do a little math:
For the sake of arugment, let's ignore the force fluctuations throughout a locomotive wheel's revolution (so that a constant force acts on the wheel all the time). Torque equals the perpendicular force times the radius from which it acts. Therefore, the perpendicular force = torque/radius. The force exerted to the rail is the aforementioned "torquing force" times the crankpin radius devided by the wheel's radius, or

F = f x r / R

(r/R is a mechanical advantage less than one). Finally,

Power = Force x velocity.

Now let's do some substitution, and you'll end up with

Power = torque x velocity / wheel radius

(or because there are 550 foot-pounds in a horsepower,
Horsepower = torque x velocity / 550 x wheel radius).

But let's just stick with Power = torque x velocity / a constant. We are graphing power vs. speed. Obviously, velocity vs. speed will be a linear graph. Even if torque vs. rpm were Gaussian (which I deny), a Gaussian graph times a linear graph would not be Guassian any more than a sinusoidal graph times a parabolic graph would be sinusoidal.

Sincerely,
Daniel Parks


Man, you just don't give up even when you are wrong!

I bet you drive your parents crazy.

If you deny that torque curves are gaussian in nature, then your don't fundamentally understand torque. Since you don't have a true fundamental understanding of this stuff, many of your assumptions are wrong from that point forward.

The difference between an man and a kid is that a kid whines and cries even when he is wrong. A man, on the other hand, admits his mistakes, learns from the experience, and moves on. Trainjunky, stop being a whiny kid, and learn to be a man.

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Posted by Anonymous on Saturday, December 3, 2005 11:15 PM
QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by trainjunky29

Dear GP40-2, maybe you have established it, but wait one minute:
If torque vs. rpm is Gaussian, wouldn't that mean that at 0 rpm's, you would have no torque? And if you have no torque when stopped, then how does a steam locomotive get things moving? Quite the contrary, a steamer's torque is at a maximum at speeds near 0, and only goes down from there. I admit that I may not have the benefit of college mechanical engineering classes, but I can still read a graph.

Secondly, wikipedia is an open source document. That makes it MORE reliable--any malicious or ignorant falacies on the sight would soon be corrected by others either well-meaning or more knowledgeable. If you don't want to use wikipedia, then be my guest to pick some other reference. Without a reference, we could very easily end up arguing over two completely different subjects.

Finally, why are we dealing with the largest of the large in terms of random numbers? You can model the Big Boy in Monte Carlo routines if you so desire. I personally prefer brass [:)]! And has anybody noticed that we are arguing about stuff completely different than what this topic started about [8D]?

Sincerely,
Daniel Parks


Torque always has to start at zero. You just can't instantly have say 10,000 lbs ft torque out of no where-it has to start somewhere-and that starting point is zero. Now, we are getting into the idea of limits. If you graph the starting torque of any locomotive in small enough increments you will see a ramp up from a zero starting point, a maximum, and a fall back to zero.

Second, as you are aware, power is torque X speed. It is possible to have a large torque reading while having zero power. Example: You are pressing hard on a wrench to remove a stuck bolt. When you first place the wrench on the bolt, you don't instantly have maximum force. Your force starts at zero, then your muscles apply all the force they have. If you are applying all your strength, and the bolt still is not turning, you have created maximum torque BUT zero power. Now, the bolt slowly starts to free itself and turn. The torque reading on the wrench will go down, but the power you have produced will go up.

Anyway, we were talking about a locomotives power at certain speeds, not it's tractive effort.. I said to graph the Big Boy's Power vs. Speed. I never said for you to graph a locomotives tractive effort curve (which is nothing more than a linear reading of the torque produced by the locomotive's wheels).

P.S. Here's a tip for the future: You can say what you want about the Wikipedia, but I guarantee you if you use that thing for a college level paper you will get a nice big fat F on it.


I agree with most of this post. I do not, however, agree with your earlier post. Here's why:
You said that torque vs. rpm was Gaussian. Certainly torque cannot go from 0 to whatever instantaneously. However, using your bolt example, you could put on, say, 150 foot-pounds, and the bolt would still be stuck. You would have 0 rpm's, but plenty of torque (not Gaussian).

Similarly, with a Big Boy, you could have full steam pressure in the cylinders, with full torque, but not be moving (say the train you're coupled to has the hand-brakes applied, and you are on a "cog Big Boy" so the wheel's won't slip) (not Gaussian).

Additionally, you said,
"Trainjunky, we already established that the locomotive's job is to apply torque to the rails, and torque curves are gaussian in nature. Therefore, it is impossible for a steam locomotives power curve NOT to be gaussian in nature."

There are three things here I hold issue with:
1.) A locomotive's job is to apply a force through the coupler to the train. Torque really isn't the issue here, it's the mechanical advantage between the crankpin and the tire on the locomotive's driving wheels (wheel and axle, so to speak) (Galileo once described the wheel as the "perpetual lever"). Then of course you have to figure in the friction between the wheel and the rail. Basically, torque isn't as important as force--the piston puts a linear force on the main rod, which creates torque, which is made into a "rectified" linear force by the wheels.

2.) We've already gotten into torque vs. rpm (or speed) curves, but just to summarize my argument: At zero rpm's (or zero mph), torque can vary from zero to whatever maximum the locomotive can produce. A gaussian torque vs. rpm curve would mean no or practically now torque at 0 rpm's.

3.) You assert that since torque curves are Gaussian in nature, horsepower curves are by default. I deny that torque curves are Gaussian in nature, but let's do a little math:
For the sake of arugment, let's ignore the force fluctuations throughout a locomotive wheel's revolution (so that a constant force acts on the wheel all the time). Torque equals the perpendicular force times the radius from which it acts. Therefore, the perpendicular force = torque/radius. The force exerted to the rail is the aforementioned "torquing force" times the crankpin radius devided by the wheel's radius, or

F = f x r / R

(r/R is a mechanical advantage less than one). Finally,

Power = Force x velocity.

Now let's do some substitution, and you'll end up with

Power = torque x velocity / wheel radius

(or because there are 550 foot-pounds in a horsepower,
Horsepower = torque x velocity / 550 x wheel radius).

But let's just stick with Power = torque x velocity / a constant. We are graphing power vs. speed. Obviously, velocity vs. speed will be a linear graph. Even if torque vs. rpm were Gaussian (which I deny), a Gaussian graph times a linear graph would not be Guassian any more than a sinusoidal graph times a parabolic graph would be sinusoidal.

Sincerely,
Daniel Parks
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Posted by Anonymous on Saturday, December 3, 2005 10:43 PM
Anybody know how to get this back on topic?

All I see is a couple of guys trying to out-brain each other. I don't see either one making any particular points on it.

Old Timer
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    July 2004
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Posted by GP40-2 on Saturday, December 3, 2005 9:37 AM
QUOTE: Originally posted by trainjunky29

Dear GP40-2, maybe you have established it, but wait one minute:
If torque vs. rpm is Gaussian, wouldn't that mean that at 0 rpm's, you would have no torque? And if you have no torque when stopped, then how does a steam locomotive get things moving? Quite the contrary, a steamer's torque is at a maximum at speeds near 0, and only goes down from there. I admit that I may not have the benefit of college mechanical engineering classes, but I can still read a graph.

Secondly, wikipedia is an open source document. That makes it MORE reliable--any malicious or ignorant falacies on the sight would soon be corrected by others either well-meaning or more knowledgeable. If you don't want to use wikipedia, then be my guest to pick some other reference. Without a reference, we could very easily end up arguing over two completely different subjects.

Finally, why are we dealing with the largest of the large in terms of random numbers? You can model the Big Boy in Monte Carlo routines if you so desire. I personally prefer brass [:)]! And has anybody noticed that we are arguing about stuff completely different than what this topic started about [8D]?

Sincerely,
Daniel Parks


Torque always has to start at zero. You just can't instantly have say 10,000 lbs ft torque out of no where-it has to start somewhere-and that starting point is zero. Now, we are getting into the idea of limits. If you graph the starting torque of any locomotive in small enough increments you will see a ramp up from a zero starting point, a maximum, and a fall back to zero.

Second, as you are aware, power is torque X speed. It is possible to have a large torque reading while having zero power. Example: You are pressing hard on a wrench to remove a stuck bolt. When you first place the wrench on the bolt, you don't instantly have maximum force. Your force starts at zero, then your muscles apply all the force they have. If you are applying all your strength, and the bolt still is not turning, you have created maximum torque BUT zero power. Now, the bolt slowly starts to free itself and turn. The torque reading on the wrench will go down, but the power you have produced will go up.

Anyway, we were talking about a locomotives power at certain speeds, not it's tractive effort.. I said to graph the Big Boy's Power vs. Speed. I never said for you to graph a locomotives tractive effort curve (which is nothing more than a linear reading of the torque produced by the locomotive's wheels).

P.S. Here's a tip for the future: You can say what you want about the Wikipedia, but I guarantee you if you use that thing for a college level paper you will get a nice big fat F on it.
  • Member since
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Posted by Anonymous on Saturday, December 3, 2005 1:00 AM
Dear GP40-2, maybe you have established it, but wait one minute:
If torque vs. rpm is Gaussian, wouldn't that mean that at 0 rpm's, you would have no torque? And if you have no torque when stopped, then how does a steam locomotive get things moving? Quite the contrary, a steamer's torque is at a maximum at speeds near 0, and only goes down from there. I admit that I may not have the benefit of college mechanical engineering classes, but I can still read a graph.

Secondly, wikipedia is an open source document. That makes it MORE reliable--any malicious or ignorant falacies on the sight would soon be corrected by others either well-meaning or more knowledgeable. If you don't want to use wikipedia, then be my guest to pick some other reference. Without a reference, we could very easily end up arguing over two completely different subjects.

Finally, why are we dealing with the largest of the large in terms of random numbers? You can model the Big Boy in Monte Carlo routines if you so desire. I personally prefer brass [:)]! And has anybody noticed that we are arguing about stuff completely different than what this topic started about [8D]?

Sincerely,
Daniel Parks
  • Member since
    July 2004
  • 803 posts
Posted by GP40-2 on Friday, December 2, 2005 10:23 PM
QUOTE: Originally posted by trainjunky29

QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by trainjunky29

How is a steamer's power curve related to a Gaussian Curve?
1.) A Gaussian curve returns to 0 as the x-component increases, a steamer's does not
2.) A steam locomotive has nothing to do with probability nor with quantum physics
3.) A steam locomotive's power curve has no points of inflection
4.) I plotted feltonhill's data, and it looks nothing like the curves shown in the above link or a "classic Gaussian distribution curve."

Sincerely,
Daniel Parks


Let's look at the data, and focus on speed vs. hp:

Speed - Calc TE (lbs) - Actual DB Pull (lbs) - Actual DBHP

0 - 135,300 - 131,000 - 0
10 - 132,500 - 124,000 - 3,307
20 - 109,000 - 98,000 - 5,227
30 - 83,000 - 75,000 - 6,000
40 - 67,000 - 57,000 - 6,080
50 - 56,100 - 43,000 - 5,733
60 - 48,700 - 32,000 - 5,120

SPEED=X HP=Y

X Y
0 0
10 3307
20 5527
30 6000
40 6080
50 5733
60 5120
70 4000 (extrapolated)
80 2800 (extrapolated)

Plot those, and you will get a bell shaped curve. Maybe not a "pure Guassian", but a bell shaped curve none the less.

I'm also curious why you think probability and statistics can not be used to describe how a steam locomotive works? After all, Monte Carlo routines are often used now in mechanical engineering design...


Dear GP40-2,
Due to the reasons I have sighted as points 1, 3, and 4 above, a horsepower curve looks little like a Bell-shaped curve.

I presume by Monte Carlo Routine you mean what is described here: http://en.wikipedia.org/wiki/Monte_Carlo_method. You will notice that these have to do with random numbers.

At the macroscopic locomotive level, as I'm sure you realize, random motions tend to cancel one another out. There's not much that's random on a Big Boy (other than which bolt will rust in place next [:)]).

Sincerely,
Daniel Parks



First, please stop using Wikipedia as a reference. It is an open source document where anybody can post anything they want about any subject. It is not an academic source, and using it totally destroys any validity you may have in an argument.

Second, your explaination of Monte Carlo calculations is not what I meant. It shows me that you are just fishing around for a "cute" come back on a subject that you know little about.

A full blow discussion of probability and statistics and Monte Carlo simulations goes way beyond the scope of this forum. I would venture to say that 99% of the people reading this have no idea what we are talking about, not alone know how to use it. Nor do I have the time to play college professor and teach you graduate level engineering theory.

Suffice to say, a simple definition of Monte Carlo simulations is not about random motion as you have stated, but using the generation of random values for variables multiple times to find solutions for quanitative problems (such as how much power a locomotive or car or whatever will make under given conditions). Probability/Statistics and Monte Carlo methods are not just limited to quantum physics as you argued in #2. These methods can and ARE used to find solutions to quanitative problems in biology,chemistry, finance, medicine, engineering and design just to name a few. One can describe the complete operation of a steam locomotive from burning the coal/oil to how the whistle blows using Monte Carlo simulations. This goes way beyond high school classical physics and calculus you may be studying.

Now, on to your other argument that a steam locomotive power curve is not Gaussian in nature.

Let's look at what any locomotive really does: It applies torque through its wheels to the track to propel the train forward. The torque from any locomotive can be plotted in a curve as torque vs. rpm. ***Torque curves are Gaussian in shape.***---A freshman level mechanical engineer will know this.

Now, if you are paying attention, you may be thinking "that sucks because a gaussian shaped torque curve has a peak, and what good is it to have all your force at a peak" Exactly, that's why cars/trucks have mechanical transmissions--to create multiple gaussian curves so you have a broader power band. New automotive engines also have variable valve timing to "smear" the gaussian torque curve from the engine around the rpm band. Couple this with a 5 or 6 speed transmission, and you will have a fuel efficient 4 cylinder engine with both high torque and high rpm power.

What about diesel-electrics? Ahh, that's the beauty of an electric traction motor. Every possible voltage/amperage combination produces its own gaussian torque curve. It is possible to have an infinite amount of voltage/amperage combinations for a given power output (watts), so it is possible to have an infinite amount of gaussian torque curves. In reality, all these curves "smear" together over the operating range of the motor, so you end up with a very, very flat power curve.

Feltonhill: The above paragraph explains why the diesel-electrics I provided test results for can maintain so much of their nominal rating at high speed. I will comment later this weekend on the idea of "nominal" hp ratings and the current optimalization of locomotive's electrical gear to answer (or at least try to answer) your other questions.

Now what about our friend the steam locomotive. A steam locomotive dosen't have a transmission. The speed of the pistons are directly linked to the stroke length and the driver diameter. You get one ratio, that is it. That explains the "peaky" nature of any steam locomotive's power curve--you only get one gaussian torque curve! Trainjunky, we already established that the locomotive's job is to apply torque to the rails, and torque curves are gaussian in nature. Therefore, it is impossible for a steam locomotives power curve NOT to be gaussian in nature.
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Posted by Anonymous on Friday, December 2, 2005 11:17 AM
QUOTE: Originally posted by GP40-2

QUOTE: Originally posted by trainjunky29

How is a steamer's power curve related to a Gaussian Curve?
1.) A Gaussian curve returns to 0 as the x-component increases, a steamer's does not
2.) A steam locomotive has nothing to do with probability nor with quantum physics
3.) A steam locomotive's power curve has no points of inflection
4.) I plotted feltonhill's data, and it looks nothing like the curves shown in the above link or a "classic Gaussian distribution curve."

Sincerely,
Daniel Parks


Let's look at the data, and focus on speed vs. hp:

Speed - Calc TE (lbs) - Actual DB Pull (lbs) - Actual DBHP

0 - 135,300 - 131,000 - 0
10 - 132,500 - 124,000 - 3,307
20 - 109,000 - 98,000 - 5,227
30 - 83,000 - 75,000 - 6,000
40 - 67,000 - 57,000 - 6,080
50 - 56,100 - 43,000 - 5,733
60 - 48,700 - 32,000 - 5,120

SPEED=X HP=Y

X Y
0 0
10 3307
20 5527
30 6000
40 6080
50 5733
60 5120
70 4000 (extrapolated)
80 2800 (extrapolated)

Plot those, and you will get a bell shaped curve. Maybe not a "pure Guassian", but a bell shaped curve none the less.

I'm also curious why you think probability and statistics can not be used to describe how a steam locomotive works? After all, Monte Carlo routines are often used now in mechanical engineering design...


Dear GP40-2,
Due to the reasons I have sighted as points 1, 3, and 4 above, a horsepower curve looks little like a Bell-shaped curve.

I presume by Monte Carlo Routine you mean what is described here: http://en.wikipedia.org/wiki/Monte_Carlo_method. You will notice that these have to do with random numbers.

At the macroscopic locomotive level, as I'm sure you realize, random motions tend to cancel one another out. There's not much that's random on a Big Boy (other than which bolt will rust in place next [:)]).

Sincerely,
Daniel Parks
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    December 2001
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Posted by tree68 on Friday, December 2, 2005 7:49 AM
I don't recall the article saying that HP increased - only that speed could. That would mean that as long as the HP was sufficient to move the train involved the speed could continue to increase until a)the engine ran out of sufficient steam or b)the mechanical forces involved threw the locomotive off the track.

Design considerations obviously limited the locomotives in question to a certain speed. Higher pressures and larger ports would be necessary to achieve higher speeds, not to mention dealing with mechanical issues, first and foremost being the balance of the wheels and rods.

LarryWhistling
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