Phoebe Vet wrote:Perhaps you can help me out here and tell me how to turn off the replies to this thread without turning off all replies.
Perhaps you can help me out here and tell me how to turn off the replies to this thread without turning off all replies.
The instructions is at the very bottom of each of those emails. Just read them and follow what it says.
Oh, by the way... it is the "Notify" button you need to look for since there is no "Email me when someone replies..." button or link.
Bucyrus:
Well, I guess that answers my question.
The answer is "forever".
I guess my wife will continue to be amused.
Wake me up when a railroad, not involved in the tourist industry, actually starts shoveling coal into fireboxes again. I will be the first one out there with my camera.
Dave
Lackawanna Route of the Phoebe Snow
I wouldn't be too worried about the railroads doing what's best in the face of the rising costs of fuel. They have profit margins to maintain and they don't have the same regulation environment that was around half a century ago influencing thier choices.
Phoebe Vet wrote: Norman Saxon wrote: Phoebe Vet wrote: "Topic has 822 replies."How long are you guys going to beat this dead horse?The Railroad History Quiz Game thread has 1,323 replies as of this writing.The Trackside Lounge thread has 889 replies as of this writing.The THE FLAT WHEEL CAFE thread has 1,861 replies as of this writing.Have you complained about how long those "dead horses" are going to be beaten? No? Why not, since you seem to be the resident complainer of thread length?If you don't like a thread, you don't have to read it. Try beating that horse for a change.None of those threads are arguments that are going nowhere. They are just people socializing.No one in this thread has any intention of changing his position. It started out as a valid discussion, but hundreds of posts ago it degenerated into just a pointless argument.I made the mistake of asking a couple of questions in here in an attempt to understand the numbers being thrown around in the debate and now, much to the amusement of my wife, get 30 or 40 e-mails a day showing the posts of the same 3 or 4 guys.Perhaps you can help me out here and tell me how to turn off the replies to this thread without turning off all replies.
Norman Saxon wrote: Phoebe Vet wrote: "Topic has 822 replies."How long are you guys going to beat this dead horse?The Railroad History Quiz Game thread has 1,323 replies as of this writing.The Trackside Lounge thread has 889 replies as of this writing.The THE FLAT WHEEL CAFE thread has 1,861 replies as of this writing.Have you complained about how long those "dead horses" are going to be beaten? No? Why not, since you seem to be the resident complainer of thread length?If you don't like a thread, you don't have to read it. Try beating that horse for a change.
Phoebe Vet wrote: "Topic has 822 replies."How long are you guys going to beat this dead horse?
"Topic has 822 replies."
How long are you guys going to beat this dead horse?
The Railroad History Quiz Game thread has 1,323 replies as of this writing.
The Trackside Lounge thread has 889 replies as of this writing.
The THE FLAT WHEEL CAFE thread has 1,861 replies as of this writing.
Have you complained about how long those "dead horses" are going to be beaten? No? Why not, since you seem to be the resident complainer of thread length?
If you don't like a thread, you don't have to read it. Try beating that horse for a change.
None of those threads are arguments that are going nowhere. They are just people socializing.
No one in this thread has any intention of changing his position. It started out as a valid discussion, but hundreds of posts ago it degenerated into just a pointless argument.
I made the mistake of asking a couple of questions in here in an attempt to understand the numbers being thrown around in the debate and now, much to the amusement of my wife, get 30 or 40 e-mails a day showing the posts of the same 3 or 4 guys.
That's interesting. I cannot turn off the email automatic notification either, and this is the only thread that notifies me. Well if a thread goes nowhere, who cares whether it is an argument or a socializing thread? Without going back to check, I do recall that you posted a very worthwhile question a ways back. As far as people on this thread changing their positions, I have a very hard time even seeing what their positions are. So I say we need to keep on arguing until we get it all straightened out.
Lars Loco wrote: Hi Michael,as I reread the later part of this thread and postings several times again, the discussion turned to became out what transition-system is better: A mechanical / reciprocating against an electric one.The later one does not care if the power-plant / prime-mover of a locomotive is- a diesel,- gas- coal- hydrogenor...whatever fueled engine, independent they are internal combustions, approach as a turbine or jet engine. The last steam-engines were built with 10-15% machine losses (from the Cylinders), new diesels have less than 10%. This should be done with actual engineering, too, but better? No.'Cause other transition-systems, e.g. hydraulic, never really widely approached, I hardly believe there is a better transition than the electric.Now, you could have the benefit of a:- computer-controlled,- high availability,- rugged and stable system,and even could use the braking energy. Electric-engines turn their energy into the power-net back again (commonly used in Europe and other), why not keep the energy into batteries (which also have become better now), placed into a "Tank-car" as Mr. Modelcar suggested?Steam-engines keep a high potential energy in their boilers, but it takes some time to produce it. With a combustion-engine just start it and off you go...Turbines work in a small frame of load efficiently. Not saying there would not be an application for this, but a limited one.Nowadays, even cars (hybrid) are partly driven with electric-motors, to make them more efficient.Regarding the last posts about TE curves Steam vs. Diesel that:... Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) ...If both engines have same HP they will deliver same HP.I think there is a lot of confusion about particular engine-Types from both sides, the diesel (First Gen., Second Gen., DC/AC) ones vs. the 4-8-4s, 2-6-6-4 and so far. It is pointless to compare them. Yes, steam-engines were magnified machines, sometimes more powerful than that what we have now, but please have a look at my post earlier: The 5600DBHP Y6B N&W engine will just half win against a 4000DBHP GE-4400AC engine, given a speed range of 0-60mph.I did not calculate the area beyond their TE-Curves exactly, nevertheless, we compare technology 50 years apart.Yes, one point is true, with the arrivals of the first and second generation diesels, the railroads were not happy with the speed capabilities of their diesel-engines, because the had to buy many, expensive units to beat steam-locomotives delivering 5000-6000 or more HP. Quite possible that the steamers also had some extra-reserves.Having a lot of respect, that people achieved many years ago, erecting power plants more than 500tons and running about 70mph, anything else than awesome would be totally inappropriate to describe them, but some must wonder, is there really a need to built more than 4000-6000DBHP freight engines? Even the U.P. ( = U.nlimited P.ower) came to the economic conclusion that smaller, but less powerful units than their 5000-6600HP Double-diesel engines are enough. And no, it was not the reason that if one prime-mover fails, the whole locomotive was out of service, it were just rising maintenance costs (frame cracking).As far as I know, most RR nowadays are quite happy with their 4000HP engines. The benefit nowadays is: The better transition of energy.What makes me really think is, how we can use steam as a efficient transition-system? As a turbine? Limited use. Reciprocating/Classic design? The transition-system goes lost while using it.Condensing concepts are also of limited use.While we can debate about various kinds of fuel, burning processes, in my opinion, the electric-transition is the best and there is still place to refine it in future. Lets use Cables near superconductor capabilities and maybe we have transmission systems near 99%. Hard to beat with mechanic.Excitingly waiting your replies!Kind regardsLars
Hi Michael,
as I reread the later part of this thread and postings several times again, the discussion turned to became out what transition-system is better:
A mechanical / reciprocating against an electric one.
The later one does not care if the power-plant / prime-mover of a locomotive is
- a diesel,
- gas
- coal
- hydrogen
or...whatever fueled engine, independent they are internal combustions, approach as a turbine or jet engine.
The last steam-engines were built with 10-15% machine losses (from the Cylinders), new diesels have less than 10%. This should be done with actual engineering, too, but better? No.
'Cause other transition-systems, e.g. hydraulic, never really widely approached, I hardly believe there is a better transition than the electric.
Now, you could have the benefit of a:
- computer-controlled,
- high availability,
- rugged and stable system,
and even could use the braking energy. Electric-engines turn their energy into the power-net back again (commonly used in Europe and other), why not keep the energy into batteries (which also have become better now), placed into a "Tank-car" as Mr. Modelcar suggested?
Steam-engines keep a high potential energy in their boilers, but it takes some time to produce it. With a combustion-engine just start it and off you go...
Turbines work in a small frame of load efficiently. Not saying there would not be an application for this, but a limited one.
Nowadays, even cars (hybrid) are partly driven with electric-motors, to make them more efficient.
Regarding the last posts about TE curves Steam vs. Diesel that:
... Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) ...
If both engines have same HP they will deliver same HP.
I think there is a lot of confusion about particular engine-Types from both sides, the diesel (First Gen., Second Gen., DC/AC) ones vs. the 4-8-4s, 2-6-6-4 and so far. It is pointless to compare them. Yes, steam-engines were magnified machines, sometimes more powerful than that what we have now, but please have a look at my post earlier: The 5600DBHP Y6B N&W engine will just half win against a 4000DBHP GE-4400AC engine, given a speed range of 0-60mph.
I did not calculate the area beyond their TE-Curves exactly, nevertheless, we compare technology 50 years apart.
Yes, one point is true, with the arrivals of the first and second generation diesels, the railroads were not happy with the speed capabilities of their diesel-engines, because the had to buy many, expensive units to beat steam-locomotives delivering 5000-6000 or more HP. Quite possible that the steamers also had some extra-reserves.
Having a lot of respect, that people achieved many years ago, erecting power plants more than 500tons and running about 70mph, anything else than awesome would be totally inappropriate to describe them, but some must wonder, is there really a need to built more than 4000-6000DBHP freight engines? Even the U.P. ( = U.nlimited P.ower) came to the economic conclusion that smaller, but less powerful units than their 5000-6600HP Double-diesel engines are enough. And no, it was not the reason that if one prime-mover fails, the whole locomotive was out of service, it were just rising maintenance costs (frame cracking).
As far as I know, most RR nowadays are quite happy with their 4000HP engines. The benefit nowadays is: The better transition of energy.
What makes me really think is, how we can use steam as a efficient transition-system? As a turbine? Limited use. Reciprocating/Classic design? The transition-system goes lost while using it.
Condensing concepts are also of limited use.
While we can debate about various kinds of fuel, burning processes, in my opinion, the electric-transition is the best and there is still place to refine it in future. Lets use Cables near superconductor capabilities and maybe we have transmission systems near 99%. Hard to beat with mechanic.
Excitingly waiting your replies!
Kind regards
Lars
You're missing the boat there Lars. A compression-ignition engine is still the best way to generate on-board current for traction motors, but of course that same engine is limited to the most expensive fuel out there, for now and the foreseeable future.
If you start using turbines to generate the current, yes you can now have greater fuel flexibility (except for solids like coal), but due to the need of turbines to run full out or not at all to achieve efficiency, you now need a turbine array to allow different speed settings. More complexity, more costs, thus savings of using lower cost fuels such as CNG is offset by other costs. Perhaps this might be the area where technology will allow cost effectiveness. That remains to be seen.
Stored energy concepts will favor DE's only where there is a demand for constant stop and go movements, aka yards.
The ability to utilize all forms of fuel, solid or liquid or any combination thereof, favors external combustion over internal combustion.
The emissions profile will still favor external combustion over internal combustion, except for CO2 where coal is utilized for the former compared to liquid or compressed gas fuels for the latter.
Finally, the TE at speed dynamic will always favor reciprocating engines over electric traction engines in terms of doing so at lowest possible costs. This is where I have less confidence than you that technological improvements will allow DE's to achieve the same TE/speed profile as reciprocating steam.
And does anyone really need a locomotive that can start up and go at a moment's notice?
As long as it takes for one or more of the railroads to realize they have options or until the cost of gas comes back down to $2.00... personally I believe the former will come before the latter.
JayPotter wrote: Michael, I'm not sure what "data" Anthony had in mind; but it would be helpful to me if you would at least tell us which specific locomotives you're using as a basis for your conclusion. Your approach of "removing" some tractive effort from consideration because of "reality" is statistically ingenious; but I'm unclear why you took that approach because the "catastrophic failures" that you mentioned simply don't happen with AC-traction units (which can operate essentially indefinitely at speeds below 11 mph without overheating their traction motors) and seldom happen with modern DC-traction units (which have thermal protection circuits that prevent their traction motor from overheating).
Michael, I'm not sure what "data" Anthony had in mind; but it would be helpful to me if you would at least tell us which specific locomotives you're using as a basis for your conclusion. Your approach of "removing" some tractive effort from consideration because of "reality" is statistically ingenious; but I'm unclear why you took that approach because the "catastrophic failures" that you mentioned simply don't happen with AC-traction units (which can operate essentially indefinitely at speeds below 11 mph without overheating their traction motors) and seldom happen with modern DC-traction units (which have thermal protection circuits that prevent their traction motor from overheating).
Well, if the thermal protection "protects", the Traction Motor isn't producing Tractive Effort. The point was that there is no TE available -- either the engine shuts down, or the motors burn up.
AC motors do solve the problem -- at much higher cost and that's really part of the meme of this thread regarding Steam -- cost advantages.
But, while an ingenious solution at great cost, statistically, it doesn't resolve the fact that, as motive power fleets, the area under the curve is greater for Steam. If the current motive power fleet of today were weighted by AC power, the Steam curve would still have a larger surface area of TE at speeds between 0 and 40 mph, if my guess that the current industry fleet of AC power constitutes something like 20% of the total available horsepower is anywhere near the mark, and it may not be.
....As a bystander and reader of much of this discussion....That last post was interesting.
Quentin
MichaelSol wrote: AnthonyV wrote: MichaelSol wrote: Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) and all of that power advantage exists between 0 and 11 mph because the Diesel-electric can't operate there continuously without catastrophic failure.That's interesting. Could provide the data from which you draw that conclusion?Published Tractive Effort Curves; but since these show the Diesel-electric producing prodigious TE below 11 mph, removing that TE because the reality is different for continuous TE. Then adding the remaining area under the respective curves for the respective motive power types to determine the total area of each kind of TE; then creating a percentage relationship of one area measurement to the other.
AnthonyV wrote: MichaelSol wrote: Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) and all of that power advantage exists between 0 and 11 mph because the Diesel-electric can't operate there continuously without catastrophic failure.That's interesting. Could provide the data from which you draw that conclusion?
MichaelSol wrote: Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) and all of that power advantage exists between 0 and 11 mph because the Diesel-electric can't operate there continuously without catastrophic failure.
Indeed, for locomotives of the same maximum horsepower, the Steam engine has nearly 40% more Tractive Effort continuously available between 0 and 40 mph than the Diesel-electric (the area under the respective Tractive Effort curves) and all of that power advantage exists between 0 and 11 mph because the Diesel-electric can't operate there continuously without catastrophic failure.
That's interesting. Could provide the data from which you draw that conclusion?
Published Tractive Effort Curves; but since these show the Diesel-electric producing prodigious TE below 11 mph, removing that TE because the reality is different for continuous TE. Then adding the remaining area under the respective curves for the respective motive power types to determine the total area of each kind of TE; then creating a percentage relationship of one area measurement to the other.
Michael:
Could you provide us with the specific published tractive effort curves?
Anthony V.
If I were suggesting examplar diesel models for your 0-to-40 mph comparison, I'd use either the AC6000CW or the AC4400CW. The former is rated at about 52,000 lbs TE at 40 mph and 180,000 lbs TE at speeds below about 10 mph. The latter is rated at about 36,000 lbs TE at 40 mph and 180,000 lbs TE at speeds below about seven mph. The maximum TE of both models can be increased to 200,000 lbs with advanced software. And since both models are AC-traction units, they are capable of producing those levels of tractive effort at those speeds for essentially indefinite periods of time without "catastrophic failures".
So those are the diesels that I would use for comparison purposes. I'm not suggesting that you should be using either of those same diesels in your comparisons. I'm just suggesting that your comparisons would mean more -- at least to me -- if you would let us know what diesel you are using.
Thank you.
Bucyrus wrote:Conclusion: At these levels of hp, both locomotives have nearly identical hp curves; so neither has an advantage over the other in pulling a train.
Well, there is a difference, it's just not particularly large, and is within the practical limits of adhesion under a variety of circumstances. That is, under a variety of circumstances, their performances are close enough that one will outpull the other in such a fashion that for the practical purposes of pulling a given train they both fall within a given expected performance range. However, as pointed out earlier, the overall performance of these engines, due to the electrical limitation of the traction motors, gives the Steam engine a significantly greater Tractive Effort capability over a broader range -- absolutely equal at higher speeds, but particularly at lower speeds where a train might be forced to drop speed to acquire Tractive Effort to overcome resistance due to grades and curvature.
MichaelSol wrote: Bucyrus wrote: Michael, I did not think I was being shrill and arguing with a mind made up. It's still not made up. And I don't have a religious conviction that steam must be inferior.Don't take it personally. My students would gladly tell you I have two rules in class: 1) there IS such a thing as a stupid question, and 2) what's it cost? The idea is -- do your homework (read the book), don't make assumptions, think about it, and calculate everything through to the ultimate financial impact. I am not well designed for Trains forums where these useful rules are inverted ...
Bucyrus wrote: Michael, I did not think I was being shrill and arguing with a mind made up. It's still not made up. And I don't have a religious conviction that steam must be inferior.
Michael, I did not think I was being shrill and arguing with a mind made up. It's still not made up. And I don't have a religious conviction that steam must be inferior.
Don't take it personally. My students would gladly tell you I have two rules in class: 1) there IS such a thing as a stupid question, and 2) what's it cost? The idea is -- do your homework (read the book), don't make assumptions, think about it, and calculate everything through to the ultimate financial impact. I am not well designed for Trains forums where these useful rules are inverted ...
I agree that homework, calculations and cost effectiveness are certainly important, but I am skeptical of a prohibition on making assumptions. Assumptions help frame a possible explanation. So rather than just looking for an explanation, I think it helps to imagine every possible explanation, and then work backwards to verify them if possible.
Just to review, I have a question for you. During our discussion of HP/TE, you have established the following:
If you compare a 5600 hp diesel to an 8400 hp steamer that have equal weight on drivers:
The steamer develops higher maximum hp.
The steamer develops its maximum hp at a relatively high speed during its acceleration, while the diesel develops its maximum hp at a relatively low speed during its acceleration.
Conclusion: At these levels of hp, the steamer has an hp curve that gives it an advantage over the diesel in pulling a train.
If you compare a 3000 hp diesel to a 3000 hp steamer which has 1/3 the weight on drivers of the diesel:
The two locomotives develop identical maximum hp.
The two locomotives develop their maximum hp at a relatively low speed during their acceleration.
Conclusion: At these levels of hp, both locomotives have nearly identical hp curves; so neither has an advantage over the other in pulling a train.
Is my understanding of this correct?
The Steam era lasted 120 years, the Diesel-electric era on railroads is less than 60 years old, and may be coming to a close. I'm not sure its even useful to look for a "permanent" solution. The Diesel-electric decision certainly didn't: it looked at costs at the time, mainly fuel. Knowledgeable people warned at the time that the "trends" suggested that the price of fuel was a short term phenomenon and predicted that the coal/oil price differential would eventually flip. Brown said that in his paper. He was right.
These very long term assessments remind me of the answer to the inevitable question "what about in the long run?" to which Lord Keynes answered, "In the long run we are all dead."
Here's an interesting except from the 5AT steam engine page. Remember this is the steam engine design for the 21st century. They address the issue of oil firing vs coal firing in the locomotive:
In May 2008, John Tasker wrote to ask: "With the current price of oil and the re-opening of some coal mines, has any thought been given to coal-fired alternative mentioned in the design spec for the 5AT?".
Chris Newman offered the following response:
"What you say about the effects of oil price rises is quite correct. And yes, consideration is being given to the use of coal as an alternative steam locomotive fuel. No serious thought has yet been given to burning coal in the 5AT, we have for some time been looking at the possibility of developing a freight haulage version of the 5AT specifically for coal haulage duties that would burn coal as its fuel. I have done quite a lot of work over the last four years in developing and putting forward economic arguments in favour of steam traction wherever coal and labour costs are low. In fact I presented a paper on the subject at the conference on modern steam traction at York in December 2006, and have developed my cost models quite a lot further since then.
As for the 5AT, it is still difficult to consider coal as a fuel when the rest of the railway is using gas oil. Whilst ever that situation exists then logistically gas oil will remain the preferred choice, bearing in mind that the 5AT is intended to operate in the modern railway environment. Of course it will not be able to compete with diesel traction in terms of fuel consumption, which is why it is intended to operate only in the tour train market in which steam traction has particular appeal. Furthermore, the use of oil as fuel brings with it several subsidiary advantages including ease of firing, reliable combustion and steam generation, zero spark emissions, no tube abrasion, no ash disposal, no smokebox cleaning, and greater operating range.
Lump coal is a nasty fuel that is difficult to fire, unreliable in its combustion, creates ash, emits char that erodes tubes, fills up smokeboxes and throws out sparks. GPCS combustion certainly reduces these problems but it does not eliminate them whereas the use of pulverized coal would, which is presumably why power stations all prefer to use pulverized coal these days. The technology was successfully developed and tested in steam locomotives in Germany and Australia and the UK the 1940s and 50s, so presumably it can be resurrected for use again. Certainly it would be the best option for the 5AT if/when oil prices become so high that the railways have to think about alternatives to diesel traction. In the meantime, if we can develop a market for steam traction for coal haulage in developing countries, then this would be where pulverized coal combustion technology should be tried and perfected.
The sad thing is that even coal is not an inexhaustible fuel, and whilst "peak oil" is just probably around the corner (if it's not already past), "peak coal" is not so many years away. Brian McCammon reports that peak coal may be only 17 years away, and if he's right then coal is not going to be a panacea for an oil-depleted world. Our children are going to be facing some difficult times in the future, and more than likely we will witness them ourselves. Nuclear power will inevitably have to take up some of the demand for power, but I'm not optimistic that renewable fuel and power sources will be able to fill the gap. Food-based bio-fuels may keep rich countries' SUVs going, but they are not going to help the poor and the starving. The best option that I can see is "fuel from waste" but the UK and other governments seem to be astonishingly slow in promoting it.
JonathanS wrote: MichaelSol wrote: However, something to remember: the average US train and locomotive combination encounters the following average North American rail system gradient: 0.00000%.While that statement is an obvious truth for the rolling stock, what is the average gradient in the US for the lading?
MichaelSol wrote: However, something to remember: the average US train and locomotive combination encounters the following average North American rail system gradient: 0.00000%.
However, something to remember: the average US train and locomotive combination encounters the following average North American rail system gradient: 0.00000%.
While that statement is an obvious truth for the rolling stock, what is the average gradient in the US for the lading?
Back in the days of coal and iron ore coming out of mountain ranges, and being such a significant percentage of railway tonnage, I would not be surprised if the average gradient were negative. Today, Powder River tonnage and far heavier import traffic might change that, but that would be an interesting speculative point.
AnthonyV wrote: Don't the specifics characteristics of a route (grades, grade length, curvature, etc.) determine the amount of power assigned to pull a certain tonnage?I suppose that if power was assigned based on the average topography of the county, all trains of a certain tonnage would be pulled by the same power. I also suppose there would be no need for helpers.
Don't the specifics characteristics of a route (grades, grade length, curvature, etc.) determine the amount of power assigned to pull a certain tonnage?
I suppose that if power was assigned based on the average topography of the county, all trains of a certain tonnage would be pulled by the same power. I also suppose there would be no need for helpers.
I suspect you are asking a question you know the answer to. It is true that to maintain a given running speed in the mountains, takes more power than out on the flats. I don't know if that's as obvious as it seems to me. The GE program actually lights up in red those portions of a given route that are underpowered for the given desired track speed, and tells you what the estimated track speed would be for the specified conditions -- power and train size. With grades and curvature adding resistance, you can decide to add power, a helper or take the drop in speed as is. The Diesel-electric offers "a" strength in that regard because below 6 mph or so it can really put the TE to the rail, and if you are running a one-train-a-day railroad, the cost justifies letting that trainset slug it out without additional power or a helper.
Just one problem for anyone who thought that slow speed power was a big boost on a heavy grade: the DC traction motors would burn up pretty quickly when run long under 11 mph.
Ironically, because of that, even as the superiority of the Diesel-electric appears greatest -- on paper -- at the lower speeds, you have the practical circumstance that Steam worked better in sustained use at those same speeds because it could actually work a train at those speeds. And, since the Diesel-electric had to avoid that operating range, the train had to be overpowered with Diesel-electric horsepower, compared to what was necessary with Steam power, which could just lean into the harness -- and pull that train, no matter what.
So, the locomotive that could actually "slug it out" on a long grade by dropping speed to obtain Tractive Effort was the Steam engine, not the Diesel-electric of that era.
And this is the supreme irony for those who felt that MAXIMUM horsepower comparisons "meant" something: what it meant was that the train with the Diesel-electrics, encountering grades and curvature, had to assign substantially more actual horsepower --using the MAXIMUM horsepower measurement -- to the train with the Diesel-electric than for the Steam, because the Diesel-electric was unable to drop down to the speeds that the Steam engine could in order to develop enough Tractive Effort to keep the train moving without burning up the traction motors. In order to have that Tractive Effort at the higher speeds, that train needed more absolute hp as measured by the MAXIMUM horsepower metric. Since these ratings are in discrete, not continuous, units, for locomotives of equivalent MAXIMUM horsepower, a given train could get by with one Steam engine (say 3,000 hp), but needed two Diesel-electrics, or 6,000 hp, to get over the same route. But, it's a close call: within the margin of each power type's adhesion due to environmental circumstances, with the Steam engine having perhaps a definitive margin due to its lower likelihood of slipping.
And it's not just that the peculiar fascination with MAXIMUM horsepower was weird to begin with, its because it means that the ACTUAL horsepower assigned to the train required more Diesel-electric hp on that basis; that the total of MAXIMUM horsepower had to be significantly higher for the Diesel-electric than for the Steam. The use of the metric alone gave exactly the wrong answer, if the train had to work in the range of speeds at which the Diesel-electric was thought to be strongest.
And that is something neither the equations nor the power curves show you.
But arguendo that a Diesel-electric could operate in that range, and now with AC they can, the Diesel-electric does something there if and only if 6 mph running works from the standpoint of cost, capacity, and congestion. But, there is a "cost" to that benefit and it is inevitably found in the cost of lower average train speeds, which can range from negligible to 90% of your allocated net profit. And if you run a division's average train speed down to 6 mph or so -- or at least bottleneck at that speed -- there is an enormous loss of line capacity and that can be far more expensive than the cost of helper service in terms of opportunity cost -- lost revenue -- and higher operating costs per ton mile.
So, at more typical mountain speeds that a railroad might want to run, the answer for both motive power types remains either more power or helpers because the Diesel-electric's key distinctive strength really puts a burden on the railroad's key constraints: time and capacity. And by the same token, that big Steam engine has some strengths at higher speeds that come in handy as well.
If I am recalling correctly, railroad helper service during the days of Steam accounted for something like 1.2% of railway ton miles in the United States and after Dieselization accounted for something like 1.0% of railway ton miles. These could be wildly off as it has been a while, and might be high by a full decimal point, but the substance of my recollection on the point is that Dieselization didn't make that much difference on that particular point in the broader scheme of things. Indeed, if the argument turns on whether or not it made sense to spend 100% more in purchase price per horsepower over the entire power fleet, just to purchase an advantage for 0.2% of the ton-miles, I would say the bet was a poor one.
Too, that decline in helper service occured during a period of a significant drop in overall railway tonnage. Dieselization may have had less to do with the overall decline in helper service than many have attempted to argue.
And while the whole discussion is of transcendent importance to people who like to focus on single points of data -- the data set as a whole reflected the fact that fuel cost savings represented about 95% of the savings obtained by Dieselization, although as Brown points out, after the financing was factored in, there was a negative net rate of return from the transition.
MichaelSol wrote:[ However, something to remember: the average US train and locomotive combination encounters the following average North American rail system gradient: 0.00000%.
A college prof!!! Now I see why you answer and argue as you do.
Lars Loco wrote:There is a nice comparison between Y6b, Class A and Jawn Henry.
Thank you. I was especially interested in the steam turbine data. I couldn't tell if its maximum TE was 180K or if the curve just wasn't plotted any higher. The CSXT units that I mentioned would be capable of 216K (i.e. 36K per traction motor); however the 200K limit was imposed to prevent two-unit consists from breaking drawbars by exceeding 400K.
You guys are trying to teach a pig to sing.
Never try to teach a pig to sing; it wastes your time and it annoys the pig.
I do not own much Steam-Books, unfortunately, but please have a look at
http://locofonic.alphalink.com.au/te1.htm
There is a nice comparison between Y6b, Class A and Jawn Henry. That's my information source.
Kind Regards
Lars Loco wrote:The only succesful and widely used Steam engine that produces such a high TE at low speeds were the later, refined Y6b ( in the ~'50ties and later).
I have -- but have never thoroughly read -- a two volume set of books by Eric Hirsimaki entitled Black Gold - Black Diamonds. They deal with the PRR's shift from steam to diesel; and I have a vague recollection that they mention Y6b performance in comparison to the performance of PRR steam power. Being from West Virginia, I've heard of Y6bs; but I've never concentrated enough on non-B&O steam to learn much about them.
Hi Jay,
the only succesful and widely used Steamengine that produces such a high TE at low speeds were the later, refined Y6b ( in the ~'50ties and later)
They could deliver a starting TE of 170.000lbs, to 150.000lbs at 7mph and 125.000 at 10mph.
From here, until 40mph they had more output than a 4400AC, after 40mph the diesel will surpass.
Hope these infos are useful for you.
AnthonyV wrote:Don't the specifics characteristics of a route (grades, grade length, curvature, etc.) determine the amount of power assigned to pull a certain tonnage?
That's correct. And system-wide characteristics of a railroad can determine the type of power that it acquires.
One of the primary characteristics that CSXT desires in its road locomotives is the ability to minimize stalling on grades. As a result, its current locomotive-of-choice is an AC-traction unit with a maximum horsepower of about 4400 and a fully serviced weight of about 431,000 pounds. One of these units produces about 20,000 pounds of TE at 70 mph and about 47,000 pounds of TE at 30 mph. Rail conditions permitting, it can produce 200,000 pounds of TE in the speed range from less than one mph to around seven mph; and since it's an AC-traction unit, it can continue to operate within this speed range for an essentially indefinite length of time.
Knowing next to nothing about steam-locomotive performance, I have no idea what the steam-technology counterpart to this diesel would be.
Our community is FREE to join. To participate you must either login or register for an account.