Could steam make a comeback?

[fredswain]

I have always been fascinated by steam. I'm into live steam in 1-1/2" and am currently working on one of my own. I consider it a life project though so it won't be any time soon that I complete it. I've started with some existing plans. As a mechanical engineer I am modifying and improving them as I feel neccessary. Only after I redesign certain things will I actually begin constuction.

I love going to see working steam engines. There is just something about them that seems to be alive. The more complicated, the more interested I get. Saying that, I love watching the big modern engines go roaring by too. I'm fascinated with machinery in general. I see merits in each system and from the standpoint of whether or not steam could make a comeback, I'll stay out of. I merely only want to know the technical aspects and the hows and whys of each system's advantaged and disadvantages. My goal wasn't to directly prove anyone wrong. It was merely to figure out how it all actually works and now I feel I grasp it. There is much I couldn't get into words but I can picture in my head.

This whole thing got me thinking in relation to cars as I've always thought that the perfect hybrid system wasn't parallel but rather series as locomotives do it and I've always thought the best application of it would be on the road going versions of trains which are tractor trailers. Now I need to rethink the whole thing. Fortunately the weights we are talking about don't scale down the same to give the same proportions required for traction and power. I'll run the numbers in a table for them too. It's just something else for me to wrap my head around and plug numbers into. In this case trains made me think about road going vehicle propulsion a bit differently.

I can't criticize this forum for it's members as from what I've seen it's actually a very friendly place. There are disagreements on every forum. That's just the way it goes. I'm an avid Mazda rotary fanatic and am a moderator on the RX-8 forum and I can tell you that this place seems quite docile by comparison and they are even quite tame compared to many others. Debate is a good thing. It forces people to think differently. In this case, this topic made me think about the differences in power generation between steam vs diesel/electric as well as getting it to the rails. As far as I'm concerned, this little argument has been a benefit.

[MichaelSol]

The entire point of the example and it's assumptions was to see if there was a trend that corroborated the chart shown here. As an unbiased person in the debate who is trying to learn, I just wanted to see if it holds true. In fact it does which is fascinating.

...What I learned in that exercise was that tractive effort has 3 things that determine it at any speed and with any engine. Those 3 things are torque at the rails, wheel diameter, and weight on the drive wheels.

Compare to comments on this thread:

I think the thing that is made up is the concept of equal weight on drivers.  It is irrelevant.

Anthony V.

There are people on these forums, and they almost always nearly show up on the same subjects in the same contexts, who bring not only an extraordinary bias, but a near malice to the conversation. I doubt that I have seen so much personal venom generated as discussions about steam vs diesel, unless it was the contingent that argued about wheat rates ad nauseum -- and not a single one ever apologized after the GAO came out with its landmark study showing that wheat rates had, in fact, increased. Yup, they were flat out wrong. Oddly, it was nearly the same group on these forums that misrepresented that data right and left, that moved on to steam vs diesel.

Like you, I had zero interest in, at best, little understanding of, Steam power -- my background was railway electrification, and although I had worked with H.F. Brown, it was on diesel and electric issues, notwthstanding his landmark study on Steam vs. Diesel. I remembered being vaguely surprised at Steam maintenance costs -- it went against my own conventional understanding -- but it was also about a bygone era; certainly one that I was never enamored with, nor had any reason to be interested in. However, a closer look at Brown's paper recently brought forward many questions, and suddenly these forums took on the attitude of "ignore the man behind that curtain" on issues of both performance and economics.

  I find it very interesting because I've always been under the assumption that a diesel with it's average power being everywhere, should have been the winner. When you only focus on a part of the information though, anything can be made to look like you want it to. This was very fascinating to me.

It was a revelation to me as well. I had no idea how well suited Steam power was to the practical needs of railway operation. As someone with a "constant horsepower" background -- traction motors pulling from a catenary -- the idea of a whole different philosophy of propulsion was a little hard to get a handle on. It wasn't intuitive for me at all. Like you, I had to run this through some modelling to convince myself.

For me, it goes back to Brown's paper. I consider it a model of its kind. Having worked with Brown, and debated this issue in detail on these forums, I can conclude that there is not one single person here qualified to sharpen Brown's pencils, let alone challenge him on the merits his study.

I appreciate your efforts in this regard. Far too few people here are willing to do their homework before they offer opinions. It is the sad sickness of Trains forums.

 

[fredswain]

Hint: You are forgetting that you have to cut off the steam due to increasing back pressure to get the locomotive to accelerate. This is a physics property ,despite what others in this thread claim, and can not be ignored. Once you start limiting steam into the cylinders, a steam locomotive is no longer a constant thrust (e.g. tractive effort) /increasing HP machine, it becomes a constant HP/ decreasing tractive effort machine JUST LIKE A Diesel-Electric.

Actually I didn't forget anything. I tried to make it clear numerous times that the example was based "in a perfect world" which we all know isn't like that in reality. The entire point of the example and it's assumptions was to see if there was a trend that corroborated the chart shown here. As an unbiased person in the debate who is trying to learn, I just wanted to see if it holds true. In fact it does which is fascinating. It should be obvious that neither engine can sustain power indefinitely as speed rises.

What I learned in that exercise was that tractive effort has 3 things that determine it at any speed and with any engine. Those 3 things are torque at the rails, wheel diameter, and weight on the drive wheels. That's it. In a perfect world (there's that term again), this tells us howmuch an engine can theoretically pull, and at what speeds. Running out of tractive effort does not mean we run out of power. Bringing that into the mix will tell us what our theoretical limit of adhesion is. For all intents and purposes tractive effort can be simplified to be thought of as torque at the rails. Remember that torque and horsepower while mathematically related are related through another constant that needs to be known and that is time or in the case of our example, wheel speed which is really just distance over time.

Modern locomotives aren't only trying to increase tractive effort, they are trying to control wheel slip, or adhesion. Everything on paper is nothing more than a theoretical limit. Modern traction control is tryng to get the locomotives closer and closer to that limit.

Torque at the wheels seems obvious now when it comes to TE. TE is measured in lbs. A locomotive is weighed in lbs and torque is rated in ft lbs. Simple math to convert out the distance from ft lbs takes us to the theoretical limit of tractive effort.

Remember it was nothing more than an example. That's it. The end numbers didn't matter. The trend did. I could sit down and mathematically take the other things into account but that would probably take a while and I'd need more detail off of each engine to be compared and as far as I'm concerned, the answer has been proven. I find it very interesting because I've always been under the assumption that a diesel with it's average power being everywhere, should have been the winner. When you only focus on a part of the information though, anything can be made to look like you want it to. This was very fascinating to me.

[MichaelSol]

So you're saying a diesel locomotive can't replace a stationary steam boiler? This seems to come under the "no kidding" heading. What has that got to do with current railroad motive power?

Tell you what. Go back to the Steam vs Diesel thread where you spent 20 pages denouncing H.F. Brown's study because it was "unpublished" and "obscure" and "no one ever heard of it." Then go and read the published article from the most widely read professional engineering journal in the world, the article of which is now widely available on the internet, and then go and read David P. Morgan's editorial in Trains Magazine published to a nationwide audience, all about H.F. Brown's Dieselization study, and clarify, if you will, your entirely false statements on the matter. And when you do, and become an honest broker of opinion and comment instead of what you were there, you can ask questions, and I will gladly answer them for you.

[TomDiehl]

Interesting News Item: 

No Job for a Diesel

"The boiler at the Oak Grove Dairy sprung a leak on Sunday and for a while Francis Trudell, manager of the plant, was in a quandary. The plant operates 24 hours a day and had to be kept running somehow. Mr. Trudell went to Minneapolis early Monday and rented a locomotive from the Milwaukee Road. It was brought out immediately and workmen had it hooked up and the creamery was in full operation again in the afternoon. Mr. Trudell expects the creamery boiler to be in working order again by the end of the week." from the Norwood (Minn.) Times, Dec. 6, 1946. Milwaukee Road Magazine, January, 1947.

So you're saying a diesel locomotive can't replace a stationary steam boiler? This seems to come under the "no kidding" heading. What has that got to do with current railroad motive power?

[MichaelSol]

Interesting News Item: 

No Job for a Diesel

"The boiler at the Oak Grove Dairy sprung a leak on Sunday and for a while Francis Trudell, manager of the plant, was in a quandary. The plant operates 24 hours a day and had to be kept running somehow. Mr. Trudell went to Minneapolis early Monday and rented a locomotive from the Milwaukee Road. It was brought out immediately and workmen had it hooked up and the creamery was in full operation again in the afternoon. Mr. Trudell expects the creamery boiler to be in working order again by the end of the week." from the Norwood (Minn.) Times, Dec. 6, 1946. Milwaukee Road Magazine, January, 1947.

[wsherrick]

I had to think about this for a while and run some math formulas but I think I've figured out why a steam engine has a higher tractive effort. It actually wasn't that hard to prove. For my simple comparison I used some made up numbers trying to equal things out on paper and making some 100% efficiency assumptions. The actual answer isn't what is important, it's the trend that is. The whole idea was to make a mathematical chart that would need to prove true by showing that the diesel in some way was more efficient (for lack of a better word) blow a certain point with the steam eclipsing it above. The trend in my example did hold true.

For my examples, I assumed that each engine could get the same peak power to the rails. I just for example sake used 3000 hp. I also decided on a max top speed for which to measure this power at. I used 60 mph. The weight of the locomotive(s) was actually not relevant to determine a trend. It is relevant to see where the final lines cross.

My assumption was that at all mph points on my chart, the diesel/electric engine made 3000 hp. That's what it does everywhere. Again it assumes 100% efficiency which isn't going to happen. For the steam engine, I assumed that it would make 3000 hp at 60 mph and that power would fall linearly with speed. In other words 1500 hp at 30 mph and so forth and so on.

There was one important factor that really affects the results though and I haven't seen it mentioned here. That factor is wheel (driver) diameter. A diesel/electric engine typically has a much smaller diameter wheel(s) than a steam engine does. Obviously there have been many different sizes on both accounts depending on application but the statement is true from the standpoint of generalization. I plugged in 40" drivers for the diesel/electric engine and just for giggles didn't go too crazy and just assumed 50" for the steamer.

Now that we know this, we need to figure out how many times the engine is turning over per mph. It's easy to just figure around 60 mph and then scale the rest of the numbers from there. Once you know wheel rpm, and obviously the larger drivers are turning slower for the same speed, we need to mathematically figure out how much torque is actually getting the the rails based on the amount of power each engine is producing at each rpm. It's just simple math. I will give an example of 3 different rpms that I used. Keep in mind the location that these cross in is not important. All that matters is proving the trend to exist.

My diesel/electric engine makes 3000 hp at every wheel rpm. Again don't kill me for accuracy. With a 40" wheel, and assuming the traction motor spins at the exact same rpm as the wheels, which they don't, at 25 mph, the wheel and motor rpm would be 105.12. At 40 mph at 3000 hp, you have 168.18 rpm. At 60 mph and 3000 hp, you have 252.27 rpm. Bear with me. You need to figure out torque at each rpm now. When you plug it in, you get:

25 mph, 149,885.84 ft. lbs

40 mph, 93,685.34 ft. lbs. 

60 mph, 62,456.90 ft. lbs.                      

Again this is just an example that I shortcutted but the trend is still the same.

Now on to the steamer. With it's larger drivers at 25 mph, it's wheels are spinning at 70.07 rpm. Since I assumed that power was linear with rpm, and it's not, this gave me 1250 hp. At 40 mph we get 112.10 rpm at 2000 hp. At 60 mph we get 168.15 rpm and 3000 hp. Same hp at the same train speed. The key was the plug in the numbers and see if the torque at the rails was greater than that of the diesel/electric. If it is, we've proven it.Here's what I got:

25 mph, 93,692.02 ft. lbs.

40 mph, 93,702.05 ft. lbs.

60 mph, 93,702.05 ft. lbs.

The numbers theoretically should stay the same. They were off for me as I rounded. We also know that this is also a perfect world scenario and that not everything works in the real world as it does on paper and would in reality fall off as rpms rise. Again, this was just to prove a point and see if there is a trend at work. We can see that there is. In my example, the diesel/electric has more torque at the rails below 40 mph but the steamer has more torque at the rails above 40 mph. Now I obviously didn't take into account efficiency differences of each engine in relation to rpm but that's fine. I also didn't take into account the gear ratio between the traction motor and the wheels which would also change the results. RPM's on the motor would rise which would mean torque would go down by the same ratio in relation to the assumptions I made. Suddenly instead of the steamer making more torque at the wheels than the diesel at 40 mph, it would do it well under 20 mph.

Weight comes into play now to finalize the results. We can't have traction without weight. We can see now that after you plug in all the numbers the relevant information to figuring out tractive effort is torque generated at the wheels in accordance with the weight on the drive wheels per unit time. This means if you have less torque at the wheels, you'd need more weight to keep traction compared to the other engine that has more torque at the wheels with less weight. Obviously you hit a point where you can't get enough weight to off set the advantage and now the added weight is working against you. The whole point of this was an exercise to prove a trend and it verifies the info in the tables that have already been posted here.

I get it now. Play with some numbers and see what you get. You'll find the same trend everytime and it matches the trend that a steamer will have more tractive effort above a certain point. Basically an engine that has a flatter torque curve will have a more favorable tractive effort as speed increases. An engine with a flatter horsepower curve will have a less favorable tractive effort as speed increases. It's neat how that works. If each locomotive weighed the exact same and had the same peak horsepower as measured at the rails, the diesel would have a higher initial tractive effort and the steamer would pass it at a certain point, which wouldn't take very long, and would surpass it above that speed.

Hint: You are forgetting that you have to cut off the steam due to increasing back pressure to get the locomotive to accelerate. This is a physics property ,despite what others in this thread claim, and can not be ignored. Once you start limiting steam into the cylinders, a steam locomotive is no longer a constant thrust (e.g. tractive effort) /increasing HP machine, it becomes a constant HP/ decreasing tractive effort machine JUST LIKE A Diesel-Electric.

What??!! Backpressure has nothing to do with the cut off.  It is a function of nozzle performance which has nothing to do with the cylinders.

Backpressure does limit power but not in the way you describe it.

You cut off the steam to the cylinders as the locomotive accelerates because it needs less steam to operate.  The steam is used EXPANSIVELY, therefore much less is needed to move the train at speed. 

Backpressure in the nozzle causes a loss of power more at starting and when the locomotive is operating at capacity at a slower speed with a longer cutoff setting on the reverse lever; not at speed because at starting and when pulling hard you are admitting steam for the full stroke of the piston and steam demand is at its greatest. Those are the points which the nozzle design really effects overall performance.

What finally limits the locomotive to produce more power after a certain speed is the valve's ability to admit enough steam volume in shorter and shorter intervals of time to act expansively on the entire face of the piston.

That phenomenon was the reason for the experimentation with poppet valves. Poppet valves are much more responsive at high speeds than standard piston valves.

This problem has been improved greatly, however; with the introduction of lighter materials and better piston valve design, port modification and steam circut streamlining.

Chapelon was the first to recognize this difficulty and do something about it.  In his studies he learned enough to take a wasteful locomotive with only a 1,500 horsepower maximum output and modify it into a locomotive that produced 5,500 horsepower with a large reduction in steam consumption simply by improving the ability of steam to rapidly enter the cylinder with enough volume to allow for  more power to be developed at speed.

[jmlaboda]

I am behind on messages so I am having to play a little bit of catch-up, so please forgive me...

As to the draw bar and horsepower ?'s i will leave that to others more knowledgable in those areas to answer you, i will say this though, what is the cost to electrify the lines as opposed to going with coal fired steam loco's? on the one hand you have miles and miles of expensive copper lines, poles, substations and new fixed power plants, on the other you have to be able to load coal, provide water, and get rid of ash.

Electrification in its initial stages is not a viable option, not when you consider the costs involved for catenary, substations and power plants.  A good example was Amtrak's electrification of the New Haven, Conn. to Boston, Mass.  It cost roughly $500 Million to do the catenary construction and related support items, which, if it were to be done for a heavy mainline freight hauler would wipe out whatever costs advantages within the first decade or two (if not longer).  The tool-up costs just to prepare for electric operation would be astronomical and impractical in a number of ways.

If you propose to operate steam locomotives west of the Mississippi River, water availability is also going to be a problem for more areas than the BNSF Transcon line across Arizona.

Both of these folks mention the idea of water, where it would come from, how they would get it but the answer to that issue was dealt with over 60 years ago by a number of railroads by hauling auxilary tenders, the same principle that would be of use today.  One big advantage is the size of tank car that can be used for such, which are in a number of ways considerably larger than most auxilary tenders.  The same type of tank cars that were employeed by Burlington Northern could be used to haul water, switched out at certain points along the line as needed, providing for extended operation of the steamer's capability.  And I have plenty of reason to believe that as a part of a modern day steam locomotive there would be a recovery system for the steam so that it could be sent through cooling condensers, helping to use what water the engines had more efficiently.

And what of coal and cinders?  Answers to that were provided back when the concept of the AC3000 was first introduced.  Coal would have been containerized as would the cinders be (sorry, I don't know the technical details off hand), and if the coal was pulverized the amount of coal that could be carried in the containers would be more and cinders that would be created would be considerably less.  As one who has worked with industrial coal-fired boilers I know that to be true. 

Some of the coal that we received by rail and burned was little more than dust but it packed a lot of punch with very little cinders and soot to deal with (and I have been on the opposite end when we would receive trash coal, where over half of it would be unburned cinders, a back breaking part of the job when it come to dumping and hauling out all of the cinders and soot).

Its something to think about...

[wsherrick]

The problem is not coal v. oil nor tractive effort curves, but pulling fast, heavy trains. It has been ever since the decade after dieselization, within a decade after dieselizing on fast, light trains and slow, heavy trains, on which the diesel's advantages are most apparent.

It is well documented if not fully realized that diesels are very, very expensive on fast heavy trains. TRAINS, July 1970, January 1974, May 1986, and April 1990, the last recording Santa Fe experience that 5 hp/ton is about the economic max.

In recent years fuel costs have further cramped train speeds. Higher speeds, on the other hand, not only improve customer service, but increase productivity of the physical plant. The railroad overcapacity problem was solved over a decade ago. Now it is an undercapacity problem. TRAINS, May 2008

The non-debatable shortage is not oil but capital. Anyone want to argue the current federal and trade deficits are sustainable? For some impeccable Establishment credentials anticipating sharply higher interest rates, see Peter Peterson, Running on Empty, and Robert Hormats, The Price of Liberty.

Electrification has never been the way to save on capital. Don't even suggest electrification before reading Pinkepank's July 1970 article. The power industry has its own investment problems. The standard argument for powerplant centralization, however, shows the capacity problem of mobile (decentralized) generation. During WWII the central power plant load averaged 16% of fleet horsepower and never exceeded 22%. (Barriger's foreword, When the Steam Roads Electrified)This means high horsepower mobile generation will have considerable, and very expansive, excess capacity.

The MYC Niagara, on the other hand, deliberately built with excess capacity, was more powerful at 60 mph than a three unit E7 and cost less to operate, and that without poppet valves, combustion chamber, or more efficient exhaust. TRAINS, March 1984. Of course the capital costs were but a small fraction of diesel. Too bad one was never tried on a Flexi-Van.

Recently on this line there was corroboration that the N&W A hauled 7500 ton trains over 60 mph. Apparently it did this in regular service. Judging by the figures in Jan 1974 TRAINS, this is the work of 4 1/2 SD45s.

Let's see if 1218 can do this again. Let's see what three current 4300 hp units can do too. Let us compare present costs, capital and operating, and let us anticipate future costs, fuel and interest.

And we might anticipate what an A with a Porta/Wardale boiler, Lempor exhaust, and other improvements might do too.

The railroads will see this as a godsend, if it ever sinks in and the costs check out. We do not have to wrangle about anything.

Defining a problem is half of solving it. Let's subordinate the subordinate considerations and avoid personal wrangling. Let's also try to do things economically, as opposed to the wastrel ways of recent decades.

Rush Loving, The Men Who Loved Trains, paints a vivid portrait of Stuart Saunders' highly non-economic ways of running Penn Central. One would not expect anything better at N&W.

Jeff Goodell, Big Coal, is an excellent recent study of the coal/rail/power complex.

The A would indeed be an ideal test engine, too bad they didn't save one with the roller bearing running gear. 

But, as has been previously stated here, the Challenger has been extensively modified at great expense for an unstated reason by the UP.  As a stock holder perhaps I should inquire.

As of a few weeks ago the Challenger was spotted out side of the shops fighting back and forth with a diesel unit out in the yard.  There has been no press about this project and outside inquiries have been rebuffed, repeatedly.

Nothing but stone silence.

So perhaps soon we will have our test comparisons, except that the Challenger is now an oil burner so comparing the costs in burning coal will not be forth coming.  Those of you out in that area should keep a close eye out.

[AnthonyV]

Anthony,

I certainly don't think you are ignorant and I apologize if I came across as implying such.

Erik

I assure you that in no way did I get that impression from you, so there is no need to apologize.  I always find your posts polite, well written, and informative.

Anthony V.

[erikem]

Erikem:

I agree with your point regarding performance dropping off at high track speeds.  I didn't mean to imply that Diesels had an unlimited speed range.  My comment was limited to the range of speeds for normal freight train operation.

My understanding is that the gear ratio plays a large part in the top speed of a Diesel.  Diesels geared for normal freight operation have top speeds in the range of 70 mph, while Diesels intended for passenger and fast freight operation have a lower gear ratio and higher top speeds.  I think the UP Centennials were geared for 90 mph top speed.  While a lower gear ratio results in higher top speeds, it can reduce tractive effort at lower speeds.

I have no clue as to what happens electrically so I must defer to your expertise.

Anthony V.

Anthony,

I certainly don't think you are ignorant and I apologize if I came across as implying such. My intent was to convey to the general audience why a diesel electric locomotive may have a power drop off at high speeds.

You are correct in that the gear ratio's do have an effect on top speeds and tractive effort, although continuous tractive effort is more affected by the gear ratio than starting tractive effort. The amount of overload that you can impose on a traction motor declines rapidly with the amount of time the overload is applied (e.g. 13% more TE for 30 minutes, 9% for 60 minutes).

For a DC series traction motors, the maximum rotational speed is limited by three factors:

1. The speed at which the windings pop out of the armature due to 'centrifugal force'. It isn't a good idea to operate motors near this limit.
2. The speed at which maintenance becomes more of an issue due to increased wear and tear on the commutators. BART started out with an 80 MPH limit for the trains, but dropped it to 70 MPH due to maintenance issues.
   
3. The point where it is no longer possible to maintain rated power output at the rated voltage. By changing the gear ratio, it is possible to increase the track speed where this limit kicks in, but at the cost of lower continuous tractive effort.

Steam locomotives also have a speed/tractive effort trade-off. It is possible to get high horsepower at low speeds (e.g. Y-6b) or high horsepower at high speeds (e.g. the steam engines used on the Hiawathas, the Pennsy T-1, or Pennsy S-2). I can't improve on what Robert La Massena said in his article in the June 1968 issue of Trains.

[Anonymous]

The problem is not coal v. oil nor tractive effort curves, but pulling fast, heavy trains. It has been ever since the decade after dieselization, within a decade after dieselizing on fast, light trains and slow, heavy trains, on which the diesel's advantages are most apparent.

It is well documented if not fully realized that diesels are very, very expensive on fast heavy trains. TRAINS, July 1970, January 1974, May 1986, and April 1990, the last recording Santa Fe experience that 5 hp/ton is about the economic max.

In recent years fuel costs have further cramped train speeds. Higher speeds, on the other hand, not only improve customer service, but increase productivity of the physical plant. The railroad overcapacity problem was solved over a decade ago. Now it is an undercapacity problem. TRAINS, May 2008

The non-debatable shortage is not oil but capital. Anyone want to argue the current federal and trade deficits are sustainable? For some impeccable Establishment credentials anticipating sharply higher interest rates, see Peter Peterson, Running on Empty, and Robert Hormats, The Price of Liberty.

Electrification has never been the way to save on capital. Don't even suggest electrification before reading Pinkepank's July 1970 article. The power industry has its own investment problems. The standard argument for powerplant centralization, however, shows the capacity problem of mobile (decentralized) generation. During WWII the central power plant load averaged 16% of fleet horsepower and never exceeded 22%. (Barriger's foreword, When the Steam Roads Electrified)This means high horsepower mobile generation will have considerable, and very expansive, excess capacity.

The MYC Niagara, on the other hand, deliberately built with excess capacity, was more powerful at 60 mph than a three unit E7 and cost less to operate, and that without poppet valves, combustion chamber, or more efficient exhaust. TRAINS, March 1984. Of course the capital costs were but a small fraction of diesel. Too bad one was never tried on a Flexi-Van.

Recently on this line there was corroboration that the N&W A hauled 7500 ton trains over 60 mph. Apparently it did this in regular service. Judging by the figures in Jan 1974 TRAINS, this is the work of 4 1/2 SD45s.

Let's see if 1218 can do this again. Let's see what three current 4300 hp units can do too. Let us compare present costs, capital and operating, and let us anticipate future costs, fuel and interest.

And we might anticipate what an A with a Porta/Wardale boiler, Lempor exhaust, and other improvements might do too.

The railroads will see this as a godsend, if it ever sinks in and the costs check out. We do not have to wrangle about anything.

Defining a problem is half of solving it. Let's subordinate the subordinate considerations and avoid personal wrangling. Let's also try to do things economically, as opposed to the wastrel ways of recent decades.

Rush Loving, The Men Who Loved Trains, paints a vivid portrait of Stuart Saunders' highly non-economic ways of running Penn Central. One would not expect anything better at N&W.

Jeff Goodell, Big Coal, is an excellent recent study of the coal/rail/power complex.

[MichaelSol]

I presume this is a water tube, not a fire tube boiler? 

Well, our General Manager, with whom I had a enjoyable consulting relationship, just got promoted to the head of the North American Mill Division, and we had his "going away" party last week. The new GM, a mechanical engineer by training, is still in the moving process, and because of Summer hiatus, we will not have a board meeting with him again until September. So my response here is not to ignore the questions, but to offer that's its just not an appropriate time for me to take someone else's time to get the definitive answers you seek, but that I'm not just blowing off the questions.

[Railway Man]

Grades along the route have a huge effect on the power/TE required to move the train, and can be the most important factor when assigning power.  I've never seen an official definition of the term "ruling grade", but doesn't it mean that grade at some point along the route is such that it establishes power/TE requirements or maximum tonnage.

Is it possible that on routes with even modest grades, trains might be overpowered for operation on level track anyway?

Can anybody in the industry shed more light on this?

Anthony V.

Tractive effort required to overcome a grade is 20 lbs. per ton of train per percent of grade.  For example, the locomotive(s) on a 10,000 ton train (including weight of locomotive) climbing a 1% grade must exert 200,000 lbs. of tractive effort just to overcome gravity.  This is a derived number from the acceleration of gravity, not an empirical number.

Rolling resistance varies with speed, friction coefficient of wheel bearings, wheel and rail profile, weight on axles, temperature, etc., and is empirically determined because these variables have a broad range in a real-world setting.  Various formulas (Davis, Tuthill, Schmidt, CN, etc.) proposed constants that state that rolling resistance is between 1-8 lbs. per ton at low speeds, depending on which formula you like.  Empirical testing with modern equipment gives a range of 1-2.5 lbs. per ton at 10 mph and 2-5 lbs. per ton at 50 mph.

Note that as grade increases from dead flat, grade resistance quickly dwarfs rolling resistance.

RWM

[Paul Milenkovic]

I presume this is a water tube, not a fire tube boiler?  Am I to assume that the draft is fan and not ejector operated as on a traditional steam locomotive?  What kind of treatment is required of the feedwater?  In a district heating application where they are raising steam for heat, are these things once-through on the water or do they recover the condensate to send it through the boiler again?

Do you have any specs on such a thing, such as steam pressure, superheat, if any, steam generation rate in lbs/hour, maybe even weight of the package?

The things I always heard in support of the traditional water wall firebox and firetube flue and steam ejector draft steam locomotive boiler and why alternatives had been judged failures were 1) rugged construction to take the jars and jolts of railway locomotive service, 2) large water reserve of the firetube boiler along with cylinder exhaust steam ejector draft means that it allowed for greatly varying steam demand with manual boiler control (the fireman looking at water level and steam pressure gauges and tending the fire appropriately), 3) the fire tube design along with the relatively low steam pressures tolerated the scale buildup you got with questionable and variable water quality on a once-through cycle.

[AnthonyV]

And it needs reiterating, because this is the part that people forget. A train doesn't need high TE at low speeds, unless its a little switch engine and a big load. A train doesn't need a lot of hp at slow speeds. The Davis Formula shows with mathematic certainty that a given tonnage needs substantially more TE and hp with each additional mph, greater and greater force to keep the train moving, needing nearly twice as much TE at 30 mph as at 5 mph and three times as much at 55 mph.

The Diesel-electric produces prodigiously where the train doesn't need the power, and fails utterly by comparison with Steam where the train does need the power. The Steam engine, by comparison, produces plenty where the train doesn't need much power, and produces plenty more when the train does need the power. 

Grades along the route have a huge effect on the power/TE required to move the train, and can be the most important factor when assigning power.  I've never seen an official definition of the term "ruling grade", but doesn't it mean that grade at some point along the route is such that it establishes power/TE requirements or maximum tonnage.

Is it possible that on routes with even modest grades, trains might be overpowered for operation on level track anyway?

Can anybody in the industry shed more light on this?

 

Anthony V.

[Norman Saxon]

Still waiting on that AC6000 horsepower curve there jeepee.

The steam advocates provided theirs, now you provide yours.

Have them right in front of me. However, I have ask you, MichaelSol, and wsherrick multiple times your connections with the coal industry/mining industry and how mining MORE coal was going to benefit the environment.

Still waiting for that answer from all three of you.

I have no connection with either the coal industry nor the oil industry.  I have signed various petitions to (1) increase domestic oil and gas exploration/drilling/refining/distribution, (2) increase the use of nuclear power, and (3) increase the use of CTL technology.  I am thus simply one of many millions in the US yearning for relative energy independence.  If that means converting the rail industry to a coal-powered entity rather than a petroleum-powered entity, so be it.

And I can assume you have no AC6000 horsepower curve stats to share with us.

PS - if you hate coal-based energy so much, you should put your words into action and shut off your electricity 60% of the time, perhaps 80% of the time or more depending on where you live.  If you can manage that, then you might actually have a case to argue. 

[MichaelSol]

I understand that explanation, however, it raises another question that is the basis of my first question.  Is the cost of TE the same no mater what speed it is produced at, or does the cost per pound of TE rise as the speed rises?

Well, that's an interesting way of looking it. I've never thought about it before that way. Using approximate cost of purchase in 1955, the "cost per 100 lbs of TE" at various speeds does offer an interesting perspective:

Lbs of Tractive Effort

MPH	Diesel	Cost/   100 lbs	Steam	Cost/   100 lbs
0	100,000	0.07	60,000	0.07
5	60,000	0.11	59,000	0.07
10	42,000	0.16	58,000	0.07
15	32,000	0.21	56,000	0.07
20	28,000	0.24	52,000	0.08
25	22,000	0.31	48,000	0.08
30	19,000	0.36	40,000	0.10
35	16,000	0.43	33,000	0.12
40	14,000	0.49	29,000	0.14
45	11,000	0.62	24,000	0.17
50	9,000	0.76	22,000	0.18
55	8,000	0.86	20,000	0.20
60	7,000	0.98	19,500	0.21
65	6,500	1.05	18,750	0.21
70	6,000	1.14	18,000	0.22

This doesn't show, however, what the investment cost would be for the Diesel-electric to equal the TE output of the Steam locomotive at the respective speeds. I've added a column D, which shows the necessary investment cost, per 100 lbs of TE, in order to equal what the Steam locomotive is exerting at a given speed -- if the cumulative available Diesel-electrics are going to match the Steam engine in actual TE. Interesting.

 

A	B	C	D	E	F
MPH	Diesel	Cost/   100 lbs	Cost/ 100 lbs  TE to equal Steam	Steam	Cost/   100 lbs
0	100,000	0.07	0.04	60,000	0.07
5	60,000	0.11	0.11	59,000	0.07
10	42,000	0.16	0.23	58,000	0.07
15	32,000	0.21	0.38	56,000	0.07
20	28,000	0.24	0.45	52,000	0.08
25	22,000	0.31	0.68	48,000	0.08
30	19,000	0.36	0.76	40,000	0.10
35	16,000	0.43	0.88	33,000	0.12
40	14,000	0.49	1.01	29,000	0.14
45	11,000	0.62	1.36	24,000	0.17
50	9,000	0.76	1.86	22,000	0.18
55	8,000	0.86	2.14	20,000	0.20
60	7,000	0.98	2.73	19,500	0.21
65	6,500	1.05	3.04	18,750	0.21
70	6,000	1.14	3.43	18,000	0.22

It is very expensive, with the current motive power system, to run fast trains and this suggests why -- and that's before the operating costs are included!

 

[AnthonyV]

I'm not making anything up.  Each locomotive type can be characterized by its nominal horsepower rating.  The Big Boy can be characterized as a 6000 hp machine even though this occurs over a very small portion of its operating range.  Diesels rated 6000 dbhp (either single or in multiples) produce this power over almost their entire operating range except at low speeds, a subject that has been discussed previously.

Therefore, steam locomotive performance can equal the Diesel's only at a single point for equivalent nominal horsepower.

The 6000hp (prime mover HP, not dbhp) diesels with AC transmissions will produce that power over most of the operating speeds, but earlier generations of diesels may not be capable of producing constant power over the operating range. One big difference is that the alternator in the AC transmission pretty much runs at a constant voltage output, where the alternator or generator in the DC transmission the terminal voltage varies inversely with the output current (Lemp control).

Since I don't have a voltage vs current plots (VI curves) for any traction generator or alternator, I'll be making an educated guess on what's going on. The goal for an ideal Lemp control is to produce a voltage that is exactly inversely proportional to the current (i.e. constant power) for a given prime mover speed. The reality is that the voltage isn't exactly inversely proportional to current and in the low current limit, the terminal voltage may end up being substantially less than the ideal case (a likely cause would be saturation of the field steel (i.e. the frame on a generator or rotor on an alternator). The upshot is that the locomotive power will drop off at high track speeds (and I haven't brought up the issue of the maximum voltage rating for a generator).

Erikem:

I agree with your point regarding performance dropping off at high track speeds.  I didn't mean to imply that Diesels had an unlimited speed range.  My comment was limited to the range of speeds for normal freight train operation.

My understanding is that the gear ratio plays a large part in the top speed of a Diesel.  Diesels geared for normal freight operation have top speeds in the range of 70 mph, while Diesels intended for passenger and fast freight operation have a lower gear ratio and higher top speeds.  I think the UP Centennials were geared for 90 mph top speed.  While a lower gear ratio results in higher top speeds, it can reduce tractive effort at lower speeds.

I have no clue as to what happens electrically so I must defer to your expertise.

Anthony V.

[MichaelSol]

If you propose to operate steam locomotives west of the Mississippi River, water availability is also going to be a problem for more areas than the BNSF Transcon line across Arizona.  Water allocations in the Colorado River Basin already exceed the existing supply.  Increasing urbanization has also increased water usage.  And don't even think about obtaining water from the Great Lakes Basin unless you really enjoy playing political hardball.

Well, its either oil or water. Which, measured by market cost, is in shortest supply? Currently, the cost of lubricating oil alone is approximately ten times the cost of water for equivalent steam operation at today's prices. That lubricating oil is, in fact, in short supply, is transported across deserts, oceans, through pipelines, in trucks and by rail car.

You are suggesting that the finest transportation system in the world can do all that and incur a huge expense, but can't figure out how to ship water in order to save money?

Even desalinization and transportation of that water would, by conversion to steam power, save 50% over current costs of pumping, refining and transporting lubricating oil.

 

[Anonymous]

But still, both locomotives exhibit a similar rate of TE fall-off as speed increases.  The only difference is that the diesel TE falls off faster and is higher in the beginning.  As you point out, the diesel's high TE at the beginning is not useful, but is it really a penalty?  It seems to me that it is a consequence of the electric transmission that may or may not be useful, but is not a penalty assuming that the transmission is a necessary attribute for overall performance.

It costs money. In the example where the company wants to run the train at 30 mph, it needs five of the Diesel-electric version to equal or exceed the tractive effort available from two of the Steam engines. That requires the 300,000 lbs of TE of mostly reserve and useless TE capacity at 5 mph, compared to the 118,000 lbs of TE available to the Steam power; both of which are in place for a train that requires just under 15,000 lbs TE at 5 mph.

At 1955 prices, that is the difference between a $320,000 investment or a $1.7 million investment. That's a $1.4 million penalty paid to have a huge excess of TE at low speeds that is useless compared to the actual needs of the train at low speeds, but which is necessary to have the TE in order to operate the train at the higher speed that the Steam engines can run that train. But, its a $1.4 million penalty at 30 mph as well because that is what is necessary to spend to purchase the equivalent Diesel-electric TE necessary to move the train at 30 mph.

It is the need to purchase a huge reserve of TE at low speeds, in order to have enough TE at higher speeds, that represents a financial investment penalty because the unused TE still costs money.

I asked if the diesel's production of excess TE at the lowest speed was really a penalty.  You answered that TE costs money, so it is wasted money if it is produced at a speed where it is not needed. 

I understand that explanation, however, it raises another question that is the basis of my first question.  Is the cost of TE the same no mater what speed it is produced at, or does the cost per pound of TE rise as the speed rises?

It seems to me that the high TE produced by diesel locomotives at starting speeds is the result of being able to "gear down" its prime mover while it operates at full throttle, and if the steamer were similarly equipped with a transmission to enable it to start in "low gear," at high throttle, it too would exhibit high starting TE.  And yet, if you took away its transmission gearing, the extra low speed TE lost could not be utilized at higher speeds.  And the same would be true of the diesel, although its transmission is a fundamental component.  So that is why I asked if the high TE possessed by the diesel at starting is really a penalty, or at the expense of the TE it needs at higher speeds.   

[MichaelSol]

Does the manufacturing base exist to support a steam comeback?  I think not.  There are many parts on a steam locomotive for which the manufacturing capability has left the country or is otherwise not available.

Which parts? Last week at the facility I am associated with I was standing next to a relatively new, high efficiency, fully automated steam boiler used for co-generation of power from Mill waste; it was just about "locomotive sized" and was made in the USA. It utilizes a rough mixture of scrap materials and manages to meet all emissions standards -- which are higher than for diesel engines by the way. These co-generation boilers are now ubiquitous in American industry.

There are approximately 120 manufacturers of such steam boilers in the US today. Because of co-generation needs, there is a substantial installed base of high pressure boilers out there today - probably much more so than thirty years ago; the manufacturing capacity is high, the technology is advanced, and improving every day.

 

[CSSHEGEWISCH]

Due to the accident of being born when I was, steam locomotives are little more than a curiosity to me.  That being said, I will not deny that the examples cited above gave exceptional performance.  They show what well-designed steam locomotives were capable of doing, but they also appear to be the exception rather than the rule.

N&W gave up on steam unwillingly but in part because the world around it had already given up on steam.  Replacement parts were expensive because they had become custom orders for only one customer or were unavailable because the manufacturer had discontinued the product.

Does the manufacturing base exist to support a steam comeback?  I think not.  There are many parts on a steam locomotive for which the manufacturing capability has left the country or is otherwise not available.

If you propose to operate steam locomotives west of the Mississippi River, water availability is also going to be a problem for more areas than the BNSF Transcon line across Arizona.  Water allocations in the Colorado River Basin already exceed the existing supply.  Increasing urbanization has also increased water usage.  And don't even think about obtaining water from the Great Lakes Basin unless you really enjoy playing political hardball.

[MichaelSol]

...Suddenly instead of the steamer making more torque at the wheels than the diesel at 40 mph, it would do it well under 20 mph.

Weight comes into play now to finalize the results. We can't have traction without weight. We can see now that after you plug in all the numbers the relevant information to figuring out tractive effort is torque generated at the wheels in accordance with the weight on the drive wheels per unit time. This means if you have less torque at the wheels, you'd need more weight to keep traction compared to the other engine that has more torque at the wheels with less weight. Obviously you hit a point where you can't get enough weight to off set the advantage and now the added weight is working against you. The whole point of this was an exercise to prove a trend and it verifies the info in the tables that have already been posted here.

I get it now. Play with some numbers and see what you get. You'll find the same trend everytime and it matches the trend that a steamer will have more tractive effort above a certain point. Basically an engine that has a flatter torque curve will have a more favorable tractive effort as speed increases. An engine with a flatter horsepower curve will have a less favorable tractive effort as speed increases. It's neat how that works. If each locomotive weighed the exact same and had the same peak horsepower as measured at the rails, the diesel would have a higher initial tractive effort and the steamer would pass it at a certain point, which wouldn't take very long, and would surpass it above that speed.

And, of course, this follows the charts I prepared from published graphs, for both hp and TE, and its a very nice technical exposition of why it is true. Thanks for going to the trouble as it is a very useful addition to the conversation. The angry gentleman points out that there are changes in the curves due to the back pressure which, he boldly claims, "you cannot ignore."

And, of course, that's why the hp chart I developed shows a point reached of constant horsepower, and the TE chart does, in fact, show declining TE, just as he says. It was all there, but he's not on this thread to acknowledge anything except his environmental prejudices against coal, via the Steam engine. But, it's one of the advantages of using generally accepted, published information comparing contemporary motive power types. The problem is, his "objection" to your calculation offers nothing to change the chart -- and he is fabulously short on any actual data as usual -- but it does rather explain, as your exposition did, various changes throughout the actual power curves as measured in the real world.

And it needs reiterating, because this is the part that people forget. A train doesn't need high TE at low speeds, unless its a little switch engine and a big load. A train doesn't need a lot of hp at slow speeds. The Davis Formula shows with mathematic certainty that a given tonnage needs substantially more TE and hp with each additional mph, greater and greater force to keep the train moving, needing nearly twice as much TE at 30 mph as at 5 mph and three times as much at 55 mph.

The Diesel-electric produces prodigiously where the train doesn't need the power, and fails utterly by comparison with Steam where the train does need the power. The Steam engine, by comparison, produces plenty where the train doesn't need much power, and produces plenty more when the train does need the power. 

If you could step back from coal vs oil, built in prejudices, and plain ignorance, would you choose a power curve that produces exactly the opposite of what the real world train needs, or would you choose a power curve that very nicely matches the power needs of real world trains? If you didn't know this was a Steam v. Diesel debate, which power curve would you honestly choose?

People claim to be "engineers" of the mechanical variety, but I am still carrying enough of my engineering days with me to ask which engineer steps forward to say the ideal power curve is the one that is backwards and upside down from the system needs? Well, you can see why they post here anonymously ...

And now, today, Steam does so at a considerably cheaper cost than the Diesel-electric and that's really the point of the current circumstances -- the rest, everyone knew years ago and the published papers show it. But cost was upside down then, and that weighed heavily on decisions made -- it had to, that's how business worked then, when railroads needed to look to minimize costs because, for competitive reasons, they couldn't pass those costs on to customers in the same fashion that they can now.

 

[Modelcar]

.....Sounds like a locomotive to pull the drawbars out of anything, but you better send out the track crew and bridge people first.

[GP40-2]

MichaelSol,

Back to your "equivalent weight on drivers" thing. After thinking about it, I like it.

I like it so much I decided to design a locomotive around it.

I grabbed one of those old UP DD40s - you know, the ones with the 4 axle trucks. I retained the 70,000 lb per axle load, so the locomotive has a 560,000 maximum weight. The first thing I did was replace the old 645s with new 4000 HP GEVOs that NS uses. I then replaced the old DC D77 traction motors with GE AC induction motors which can comfortably produce up to 2000 HP each. I used the latest CSX/GE traction management software that produces up to 46% adhesion.

So now I have a locomotive with 8000 traction HP which becomes 7,400 HP at the drawbar after standard losses through the inverters and induction motors. That's a good 800 HP more than the Goliath H8 Allegheny can produce.

Ever mindful of the "equivalent weight on drivers" design, I only used 2 traction motors per truck, and left the other two axles nonpowered to help carry the weight of the locomotive. Just like a 4-8-4 locomotive!

That gives me a 7,400 DBHP locomotive, with only an "equivalent weight on drivers" of 280,000 lbs (less than most if not all of the typical 4000-4500 DBHP 4-8-4s!) that can produce up 130,000 lbs tractive effort.

[GP40-2]

I had to think about this for a while and run some math formulas but I think I've figured out why a steam engine has a higher tractive effort. It actually wasn't that hard to prove. For my simple comparison I used some made up numbers trying to equal things out on paper and making some 100% efficiency assumptions. The actual answer isn't what is important, it's the trend that is. The whole idea was to make a mathematical chart that would need to prove true by showing that the diesel in some way was more efficient (for lack of a better word) blow a certain point with the steam eclipsing it above. The trend in my example did hold true.

For my examples, I assumed that each engine could get the same peak power to the rails. I just for example sake used 3000 hp. I also decided on a max top speed for which to measure this power at. I used 60 mph. The weight of the locomotive(s) was actually not relevant to determine a trend. It is relevant to see where the final lines cross.

My assumption was that at all mph points on my chart, the diesel/electric engine made 3000 hp. That's what it does everywhere. Again it assumes 100% efficiency which isn't going to happen. For the steam engine, I assumed that it would make 3000 hp at 60 mph and that power would fall linearly with speed. In other words 1500 hp at 30 mph and so forth and so on.

There was one important factor that really affects the results though and I haven't seen it mentioned here. That factor is wheel (driver) diameter. A diesel/electric engine typically has a much smaller diameter wheel(s) than a steam engine does. Obviously there have been many different sizes on both accounts depending on application but the statement is true from the standpoint of generalization. I plugged in 40" drivers for the diesel/electric engine and just for giggles didn't go too crazy and just assumed 50" for the steamer.

Now that we know this, we need to figure out how many times the engine is turning over per mph. It's easy to just figure around 60 mph and then scale the rest of the numbers from there. Once you know wheel rpm, and obviously the larger drivers are turning slower for the same speed, we need to mathematically figure out how much torque is actually getting the the rails based on the amount of power each engine is producing at each rpm. It's just simple math. I will give an example of 3 different rpms that I used. Keep in mind the location that these cross in is not important. All that matters is proving the trend to exist.

My diesel/electric engine makes 3000 hp at every wheel rpm. Again don't kill me for accuracy. With a 40" wheel, and assuming the traction motor spins at the exact same rpm as the wheels, which they don't, at 25 mph, the wheel and motor rpm would be 105.12. At 40 mph at 3000 hp, you have 168.18 rpm. At 60 mph and 3000 hp, you have 252.27 rpm. Bear with me. You need to figure out torque at each rpm now. When you plug it in, you get:

25 mph, 149,885.84 ft. lbs

40 mph, 93,685.34 ft. lbs. 

60 mph, 62,456.90 ft. lbs.                      

Again this is just an example that I shortcutted but the trend is still the same.

Now on to the steamer. With it's larger drivers at 25 mph, it's wheels are spinning at 70.07 rpm. Since I assumed that power was linear with rpm, and it's not, this gave me 1250 hp. At 40 mph we get 112.10 rpm at 2000 hp. At 60 mph we get 168.15 rpm and 3000 hp. Same hp at the same train speed. The key was the plug in the numbers and see if the torque at the rails was greater than that of the diesel/electric. If it is, we've proven it.Here's what I got:

25 mph, 93,692.02 ft. lbs.

40 mph, 93,702.05 ft. lbs.

60 mph, 93,702.05 ft. lbs.

The numbers theoretically should stay the same. They were off for me as I rounded. We also know that this is also a perfect world scenario and that not everything works in the real world as it does on paper and would in reality fall off as rpms rise. Again, this was just to prove a point and see if there is a trend at work. We can see that there is. In my example, the diesel/electric has more torque at the rails below 40 mph but the steamer has more torque at the rails above 40 mph. Now I obviously didn't take into account efficiency differences of each engine in relation to rpm but that's fine. I also didn't take into account the gear ratio between the traction motor and the wheels which would also change the results. RPM's on the motor would rise which would mean torque would go down by the same ratio in relation to the assumptions I made. Suddenly instead of the steamer making more torque at the wheels than the diesel at 40 mph, it would do it well under 20 mph.

Weight comes into play now to finalize the results. We can't have traction without weight. We can see now that after you plug in all the numbers the relevant information to figuring out tractive effort is torque generated at the wheels in accordance with the weight on the drive wheels per unit time. This means if you have less torque at the wheels, you'd need more weight to keep traction compared to the other engine that has more torque at the wheels with less weight. Obviously you hit a point where you can't get enough weight to off set the advantage and now the added weight is working against you. The whole point of this was an exercise to prove a trend and it verifies the info in the tables that have already been posted here.

I get it now. Play with some numbers and see what you get. You'll find the same trend everytime and it matches the trend that a steamer will have more tractive effort above a certain point. Basically an engine that has a flatter torque curve will have a more favorable tractive effort as speed increases. An engine with a flatter horsepower curve will have a less favorable tractive effort as speed increases. It's neat how that works. If each locomotive weighed the exact same and had the same peak horsepower as measured at the rails, the diesel would have a higher initial tractive effort and the steamer would pass it at a certain point, which wouldn't take very long, and would surpass it above that speed.

Hint: You are forgetting that you have to cut off the steam due to increasing back pressure to get the locomotive to accelerate. This is a physics property ,despite what others in this thread claim, and can not be ignored. Once you start limiting steam into the cylinders, a steam locomotive is no longer a constant thrust (e.g. tractive effort) /increasing HP machine, it becomes a constant HP/ decreasing tractive effort machine JUST LIKE A Diesel-Electric.

[GP40-2]

GP40-2, 

What NS data re: 611 are you referring to?  I don't doubt the figures because 611 was never challenged very much in excursion service, but where did you find this information?  I'd like to get a copy of these figures.  I'll be in Roanoke next week so if I know what to look for and/or when it was written, that would help.

Feltonhill,

Please check your PM on this subject.

Thanks, GP40-2

[MichaelSol]

But still, both locomotives exhibit a similar rate of TE fall-off as speed increases.  The only difference is that the diesel TE falls off faster and is higher in the beginning.  As you point out, the diesel's high TE at the beginning is not useful, but is it really a penalty?  It seems to me that it is a consequence of the electric transmission that may or may not be useful, but is not a penalty assuming that the transmission is a necessary attribute for overall performance.

It costs money. In the example where the company wants to run the train at 30 mph, it needs five of the Diesel-electric version to equal or exceed the tractive effort available from two of the Steam engines. That requires the 300,000 lbs of TE of mostly reserve and useless TE capacity at 5 mph, compared to the 118,000 lbs of TE available to the Steam power; both of which are in place for a train that requires just under 15,000 lbs TE at 5 mph.

At 1955 prices, that is the difference between a $320,000 investment or a $1.7 million investment. That's a $1.4 million penalty paid to have a huge excess of TE at low speeds that is useless compared to the actual needs of the train at low speeds, but which is necessary to have the TE in order to operate the train at the higher speed that the Steam engines can run that train. But, its a $1.4 million penalty at 30 mph as well because that is what is necessary to spend to purchase the equivalent Diesel-electric TE necessary to move the train at 30 mph.

It is the need to purchase a huge reserve of TE at low speeds, in order to have enough TE at higher speeds, that represents a financial investment penalty because the unused TE still costs money.

[jmlaboda]

If steam was better, SOMEBODY would still be using it, so my guess is no.

A lot of the lines who dieselized early dieselized because they did not have more modern steam to use so it made sense to dieselize.  Lines that had the more modern steam did so later moreso because of the labor sometimes involved with servicing these beasts (the N&W had it down to a fine art) and because of public perception.

Back in the 1950s Trains magazine had an article explaining why the N&W decided to dieselize and it wasn't because the steamers that they had designed and produced weren't good, it was because of the perception of steam being old and diesels being new.  Had the N&W not been seeking a suitor at the time it is hard to say if they would have let go of steam so quickly but as it was the head of the company wasn't seeing the line as a property of the company as something to be developed, just something to sell.  Oh, did I mention that the article was by the N&W's President?

It really was a rather strange and quick turn around, in as much because he also had done a write-up about keeping steam going only about two years before.  At that time I really don't think that he was thinking forward all that well, especially considering that within the next decade N&W became a leader not a follower, first grabbing up the Virginian and then later the Nickel Plate Road and Wabash.  For the most part all he could see was that the N&W should be attractive to a suitor and that was why they decided to drop steams' fire.

Had the N&W, or the C&O, or some of the other heavy coal lines decided to stay with steam a little longer there really isn't any telling where steam might have gone.  The N&W itself had already found little "tricks" at getting more power out of the engines that they had, adding weight, modifying the combustion chamber, etc., if they had stuck with steam it is hard to say just where things really could have gone.  As it was with no big steam orders there was no reason to continue its development... but if it had...

I can't help, while I have read the various posts, but to wonder if the ACE 3000 would have succeeded, had its development been pursued.  Probably the single biggest drawback I could see was that the design itself was limited, in essance trying to build the steam equivalent of an EMD SD40-2, with computerized firing, automatic lubrication, steam condensers to help extend the engine's operating range, etc.  But the same sort of forward thinking, with appropriate backing (and I will bet that it would be there now), the ultimate steam locomotive might yet be created... especially so if the price of diesel fuel continues to rise.