Is it time for the locomotive manufacturers to come up with a new more powerful locomotive?
Despite the oddballs that exist at large railroads (AC-6000s to gensets) the railroads have pretty much come to rely on 3 groups of locomotives:
1. 4000 to 4400 Hp 6 axle (even though some only have 4 traction motors),
2. 3000 Hp 6 axle
3. 2000 to 3000 Hp 4 axle.
My thought would be for a locomotive that would be able to replace AC 4400s on a 2 for 3 basis, just like the 4400s did to the 3000 Hp SD40-2s.
Tier 4 compliant
7000+ Hp with a single power plant.
Most likely a B+B-B+B with movable bolsters for flexibility (unlike the old EMD DDs)
Possible use of LNG or CNG
Possible use of either LNG, CNG or diesel fuel tenders.
If GE could come up with at 20 cylinder GEVO it would be in the 7000 Hp range, and who knows what EMD has in the Cat motor grab bag..
Just my thoughts, what are yours?
I don't think that it's going to happen. The three groups listed cover almost every conceivable service requirement and the various manufacturers have them covered quite nicely. There doesn't seem to be any need for a super-size locomotive at this time. About 50 years ago, the Big 3 builders catalogued and built super-size locomotives (C855, U50, DD35) but there was no real demand for them beyond Union Pacific.
The limiting factor in locomotives is wheel slip control - all the horsepower in the world does no good if you are just spinning your wheels. The 4000-4400hp AC 6-axles have maxed out current wheel slip technology. For anymore HP, wheel slip technology will have to take another leap forward.
Never too old to have a happy childhood!
Also consider that for long, heavy trains, DPU in mid or end train positions helps alleviate the need for big honking power up front, so you can use 4 4K ocomotives, 2 up front, 2 in the middle, such that a 7K locomotives would be overkill.I suppose modular genset style engines would reduce excessive fuel consumption of a proposed 7K to some extent, but still you need to lug around the unused units, which still require some maintainance also.
WM7471 Is it time for the locomotive manufacturers to come up with a new more powerful locomotive? Despite the oddballs that exist at large railroads (AC-6000s to gensets) the railroads have pretty much come to rely on 3 groups of locomotives: 1. 4000 to 4400 Hp 6 axle (even though some only have 4 traction motors), 2. 3000 Hp 6 axle 3. 2000 to 3000 Hp 4 axle. My thought would be for a locomotive that would be able to replace AC 4400s on a 2 for 3 basis, just like the 4400s did to the 3000 Hp SD40-2s. Tier 4 compliant 7000+ Hp with a single power plant. Most likely a B+B-B+B with movable bolsters for flexibility (unlike the old EMD DDs) Possible use of LNG or CNG Possible use of either LNG, CNG or diesel fuel tenders. If GE could come up with at 20 cylinder GEVO it would be in the 7000 Hp range, and who knows what EMD has in the Cat motor grab bag.. Just my thoughts, what are yours?
Cat does have the C280 engine series, the 16 cylinder version can produce over 7,000 BHP. GE had an 18 cylinder HDL engine test unit (never installed in a locomotive) which was rated at around 7,000 BHP so hypothetically a GEVO version could be developed.
two major problems:
1. the split cooling systems required for Tier IV compliance are very heavy and take up a lot of space, so much so that I have read that even the currently marketed 5,000-6,000 HP units (i.e SD80Ace (some sold to a Brazilian RR),ES58AC (ditto) and the Chinese AC60/SD90MAC derived units) would not meet weight requirements if fitted with the upgraded cooling systems.
2.Which leads us to the truck considerations-there are double BB connected truck systems currently marketed by both EMD and GE, primarily for narrow gauge applications (in Brazil again). I just read that GE is offering a narrow gauge ES44AC With bolster connected BBBB trucks (Yep, to Brazil). So it is technically possible. But the Class 1 railroads in North America are big on standardization and seem very satisfied with current truck designs so it would be a hard sell. You could use a 6 axled truck with larger wheel diameter. there is such a truck on the market, the one manufactured by Bombardier for the Swedish Class 26 IORE locomotive, which has a HP rating of 7,200 HP. The truck has AC traction motors and the wheels are over 49 inches in diameter (ES44AC wheels are 42 inches in diameter.).
A locomotive maker (and keep in mind that both manufacturers R&D efforts are largely tied up in getting their existing offerings to meet Tier IV, hasn't been an easy program esp. for EMD. A heap of money would have to be spent in developing a radically new locomotive line, and I would bet that none of the "Big 7" would place an order before the bugs were worked out.
However as engine technology advances I would not be surprised to see 5,000 HP or higher road locomotives being offered again to the North American Market.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
A 6000 HP six axle is about it, for now. You gotta have a "grade E" knuckle train in order put 3 AC locomotives on the head end. So, there would be limite opportunities to go 2:3 with a B-B+B-B locomotive.
I think the opportunities for future motive power might be:
1. Braking energy recovery.
Lots of BTUs can be reclaimed and reused. Gets rid of a lot of the fuel penalty for braking vs. coasting. Could help raise avg train speed a bit.
2. Smaller units and more evenly distributed DPU.
Reduced in-train forces. Reduced draft system failures. Easier block swaping. DPUs radio relay for more robust DPU signals front to rear.
Smaller units might not all have cabs - would use RCO-like devises for switching/building trains.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmannd I think the opportunities for future motive power might be: 1. Braking energy recovery. Lots of BTUs can be reclaimed and reused. Gets rid of a lot of the fuel penalty for braking vs. coasting. Could help raise avg train speed a bit.
GE was promoting a hybrid locomotive 5 to 6 years ago, remembered the battery was good for about 2000HP equivalent, can't remember if it would last a half hour or an hour. A battery with high power density or ultracaps might be great for a commuter locomotive.
One application for a hybrid freight locomotive would be on a line with a long tunnel - running the diesel prime mover at half power with the battery picking up the other half would reduce the amount of crap that has to be blown out of the tunnel before another train can use it.
2. Smaller units and more evenly distributed DPU. Reduced in-train forces. Reduced draft system failures. Easier block swaping. DPUs radio relay for more robust DPU signals front to rear. Smaller units might not all have cabs - would use RCO-like devises for switching/building trains.
Tier 4 ??. Anyone else note what NS is doing?? As well as others?. Tier 4 sucks, plain and simple. For those who love the EPA and regulations made by "carbon counters" Its easy to prove how stupid it really is. Most think that The carbon output causes a "greenhouse gas" and that raises temps, its a pretty much given in the way its explained today to the masses, BUT Tier 4 has HUGE maintenance costs involving the stacks, and filters, and the stack temps are 20 times what they are with tier 2 regs. To see for yourself go find a brandy new 18 wheeler with tier 4 and point your laser IR thermometer at the stack. The EPA didnt want this on trains so they told them they had to cool it some, and how much does this mess weigh and cost to maintain?? For over the road truckers Tier 4 trucks will STOP running if the filter isnt serviced by a SERVICE center....
Tier 3 already has Diesels running at faster RPM to make the emissions ( which uses more fuel, so more injection engineering, etc, big rat race. For the amount of work a SD70 does, its pretty darn efficient...and its NOT new..
You see how many tenders they need fro a CNG train engine>? the cost to make CNG is still more than its worth to sell.. It has to be purified and condensed, now you have a big rolling bomb... IF you have been in the Navy or around ports you'll notice they CLEAR the harbor for LNG or CNG tankers.......hows the first derail gonna look like??
Getting efficient is great, making MORE heat and more cost and more problems at the expense of others makes NO sense. Railroads cannot compete with tier 4 engines on their trains...
oltmannd A 6000 HP six axle is about it, for now. You gotta have a "grade E" knuckle train in order put 3 AC locomotives on the head end. 2. Smaller units and more evenly distributed DPU. 3. Reduced in-train forces. Reduced draft system failures. Easier block swaping. DPUs radio relay for more robust DPU signals front to rear.
A 6000 HP six axle is about it, for now. You gotta have a "grade E" knuckle train in order put 3 AC locomotives on the head end.
3. Reduced in-train forces. Reduced draft system failures. Easier block swaping. DPUs radio relay for more robust DPU signals front to rear.
7000hp? No, 5000hp is really the limit of what's useful/efficient and 4000-4400hp is a good level for the RRs. AC traction has been the bigger factor more than anything.
ML
This is not going to be a defining answer about....
Couplers, and knuckles, (specifically the designed weakest link of freight cars) which had designed stress levels.
The common knuckle could pull against 240,000 lbs of train resistance, (resistance...If your baby weighs 8 pounds, until you lift with more than 8 pounds energy, the babe won't lift from the cradle, or the crib...
Those numbers are from the early 80's. So am I.
The E knuckle could pull against...330,000 pounds?
Metallurgy matters?
Sure does.
Every step forward in the HP war is done at the behest of improved efficiency. Three Dash 8-40Cs were more efficient than four SD40-2s and Two AC4400s are more efficient than three Dash 8s and so on. There will be a next step eventually but right now the railroads (and our suppliers) have bigger problems to deal with.
Editor Emeritus, This Week at Amtrak
UP (the big locomotive railroad) ran their monsterlocos until mounting operating expenses relegated them to the dead lines - while smaller, simpler 'standard' designs kept on rolling.
When each unit of motive power had to have its very own crew it made sense to make each one as big and powerful as possible. Now a single engineer can control as many units as the railroad wants to connect together. That kills the need to max out each individual unit.
One other item. If something major requires shop attention, that bigger, more powerful locomotive takes a bigger bite out of available train-moving capacity, and will probably take longer and cost more to fix.
History is replete with examples where 'biggest' was not most efficient. That's why humongu-anythings tend to be one-off experiments. When there is a legitimate need for a bigger, faster or more powerful (fillintheblank) the need will be identified and driven by market forces - but not until the need is demonstrated - again, by market forces.
Chuck
I think you will find that the sweet spot for horsepower has increased in lockstep with improvements in wheel slip control. The modern AC locomotives have a factor of adhesion that is considerably higher than first generation units such as the GP9, so the extra power does translate into extra tractive effort. Wheel slip on heavy grades with the higher horsepower units arriving in the 60s (2400-3000hp) was found to be a problem by several railroads. Lots of R&D over the following years went into improving the issue.
I suspect that modern technology has reached the limit of what can be achieved with the current rail-wheel interface. This can be solved in model railway field by such expedients as traction tires; that's not an option for the real thing!
Greater horsepower will still be desirable when speed is the primary objective, primarily in passenger applications, and the railroad is willing to pay the extra fuel costs for that higher speed.
John
My poor switchpoints and curve rails....especially in the terminals that have to handle the darned things....
You may say "Oh , there she goes again!" - yet , here I go again with my voting for electrification :
CSSHEGEWISCH
quote : The three groups listed cover almost every conceivable service requirement and the various manufacturers have them covered quite nicely. There doesn't seem to be any need for a super-size locomotive at this time.
I don’t think so , they only cover service requirements in multitudes , no single unit covers but the easiest of demands . That means for every freight train worth mentioning you have to assemble diesel units easily amounting to 800 .. 1000 .. 1200 tonnes combined – a sizeable fraction of total train load and a way to compose power needed nowhere but in the US deemed acceptably economic . So , technically , although it’s correct no doubt the RRs didn’t appreciate it , there *would be* scope for larger power units .
BaltACD
quote : The limiting factor in locomotives is wheel slip control - all the horsepower in the world does no good if you are just spinning your wheels.
If that was so how do you explain synchronous electrics like the European standard Taurus class developing 6400 kW on but four axles *and* but 2/3 of axle load as used by US diesels ?
D. Carleton
quote : Three Dash 8-40Cs were more efficient than four SD40-2s and Two AC4400s are more efficient than three Dash 8s and so on.
Exactly that’s the point ! And one unit is more economic than two units . Why did European railways go a long way to eliminate double traction – not to speak of ponderous mass multiple unit traction ? True , conditions of train masses differ substantially from those in the US , still electric traction should not be banned from thought , even if economies can be a trap for technical development . In my view dieselization the way it happened on American RRs was a fatal short term modernization in the long term having turned into a dead-end road with relatively low power ceilings as mentioned by users in this thread and – let me add – very high motive power unproductive mass .
Cx 500
quote : I suspect that modern technology has reached the limit of what can be achieved with the current rail-wheel interface.
See electric traction , for example before mentioned Taurus family synchronous electrics
http://www.jmpet.de/taurus.htm
having arrived at over 100 hp [metric] per t [metric] of unit mass and compare with typical contemporary diesel 15 – 20 hp / t . Diesels are formidable starters – but going at start-away speed all day makes traffic move slow and keeps line sections occupied longer than they should in view maximizing daily tonnage passed .
Regards
Juniatha
I'm sorry but you cannot compare European railways to the US, simply put they're chalk and cheese when it comes to similarities. Sure they use steel wheels on steel rails but the fundamentals of each system are widly different.
Those high HP electrics can't start a train the same size as an equivalent diesel loco from the US because they weigh so little (in the order of 60t difference) but where that HP comes into play is keeping up train speed. Short frequent freights is how Euope operates, not with the long heavy freights American has a network designed to deal with.
Diesels are formidable starters – but going at start-away speed all day makes traffic move slow and keeps line sections occupied longer than they should in view maximizing daily tonnage passed .
Add the weight the US diesels have to a European electric and you'll get pretty close to the same starting TE (well maybe the same as a 4-axle unit) but they'll still have a higher balance speed. Electric has it's merits but comparing Europe with the US? Wrong way of going about it.
WM7471 My thought would be for a locomotive that would be able to replace AC 4400s on a 2 for 3 basis, just like the 4400s did to the 3000 Hp SD40-2s. Tier 4 compliant 7000+ Hp with a single power plant.
(Highlighting mine.)
A significant cause of the downfall of 6000 HP locomotives was flexibility, and the 7000 HP locomotive loses much of it. Many trains that I have observed operate in a 2x1 DPU configuration. You'd need a 7000 HP locomotive and a 4400 HP locomotive to operate the same train, otherwise power would be unused. As a whole, less standardization, a primary goal of railroads. Also, if that 7000 HP locomotive fails, (and it will happen, especially with a single prime mover) you've lost two thirds of the power on the train, instead of a third.
4400 HP locomotives are the best for American railroads right now. The horsepower race is over, and the emissions race and AC traction have been the bigger deal since the failure of the 6000HP locomotives.
Juniatha:
Wheel slip occurs when the force exceeds the coefficient of friction, and as far as I know the steel rails and steel wheels are pretty much the same composition, whether in Europe or North America. In fact NA has the advantage since the generally higher axle loadings allows higher tractive force. The higher horsepower in Europe does allow faster speeds and acceleration, of critical importance when mixing in with fast frequent passenger trains. I would guess wheel slip is rare except when starting from a stop.
Rightly or wrongly, the more usual operating philosophy in North America accepts that a freight train on the maximum grade will not maintain speed; the primary criteria being that it can reach the summit, and start again if stopped. When crawling uphill at slow speeds that higher horsepower would overpower the grip of the wheels. Microprocessors now limit the power so wheels are just starting to slip, and continue to do so for many kilometres on some famous grades.
Many North American railroads have used "slugs" for specific services, especially in yards or humps. They take advantage of the fact that there is too much horsepower (even at our lower numbers!) to be used by one diesel locomotive at slow speeds. They take the surplus and feed it to what is in reality a pure electric locomotive. The extra weight and powered axles of the slug allow the surplus horsepower to be used effectively and move heavier trains, admittedly at slower speeds.
JayPotterThe reference to locomotive consist weights of between 800 and 1200 tonnes for "every freight train worth mentioning" seems somewhat high to me. On CSXT, the most common consist for tonnage trains, two AC-traction units, has a total weight of about 392 tonnes.
Jay is 100% correct. If anybody doubts him, watch and learn:
watch?v=FLOguuLnhH0
Since the current locomotives have the horsepower and tractive effort to exceed the strength of the strongest knuckles and couplers currently manufactured - increasing the power and tractive effort of yet to be designed locomotives will be in large part dependent upon increased strength in the coupling systems of cars and locomotives, that also have yet to be designed and manufactured.
GP40-2 JayPotterThe reference to locomotive consist weights of between 800 and 1200 tonnes for "every freight train worth mentioning" seems somewhat high to me. On CSXT, the most common consist for tonnage trains, two AC-traction units, has a total weight of about 392 tonnes.
There was the Gandy Dancer Festival west of Madison, WI, which is mainly folk and bluegrass music down by the WSOR railroad tracks. We were running model trains in the old train station, Lions Club had a "train" of wheel barrows behind a garden tractor with steam locomotive sound effects to give rides to the children, and the WSOR was sending trains right through the middle of this. I would leave the room from supervising the model trains to (gently) scold people to stay back from the tracks to varying effect. Wish there was a way to coordinate with the WSOR that they wouldn't be conducting switching operations on a Saturday in the middle of that huge crowd of people, where for a railroad themed-event the real train constitutes an "attractive nuisance" or get the Gandy Dancer event moved away from the tracks without taking away they railroad-themed ambience.
Here is the consist that I saw the WSOR crew switching with: 2 SD40-2's and 1 GP-38 (it had the two stacks so it was the 16-cyl non-turbo version -- WSOR also has B-B's with the fat turbo stack that I figure are more rare GP-39s).
Let me see, 16 axles, over 500 tons, 8000 HP burbled by pulling one tank car. This is the kind of switching consist used on a model railroad because we keep "collecting" locomotives and need some use for them on our layout?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
efftenxrfe This is not going to be a defining answer about.... Couplers, and knuckles, (specifically the designed weakest link of freight cars) which had designed stress levels. The common knuckle could pull against 240,000 lbs of train resistance, (resistance...If your baby weighs 8 pounds, until you lift with more than 8 pounds energy, the babe won't lift from the cradle, or the crib... Those numbers are from the early 80's. So am I. The E knuckle could pull against...330,000 pounds? Metallurgy matters? Sure does.
Close enough.... Those might be close to the yield strength, but the ultimate strength is higher. Problem with operating between yield and ultimate it you get into the fatigue life of the steel. RRs typically DO operate above the yield strength of knuckles, but it's game of chance... Most of the time a knuckle fails, it's note how much of the break is "old" i.e. rusty. Too bad there's not a knuckle fatigue life indicator...
Maybe we could create one from train consist data?
JayPotterThere is an August 2012 55-page AAR research report titled "Comprehensive Evaluation of the Structural Durability of Railroad Coupler Assemblies".
AAR-TTCI R-1002, if I am not mistaken, and you can order it from this form..
Reason being when you run a train with two 6,000 hp units and one goes down you will more than likely stall. Most trains are capable of being pulled by two 4,400 hp units. The third is added to help maintain schedule and to be a backup in case one of the other units goes down during the trip.
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