zkr123Why are there no AC traction 4 axle locomotives such as GP40AC or SD40-2AC?
(Well, the 40 series hasn't been built since the '80s)
1. Weight. An AC B-B would probably be overweight, thus the AIA-AIA ES44C4.
2. AC came after railroads had standardized on C-C power. ACs came along in the late '90s, the last GPs were built in the early '90s.
3. Demand. There is no real service for them, especially since anyone who want DC performance from AC can purchase the ES44C4.
zkr123They would be perfect helpers on coal trains.
zkr123Or pull heavier local trains without putting road engines on local services.
There are plenty of older four axle units that aren't worn out for this. AC is expensive, as is any new locomotive, so carriers use demoted road power that would otherwise have no use.
Because they wouldn't be perfect helpers. The adhesion that a big CC offers is what you want in a helper. And in no way, shape, or form is AC needed for locals. GP38-2's, SD40-2's, and the like are perfectly suited to such assignments.
And modern locomotives outgrew the wheel arrangement. Also, the assignments where powerful BB's were well suited for have diminished over the years (Even intermodal since double stacks are so heavy). And while the latest six axle machine from GE or EMD can easily pull duty on an assignment where a 3,500-4,000 HP four axle unit is well suited for, it doesn't work so well in the other direction.
Going with six axles and AC provides more versaility for mainline power.
There were! Amtrak had a couple Siemens equipped four axles built by EMD, plus F40PH 202 that they converted themselves with ABB equipment. The 202 was a flop, but the other two did okay before they went back to EMD.
You could probably make a good case for a 4000 HP AC four axle for a flat-land road pulling merchandise and intermodal, but you'd wind up with the problem of fuel capacity and range. Without creating a complicated frame/carbody structure, you'd can't accomodate a large enough fuel tank without the locomotive being too heavy.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
zkr123Why are there no AC traction 4 axle locomotives such as GP40AC or SD40-2AC? They would be perfect helpers on coal trains. Or pull heavier local trains without putting road engines on local services.
No they wouldn't be perfect helpers. Helpers are about relative low speed tractive effort, and that's all about weight, so with an axle load limit, the more axles the better. Also sorry to use a Wikipedia reference but here one is.
http://en.m.wikipedia.org/wiki/MPI_HSP46
I have been wondering if there was a market for a 3000ish HP BB AC locomotive. Possibly from a second tier builder. The smaller engine, along with the lighter cooling system, would not overload the frame like a 4500 HP would and the AC would provide a high level of adhesion. They should work well with current AC loco and there still is some advantage to a BB. The big thing would be cost.
A 4300-4400 would be too heavy for a BB.
By definition a "SD40-2AC" would not be a four-axle locomotive.
The existence of the four-motor six-axle AC units confirms that many of the previous points in this discussion are valid. I don't think there is any problem in building high-horsepower four-axle units -- the question is where they can be used cost-effectively. You would need a dedicated high-speed service where the higher horsepower wouldn't be adhesion-limited, perhaps like the proposed accelerated Z trains a while back that were to be tested using borrowed Genesis locomotives. I don't see a service like this being implemented in most corridors; although you could theoretically schedule fast trains 'fleeted' in Amtrak time slots to get them over the road, that's only part of the overall operation of moving the freight, and the fast locomotives would be something of a waste in other service. (As with the Super C and other services, there's also the question whether there will be adequate stable demand for fast end-to-end service vs. kanban-style precise delivery time...)
Are the first-generation AC inverters and other components going to be reliable enough, especially as they age, to be a good source for secondary-market locomotive builders? While there are good reasons the major builders are phasing out DC drive for road locomotives, there is likely to be large aftermarket support for DC for a considerable time, and (as noted) the advantages of AC drive for local services aren't generally great enough to justify additional cost.
For future local B-B power, I suspect we will mostly see things along the line of EMD's GP20ECO, DC power "rebuilt" to get around emissions regulations.
NorthWest ", DC power "rebuilt" to get around emissions regulations."
", DC power "rebuilt" to get around emissions regulations."
*You do know "President Cruz" is a standing joke for possible policy change?
The MBTA just got a fleet of 40 HSP46 commuter engines with four AC motors on new 2 axle trucks.
Randy
If Cruz ever becomes president I am moving to Pyongyang with dear sweet Kim Jung Um. I will be much better off there until he gets out of office.
Randy Stahl The MBTA just got a fleet of 40 HSP46 commuter engines with four AC motors on new 2 axle trucks.
I think most of the discussion involves freight power. Almost by definition the 'next generation' of high-speed passenger locomotives have up to 4700 nominal hp with four (AC) motors...
caldreamer If Cruz ever becomes president I am moving to Pyongyang with dear sweet Kim Jung Um. I will be much better off there until he gets out of office.
New Zealand would be better. (And a lot more sane then NoK Land)
Overmod Randy Stahl The MBTA just got a fleet of 40 HSP46 commuter engines with four AC motors on new 2 axle trucks. I think most of the discussion involves freight power. Almost by definition the 'next generation' of high-speed passenger locomotives have up to 4700 nominal hp with four (AC) motors...
Not quite...with modern passenger power you have to factor in HEP which takes some available power away from the traction motors.
I seem to recall reading that the new MBTA units being built by Wabtec (with GE engines and electrical systems) have about 4300-4400 HP available for traction.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
LensCapOn I have been wondering if there was a market for a 3000ish HP BB AC locomotive. Possibly from a second tier builder. The smaller engine, along with the lighter cooling system, would not overload the frame like a 4500 HP would and the AC would provide a high level of adhesion. They should work well with current AC loco and there still is some advantage to a BB. The big thing would be cost. A 4300-4400 would be too heavy for a BB.
There are some Switchers/Roadswitchers in Europe that use AC traction motors.
If you want to buy the type of locomotive you are proposing I bet, for the right (very high) price CAT/EMD could build you a GP carbody type locomotive with the engine and systems of the new Vossloh "Eurolight" locomotive series.
3600 HP (in US nomenclature, In Europe diesels are often marketed by Gross rather than net Engine/Alternator output) from the Cat C175-16 engine into 4 AC traction motors:
http://en.wikipedia.org/wiki/British_Rail_Class_68
The good news is it can meet Tier IV now, the bad news is it needs SCR/Urea to do it.....
A 3000 HP "GP69"Ace might also be do-able given that the two F69PH's were mechanically GP59's wearing shrouds but the 12-710 powerplant is not tier IV compliant (maybe as a re-power?)...
Admittedly passenger units are a very small market, but I am wondering why there is no interest in a (lightweight) 2000-traction hp quill-drive (or Carden-drive) 125 MPH capable passenger locomotive. That would be a unit much like the British HST (later Intercity 125) "power car."
If you are Amtrak running corridor trains, you want them push-pull, and by FRA rules, you have to have a locomotive or a non-revenue cab car at each end of the consist. For up to as many as 8 passenger cars, 4000 HP is plenty? And you need a pair of locomotive/cab units at each end of the train, so why not make them 2000 HP. And at 2000 HP, you could make them much lighter (still heavier than most passenger cars and OK to put at the ends of the train)?
And at 2000 HP, do you think you could swing that with a pair of 1000 HP Diesels under the floor motoring through torque converter transmissions, sort of a beefier version of the Colorado Railcars DMU? And since the FRA doesn't allow you to carry passengers there, could you use the space for baggage and bike racks?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
carnej1,
The Eurolight is not quite focused the way I would like, being more of a light weight hi-speed design.
A base assumption is the BB would have a performance curve close to the new AC engines, just down sized for the lower power and weight. AC bits should be widely available soonish and a V-12 Cummings QSK95 would be another way to the needed power. A tier 2 builder might try something like that on a GP38/40/50/60 frame.
GE and Cat would need 8 cylinder versions of their GEVO and H265 engines as a start.
EMD did build a GP38AC in 1970 and 1971.
http://en.wikipedia.org/wiki/EMD_GP38AC
Bob Schuknecht EMD did build a GP38AC in 1970 and 1971. http://en.wikipedia.org/wiki/EMD_GP38AC
AC drive has AC motors, and flashes the AC to DC for control, then back to AC for the drive.
The advantage would have to save you something or give you some sort of beneficial replacment ratio over a GP40-2. I don't think there's much "there" there.
LensCapOnA 4300-4400 would be too heavy for a BB.
Not really. The diesel engine in and SD70ACe weighs the same as the one in a GP38-2 +/- a small bit.
The issue is weight that comes from the size of the desired fuel tank.
Paul MilenkovicAnd since the FRA doesn't allow you to carry passengers there, could you use the space for baggage and bike racks?
Oh, I'm not going to let that just lay there! What will we do with all those new baggage cars when they come? Put people in them?
oltmannd LensCapOn A 4300-4400 would be too heavy for a BB. Not really. The diesel engine in and SD70ACe weighs the same as the one in a GP38-2 +/- a small bit. The issue is weight that comes from the size of the desired fuel tank.
LensCapOn A 4300-4400 would be too heavy for a BB.
A smaller diesel would have a slower burn rate and get the same number of hours from a smaller tank. That was an, unstated, part of my reasoning for a smaller engine on a BB.
Also, AC tranction would be a huge advantage over a GP40-3 at lower speeds and heavy loads. Just don't know if it could make $$ sense.
Don:
The FRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU. If the train is run push-pull, you cannot seat anybody in either the lead or the trailing unit of a passenger consist.
Amtrak corridor trains have a 4000 HP 120+ ton locomotive at one end and a ballasted-with-cement-to-120 ton "cabbage car" at the other end, which has a baggage door but I don't think they provide checked baggage service on thise trains.
In some cases, they have a Genesis Diesel at each end of the consist -- does the Vermonter or the Wolverine really need 8000 Hp?
My proposal is for a pair of (lightweight -- maybe 80 ton) power cars on each end of a corridor consist, better matched with the rooflines of the cars for better aerodynamics if you want to run 110 MPH or even 79 MPH. A saving of at least 80 tons in weight. Also a substantial saving in peak axle load.
Maybe what I am saying is that if you put a lot of money into "baggage cars", put engines and safety/wide cabs on them so they can do something useful like propel the train and keep passengers out of the lead of the consist where they are in peril.
What I am proposing is something they had for years in the UK -- the HST aka Intercity 125 train. 2 of these "power cars" at the ends, 8 cars in the middle, and yeah, if you had baggage space and bike racks in the power cars, as you are not allowed to seat passengers there, that may create a mini-scandal
Paul Milenkovic Don: The FRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU. If the train is run push-pull, you cannot seat anybody in either the lead or the trailing unit of a passenger consist. ...... What I am proposing is something they had for years in the UK -- the HST aka Intercity 125 train. 2 of these "power cars" at the ends, 8 cars in the middle, and yeah, if you had baggage space and bike racks in the power cars, as you are not allowed to seat passengers there, that may create a mini-scandal
......
Exactly how is this ban on passengers in leading vehicles defined?
The great majority of passenger trains in the USA are commuter trains on which driving cab cars are allowed. Given that such commuter trains run as fast and often as far as intercity trains, particularly in California (Capital Connection, Pacific Surfliner) exactly how do these trains avoid being Intercity?
The Vossloh Eurolight would do most of what you want although it might need some modifications to neet FRA regulations.
M636C
The cab cars on the Pacific Surfliner are all bi-levels, the one Amfleet/Horizon trainset has a cabbage car.
What Amtrak does is to prohibit people from sitting in the front four or five rows on the upper level when the train is being pushed. The front of the lower level is dedicated to baggage and bicycles. Both of these policies put some crush space between the actual front of the train and the passengers.
- Erik
Paul MilenkovicFRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU.
On Caltrain, passengers sit less than ten feet behind the train's front coupler; on Oakland-Sacramento Amtrak trains they sit less than 20 ft behind it. Suspect the Oakland-Bakersfield trains are the same.
Bob SchuknechtEMD did build a GP38AC in 1970 and 1971.
timz Paul Milenkovic FRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU. Why would FRA make a rule for intercity trains and a different one for unintercity trains? On Caltrain, passengers sit less than ten feet behind the train's front coupler; on Oakland-Sacramento Amtrak trains they sit less than 20 ft behind it. Suspect the Oakland-Bakersfield trains are the same.
Paul Milenkovic FRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU.
Why would FRA make a rule for intercity trains and a different one for unintercity trains?
You guys are confusing tier I vs. tier II regulation. Passengers OK on tier I not on tier II.
M636C Paul Milenkovic Don: The FRA doesn't let you seat passengers for intercity trains in the lead "thing", whether it is a locomotive, a power car, or a DMU. If the train is run push-pull, you cannot seat anybody in either the lead or the trailing unit of a passenger consist. ...... What I am proposing is something they had for years in the UK -- the HST aka Intercity 125 train. 2 of these "power cars" at the ends, 8 cars in the middle, and yeah, if you had baggage space and bike racks in the power cars, as you are not allowed to seat passengers there, that may create a mini-scandal Exactly how is this ban on passengers in leading vehicles defined? The great majority of passenger trains in the USA are commuter trains on which driving cab cars are allowed. Given that such commuter trains run as fast and often as far as intercity trains, particularly in California (Capital Connection, Pacific Surfliner) exactly how do these trains avoid being Intercity? The Vossloh Eurolight would do most of what you want although it might need some modifications to neet FRA regulations. M636C
Passengers in lead vehicles OK on tier I operations not OK on tier II. IIRC break point is 90 MPH.
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