Would converting the P42s to AC traction prolong their lifespan? I know it had helped prolong the lifespan of the P32AC-DM's.
The P32AC-DMs were built as AC, hence the designation.
A rebuild for AC traction would be expensive and makes sense only if one of the GEVO repower proposals is put in place. It is more likely that they will simply be retired by the Siemens Chargers.
GE's 752AH is a great traction motor. Not going to limit the lifespan of their P40/P42 fleet any.
There's also GE's HSP46, developed and produced by MPI using many GE supplied components and technology. Would need a revamp to Tier 4 specifications though, which may or may not be a major issue. And it uses the same AC traction motor from GE as the dual-mode Genesis units did.
Or perhaps the EMD model, the F125 (Although there's commonality with the Siemens locomotive and Amtrak's new electric locomotives that probably makes an order unlikely, among other advantages).
I'm just a casual follower of Amtrak, but I was under the impression that they had rebuild programs of some sort underway for both the dual-mode locomotives and the P32-8WH's that immediately preceded the first Genesis locomotives?
Of course you can't draw a direct correlation here since the hood units offer versatility that a typical Amtrak locomotive doesn't and there isn't an off the shelf model available to replace the dual mode Genesis units.
But between this, other major GE capital rebuilding programs that are starting to crop up on Class 1's at long last, and GE's own version of an Eco repowering program that Amtrak could take advantage to upgrade these with GEVO engines and other modern features (Perhaps including GEB-15 AC motors?), I'm not sure that they're doomed just yet.
All depends on Amtrak's budget. I suspect the Siemens offering is what they'd love to get though to eventually replace the Genesis fleet.
Expensive - New AC traction motors, inverters, control circuitry, and maybe a new alternator as well. And the Locomotive still has a Tier 0 FDL prime mover. BNSF has been experimenting with something similar in converting old Dash 9 C44's into AC4400C4's. They had GE convert one Loco last year, and the rumor is that another 10 will be done this year. BNSF has money, Amtrak is cash strapped....
Modeling BNSF and Milwaukee Road in SW Wisconsin
There isn't any real benefit of AC traction in LD passenger service to justify the cost of retrofitting it to the Genesis fleet.
AC traction is really only necessary in heavy haul service on freight trains, and in commuter service where DC motors get put into their short time load ratings all day long.
DC traction is just fine in long haul passenger and intermodal service. As already mentioned, the 752AH traction motor found in the Genesis units is an excellent traction motor anyway- fae and away the best DC motor ever produced.
It would be wise for Amtrak to order AC traction on its next diesel order because they do require less long term maintenence, but the P42s are so worn out already Amtrak would never make up the cost of the conversion in maintenence savings, they're just too old.
No advantage of AC traction ? Beg to differ.
1. P-40s, -42 geared to 110 MPH. That means lower tractive effort at most speeds until ~ 40 - 50 MPH.
1a. AC traction has much higher acceleration with same HP and trailing tonage.
2. Higher speed gearing increases minimum short time continuous rating speed of DC traction motors. Is important for long climbs ( Raton ) or whenever one loco of multi loco power fails.
3. DC traction motors much more likely to fail in snow especially small particle powder. Bad time to have your DC traction motors to fail ( flash over ) out on the plains or unaccessible mountain pass. Can also happen around salt water spray.
4. AC traction motors have better regeneration / dynamic braking capabilities saving train brakes.
5. Higher power thru put to traction wheels.
We have no idea what the mileage on the present locos has done to fatigue of various components of locos.
ML
You are dead on with all these observations. And that's exactly why I said Amtrak would be wise to specify AC traction on the next order.
That being said, in my personal opinion the benefits don't justify spending all that money retrofitting them into 20 year old P42s with millions of miles on them. It doesn't make financial sense.
The only benefit to retrofitting DC locomotives with AC traction opposed to buying new is you can avoid dealing with the Tier 4 stuff- which is exactly why NS and BNSF are doing just that. A Genesis is only required to meet Tier 1 once its overhauled.
To add to what the Streak said...
An AC motor is likely to weight less than the DC motor it replaces, which would reduce unsprung weight. Not a big advantage in 79MPH territory, but does become important at 110MPH.
- Erik
While AC traction would improve the performance of the P42, it would cost a lot to implement and may not provide a measurable improvement on the road with relatively light passenger trains.
I would expect that a serious rebuild program would match that just recently performed to the Cv40-9i units in Australia which work the few remaining long distance passenger trains along with about half the long distance freight.
These locomotives were fitted with a new 7FDL-16 with the latest electronic fuel injection and most of their cab and control electronics were replaced. This removed issues with obsolescent electronics and gave the locomotives the same expected life as a new unit, for around a million dollars a unit, I understand.
P40s and P42s could be rebuilt this way and could be expected to run for another 15 years before needing replacement. This would allow Amtrak to try out the F125s and Chargers and not have to commit themselves until the new units were proven on the road. There would be far fewer on line failures and the cost must be attractive to an organisation that rarely gets the funding it needs.
M636C
Think that if they were rebuilt into essentially new locomotives, that they'd get GEVO engines?
I think the follow-ons to your Aussie example, the C44ACi, got new FDL's instead due to the lack of vertical space under the hood because of Australia's restricted loading gauge. I imagine that also played a role in the power plant selection for the NR class rebuilding project.
Seems like a potential issue if the P40/P42 fleet were to be repowered with GEVO's, since they're designed to fit in some low tunnels by modern standards.
The reasoning though wouldn't be meeting an EPA mandate since as as you said, they don't need such an engine to be compliant. Rather, it would be because they decided it was the best choice for some other reason, were a major capital rebuilding project that included repowering the fleet to occur.
I suspect that size constraints would play a role in sticking with brand new FDL's in place of the old, but was wondering what M636C would bet his money on if this theoretical rebuilding program were to occur.
Yeah, I agree.
I suppose what I was most curious about isn't really if Amtrak would select it, but if it would even fit on the off-chance that they did.
And that's because his mention of the rebuilding of the Cv40-9i class reminded me of something I had read about the GEVO engine being too tall for use in that repowering project or the newbuild C44ACi's.
Given that the loading gauge that the Genesis conforms to isn't exactly the most generous, I assume that the use of a GEVO engine within these dimensions if these were repowered or Amtrak went with a new design utilizing the GEVO engine, would be a very close fit?
One possible illustration of this are the dimensions of the GEVO powered HSP46. That's over a foot taller than a Genesis, several feet longer, and features a longer wheelbase.
Leo_Ames Think that if they were rebuilt into essentially new locomotives, that they'd get GEVO engines? I think the follow-ons to your Aussie example, the C44ACi, got new FDL's instead due to the lack of vertical space under the hood because of Australia's restricted loading gauge. I imagine that also played a role in the power plant selection for the NR class rebuilding project. Seems like a potential issue if the P40/P42 fleet were to be repowered with GEVO's, since they're designed to fit in some low tunnels by modern standards.
zkr123 Would converting the P42s to AC traction prolong their lifespan? I know it had helped prolong the lifespan of the P32AC-DM's.
That's kind of a tough question.
The P42s can be made to last indefinitley. All the major components get rebuilt periodically as it is. The trucks likely every couple of years, the diesel engine likely every 5 years, etc. So, the locomotives really aren't "wearing out" so that they need to be replaced.
Replacement occurs when the cost to own an operated a new one is less than keeping going with the old one. Improved technology eventually makes the old locomotives obsolete, but it has to be in concrete ways. Less fuel, fewer locomotives, cheaper maintenance.
So, would retrofitting AC traction to P42s make them cheaper to own and operate?
AC traction would give you more tractive effort at low speeds (below 38 mph). It also should reduce maintenance costs. DC traction motors generally consume big chunks of repair dollars.
So, would it be worth it for Amtrak?
Fuel: no real difference
Need fewer locomotives per train: Not really. I can't think of any trains where you could reduce the number of locomotives because you'd have more low speed TE.
Fewer locos in fleet: Maybe. Lower shop count might save you a few locomotives in the fleet.
Performance: Getting more HP to the rail during acceleration from stops is worth some time, but those P42 load so slowly and passenger trains generally accelerate quickly, so by the time you get that diesel engine up to full HP, you are already moving at a pretty good clip.
Lower maintenance costs: Some, but not enought on it's own to get you over the hurdle.
The P42s are are a pretty good fit for Amtrak's LD trains. Their traction motors aren't generally stressed too heavily with current, but take a good beating from rotational speed and being nose-suspended and operating at speed. But, I suspect they'll be around a long time hauling Superliners accross the landscape - as is.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
blue streak 1AC traction has much higher acceleration with same HP and trailing tonage.
In a standing mile- maybe.
The P42 has 1000 more horsepower. There's no way an F40 keeps up with it for very long.
Acceleration isn't all that important in LD passenger service, anyway. What matters is being able to maintain high speeds- something the Genesis is MUCH better at than an F40.
The GEVO repower was brought up as a result of the HSP-46, which could potentially have the same mechanical arrangement as a P42DC repower. I doubt it has ever been officially proposed but I have seen it brought up by railfans several times. Since the corridors will be standardizing on Chargers it makes sense for Amtrak to simply replace the LD fleet with them.
(Yes, I think it was NSW that came up with the noise emission standards that have proved troublesome. Notable in my mind is the fun that QR had with the standard gauge 2800s. Really, whether or not the standards are national or not matters little, as it makes no sense to buy a new standard gauge locomotive that is not operable in NSW.)
This is the first time that I had heard that the GEVO wasn't much taller than the FDL. Interesting. Thanks for the information, you certainly know a lot more about these subjects than me.
timz blue streak 1 AC traction has much higher acceleration with same HP and trailing tonage. Suspect NJ Transit's PL42s can out-accelerate F40s-- along with more power they probably load a bit faster. But I'll bet an F40 would beat an AC-converted GE in a standing-start mile with a normal passenger train. (With 50 or 100 cars the GE would likely win.)
blue streak 1 AC traction has much higher acceleration with same HP and trailing tonage.
Suspect NJ Transit's PL42s can out-accelerate F40s-- along with more power they probably load a bit faster. But I'll bet an F40 would beat an AC-converted GE in a standing-start mile with a normal passenger train. (With 50 or 100 cars the GE would likely win.)
I would agree!
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