I think I know that the -2 upgrade on EMDs is related to traction and fuel management issues that the original engine was blessed with. My question is would the upgrade have the same effect from SD40 to SD40-2 as the SD70 to SD70M-2 or something along those lines? Thanks in advance!
I think reason for the SD70M-2 being called a “dash 2” is really just that EMD wanted to call it’s upgraded SD70M something besides SD70M. The SD70M-2 is different from the SD70M (the Tier 2 engine being the biggest), but not in the same respect as the jump from the SD40 to the SD40-2. They could have just as easily called it the “SD70e” or left it SD70M.
This is essentially true.
The original -2 signified solid state electronics and computer controlled anti wheel slip. When an older, non-2 is remanufactured with aftermarket versions of this, it’s often relabled as -2.
The SD70M-2 refers to something completely different though. It’s referring primarily to the prime mover change. Though there are other differences. Still, for marketing reasons, they wanted to keep it the SD70. It’s still a V-16 710 prime mover.
The real question is why the AC version isn’t a SD70MAC-2 or conversly, why the DC version isn’t an SD70Me.
… or SD70DCe.
I have read that the -2 in the SD70M-2 is to show that it is Tier-II compliant.
Would that make it a Microsoft product? [:D]
Heaven forbid [angel]- that would require OS software patches every two weeks. [}:)]
(Getting ready for flaming…)
Couldn’t UP handle that? LOL! Sorry, I had to!
Incorrect. That would only apply to the SD70XP Professional. The SD70Me will just simply refuse to work from time to time, needing to have the engine restarted before the alternator would produce power.
The guts of EMD’s original Dash 2 improvements was that they modularized the electronics. They took the existing IDAC panel and repackaged it as a WS10 module, for example. No real improvment in wheelslip performance, but much easier to test and replace. The same went for the other modules, the sensor, sensor bypass, rate control, etc. The other big chunk was the HTC truck, which did improve overall adhesion. The rest of the changes were small and related to easier servicing. The only other big change - on the 38 series only - was the use of a traction alternator and diodes replacing the DC main generator.
Almost. The GP38AC was the first locomotive with a traction alternator in EMD’s lineup, and this preceeded Dash 2 - but Dash 2 saw the entire lineup receive traction alternators.
Yeah, all Dash 2s received Alternators. Not just the 38s.
Hmmm, I’d argue a bit on that. My recollection is that the 40 series all had traction alternators as EMD’s traction generator was running out of steam at 2500HP - witness the large number of transition steps on the 35 series to keep the generator voltage and current within limits.
You may be correct in asserting that the GP-38AC preceded the Dash-2’s.
Forgot about the GP38ACs as a variant of the GP38. The 1965 version of the GP40, SD40, SD45 all had alternators while the GP38 had a generator. In the last couple of years before the Dash 2 line came out, you could get AC as an option on the GP38…
CSX must have microsoft SD70MACs [:D]
In the upgrade process would a RR want to ‘switch’ a loco from DC to AC? Would that mean swapping ‘alternator’ and ‘motors’ only or more? Wouldn’t that help a loco in yard service, perhaps?
I think that you are confusing changing the main generator from a DC type, to an AC Alternator with a Rectifier, and a locomotive having an AC traction motors. All locomotives now use an AC alternator to produce the electric power to propel the locomotive, those locomotives designated as “AC” locomotives also use AC traction motors, while those labeled as “DC” use DC traction motors. The reason that the main generators were changed from DC generators to AC alternators is that as the locomotives power rating reached 2800hp. the DC generators became so massive they barely fit inside a locomotive carbody. An AC alternator of similar capacity is smaller and requires less copper. Also the higher capacity of the AC alternators allowed a simplification of the transition stages of the motor connections, as in a GP35 needed to have 25 stages of traction motor transition, while a GP60 has but one stage of alternator transition.
So everything comes with AC power going to the trucks and it’s switched/transformed to what’s specified at/just before that point?
Actually CSX has some of the best SD70MACs, beating even BNSFs. They got the “heavy MACs” and all of the engineers I’ve talked to love them.
Alec
Actually, the guys designing the locomotive probably had Microsoft as the operating system (OS) for their computers. [:O]
I don’t remember off hand if it was GE, EMD, or both that Microsoft XP was being used as the background OS for the locomotive’s control system. Ironically it is “more stable” as the OS can be redesigned specifically for the diesel locomotive. Computer OS typically are “more unstable” is that they have to take into account all the different hardware and hardware configurations on the market