GDRMCoDon't see why it matters...
Didn't say that it did. But they didn't just put it there because it looked nice. There's no harm in being curious what BNSF's motive power department was thinking when they came up with their in-house designation for this rebuilt locomotive.
The AC clearly makes sense to denote AC traction, the 44 reflects the horsepower rating, and together, it indicates it's an older pre GEVO design due to the AC4400CW designation for GE's AC offering of the time. And C4 appended to the end clearly signals that it's a A1A locomotive along the lines of the ES44C4.
But since there isn't anything designated as AC44C4's, the need for the M isn't completely clear. I'm sure it's being used in the context we're all familiar with it being used in to denote "modified", but it seems superfluous.
It doesn't really matter, the M is also applied to the Pilbara ALCo rebuilds (CM40-8, sometimes called CM40-8M). In reality they're an AC44C4 now, but as they were rebuilt they can carry the M. Don't see why it matters...
ML
The point is that there aren't any stock AC44C4's to necessitate the use of the M to differentiate the rebuilds from.
Plus, most M's actually are railfan fabrications appended to the end of the builder's original model designation for the sake of clarity and brevity for our convenience rather than anything remotely official (Same with E's, R's, and so on... almost always they originate from folks like ourselves.).
The only M I can think of that formed part of a GE model designation was for the cowled Canadian Dash 8's during the early days when Erie finally had cracked the Canadian marketplace (And I can't think of any informal uses of it by a railroad for GE's until this BNSF example, if accurate).
And in that case of those C40-8M's, it indeed officially stood for modified to denote the cowl to differentiate them from the normal hood models.
M on most GE rebuilds denotes Modified.
I wonder what the M denotes? Railfans put too much thought into this junk so I'm hesitant to question it, but I would've thought that AC44C4 would've been sufficient to clearly indicate the nature of this locomotive and to differentiate it from other models on the roster.
'Keeps the old 7FDL-16' as in same engine type, likely not the same engine or atleast same crankcase it left Erie with.
GDRMCo So it appears the model designation for this rebuild is AC44C4M. Only Tier 0 (keeps the old 7FDL-16 and existing radiator/cooling setup).
So it appears the model designation for this rebuild is AC44C4M. Only Tier 0 (keeps the old 7FDL-16 and existing radiator/cooling setup).
Much of the C44-9W and AC4400CW is fundamentally the same (length, much of the equipment layout, etc aside from the actual traction package) whilst the SD70M (and 75 variants) are 2 feet shorter than the SD70MAC with a different equipment layout. It may be possible to use ACe parts such as the inverter cabinet but that'd be a serious bit of work in comparison to the -9 to AC44 conversion.
Not as simple as the C44-9W to AC4400CW conversion.
NorthWest I think this conversion wasn't cheap. I suspect this may be hedge against the potential disruption of new locomotive orders when the Tier IV regulations kick in at the end of the year, as these locomotives are getting old.
I think this conversion wasn't cheap. I suspect this may be hedge against the potential disruption of new locomotive orders when the Tier IV regulations kick in at the end of the year, as these locomotives are getting old.
Editor Emeritus, This Week at Amtrak
GP40-2, thanks. I should have explained it, IIRC the CTE numbers for the ES44AC are at around 14MPH. It is interesting to note that the ES44C4 isn't able to fully compensate for having a third of the weight on unpowered axles (though the lifting helps some at starting) by using AC motors, although it is close.
Have they even said that they've decided one way or another to proceed with such a rebuild program? What I read portrayed this as a test unit. Presumably, they're going to want her to roll some miles off in various types of services as they monitor her first before deciding where to go from here.
It would hardly be unusual if she ended up a species of 1. Has happened before including in recent BNSF history (Remember the GP60B that was converted with a spartan cab off a scrapped SD40 a few years ago?).
Has BNSF indicated what their planned rate of conversion is going to be ? As well how many out of service at one time ? Will they convert units due for major overhaul ?
NorthWest If it is the same as an ES44C4, (should be close) Starting TE is 144,000lb, and Continuous TE is 105,000lb. For comparison: Dash 9-44CW: STE: 142,000lb, CTE: 105,000lb. ES44AC: STE: 183,000lb, CTE: 166,000lb. ES44DC: STE: 142,000lb, CTE: 109,000lb.
If it is the same as an ES44C4, (should be close) Starting TE is 144,000lb, and Continuous TE is 105,000lb.
For comparison: Dash 9-44CW: STE: 142,000lb, CTE: 105,000lb.
ES44AC: STE: 183,000lb, CTE: 166,000lb.
ES44DC: STE: 142,000lb, CTE: 109,000lb.
It should be noted that CTE doesn't have the same meaning for AC traction vs DC traction.
For DC traction, the CTE continuous force the locomotive can make without overloading / over heating the traction motor.
For an AC traction locomotive, the "CTE" is made at the speed where the locomotive can apply full horsepower. An ES44AC can run all day above its "CTE" rating with no motor damage, however it won't be producing its full traction HP rating.
DC locomotives are limited by their traction motors, AC locomotives are limited by their adhesion.
As far as TE is related, it should be I think be mathematically related: 2/3rds the traction motors, axle loadings (engine weight per axle) similar, pushes reasoning towards
2/3rds of the TE.
Software can keep the motors cool (talkin' cont. TE).
What will the starting and continuous TE ratings be on these units, since you say that they will not be close to the AC's which they will be?
My comment was comparing the conversion to the pre-conversion Dash 9-44CW. Sorry about the confusion, I need to elaborate more.
Performance is approximately the same as the ES44C4s if the marketing is to be believed, HP wise it's the same as any other modern GE but TE, not even close to the ACs.
zkr123But they have a fleet of SD70MAC'S, SD70ACe's, ES44AC, and AC4400's. Wouldn't that be too many?
The performance of the converted locomotive is approximately the same in terms of HP and TE, so it has no impact, although higher short time ratings and other AC advantages do help a bit.
Too many as in too many variances in motive power? These rebuilds should share common components with AC4400 and/or ES44AC types.
I also suspect that a lot of other work is involved to make this 20 year old locomotive good to go for another 15-20 years like a overhauled prime mover.
Also DC specific component parts removed can be used on remaining DC units.
...and fewer road failures, higher availability.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Lower traction motor maintenance expense, and eventually less spare parts inventory costs.
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