BNSF converting Dash 9s from DC to AC

[zkr123]

How will this benefit BNSF?

[beaulieu]

Lower traction motor maintenance expense, and eventually less spare parts inventory costs.

[oltmannd]

...and fewer road failures, higher availability.

[blue streak 1]

Also DC specific component parts removed can be used on remaining DC units.

[Leo_Ames]

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. 

[zkr123]

But they have a fleet of SD70MAC'S, SD70ACe's, ES44AC, and AC4400's. Wouldn't that be too many?

[D.Carleton]

zkr123

But they have a fleet of SD70MAC'S, SD70ACe's, ES44AC, and AC4400's. Wouldn't that be too many?

Too many as in more locomotives than BNSF needs? BNSF is scrambling for power; I had trains cancelled or postponed for wont of power.

Too many as in too many variances in motive power? These rebuilds should share common components with AC4400 and/or ES44AC types.

[NorthWest]

zkr123

But 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.

[GDRMCo]

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.

[NorthWest]

My comment was comparing the conversion to the pre-conversion Dash 9-44CW. Sorry about the confusion, I need to elaborate more.  

[caldreamer]

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?

[efftenxrfe]

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).

[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.

[GP40-2]

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.

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.

[blue streak 1]

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 ?

[Leo_Ames]

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?). 

[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.

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.

[D.Carleton]

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 am sure you are correct. It also appears they retained the origianl FDL primemover but changed everything downstream of the alternator. Typically the locomotive that leaves the factory and the same locomotive that gets removed from the roster at the end of its service life will be different due to revisions,  redesigns and updates of replacement parts. Due to the new regs that primemover is now "frozen" in its "Tier 0" state. Now the railroads and manufacturers will have to come up with different ways to tweak their locomitives without touching the engine.

[YoHo1975]

I wonder as a matter of Curiosity if an SD70 or 75M would be equally easy (a relative concept) to convert to AC? Perhaps cheaper due to fewer inverters if you simply turned it into a MAC? I wonder if UP and to a much lesser extent BNSF have contemplated such a thing?

[GDRMCo]

Not as simple as the C44-9W to AC4400CW conversion.

[YoHo1975]

Howso?

[GDRMCo]

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.

[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).

[M636C]

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).

I'd be surprised if the original engine was used. It might not have met tier 0. The Hamersley Iron Dash 9s had new engines (or at least new crankcases) after only ten years. It was a dramatic comparison that Hamersley needed new crankcases on their GEs while BHP Billiton were putting forty year old ex SP SD40s into service with their original crankcases. Cracking is a problem with all FDLs. I saw stacks of them (literally, three deep) in Argentina, one of the original customers from the late 1950s.

As an aside, after looking at the "Locomotives" section in the current issue showing an SF30C under conversion, I remember seeing a "Kodachrome" SF30C in Fostoria Ohio in 1992. It was being added to a CSX consist (if I remember correctly). The driver climbed into the cab, set up some controls, and then climbed down and walked up to the builder's plate and read it. I assume it was the first SF30C he'd seen, and I don't imagine he checked the plates on every locomotive he used. I'd expect a few crewmen will check the details on an AC44C4M the first time they encounter one.

M636C

[GDRMCo]

'Keeps the old 7FDL-16' as in same engine type, likely not the same engine or atleast same crankcase it left Erie with.

[Leo_Ames]

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. 

[GDRMCo]

M on most GE rebuilds denotes Modified.

[Leo_Ames]

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. 

[GDRMCo]

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...

[YoHo1975]

BN and BNSF has applied M to mean Morrison Knudsen in the past to be the source of the rebuild as in GP39M (versus E for EMD and V for VMV) Presumably however, it does in this case mean Modified.