New ES44C4 (A1A-A1A) Locomotive

[D.Carleton]

It's just been reported on Trains.com that BNSF has ordered 25 ES44's with an A1A truck set-up. The idea is to save weight of two traction motors thus saving fuel. These are to be used in fast freight service on the transcon. If this comes to pass I'm sure the 'roller-blade' truck will be utilized. However, for an A1A set-up, is there another truck that would be more advantageous?

[Allen Hazen]

You'd think that the springing and equalization problems would be so different in C and A1A trucks that major redesign wouold be needed, wouldn't you? I'm not an engineer, I have no expertise, I'm not sure I have anything useful to contribute... But I note that EMD used its "Flexicoil" three-axle truck in both C (on SD types) and A1A (on FL-9 and ???maybe the 1200 hp Canadian roadswitcher???). So maybe it is possible to modify a C-truck design to be at least ACCEPTABLE in an A1A application more easily than it would be to design an all-new truck.

--

The rumor I've seen has it that BNSF is getting a small number of 4-motor ES44AC (25 has been quoted). This sounds like an experimental, proof-of-concept, project. If the idea catches on, we may see further design, umm, refinements on production orders. ... I assume, but don't have any definite information, that the traction motors will be the same GEB13 used on the six-motor version: since it was used on the AC60, it seems to have the requisite capacity.

[FCP503]

I find such a claim to be non sensical. If one is on a quest to save weight, why eliminate two traction motors that weigh some six thousand odd pounds, but make no effort to reduce weight elsewhere? A typical four axle loco weighs what? About 135-140 tons? A typical modern six axle loco weigh in the area of 200 tons?

If such and experiment is in fact tried I suggest it would be ended in less than six months and that the units would be made standard C-C units in short order.

Rumors circulated back in Santa fe days that all of the GP 50's were going to be converted into B units...never happened. Santa Fe also proposed regearing some of the 500 class Dash 8 40B's to 80 MPH gearing...never happened. This sounds like just another wild rumor or idea that someone started talking up.

What is to be gained by throwing away 1/3 of tractive effort?

A FOUR AXLE unit is another matter. That would be the age old design battle of speed vs tractive turning once again to favor speed.

[MEC407]

If it was just something that somebody heard from somebody else, I would be extremely skeptical, but it does appear on the Trains.com news wire, and while Trains is primarily a railfan magazine, they do have a lot of industry connections and have gotten interviews with the CEOs of the big railroads, so I think they've got some credibility.

[D.Carleton]

If such and experiment is in fact tried I suggest it would be ended in less than six months and that the units would be made standard C-C units in short order.

Agreed. But why buy 25 locomotives for an experiment? Why not alter three or four existing ES44's and see what happens... unless they already did.

The point of the original post was concering the trucks. To the best of my knowledge the current non-radial truck has not been tried in A1A configuration. But the MLW Hi-Ad truck was tested in A1A service with AC traction motors. I'm guessing the new locomotives will come with standard trucks to facilitate a future conversion to a standard ES44. Even so, this is an interesting turn of events.

[Jay Potter]

I think that the news account, though accurate about the units having been ordered, might have explained the concept a bit differently. These units are basically AC-traction units intended to approximate the performance of DC-traction units, but with two fewer traction motors. In other words, their capabilities shouldn't be evaluated in comparison to six-motor AC-traction units but, rather, in comparison to six-motor DC-traction units. They do not have standard trucks.

[DASH9DAD]

You're forgetting one big factor behind the reasoning for the reasoning behind this purchase. $$$$. They get a AC drive locomotive for the price of a DC unit. The main reason Railroads have continued to buy DC's is their cheaper purchase price. They would also now have more parts commonality between the coal motors and the "high speed" units for TOFC/Stack service. Also with AC's they get higher adhesion ratings than DC's and if the center idler axle can be "unweighted" the TE is their to match the DC's performance.

[FCP503]

Canadian Pacific tried this when they put Brown Boveri AC traction motors on the M640.

Again 25 units is a very high number for an unproven concept.

[amtrakhogger]

Canadian Pacific tried this when they put Brown Boveri AC traction motors on the M640.

Again 25 units is a very high number for an unproven concept.

Silly question. Why can't BNSF just order a ES44 with B trucks or is it preferred to keep a 6 axle unit for the adhesion because the heavier axle loadings?

[DASH9DAD]

They need to keep the axle loading below 72K lbs/axle.

288,000 for a four, 432,000 for a six.

With manufacturing tolerances they need the nominal weight to be 286,000 for a four or 429,000 for a six.

UP did have some coal hoppers built for 315k but they haven't (or shouldn't) been/be loaded to that.

[Allen Hazen]

Santa Fe's last 4-axle high horsepower GE units, the B40-8W, weigh (acc. to Greg McDonell's "Field Guide to Modern Diesel Locomotives") 289,000 pounds: close enough to 72k/axle that maybe nobody quibbles. Take that as a starting point. I think the 12 cylinder GEVO engine weighs almost as much as the 16 cylinder FDL. (The original design of the HDL-16 was only 10% more than the FDL-16, but part of the cure for the HDL's problems was more cast iron in the engine frame: lots more. I don't have documents to back this up, but I have a feeling the GEVO has inherited the extra iron.) That's the engine: to be EPA compliant, ES-series locomotives have extra radiator/heat-exchanger gear: this probably adds up after a while.
---> Intermediate conclusion: trying to get a modernized version of the B40 might go over the permitted weight even before you think about replacing DC motors with AC.

AC traction motors are lighter than <i> equivalent capacity </i> DC motors, but the GEB13 is a much higher capacity motor than the DC 752: I'm sure someone here can give an exact figure (please, someone?), but at a guess it may be a bit heavier than the 752. And the above-the-frame part of an AC diesel electric is heavier than that of a DC motored one: after all, you have essentially the same alternator and rectifier set up, and then have to add to that the invertors to transform the DC into variable-frequency AC.
---> So, a straightforward "B40-ES-AC-W" would almost certainly be too heavy.

Could a B-trucked design be gotten within the weight limit? Well, you could omit the fuel tank, and couple a -- maybe we could call it a "tender," if that doesn't sound too steam-era -- to (or between a pair of) the locomotive(s). But that just moves the unpowered axles we wanted to get rid of to a separate vehicle! (And ATSF's partner in the merger that formed BNSF did try out fuel tenders, and seems to have decided that they were more nuisance than they were worth.) The other possibility would be an all-new carbody design-- think "Freight Genesis" -- with a lighter load-bearing structure than a road-switcher frame. That, however, would involve BIG MONEY: maybe it will come, but not on (what I called) a "proof of concept" prototype.

---

On another point: I don't think 25 units is too many for an experiment. GE fielded 50 preproduction GEVO units in railroad colors (5 to UP, 30 to BNSF, 15 with DC motors to NS) for testing before the production introduction of the ES series at the beginning of 1985. You want a test to provide meaningful statistics, and to be extensive enough that it has a fair chance of picking up a problem that doesn't occur every day. And BNSF's total locomotive fleet is up towards 7,000 units: as a proportion of total fleet size, 25 locomotives for BNSF is less than one prototype warship for the U.S. Navy!

[FCP503]

From a purely speculative standpoint, why not do a prototype four axle unit with a Jenbacher engine? It's a new engine so getting it to meet tier 3 shouldn't be all that hard. BNSF, UP, NS, and others have been buying genset locos, so one can't say that having a differant prime mover would be a deal breaker.

In some ways the Gevo prime mover series seems to leave a gap between 3000hp and 4400hp (inline 8 and vee twelve engines respectively) Is this part of what is driving this line if development?

[v8interceptor]

From a purely speculative standpoint, why not do a prototype four axle unit with a Jenbacher engine? It's a new engine so getting it to meet tier 3 shouldn't be all that hard. BNSF, UP, NS, and others have been buying genset locos, so one can't say that having a differant prime mover would be a deal breaker.

In some ways the Gevo prime mover series seems to leave a gap between 3000hp and 4400hp (inline 8 and vee twelve engines respectively) Is this part of what is driving this line if development?

The question then becomes could such a Jenbacher powered AC drive BB unit be produced for lower cost(both to buy and maintain) than the ES44AC-4? Also, would a prosective customer want something with different parts and different maintenance procedures than their existing Evolution series fleets?
I'm curious as to what 3 ES44AC-4s do that 2 ES44ACs won't?

[FCP503]

I'm curious as to what 3 ES44AC-4s do that 2 ES44ACs won't?

Well that kind of hits the nail on the head doesn't it?

Either one wants a high performance four axle loco, or an underperforming six axle loco.

In the end one gets what one pays for.

[D.Carleton]

Is this a 2-for-3 replacement, or a 1-for-1 replacement? I’m thousands of miles from the transcon but through the convenience of the web it would appear BNSF prefers four DC motored six-axle locomotives to lead their hottest trains.

Going from the GE data sheet the starting and continuous tractive effort for an ES44DC is 142K lbs and 109K lbs, respectively. Using some back-of-the-envelope calcs, two-thirds of an ES44AC would be 131.9K lbs starting but 110.5K lbs continuous (higher than the DC model). Assuming each traction motor weighs at least 5K lbs then removing two makes the modified AC weight 5K lbs less than the DC. Removing two of the six inverters lessens the total weight even more.

Replacing four ES44DC’s/DASH9-44CW’s with four ES44AC-4’s should yield significant fuel savings without sacrificing performance.