New ES44C4 (A1A-A1A) Locomotive

Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.

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Allen Hazen
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Re: styles of motor

Post by Allen Hazen » Fri Feb 13, 2009 12:39 am

The sort of motor mounting in the truck that is standard in American locomotives is called "nose suspended": the traction motor is hung between the axle and the truck frame (& I can't remember which side is called the "nose" of the motor!). This is probably the simplest way to arrange things, and (partly because of that) the cheapest. Disadvantage is that a fair portion (like, maybe: half) the weight of the motor is directly suspended from the axle with no intervening springs: it is "unsprung mass". As such, it produces (what in steam locomotives was called) "dynamic augment" whenever the axle and motor move up and down (try to imagine what happens inside the truck when the locomotive goes over a low rail joint): the momentary force is greatly increased over the continuous force of gravity on the wheelset axle and motor. Bad for ride quality, bad for track structure.

Alternative mountings reduce the unspring mass. In a quill drive (as on the GG-1 electric of blessed memory) the motors were mounted entirely on the truck frame: there were spring connections between the quill and the wheel so the motors themselves didn't have to move up and down when the axle did. Another alternative (that has been used on some high-speed European passenger power, I think) is to have the traction motors inside the carbody, connected by cardan shafts to a gear-box on the axle: gear box plus half of cardan shaft is a lot less unsprung mass than gears and half of traction motor!

Dynamic augment is more severe at higher speeds. In practice the more expensive, lower unsprung weight, options seem to be chosen for very high speed (well over 100mph) passenger power, not for locomotives intended for use a freight train speeds.

There is also a general principle of engineering: don't try TOO many new ideas at once! BNSF and GE have come up with a locomotive which, except for the four-motor idea (& related control and adhesion problems) uses the same technology as existing power. Including conventional nose-suspended traction motors.

v8interceptor
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by v8interceptor » Fri Feb 13, 2009 12:39 pm

kf7strng wrote:I had a question about a theory I have. I am NO electrical engineer, but I thought something they might have been trying to do was a concept like the Chrysler 300c. It can switch between 4 and 8 cylinders as needed. Example :when getting up to speed it uses all 8, but then at highway speed it shuts 4 off, and uses only 4. While it has been said elsewhere that AC traction motors can be heavily loaded without worry (while DC traction motors cannot) I think that by incorporating this concept it will take care of the "dead axle" concerns some of you have had. (dragging around a dead axle per wheel set). HOWEVER, this concept can also be applied to heavy hauling slow freights too. Use all of the motors to get going, or to push/pull grades, and when they are no longer needed, it goes into A1As. (I believe Gensets do this?, but with the actual diesel motors, NOT the traction motors/inverters). Thoughts?
There is a working example of the "flick-of-a-swich" CC/A-1-A system you are speculating about, though it is designed for a different application. The Alaska Railroad's SD70MACs isolate 2 traction motors (one on each truck) when they operate in Passenger HEP mode.
As far as deactivating cylinders I have read that that is difficult on large diesel engine. NS experimented with convering some GP9's with 16-567 engines to operate on 12 cylinders for switching applications but they were technical failures.
What GE/BNSF seem to be trying to do is produce a cheaper to own, operate, and maintain AC drive unit for a specific type of service (fast freight)...

v8interceptor
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Re: Effect on purchase price

Post by v8interceptor » Fri Feb 13, 2009 12:43 pm

Allen Hazen wrote:The big motive for this, at least if our speculations on this board are right, is reduction in purchase price due to not having as many motors. (There's alsoa weight saving: the two motors omitted probably weigh about three tons each, and the inverter's to go with them must weigh something... hold the total train weight constant and every ton you eliminate from the locomotive you can add to the payload.) How much of a savings is it? Not having any information about this model, I can only try some (possibly obsolete) rules of thumb.

(A) It used to be said that a diesel electric locomotive was, in terms of cost, very roughly one third diesel engine, one third "locomotive mechanical portion" (carbody, trucks, airbrakes...) and one third electrical gear. Maybe -- the electrical part being where the biggest technological innovations have been -- the elctricals would now be a FAT one third. Now, the ES44C4 gets rid of one third of the traction motors and one third of the inverters but still has the whole generator. Reduction in cost: maybe 10%, but I'd be surprised to learn it was that much,

(B) Back in the 1970s I remember it being said (a propos of SCL's purchase of new GE-built road slugs ("MATEs") to go with their U36B) that a C-C unit tended to be about 20% more expensive than the corresponding B-B: a corresponding A1A-A1A ought, therefore, to be somewhere between these. Split the difference (assume, in the absence of any more precise estimate, that the A1A-A1A is 10% more expensive than the B-B) and we get the A1A-A1A being about 8.7% less expensive than the C-C.

So maybe -- until we hear more -- we should think in terms of the cost-savings on an ES44C4, relative to an ES44AC, as being approximately in the neighborhood of something like roughly 9%. Which doesn't, perhaps, sound all THAT impressive. But remember, BNSF is a company that can, without making big headlines, buy 350 locomotives in one year! At which point even small-seeming savings begin to add up.
I have read some "informed speculation" on other boards that GE's wants to be able to sell the ES44AC-4 for about the same price as an ES44DC....

kf7strng
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by kf7strng » Sun Feb 15, 2009 11:40 pm

Thank you V8Interceptor! That is the info I was after! Cheers!

Nasadowsk
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Re: styles of motor

Post by Nasadowsk » Mon Feb 16, 2009 9:45 pm

Allen Hazen wrote: Alternative mountings reduce the unspring mass. In a quill drive (as on the GG-1 electric of blessed memory) the motors were mounted entirely on the truck frame: there were spring connections between the quill and the wheel so the motors themselves didn't have to move up and down when the axle did. Another alternative (that has been used on some high-speed European passenger power, I think) is to have the traction motors inside the carbody, connected by cardan shafts to a gear-box on the axle: gear box plus half of cardan shaft is a lot less unsprung mass than gears and half of traction motor!
Quill drive, AFAIK, is pretty much standard in Europe, now. All electrics in the US have it, too.

The TGV and Pendolinos have body mounted motors - on the TGV, they're where you'd expect the motors to be, just attached to the body, instead, and use the well-known 'tripod' shaft/drive. On the Pendolino, they're mounted "RDC-Style" and driven the same way. The French also had monomotor locomotives - I don't know how they were built. I think all the current stuff in Europe, save for the high speed stuff listed above, is quill drive, including the ICE. I'm sure Stadler or Talgo have a few interesting arrangements, since they generally tend to build stuff that attacks a specific problem in a unique way. There might be a few DMUs or EMUs in Germany with body mounted motors, I'm thinking of the ones that run 11+ inches cant deficiency, and IIRC they are body mounted motors, too.

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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by Super Seis » Thu Feb 19, 2009 8:45 pm

I suspect the reason for the A-1-A configuration is to obtain the performance (starting tractive effort) of the ES44DC in an AC package. AFAIK, most roads forbid mixed consists of AC and DC units by timetable.

The days of electrically operated intake and exhaust valves are on the way, which will enable variable valve timing and consequent optimization of combustion at all notches. BMW has been doing this for years, using a mechanical hydraulic system.

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CN5789
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by CN5789 » Wed Mar 04, 2009 2:49 pm

BNSF and GE have figured out that a 4 A.C. traction motor unit will produce the same traction as a 6 D.C. traction motor unit. BNSF intends these unit's for: intermodal, manifest, grain (BNSF only uses DC units in grain service anyway). These units will not be seen on coal where you need all 6 axles, also as far as everyone talking about the additional rigging on the Hi-ad truck that is driver weight management device for the center axle not being ballasted those are not additional brake cylinders.
Last edited by CN5789 on Mon Mar 16, 2009 1:38 pm, edited 1 time in total.

DASH9DAD

Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by DASH9DAD » Tue Mar 10, 2009 11:03 pm

The first four are being delivered tonight. CSX to BRC to BNSF then the C&I Sub to the Highline.

They should have a test car with them.

Engineer Spike
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by Engineer Spike » Wed Mar 11, 2009 9:51 pm

This discussion is getting foolish. GE units cut out motors all of the time. The AC4400 units cut out motors automatically, when they are not in a hard pull (optimal powered axles on DID screen). One of these units with a defective motor cut out still can produce maximum T/E. One with two motors cut out is only a slight decrease in power. Just look in the "locomotive Monitor" screen, if you ever have an auto motor cut out.

D.Carleton
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by D.Carleton » Wed Mar 11, 2009 10:37 pm

Engineer Spike wrote:This discussion is getting foolish. GE units cut out motors all of the time. The AC4400 units cut out motors automatically, when they are not in a hard pull (optimal powered axles on DID screen). One of these units with a defective motor cut out still can produce maximum T/E. One with two motors cut out is only a slight decrease in power. Just look in the "locomotive Monitor" screen, if you ever have an auto motor cut out.
The idea is not just cutting power to a motor but removing the motor completely along with its supporting equipment to save overall weight and thus save fuel with minimal sacrifice in tractive effort (compared to a six-motor DC version).

DASH9DAD

Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by DASH9DAD » Thu Mar 12, 2009 5:12 am

There's no motor to "remove", just some of the weight, increasing the weight on rails of the powered axles.

D9D

D.Carleton
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by D.Carleton » Wed Apr 08, 2009 10:55 pm

CN5789 wrote:...also as far as everyone talking about the additional rigging on the Hi-ad truck that is driver weight management device for the center axle not being ballasted those are not additional brake cylinders.
Our Canadian Cousins describe this system as allowing "the center axle to slightly lift and transfer more weight to the outer axles and increase the effective tractive effort to the two powered axles in each sideframe set." Years ago I remember some of the old heads complaining about the A1A equipped ALCo RSC-2/3's which, after some wheel wear, the trucks would 'see-saw' during acceleration with the unpowered axle acting as a fulcrum. I'm hoping they have that remedied by now.

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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by Tadman » Fri Apr 10, 2009 10:07 pm

The Monon had that problem with their C628 as well - the curves were a little tight for such a big unit, and the outboard wheels sets would wear down, while the inner set would become the fulcrum. After a while, the center sets would get trued at the shop to eliminate that issue. Interesting that CSX seems to have no problem running their modern 6-axle power on the same route...
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Allen Hazen
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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by Allen Hazen » Sat Apr 11, 2009 2:00 am

My impression is that modern 6-axle locomotives are designed to tolerate a certain amount of difference in wheel diameter: perhaps an inch or so. (No, I don't know how the springing and or equalization is arranged to keep weight constant on axles with different diameter wheels.... At some point, of course, the discrpancy gets too large: I believe the New South Wales Railways, in Australia, decided finally to retire its 40 class locomotive-- MLW-built RSC-3 -- when the outer, powered, wheels on their trucks got too worn down.) One of the advantages of GE's one-inverter-per-motor design philosophy for AC locomotives over EMD's one-inverter-per-truck approach is supposedly that GE's locomotives are more tolerant of minor wheel-diameter discrepancies than EMD's (so don't have to go to the shop for wheel-changes as often).

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Re: New "A1A" ES44 locomotive for BNSF (ES44C4)

Post by MEC407 » Mon May 18, 2009 11:03 pm

GE is hoping that other railroads, not just BNSF, will buy the ES44C4:

http://www.progressiverailroading.com/n ... p?id=20444

http://money.aol.com/article/ge-plans-t ... ive/487923
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