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[Junctionfan]

What is so special about the AC4400CW that railroads prefer the AC powered more than the DC powered C44-9W and visa versa?

[Anonymous]

Essentially both locomotives have the same horsepower, but it was known to the fact that the AC4400CW is the better locomotive than the C44-9W, because of the AC traction motors. AC tends to be more powerful than DC, even though DC saves fuel. Both locomotives are very good at pulling but I have to say that the AC4400CW is the better because of the AC traction motors, which produces a lot of torque.

[Junctionfan]

QUOTE: Originally posted by GTWfan6685

Essentially both locomotives have the same horsepower, but it was known to the fact that the AC4400CW is the better locomotive than the C44-9W, because of the AC traction motors. AC tends to be more powerful than DC, even though DC saves fuel. Both locomotives are very good at pulling but I have to say that the AC4400CW is the better because of the AC traction motors, which produces a lot of torque.

Why do you suppose does CN for example, not use AC traction power such as the AC4400CW or the SD90MAC or if its because of the desire of fuel efficiency, the SD70Ace? CN does not seem to be interested in anything AC and yet they are running some outlandishly long trains lately.

[Anonymous]

With out reading this topic I can most likely tell you.......the AC4400CW,The AC4400CW is the most powerful locomotive ever built. Just this evening a westbound loaded grain train pulled by 4 AC4400CW's pulled it like it was nothing.
BNSFrailfan.

[athelney]

QUOTE: Originally posted by BNSF SD70MAC

With out reading this topic I can most likely tell you.......the AC4400CW,The AC4400CW is the most powerful locomotive ever built. Just this evening a westbound loaded grain train pulled by 4 AC4400CW's pulled it like it was nothing.
BNSFrailfan.

Where was it running too-- do you have a steep grade nearby ? 4 AC4400's ? - Up here CP normally uses 2 AC4400's on their westbound loaded grain trains .

[Anonymous]

It was on it's way to north platte,ne off the sioux city & blair lines.
The westbound grade at blair is a 1.0% grade.
Not to many trains stall on blair hill any more which is kinda strange.
Of course I would love to see a few loaded coal trains attack it once in a while, but 99.9% of "all" of the coal trains take the omaha line.
BNSFrailfan.

[Anonymous]

QUOTE: Originally posted by Junctionfan

QUOTE: Originally posted by GTWfan6685

Essentially both locomotives have the same horsepower, but it was known to the fact that the AC4400CW is the better locomotive than the C44-9W, because of the AC traction motors. AC tends to be more powerful than DC, even though DC saves fuel. Both locomotives are very good at pulling but I have to say that the AC4400CW is the better because of the AC traction motors, which produces a lot of torque.

Why do you suppose does CN for example, not use AC traction power such as the AC4400CW or the SD90MAC or if its because of the desire of fuel efficiency, the SD70Ace? CN does not seem to be interested in anything AC and yet they are running some outlandishly long trains lately.

An AC4400CW costs about $500,000 more than a C44-9W. Take that into consideration.

[Overmod]

Principal advantage of AC power is that there's no effective limit on traction-motor longevity at very slow speeds or high load conditions. The AC motors won't burn up through resistance heating as DC motors can, and will survive quite happily at a full locked-rotor stall at full generator horsepower.

They also have, by far, better high-speed performance characteristics, but this would be wasted on contemporary American freight railroading.

It is also nominally a bit easier to perform microslipping or rapid slip stoppage with AC synthesized drive than on a DC system; theoretically, torque on a given axle could be fully reversed within no more than a synthesized cycle or two, dependent mainly on the rotating inertial mass of the motor and wheelset. Don't try this with a DC motor and contactors!

NS does not use AC motors because they have a large, and standardized, inventory of DC motors, and don't need a duplicated stock of parts and maintenance/training cost for a 'boutique' selection of AC locomotives. Presumably CN has made a similar choice. This situation is, of course, different at roads like UP (or KCS) which have services that benefit strongly from the characteristics of AC drive.

[Junctionfan]

In the long run, despite the $500,000 difference and equipment storage; Due to their high traction, they could save money on spending on a few AC4400CW as opposed to a few more C44-9W? I look forward to your responses.[:)]

[Anonymous]

No comment!
BNSFrailfan.

[Anonymous]

Hi i am in Becker MN and we have a coal power plant so i always see the BNSF coal trains i am a BNSF fan too. they normaly have like 4 engines they look like ac4400 sometimes the Dash 9 brings the coal cars too.

[CSXrules4eva]

Well the AC4400CW with it's AC traction motors is far more superior than the C44-9W. This is because of the use of Alternating Current (AC) in it's traction motors. AC current alternates changing it's voltage at every period. Therefore locos w/ AC traction motors are able to provid very high power at very low speeds. the SD80MAC for example has AC traction and is able to pull a 18,000 ton train at 0.5mph, this is called wheel creep. DC (direct curent) isn't as reliable as AC. DC has a current in which the voltage always stays the same at periods, it never changes. This is why locos w/ DC traction like an SD40-2 aren't able to provide high power at low speeds. Howevery, you can do this for a very short period of time. This is so because if left too long you'll run up against the adheasion levels of the locomotive resulting in seveir damage of the communtator and the brushes in the DC traction motor. This is refered to as short time ratings (which only occurs in DC tration locos). AC traction motors don't have commutators or brushes, they have induction motors. . . so, u don't have to worry about short time ratings. Tractive effort on AC locos are also mush higher than DC traction motors.

So now many railroads would opt for the AC traction vs. DC because, of all the capabilities it has over DC. There is also less maintenice on an AC than a DC. Overall AC is better at heavy haul than DC.

[Strothers]

I don't know the technical details - the above postings have been great! - but one day I was in Bluefield, WV parked along the NS rail yard - there were 2 1-mile-long coal trains (80 ton hoppers loaded) parked on adjacent tracks, each headed by 2 c40-8s. Suddenly, within about 5 seconds of each other, they both started! One moment they were still, the next they were moving - and not at 0.5mph; it was awesome, no apparent run-up after the coupler play was taken up. NS uses lots of C40s, mostly dash-8s, usually 2 per train. I don't know the grades in the area; but clearly NS loves them C40s.

[Junctionfan]

Saw some NS coal trains at Fostoria using 1 C40-8 and a lot of empty Top Gons.

[CSXrules4eva]

QUOTE: Originally posted by Strothers

I don't know the technical details - the above postings have been great! - but one day I was in Bluefield, WV parked along the NS rail yard - there were 2 1-mile-long coal trains (80 ton hoppers loaded) parked on adjacent tracks, each headed by 2 c40-8s. Suddenly, within about 5 seconds of each other, they both started! One moment they were still, the next they were moving - and not at 0.5mph; it was awesome, no apparent run-up after the coupler play was taken up. NS uses lots of C40s, mostly dash-8s, usually 2 per train. I don't know the grades in the area; but clearly NS loves them C40s.

Your right about that! Every time I go to the NS mainline that follows the PA turnpike (ex PRR trackage). I'll always see a high speed intermodel train complete w/ DTTX cars and guess wut NS's pride and joy the Dash-840C. Every time this happens. WHATS UP WIT DAT??