(Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

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David Collins
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(Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

Unread post by David Collins »

https://www.youtube.com/watch?v=HfEpQdrqRTk

Admin: I don't know if Railfanning info is the right location for this. Feel free to move it.

My first episode of train your brain: Which is a new series where I discuss news in the railroad industry, ideas or anything else related to railroads, comment as to what I should talk about next!

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Re: (Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

Unread post by Saturnalia »

DC traction is as good as dead.

The only reason DC traction lasted as long as it did is that AC is more expensive due to the alternators and generally more elaborate electrical systems. DC isn't "better" at fast, light trains, it's the only place worth running them if you have the AC traction to put on everything else.

DC traction motors are also require more extensive maintenance. Over time, the railroads have found the up-front cost of AC traction to be balanced out by the long-term costs of maintaining DC traction motors. Plus, aside from the alternator (higher cost for AC) and traction motors (higher cost for DC), all else is essentially the same between the AC and DC offerings.

There is a reason why GE never really offered nor sold ET44DCs, and it's the same reason we'll never see SD70M-3s: nobody wants DC power anymore. CN was the last holdout, as seen with their late SD70M-2 order, and everything else sold since has been AC traction.

BNSF has attempted to take advantage of the light and fast intermodal concept with the lifting axles on the ES44C4s/ET44C4s, but even that idea seems to have run its course.

Lastly, even most transit agencies are ditching DC traction on mass, for the same reasons as the freight railroads. The CTA, for instance, runs off DC third rail but beginning with the 5000-series order, have gone with AC traction motors. That greatly reduced their maintenance on the motors, which was an outsize share of the maintenance for their cars.
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Re: (Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

Unread post by cfriedri »

Gonna have to echo Saturnalia's sentiment on this one.

DC had its time but AC is more versatile. And the light, fast trains you refer to don't exist any more. Intermodal may be lighter when you compare it to a manifest or coal train but it's still not a 3,000 ton sprint train from the 90's. Plus AC doesn't have the short time rating that has gotten me into trouble in the past lol.

I like the video series concept though. Look forward to seeing what you come up with next.
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Re: (Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

Unread post by SD80MAC »

No offense, David, but perhaps you should pick a topic you know something about. Nearly everything in this video is false or a railfan rumor.
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Re: (Editorial Video) Progress Rail NEEDS to make the SD70M-3 a reality, here's why...

Unread post by PatAzo »

An short piece on AC vs. DC traction. http://www.republiclocomotive.com/ac-tr ... ction.html

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