Western Railroad Discussion > Why does BNSF rarely use their Dash 9 fleet on coal trains?

Hi Good morning, I had this on my mind. Why does BNSF not use their C44-9W fleet on coal trains very often? BNSF has a big fleet and they are equipped for use in DPU operation. So how come they aren't on coal trains very often?

The short answer would be that they, like the UP, prefer to use AC traction on the heavy coal trains. Dash 9's are DC traction. AC traction works better at lower speeds and they don't have to worry about minimum continuous ratings with AC traction.

a.c. motors are preferred for the rigors of hauling heavy unit trains.....

66

DC motors, like those on the DASH-9's are prone to overheating and other issues when they operate at low speeds and under high power. As others have said, simpler and more robust AC-motored units are preferred for trains that are likely to spend significant time crawling under full/high power.

Direct Current motored C44-9W locomotives are much better suited for the higher speed service of some manifest and intermodal trains for which they were designed. AC44CW locomotives are the Alternate Current version of the C44-9W. The AC version is officially known as AC4400CW in General Electrics catalogue. The DC C44-9W is also known as the Dash 9-44CW or simply Dash-9.

As mentioned previously, the AC traction motors are much more robust and simpler and easier to maintain than DC traction motors.

Burlington Northern Santa Fe is actually rebuilding (having them rebuilt) their earliest C44-9W locos into "AC44C4" AC drive, four motored A-1-A units. These old Santa Fe units seem to be doing pretty well with only four powered AC axles vs the six DC powered axles as delivered.

SantaFeRuss

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Edited 1 time(s). Last edit at 04/22/17 11:50 by SantaFeRuss.

Most AC motors will "locked rotor" over 200%, a similar situation on a DC motor will result in a barbeque,
steaks not provided!

Out

SantaFeRuss Wrote:
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> Burlington Northern Santa Fe is actually
> rebuilding (having them rebuilt) their earliest
> C44-9W locos into "AC44C4" AC drive, four motored
> A-1-A units

Not actively. 21 were done and that's it for now.

callum_out Wrote:
-------------------------------------------------------
> Most AC motors will "locked rotor" over 200%, a
> similar situation on a DC motor will result in a
> barbeque,
> steaks not provided!
>
> Out

What????  Explain that first sentence again.