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Throttle response on today's diesels?

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  • Member since
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Throttle response on today's diesels?
Posted by timz on Friday, August 20, 2021 12:10 PM

An SD40-2 manual says (I think) that if you're stationary with brakes set and move the throttle to Run 1 you were supposed to get 275 amps thru each motor.  Presumably today's ACs exert comparable TE in Run 1? If it's coupled to an immovable object, how much TE does an ordinary AC44 exert in Run 1? How many seconds after you move the throttle does the TE level off?

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  • From: Central Iowa
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Posted by jeffhergert on Sunday, August 22, 2021 11:39 PM

Usually what I see when starting and going to notch one is tractive effort of about 14 or 15 thousand pounds.  Notch 2 will increase to about 50K, but it will drop back.  While watching for the TE (or amps on a DC) to level off and drop back, I couldn't say the time involved.  It's going to depend on conditions that aren't going to be uniform everytime.

Jeff 

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Posted by timz on Monday, August 23, 2021 2:48 PM

Thanks for that. If you go to Run 2 with the locomotive not moving, TE increases to around 50000 lb, but then decreases -- even if the locomotive is still not moving?

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  • From: Central Iowa
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Posted by jeffhergert on Tuesday, August 24, 2021 5:22 PM

If the train doesn't move, it will just level off.  If it starts moving, or is moving very slowly in N1 and then go to N2, it will level off and fall back.  How fast or how far back depends on the train's weight and grade conditions.

I had an SD70Ace in the lead on my last trip.  When going to N1, it produced 20K tractive effort.  That seems right for that type.  While I get both SD70Ace and AC4400 types, it seems like I see more GEs.  Just luck of the draw.  I know the 14K starting effort is what I see on the GEs, so the 20K seems right for the EMDs.

Jeff 

  • Member since
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Posted by timz on Wednesday, August 25, 2021 12:35 PM

Thanks for the straight dope.

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