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Thread: Horsepower/Tonnage Ratio

  1. #1
    Join Date
    Jul 2004
    Location
    Archer, FL, USA.
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    135

    Default Horsepower/Tonnage Ratio


    Who knows the horsepower/tonnage ratio railroads use to calculate
    how much motive power a given consist will require to move over level terrain ? Obviously terrain makes a difference.

  2. #2
    Join Date
    Jun 2004
    Location
    Falls Village, CT, USA.
    Posts
    3,331

    Default RE: Horsepower/Tonnage Ratio

    IIRC, CSX uses anywhere from .5hp/ton to 2hp/ton

    If thats what your talking about :-)

  3. #3
    Join Date
    Nov 1999
    Location
    near Jacksonville, TX
    Posts
    6,205

    Default RE: Horsepower/Tonnage Ratio

    You left out one crucial component, speed.
    Actually it is a bit more complicated than that even,
    For example, I will take 3 trains
    1)An 8000 ton general merchandise freight.
    2)A 4800 ton autorack train
    3)A 16,500 ton unit coal train
    For example 1), 1.5 HP/ton may be enough to move it at 45mph over level terrain. Example 2) may require 2.0 HP/ton to get to 45 mph, and 3.5 HP/ton to get to 60 mph. Example 3) can probably get to 45 mph with 0.7 HP/ton, and may be satisfactorily operated with 0.5 HP/ton at 35-40 mph.
    I have seen 16,500 ton coal trains come through wih a SD90/43 on front and another SD90/43 on the back. That is 8,600 HP on a 16,500 ton coal train. I once saw a UPS TOFC with three 6,000 HP CW60AC on front of 30 TOFC which I would guess weighed 3,000 tons. That is 6 HP/ton, but it was doing at least 75 mph (it was a special experimental test train with CW60AC regeared for 80 mph running).
    This may give you some idea what the boundaries are. Generally, roads like NS and CSX will be lighter on HP/ton than UP and BNSF, because they do not have the higher speed traffic to clear. Ore lines can run a lot of iron ore with a pair of SD7s at 3,000 HP total, just not very fast. They may be happy with 0.45 HP/ton.
    Hope this helps,
    Bob


  4. #4
    Join Date
    Jul 2004
    Location
    Archer, FL, USA.
    Posts
    135

    Default RE: Horsepower/Tonnage Ratio

    Thanks to Bob and Dave... that's exactly the information I was looking for.

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