Stalling On Sherman Hill

Discussion in 'TSW General Discussion' started by Disintegration7, Dec 1, 2021.

  1. Disintegration7

    Disintegration7 Well-Known Member

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    Any ideas?

    Service: 09:48 Manifest Cheyenne Yard-Hermosa
    Power 4x SD70 (3 front/1 rear)
    Train weight: 11,020.5t

    I have no trouble getting started, but I'm stalling out when the grade goes from 1% to 1.5% just past the chemical plant.

    I can only get it up to 30mph coming out of Cheyenne before it starts to slow down even in notch 8.

    First thought was dragging the brakes due to not waiting long enough for them to release, but I ran it again and waited 20 min. Rear pressure was showing at 85 before I applied any power. Confirmed all units were providing power.

    Is there simply not enough power? Estimating 4300hp for the SD70 works out to 1.56hp/t, which seems low, but i'm no expert. Comparatively, the 08:48 Grain train runs 6xSD70 for 13892t, or 1.86hp/t. Q353 Manifest on SPG is 3xAC4400/1xSD40-2 for 5392t, which is somewhere north of 3hp/t. I know the grades are much steeper there, though.

    But, I assume the AI can run it or there would be lots of complaints about stuck trains, so I must be missing something...do I have to wait for the rear pressure to hit 90?
     
  2. damarjatiaji

    damarjatiaji Guest

    According to your calculation, i think you can pass the grade. I managed to climb the 1.5% grade as low as 15 mph with 4 SD70ACe pulling a 11.000+ manifest train.

    The rule of thumb of required HPPT is at least the HPPT number matches or the same number as the grade you will drive on.

    Maximum grade westbound from Cheyenne to Hermosa is 1.5%, so with 4 SD70ACe pulling 11.020,5 tons train you will have just enough HPPT for 1.5% grade, don't expect to drive fast though.
     
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  3. shacheld

    shacheld New Member

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  4. WaveyDavey

    WaveyDavey Well-Known Member

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    Silly question but did you turn banking comm on before starting?
     
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  5. Disintegration7

    Disintegration7 Well-Known Member

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    Thanks for the info.

    Don't think it was a DPU issue. I checked the reverser and throttle in the rear unit and it was synched up.

    I'll give it another shot. Maybe i just didn't build up enough speed on departure.
     
  6. jörgen Näslund

    jörgen Näslund Well-Known Member

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    After 10 minutes 90% of the train released the brake. But the last 10 wagons have still brake on
    After 19 minutes even these last 10 cars released the brakes (rear 76 psi)
    The train have 1,63 hp/ton. It is small. I guess this route should have at least 1,7
    4 engine * 4500Hk / 11000 ton = 1,63 hk/ton. If forget to bank its only 1,17 Hk/ton
    So its unpowered this train
    When its 1% climb I have 22 mph. When it is 1,5% I have 15 Mph
    100 klb force.
    if it had been slippery now (rain snow) this would not have not worked. The locomotive had slipped

    Tested with off banking off so just 3 engines. 11 mph 133 klb force
     
    Last edited: Dec 1, 2021
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  7. Disintegration7

    Disintegration7 Well-Known Member

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    You know i did have some snow on the ground- does that affect adehesion or only if it's actively snowing? Also i've seen both 4300 and 4500hp given for the SD70ACE....different versions?
     
  8. jörgen Näslund

    jörgen Näslund Well-Known Member

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    I think so.
    Found this someone wrote in another forum

    I did some research online and did find adhesion coefficients relatively close to those being used in OR. Here were my findings for adhesion adjustment factors:
    Dry rail: 100%
    Clear+Sand: 110+% (seems that OR is using 150%?)
    Rain: 67%
    Rain+Sand: 83.3%
    Snow: 33%
    Snow+Sand: 50%

    When Snow falling, max intensity:
    Adhesion for first few axles (first locomotive for simplicity): 40%, or use current Open Rails value. Sanding will improve to overall 60% adhesion.
    After first locomotive: 90% adhesion due to mild moisture condition. Sanding will improve to 100% adhesion.
     
    Last edited: Dec 1, 2021
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  9. jörgen Näslund

    jörgen Näslund Well-Known Member

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    Driving a train is a almost a Physics lesson :love:
     
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