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Pcs When Coupling

Discussion in 'Xbox Discussion' started by pauham11, Sep 13, 2020.

  1. pauham11

    pauham11 New Member

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    Hello,
    Whenever I try to couple with the alerter turned on in a GP38-2 or SD40-2 locomotive, (not tested the AC4400CW yet) the PCS indicator light comes on and I have to perform the PCS reset procedure before I can get moving again. I'm wondering if there's something I'm supposed to do when coupling to prevent this occurring, or if the alerter is meant to be switched off when coupling, or is having to frequently reset the PCS something that would occur in real life?
     
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  2. Lamplight

    Lamplight Active Member

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    I'm curious about this as well. Could someone better versed in American train operations perhaps shed some light on PCS in connection to switching?
     
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  3. Stephen Crofts

    Stephen Crofts Active Member

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    I've been searching for help on this one too.
     
  4. Mr_Crazey

    Mr_Crazey Active Member

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    If I had to guess. I would say the reason is that the freight cars do not have any air in their brake systems when they aren't attached to a locomotive. When you attach to these cars the sudden loss of air pressure in the brake system triggers the safety system. Same as if there was a mechanical failure of the brake system or if one of the various methods of applying emergency brakes were activated. I could be wrong tho, i'm guessing.
     
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  5. Stephen Crofts

    Stephen Crofts Active Member

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    The only way I can get around it at the moment is switching the alerter off and on again at the fuse. But there must be a more proper way.
     
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  6. Mr_Crazey

    Mr_Crazey Active Member

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    So I did some google deep diving. PCS or pneumatic control switch, is a safety system designed to cut propulsion power when brake pipe pressure gets too low. Various things can cause the brake pipe pressure to get low enough to trigger PCS, including emergency application of air brakes, penalty application of air brakes due to an ignored alerter alarm, or theoretically attaching a string of unpressurized freight cars to your pressurized locomotive causing a rapid loss in pressure in the brake pipe.

    As to real life procedures i have no idea. Hopefully someone else shows up with more knowledge than i.
     
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  7. pauham11

    pauham11 New Member

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    Thanks for finding this out, whilst you weren't able to find the procedure it's really cool to have the explanation as to what actually causes the PCS to trigger.
     
  8. pauham11

    pauham11 New Member

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    This makes sense and sounds correct, so I expect you're right.
     
  9. breblimator

    breblimator Well-Known Member

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    UPDATED

    My opinion on this:

    The difference between the pressure in the braking system of both coupled parts of the train causes the airflow is too high - PCS open probably depends on the airflow level.

    e.g. one part of the train is full service (low psi) and the second one, with brakes released (high psi)
    during coupling and opening Anglecock

    Anglecock:

    A valve located at each end of locomotives and cars used to open or close the brake pipe. The handle is hinged so as to lock in either the open or closed position. When the handle is in-line with the brake pipe, the anglecock is open. When the handle is crosswise to the brake pipe, the anglecock is closed.
    source

    This valve could be partially open, so the airflow isn't at level to appear PCS open.

    I don't know what this has to do with the alerter :D
     
    Last edited: Sep 17, 2020
  10. pauham11

    pauham11 New Member

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    The reason I mentioned the alerter is that turning on the alerter also turns on all the safety systems, including the PCS and it's indicator light. Having the alerter off (and thereby the safety systems) means that the PCS never stops you from being able to apply throttle, even after an emergency brake.
     
  11. Mr_Crazey

    Mr_Crazey Active Member

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    So I asked a real CSX engineer about this and the answer was so simple I can't believe I didn't think of it. In TSW the air lines for the braking system automatically attach together when you engage the couplers by bumping into them. But in real life once the engineer engages the couplers they have to manually attach the air lines from the locomotive to the air lines on the freight car. So they move the automatic brake handle to the full service positon in the locomotive before attaching the brake lines which lowers the pressure in the brake pipe and prevents an overcharge from the difference in pressure between the locomotive and freight car.
     
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  12. graeme.norton1

    graeme.norton1 New Member

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    An easier way to reset the PCS is to cut out the Automatic Brake then cut it back in.
     
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  13. breblimator

    breblimator Well-Known Member

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    I understand Your intentions, but don't know, why this is happening -> alerter :)

    UPDATE
    I did not know. I thought PCS is an independent system. Curiosity :D
     
    Last edited: Sep 18, 2020
  14. Lamplight

    Lamplight Active Member

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    I feel so stupid for not thinking of this:) Thank you for going through all that trouble for us; must be handy to have a real engineer at hand;)
     
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  15. breblimator

    breblimator Well-Known Member

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    Yes. This is about pressure differences. You are right.
    But what does the alerter have to do with it? That's the question :) // or not

    UPDATE
    I did not know. I thought PCS is an independent system. Curiosity :D
     
    Last edited: Sep 18, 2020
  16. breblimator

    breblimator Well-Known Member

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    I've checked in Peninsula. PCS has no relation to the alerter. Hmm?
    It went ON even though the alerter was OFF (too high airflow).
     
  17. pauham11

    pauham11 New Member

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    I was referring to the SD40-2 and the GP38-2 only, where the alerter is activated by a switch in the fuse cupboard which will activate the alerter, along with the PCS and all the safety indicator lights.
     
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  18. pauham11

    pauham11 New Member

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    Thanks so much for finding this out, was really interested in getting an answer, so thanks again.
     

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