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Thread: Engine Air Readouts Questions

  1. #1
    Join Date
    Jan 2006
    Location
    Hanover Park, Il., USA.
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    Default Engine Air Readouts Questions

    Hello,
    If I may ask about some oddities (I believe, anyway) on my most used engines - air related.
    At the start of many activities, I like to have my train ready to "highball", which means I am sitting with engines running, no handbrakes, a predetermined amount of train air (anywhere between 6psi-20psi reduction, for instance), and the independent brakes set full 100%. It is my understanding that the BC readout should show 73psi if 100% set and holding - is this correct?
    In my first screenshot, you'll see it shows 64%. I don't know why this is or how to correct it.

    In the second screenshot, I am running with train and independent released, and as expected, the ER & BP show 90, and the BC shows 0. But, why is my main res climbing up to 140? Shouldn't this remain at 90psi?

    Admittedly, I am physics challenged. Also noting I am running OR.

    Looking to be educated on what to add/change to start up my activity with 73psi for loco brake, and understand why the main res climbs past 90.

    Thanks very much!


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    • File Type: jpg 2.jpg (63.9 KB, 122 views)
    Neil

    Here at home, in the railroad mayhem capital of the world.

  2. #2
    Join Date
    Jun 2013
    Location
    Minnesota
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    1,261

    Default

    The reservoir should be at 140 while running since that's used to charge the brake line and doesn't directly control any brakes, so that sounds about right.

    As for how to get 73psi out of the independents, I'm not sure either

  3. #3
    Join Date
    Jan 2006
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    Default

    Thanks TE. I was going off of some pics from a tutorial Bill Preiger put out years ago, and his trains on the move always showed 90psi in the Main Res window. Wonder why?
    Neil

    Here at home, in the railroad mayhem capital of the world.

  4. #4

    Default

    MR *should* read at about 140. Equalizing reservior pressure should the same as the BP pressure. It indicates to the engineer when the brakepipe pressures are equal on all the cars on the train. For longer trains, you will notice a lag time between when you take air out at the ER readout settles. When you make an application, it does not pull air out of all the cars all at the same time; it is sequential from the first car to the last hence the lag time between when you make the application to the time that readout settles.

    73 PSI for the Independent is not uncommon on Canadian engines, based on my experiences. I've run SW1200RSs and MLW C424s - all of which were of CP heritage - where the independent runs at that range.

    I have never seen an American built engine from either ALCO or EMD run that high. Can't speak to any other manufacturers (GE, Baldwin, BLH, etc.) Most American engines I've run run at about 32 psi for the independent.

    As for AB pressures, in your first photo, the readout indicates that there is a full service application on the train (26 lb application), so the reading is correct - 90-26=64. Notice the numbers are the same - 64, 64, 64. You've achieved equalization. Full service is the maximum braking force you can get short of big holing it.

    2nd photo shows everything released, but the rear of the train is not quite there yet, which is normal. You have a 10 psi reading on the AFM, so you're still pumping air and the rear of the train will eventually get to 89-90.
    Last edited by kknobl; 12-14-2019 at 11:05 AM.

  5. #5
    Join Date
    Jan 2006
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    Hanover Park, Il., USA.
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    Thanks very much, kknobl, I do appreciate the real world input.
    I get all that you are saying, but don't know if I am straight on the 64 on the AB pressure. I know in the .eng file I have this 3rd value set to 0.4: Brake_Train ( 0 1 0.0125 0.4
    I need to verify the actual reduction when I play next, and my train is at a standstill, but I know it's not 100% full service. I apply this value physically at the start of the activity by pressing the ' key, just like I have the loco brake value at 1: Brake_Engine ( 0 1 0.025 1, which sets the loco's at 100% when I tap ].
    Neil

    Here at home, in the railroad mayhem capital of the world.

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