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Thread: Prototypical steam locomtive cocks operation

  1. #1
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    Default Prototypical steam locomtive cocks operation

    In the real world, if the throttle it totally closed, is it a good idea to open the cocks and drain water that is stuck in the cylinders? If that works, do the cocks have to be opened when starting?
    Bob

  2. #2
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    Default RE: Prototypical steam locomtive cocks operation

    My understanding of the situation says that in the real world there would be steam left in the cylinders when you stop, which would condense into water before you started up again (the cylinders would cool down). So my short answer would be to open the cylinder cocks before starting any steam run. Bad plan to try to force water against your pistons.

    I donít think itís weighted that heavily in the sim; itís just a small penalty on the overall performance of your loco. Still, itís a good idea to close them after you gain some speed.


  3. #3
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    Default RE: Prototypical steam locomtive cocks operation

    Also don't leave them open too long after you start moving. It only takes a few turns of the wheel to get all of the water out. Having them open for a long time will hurt you especially when you are trying to start a heavy train on a grade.

  4. #4
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    Default RE: Prototypical steam locomtive cocks operation

    >In the real world, if the throttle it totally closed, is it a good idea to open the cocks and drain water that is stuck
    >in the cylinders? If that works, do the cocks have to be opened when starting?

    If the throttle is closed and the loco is moving, its loco dependent.
    I drive one loco that must have the dc open before the throttle goes back to zero, or it forces water up the oiler.

    The other loco's are not so touchy.

    Cheers
    Derek

  5. #5
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    Default RE: Prototypical steam locomtive cocks operation

    >Also don't leave them open too long after you start moving. It only takes a few turns of the wheel to get all of the
    >water out. Having them open for a long time will hurt you especially when you are trying to start a heavy train on a
    >grade.

    Yes, but if the cylinders are not warm, you need to leave the dc's open until its all warmed up.

    Cheers
    Derek

  6. #6
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    Default RE: Prototypical steam locomtive cocks operation

    Anytime the locomotive is at rest it's a good idea to have the cocks open. As you get going it's also a good idea to leave them open for a few wheel revolutions; not only does this allow the cylinders to warm up and expell any condensation inside, it also gives you an "out" in case of priming. If for some reason the boiler water is foaming, it has the potential to also circulate water through the dry pipe and into the cylinders (a different concept from priming). With the cocks open, any water "carried over" will be expelled and not cause you to blow the endcap off the cylinder. There is at least one example of a Crown locomotive doing just that, in a tunnel no less, at a theme park. Blew the cap at least 50 feet, and believe me it's a bear to replace.

    Also, though it is not represented in MSTS, your steam pump(s) for the air brakes also have cocks, as do the main res air tanks. Basically, anywhere you have air or steam in a confined spot, you have the potential for condensation and equipment failure...and ergo, you find drain cocks.

    I do half disagree that you have to "be careful of cocks when starting a heavy grade" though...while in theory it'd seem like you'd waste a lot of steam, in practice you actually SAVE gaskets! If you're driving a locomotive that has a steam chest pressure gauge, open the cocks and then the throttle. After a couple revolutions, close the cocks and you should see a pretty good jump in steam chest pressure. In the real world, that jump can easily blow out the head gasket between the steam chest and the cylinder. It's happened to us when starting a fairly light train. In practice, I ALWAYS knock the throttle down just before closing the cylinder cocks.

    As the fellow just above me said: lots of techniques are loco dependant. My experiences with the 3985 vs our little 4-4-0 prove that, but the fundamentals remain. You also must keep in mind that MSTS was not intended for steam locomotives...it just doesn't come close. But you take what you can get, right?

    Later

  7. #7
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    Default RE: Prototypical steam locomtive cocks operation

    I understand what you mean Black. I have had times where I could not start the train if I had the cocks open but like you said the sim doesn't do justic to the steam locomotive. Thanks for you explanation!

  8. #8
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    Default RE: Prototypical steam locomtive cocks operation

    No problemo!

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