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Thread: Continuous Suppression

  1. #1
    Join Date
    Nov 2003
    Location
    Wilmette, Illinois
    Posts
    127

    Default Continuous Suppression

    On a brake stand what is "continuous suppression" and what is it used for? Also when there is a "hold" position on a brake stand what does this do and when is it used?

    Thanks,
    Barry

  2. #2
    Join Date
    Nov 1999
    Location
    Savannah, Georgia, USA.
    Posts
    3,746

    Default RE: Continuous Suppression

    Suppression is just beyond a full service application.It'll also give you 23-26 pound reduction in the brake system.Supression is also used to recovery from a brake penalty application.You go to this position to reset the PC valve after an emergency application also.Handle-Off position is used when the unit is in the trailing position.Also if the handle is moved to this position on the lead unit the equalization reservoir will be reduction to zero and and the brake pipe pressure is reduced to 10 pounds.The hands-off position is a notch past the suppression notch which is a notch past the first service zone.Hope this helps you.

  3. #3
    Join Date
    Nov 2003
    Location
    Wilmette, Illinois
    Posts
    127

    Default Thanks and a bit more....

    I thought I had learned something about brake systems, but the more I learn, the more I realize I don't know.

    A few other questions. What is the PC valve? Also when you use the term "handle-off" is that the same as "hold"? Finally, what is the reason the equalization reservoir is reduced to zero and the brake pipe pressure to 10 psi when the handle is in handle-off (hold?) on the lead unit?

    I appreciate you patience.

    Barry

  4. #4
    chazlee1 Guest

    Default RE: Thanks and a bit more....

    "PC" is actually a electronic switch; it means "Power Cutoff". When you have an emergency application of the brakes, it cuts off power to the traction motors; it automatically resets itself when the emergency application is cleared and brakes release. I think the "Brake-off" position is more than likely the brake valve control. It has 3 positions: Trail-cuts out the automatic brake valve; FRT-places automatic brake valve in freight position; and PASS-places automatic brake valve into Passenger position.

  5. #5
    Join Date
    Nov 1999
    Location
    Savannah, Georgia, USA.
    Posts
    3,746

    Default RE: Thanks and a bit more....

    When the PC valve or switch is activated it knocks the RPM to idle and unloads the generator or alternator.

  6. #6
    chazlee1 Guest

    Default RE: Thanks and a bit more....

    AhHa..now I see!! On the BNSF, the HO position is marked CS for Continuous Service. The handle has to be in this position for the unit to be set up for Trail, as it bleeds the Eq. reservoir down to zero.

  7. #7
    Join Date
    Nov 2003
    Location
    Wilmette, Illinois
    Posts
    127

    Default RE: Thanks and a bit more....

    You'll have to forgive my ignorance. I'm a radio and television reporter by profession and a serious rail fan all my life.

    In this series of posts everyone seems to be talking to each other as fellow experts. I would appreciate if anyone could simply answer my second question. What is the "hold" position and when is it used. No one in any answer has specifically referred to the term "hold". Is "hold" the same as with "lap"? And what is "handle-off" and how, if at all, does this relate to "hold"?

    Again, all I'm trying to do is increase my knowledge base in terms I can understand. Anything you can do to help would be greatly appreciated.

    Thanks for the time and effort.
    Barry

  8. #8
    Join Date
    Aug 2002
    Location
    Boston, MA.
    Posts
    693

    Default RE: Thanks and a bit more....

    If you want to learn more about brakes I would suggest checking here it has a section on lap which is something I believe you are looking for.


    http://www.railroad.net/articles/rai...akes/index.php


    Claude350 told you what handle off was here

    Handle-Off position is used when the unit is in the trailing position.Also if the handle is moved to this position on the lead unit the equalization reservoir will be reduction to zero and and the brake pipe pressure is reduced to 10 pounds.The hands-off position is a notch past the suppression notch which is a notch past the first service zone.Hope this helps you.

  9. #9
    Join Date
    Nov 2003
    Location
    Wilmette, Illinois
    Posts
    127

    Default RE: Thanks and a bit more....

    Thanks:

    I've had that article for some time. Very helpful. Again, my only confusion is whether the term "hold" = "handle off" or does is it the same as lap.

    Pardon my density.

    Barry

  10. #10
    Join Date
    Apr 2003
    Location
    East Northport, New York, USA.
    Posts
    309

    Default RE: Continuous Suppression

    Greetings All,
    The "Hold" position allows the engineer to recharge the brake pipe while maintaining Brake cylinder pressure throughout the train until the handle is moved to the release position.

    KRO52

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