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Thread: Retainers

  1. #1
    Join Date
    Sep 2002
    Location
    Taylorsville, NC, USA.
    Posts
    572

    Default Retainers

    On most steep grades in the U.S., train crews set up retainers in so many cars on the head end of a consist. Without going into a long technical discussion, retainers keep the brakes on those cars partially applied, so the engineer can recharge the rest of the train.
    MSTS doesn't have that capability, and I have had runaway problems with heavies on Marias. My answer? I set up the hand brakes on the first 5 to 10 cars at the top of the grade past Spotted Robe, and kick them off at the bottom. For realism, I stop the train to do this. Works wonders. Anyone else tried it?
    de N4JNM former KC6YJN
    JOhn Oldrailfan - Railfan means anything on rails! Trains Trolleys Rollercoasters - you name it.

  2. #2
    I_totally_love_trains Guest

    Default RE: Retainers

    Do real trains have to stop to recharge the train in real life?

    Adam

  3. #3
    Join Date
    Nov 1999
    Location
    Savannah, Georgia, USA.
    Posts
    3,587

    Default RE: Retainers

    Yes they do.

  4. #4
    Join Date
    Jul 2002
    Location
    oklahoma city, ok, usa.
    Posts
    1,473

    Default RE: Retainers

    Sounds like a plan. Thing is, I've gotten so many "this car doesn't have hand brake" messages while switching that I've about forgotten about using them.

  5. #5
    I_totally_love_trains Guest

    Default RE: Retainers

    So how does a train lose it's brakes then? Do they get hot and fail like trailer truck brakes going down a steep grade?

    Do train wheels have to be replaced every so often from brake rubbing or doesn't the brake pads rub the wheels?

    Adam

  6. #6
    Join Date
    Nov 1999
    Location
    Ohio, USA.
    Posts
    480

    Default RE: Retainers

    Those are excellent questions and responses. It sounds like some of the activity designers should look into building this into their routes. Perhaps in the briefing, or a pop-up window before the grade begins. (which people seem to hate, but I find them informative)


  7. #7
    Join Date
    Nov 1999
    Location
    Valley Center, KS, USA.
    Posts
    656

    Default RE: Retainers

    Hi Adam.
    Usually, a train loses the brakes when the air pressure runs out. The usual scenario is that the engineman tries to make repeated air brake applications without recharging the line between the applications. At least with the way the air brakes on North American freight trains are set up, it is not possible to partially release the brakes and then reapply them, unless the full pressure in the air line has been recharged. This process may take several minutes, so on a steep grade the train may get out of control during that several minutes.
    Train wheels do get hot while the brakes are applied. The brake shoes rub on the wheel treads, and they do wear out. Usually, it's the shoes that have to be replaced first, but the wheels wear, too.
    There are some cars, mostly passenger cars, that have disc brakes with rotors on the axle so the brake pads rub the rotor instead of the wheels.
    Dan

  8. #8
    Join Date
    Nov 1999
    Location
    .
    Posts
    857

    Default on wheel wear, and a book recommendation..

    Some good info here...
    http://www.sdrm.org/faqs/brakes.html

    Also, yes, brake pads wear and need to be replaced, there are specifications for how worn a pad can be.
    Wheel wear is unavoidable on trains. However the rates of wheel wear can vary very widely, depending on circumstances. When a wheel reaches a certain point in the wear cycle, it must be either reprofiled by machining, or replaced. This is expensive. Usually wheels are replaced or reprofiled for either 1) excessive flange wear, or 2) excessive tread wear. One factor or the other will limit the wheel life. There are many sub factors within each of these groups. Examples of wheel tread wear shelling (prevalent in cold weather in freight) and skid flats (related to poor braking control / practices). One way to help reduce whell wear is by rail grinding to maintain the correct rail profile. The phsyics of the rail/wheel interface are very complex, lots more going on that it looks like..

    Some other good info at:
    http://www.railjournal.com/2001-09/cpr.html
    http://www.railsciences.com/wheel.html
    http://www.rtands.com/jul99/optimizing.html
    http://www.pennsy.com/AdapterPlus/AdapterPlus.pdf
    http://www.cs.wayne.edu/~grb/Wheeldoc.htm
    http://www.railwayage.com/apr00/wheeldesign.html

    Hope that helps..One more recommendation, a really good book on railroads and railroad operations is:

    "The Railroad: What It Is, What It Does" by John Armstrong.
    Its in its 4th edition, and its really explains a lot of railroad basics.

    Cheers
    Harold



  9. #9
    Join Date
    Nov 1999
    Location
    Ohio, USA.
    Posts
    480

    Default RE: on wheel wear, and a book recommendation..

    Thanks for all the links. I will try some of them out, too, if you don't mind! Here is another link to railroad related items, and most importantly, railroad brakes. As far as I can tell this is THE definitive explanation of RR brakes from a real enigneer. He explains it in plain english, but takes it a step farther into the technical aspects, as well. Some may be over my head, but there is as much info there as you need, to understand RR brakes.
    http://www.vcn.com/~alkrug/rrfacts/rrfacts.htm

  10. #10
    PatchCrew Guest

    Default RE: on wheel wear, and a book recommendation..

    oldrailfan:

    Retainers are rarely used nowadays on mainline steep grades. That doesn't mean that they are NEVER used anywhere, it just means that in most cases a combination of dynamic braking and a brake application is sufficent to control train speed. In my railroad career I have never stopped and then had the Conductor set retainers. And yes the subdivision I work has mountain grade territory. Usually everything is done to prevent setting retainers. Now in the days past setting retainers was common.

    The reason you have Marias pass runaways is because the physics in MSTS are not like reality.

    PatchCrew
    UP Engineer

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