Discussion in 'Getting Started' started by Cactus, Apr 28, 2002.

  1. Cactus

    Cactus Member


    I have a yard with the configuration that sidings leading from the yard throat each come to a dead end. My questions have to do with parking freight cars on the sidings. 1970's era, if that makes a difference.

    Would a prototype road have all the parked cars coupled together, at the end of the siding, using a house air supply to keep up the air brakes?

    Or would the extra step of coupling up a car to the parked lineup when the switcher drops it off be too time-consuming?

    How are the air brakes usually kept up when a car is parked in a yard?

    How long does it take for an isolated car to lose the pressure in its air brake system?

  2. Vic

    Vic Active Member

    Hello Catus, Around here...Norfolk Southern territory... I don't recall seeing the car brakes being set on cars in the switching yard. Of course the yard is not on any grade and is flat and level. This seems logical as it would appear that it would double or triple the time that it would take to move a car or a cut of cars if the switch engine had to pump up the air every time it went to make a movement. When the switch engine shoves a car and the switchman "pulls the pin" the air connection is broken at the gladhand on the air line. When the "shoved car" hits the next car on the switch track it generally couples but the air line has to be restored manually, usually when the train is made up for departure. It is possible to set the brakes on a particular car using the retainer valve and the air resevior or manually using the brake wheel.

    As for sidings ( such as industrial location) the brakes are set by the switchman once the car is spotted so that the car will not creep and foul the mainline. Depending on the degree of protection required the use of a derailer on the siding track maybe required also.

    Perhaps there are some guys on here that are actually real railroader and can comment further on this.

    As you probably already know air brakes work just the opposite of hydraulic brakes...a reduction in pressure applies them and and an increase in pressure releases if a sitting car "leaks down" the brakes will apply and they will have to released manually or by the application of pressure.
  3. RI541

    RI541 Member

    I think that Vic hit the spike right on the head:) :)
  4. 60103

    60103 Pooh Bah

    Air Brakes

    I expect someone will correct me if I'm wrong, but I think that the brakes are applied by the pressure in the reservoir on the car and is activated when the air is released from the line. The air in the reservoir will gradually leak off and the brakes will release. If you plan to keep a car in a siding, you use the hand brake. There's also a lever under the car that does something to release the brakes so that switching can be done without pumping up the air all the time.
    So the brakes can both leak on and leak off, depending on where the leaks are.
  5. Drew Toner

    Drew Toner Member

    Re: Air Brakes

    Your right!!

  6. Bill Stone

    Bill Stone Member

    Wait a minute. I thought that the brakes are set by the LACK of air pressure --- in other words it takes air pressure (or manual labor via the brake wheel) to get them off.

    Am I off on this?

    Bill S
  7. 60103

    60103 Pooh Bah

    This is the bit where I fall down in the technology. The device is called the TRIPLE VALVE and was invented by George Westinghouse over 100 years ago. It directs the air all over the place.
    To start, you pump up the air and put pressure in the pipe. The valve directs air into the reservoir and somehow the brakes come off.
    When the pressure in the pipe decreases, the valve directs air from the reservoir to the brake cylinders in proportion to the reduction. (you hear talk of a 5 lb or 10 lb reduction; that's the pressure in the pipe. When the pressure increases again, the brakes come off and air gets pumped into the reservoir.

    If you make too many reductions in a row, you use up all the air in the reservoir and there's no more brake power. ("It was on that grade that he lost his air brakes..."). There are regulations about pumping up the air after making a major brake application.

    Is this as clear as mud?

    When I get home, I'll see if I can find a diagram, but my wife's taking me to the duct tape movie tonight.
  8. Vic

    Vic Active Member

    Hello Everybody, The above link is a very complete discussion on the history and development of railroad air brakes. First time I've tried to put a link in a message here so if it doesn't work just type it into your browser.
  9. Vic

    Vic Active Member

    David, By the way, What is a "duct tape movie"??? Sounds painful to me:eek: !! Does that have to do with keeping one's mouth shut during the film?...or is it something I should try to see???:p :eek:
  10. 60103

    60103 Pooh Bah

    Duct Tape Movie

    New movie by Red Green of Possum Lodge called Duct Tape Forever.
    The TV show may be carried on your local PBS station.

    btw: Rick Green (who plays Bill on the Red Green show) is a model railroader and member of the local O gauge club.

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