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O/T: Sorry. A Train question.

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  • #16
    Fourth is spelled forth in the 5th paragraph.
    Kansas City area


    • #17
      Originally posted by Mike Amick View Post
      Wow .. that must have been written a while back. Everything is pretty much spot on except where he is
      talking about applying the brakes by releasing air from the brake pipe and then going to lap to lock that in.
      There may be a couple of yard switchers around that have that brake valve, but they haven't been used on
      the road in decades.

      Now they use a brake valve that you just set/reduce the air by pulling the brake handle and it laps so to speak
      automatically and the air compressor does not disengage because it has to maintain that reduced pressure in
      the brake pipe. If this new reduced pressure in the brake pipe is not maintained, it will leak down and the
      brakes will continue to set harder.

      Back in Pennsylvania coming down the horseshoe curve in Altoona, it was a pretty steep grade like 10 or 20 miles
      long (can't remember). Anyways .. when we came out of the tunnel at the top and started down the hill you had
      to set just the right amount of air. It was a matter of the train running away, or you having to have it in notch 8
      (full throttle) to pull it down the hill.

      Man .. the stories I could tell you.
      What id the term "lap" in this context?


      • #18
        On the old brake valves, When you moved the brake handle from its released position to the braking position, it takes
        air out of the brake pipe triggering a valve on the cars to apply the brakes.

        If you left the handle is this braking position, it would just drain all the air out of the brake pipe, so to prevent that,
        you moved the handle to a position that was nether release nor application. It was just a spot that stopped the
        reduction without releasing the brakes. This spot was the lap.

        As I said in the earlier post ... the new brakes just automatically lap. You move the handle to put the brakes on
        and the distance you move the handle determines how much air is removed from the brake pipe. On the other
        system .. its how long you leave the handle in braking that determines the amount of air.
        John Titor, when are you.