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Re: Suggested Grades

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  • jeremypbrandon
    ... I agree with 2.5%, but remember the transition from level to grade=2.5% should not be abrupt, otherwise wheels can lift off the track. It would be better
    Message 1 of 5 , Jun 3, 2002
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      --- In z_scale@y..., Reynard Wellman <micron@m...> wrote:
      > 2.5 % is just about ideal for a small layout and if you want good
      > general performance for most locomotives that is the number.

      I agree with 2.5%, but remember the transition from level to
      grade=2.5% should not be abrupt, otherwise wheels can lift off the
      track. It would be better if the change in angle (2.5% = 1.5 degrees)
      was spread between three successive joins in the track: 0.5 degrees
      at each join. This applies to the top and the bottom transitions. It
      makes the grade slightly longer but it's really worth it if the
      trains run troublefree.

      If the piers are every 110 mm, successive heights (in mm) are at the
      bottom approximately: 0, 1, 3, 6, 9 and so on, each increasing by
      3mm. At the top: -9, -6, -3,-1, 0.

      Hope that helps! Jeremy.
    • optimamid
      Thanks for the responses! As I understand it, a 2.5% grade would result in an increase of .328 in. over a distance of 3 marklin 8500 track pieces (13.125 in).
      Message 2 of 5 , Jun 3, 2002
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        Thanks for the responses!
        As I understand it, a 2.5% grade would result in an increase of .328
        in. over a distance of 3 marklin 8500 track pieces (13.125 in). Does
        that sound right to you guys? That converts to .109 in per section.
        Are you saying that maybe it would be better to absorb that
        initial .109 spread out over 2 sections in lieu of all of it on one
        section?
        Thanks again for the help!
        Steve


        --- In z_scale@y..., "jeremypbrandon" <Jeremy.Brandon@t...> wrote:
        > --- In z_scale@y..., Reynard Wellman <micron@m...> wrote:
        > > 2.5 % is just about ideal for a small layout and if you want good
        > > general performance for most locomotives that is the number.
        >
        > I agree with 2.5%, but remember the transition from level to
        > grade=2.5% should not be abrupt, otherwise wheels can lift off the
        > track. It would be better if the change in angle (2.5% = 1.5
        degrees)
        > was spread between three successive joins in the track: 0.5 degrees
        > at each join. This applies to the top and the bottom transitions.
        It
        > makes the grade slightly longer but it's really worth it if the
        > trains run troublefree.
        >
        > If the piers are every 110 mm, successive heights (in mm) are at
        the
        > bottom approximately: 0, 1, 3, 6, 9 and so on, each increasing by
        > 3mm. At the top: -9, -6, -3,-1, 0.
        >
        > Hope that helps! Jeremy.
      • jeremypbrandon
        ... of .328 ... Does ... A #8500 is 110mm long = 4.33 inches, so 3 x #8500 = 13.0 inches. A 2.5% grade is 0.025 up or down for every 1.0 along. So 13.0 * 0.025
        Message 3 of 5 , Jun 3, 2002
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          --- In z_scale@y..., "optimamid" <steve@t...> wrote:
          > As I understand it, a 2.5% grade would result in an increase
          of .328
          > in. over a distance of 3 marklin 8500 track pieces (13.125 in).
          Does
          > that sound right to you guys? That converts to .109 in per section.

          A #8500 is 110mm long = 4.33 inches, so 3 x #8500 = 13.0 inches.
          A 2.5% grade is 0.025 up or down for every 1.0 along. So 13.0 * 0.025
          = 0.324 inch. Near enough!


          > Are you saying that maybe it would be better to absorb that
          > initial .109 spread out over 2 sections in lieu of all of it on one
          > section?

          Yes. At 2.5% each #8500 rises 0.108 inch (say 0.1 inch). At the
          transition from level to 2.5% grade, the first #8500 should rise 1/3
          of that = .036 inch (1mm), the second should rise 2/3 = .072 inch
          (2mm) from .036 to .108, the third and ones that follow rise the
          full .108 (3mm). This means the transition is one #8500 longer, but
          it is smoother.

          Jeremy.
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