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RE:Gradients in Z gauge

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  • Chris Sheldrake
    Selecting gradients is fraught with difficulty ! What s acceptable on a straight stretch of track will not work on a rising curve and similarly, the type of
    Message 1 of 2 , Jun 3, 2002
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      Selecting gradients is fraught with difficulty !

      What's acceptable on a straight stretch of track will not
      work on a rising curve and similarly, the type of locomotive
      and rolling stock used effects the maximum acceptable
      gradient as well.

      I started by using the same gradients as I have successfully
      employed with an HO layout but these proved too steep for Z.
      This is almost certainly because I was using weighty Swiss
      Hag locomotives in HO which have powerful motors, metal
      bodywork and traction tyres fitted. None of my Marklin Z
      locomotives have traction tyres.

      What's certain in Z as with every other gauge is that a much
      steeper gradient can be used on straight track than on a
      curve. Similarly, a train with two axle rolling stock seems
      to take a gradient better than one with four axle bogey
      coaches or wagons.

      Using Marklin standard radii curves and my own locomotives
      and rolling stock I can certainly confirm that a gradient of
      2.5% is too steep and will cause wheel slip with most
      lengths of train. The same gradient on a straight is OK,
      however.

      The only way to be sure is to experiment with your own
      equipment and see what works.

      Don't forget when designing your layout, it's very easy to
      forget that if you are looking to loop one track under
      another you can halve the gradient required to reach a
      clearance height if you make the lower track go down at the
      same rate as the upper track climbs !

      Conventional thinking means a layout with three track levels
      is built off a flat board where track level one is flat on
      the board and everything else is above it.

      When I design a layout with three track levels, I make the
      "baseboard" height the middle one and construct the layout
      on an open frame. That way, in Z gauge, track level 1 might
      be at an altitude of minus 25mm and track level three at an
      altitude of + 25mm. Each track is on a shaped track bed of
      it's own at an individual height above the frame. Only the
      lowest point of the bottom level track bed might sit
      directly in the frame. That way even the lowest track can
      descend to pass under another track that is ascending.


      Chris Sheldrake
    • Reynard Wellman
      Hello Chris, ... We want to do more in a small space -- unfortunately we cannot just scale down standards from another scale and expect them to work for Z
      Message 2 of 2 , Jun 4, 2002
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        Hello Chris,

        Chris Sheldrake wrote:

        > Selecting gradients is fraught with difficulty !

        We want to do more in a small space -- unfortunately we cannot just
        scale down standards from another scale and expect them to work
        for Z scale. Our engines are lighter and even the slightest differences
        in track height and gauge can derail a train. The tolerances kick in.

        > SNIP>
        >
        > Using Marklin standard radii curves and my own locomotives
        > and rolling stock I can certainly confirm that a gradient of
        > 2.5% is too steep and will cause wheel slip with most
        > lengths of train. The same gradient on a straight is OK,
        > however.

        A 2.5% grade will work fine as long as you use much larger radius
        standards than Marklin has and make sure that you have built in
        easements for both the approaching grade and curve. I try to think
        outside the Marklin track box. As for wheel slippage, just double
        header your locos along the grades and it will look even more
        prototypical.

        > SNIP>
        >
        > When I design a layout with three track levels, I make the
        > "baseboard" height the middle one and construct the layout
        > on an open frame. That way, in Z gauge, track level 1 might
        > be at an altitude of minus 25mm and track level three at an
        > altitude of + 25mm. Each track is on a shaped track bed of
        > it's own at an individual height above the frame. Only the
        > lowest point of the bottom level track bed might sit
        > directly in the frame. That way even the lowest track can
        > descend to pass under another track that is ascending.

        I must admit that the "base" level of any complex layout should always
        have it's zero datum elevation at least 2" above the plywood base. This
        is to allow for drainage and creeks, etc. and perhaps an occasional
        "dip"
        under a crossover loop. --Reynard

        >
        >
        >
        > Chris Sheldrake
        >
        >
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