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55848Re: Turnout Derailment

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  • Garth Hamilton
    Mar 1, 2008
      Hi Andy;

      The "back to back" measurement of a wheel set is the distance between
      the back fo the two wheels located on teh same axle. THis distance
      has to be slightly larger than the distance between the inside of the
      guard rails on the inside of outside rail and the one on the inside
      of the frog. So you are checking whether the flange of the wheel set
      can pass through this tight clearance without binding. If the wheels
      are too far apart the flange will climb the point of the frog and if
      they too close together and the wheel will climb the bend in the
      point rail where it transitions to be come the guard rail for one
      side of the frog.

      It is not uncommon for a car to roll through the switch without
      derailing when going through on its own as one wheel at a time can
      climb the tight spot and return to the track. IF you watch closely
      you can see the car and truck bumb over the tighness. The most common
      cause is being too tight as being to wide will cause problems
      elsewhere in the track work. The marklin wheels can be moved on the
      axle but you need to realize that it may not require a movement of
      more than a 32nd of an inch or even a 64th of an inch to solve the
      porblem.

      Micro Trains makes a coupler height gauge Part No. 920 in the old
      numbering system which will also function as a track gague and a
      wheel back to back gauge. Some of us have a back to back gauge made
      of brass or aluminum that looks something like a horseshoe which we
      can slide between the two wheels on an axle to set them for the
      correct back to back distance.

      Hope that helps you

      cheers
      Garth



      --- In z_scale@yahoogroups.com, Andrew Poulo <apoulo@...> wrote:
      >
      > Hi Garth,
      >
      > Thanks for the response to my question, but I'm not sure I
      understand
      > what you mean by the "back to back on the Marklin wheel sets." Let
      me
      > also give you some additional information. I have a variety of
      Marklin
      > American freight and passenger cars. If allowed to roll through the
      > turnout alone, every car will make the turn smoothly. If coupled
      > together in any conceivable combination, the second car will always
      > fail to make the turn because of what you describe as a wheel pop.
      >
      > Any additional thoughts?
      >
      > Thanks,
      >
      > Andy Poulo
      >
      >
      >
      > On Feb 29, 2008, at 7:23 PM, Garth Hamilton wrote:
      >
      > > I would look closely at one car going through the turn out and you
      > > might find that the back to back on the Marklin wheel sets of the
      > > problem car is too small or tight and the wheel set can not pass
      > > through the two guard rails. This usually causes a wheel pop up
      on the
      > > guard rail beside the frog.
      > >
      > > regards
      > > Garth
      > >
      > > --- In z_scale@yahoogroups.com, "apoulo" <apoulo@> wrote:
      > > >
      > > > I'm new to the group and relatively new to z scale. I am
      > > experiencing
      > > > a problem running Marklin cars over MTL turnouts. The problem
      only
      > > > occurs on right hand turnouts when making a right hand turn.
      Marklin
      > > > cars derail a high percentage of the time while MTL cars have
      no
      > > > problem. My guess is the problem lies with the Marklin
      couplers. I
      > > > think the coupler of the first car is exerting an outside
      pressure
      > > on
      > > > the following car, causing it to want to go straight and
      jumping the
      > > > switch.
      > > >
      > > > I'm not sure my analysis is correct, and even if it is, I can't
      > > figure
      > > > out a solution. Has any one else experienced this problem, and
      does
      > > > any one have a solution?
      > > >
      > >
      > >
      > >
      >
      > [Non-text portions of this message have been removed]
      >
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