M.T. couplers, the rubberband ( or accordion ) effect

Discussion in 'FAQs' started by Biased turkey, Jan 14, 2007.

  1. Biased turkey

    Biased turkey Active Member

    Just replaced the rapido couplers equiped trucks on one of my N scale boxcars with 2 M.T. Bettendorf trucks. The rest of my locos and rolling stock use Accumate couplers.
    The M.T. trucks equiped car , specially at low speed , never keeps the same distance with respect to the preceeding car. It seems like there is an oscillation .
    That's what I call the accordion effect.
    Any explaination ?
  2. pgandw

    pgandw Active Member

    It has to do with having free-rolling trucks and the springs in the couplers. We also have the issue in HOn3, especially if you keep your cars light enough to let the engines haul reasonable loads up grades. Preferred solution is to put axle wipers or pickups for lighting on the caboose. This introduces just enough drag to keep the train strung out. A secondary benefit of the caboose wipers is that the tension prevents accidental uncoupling over a magnet on the main line.

    John Stutz of HOn3 fame has found that the MT 1015/1016 series coupler has the spring in a different place, and works better than the 1023/1025 series couplers (for both N and HOn3). Coupling requires less force, and there is less accordion effect.

    my thoughts, your choices
  3. doctorwayne

    doctorwayne Active Member

    Slack run-in and run-out can cause problems on both model trains and those of the prototype. I recently ran a long train (71 cars) on my HO layout: the total slack in the train was equivalent to the length of a 50' boxcar. With walk-around control, I could follow the train around the layout, watching the slack run in or out, depending on which part of the train was on a grade or curve.

  4. Biased turkey

    Biased turkey Active Member

    I checked carefuly holding the draft gear box in 1 hand , the shank-knuckle assembly in the other hand and exercing a slight pulling force.
    Conclusion: the MT shank-coupler has a longitudinal displacement related to the draft gear box while the Accumate coupler doesn't.
    What I'm wondering is why I'm the only one to complaint about that fact ?. Am I the only one to use M.T. couplers ? Obviously not, because there is always someone on the various scale rail modeling forums pimping M.T. couplers.
    I can notice the problem with just 1 car equiped with M.T. coupler I don't even want to think about what'll hapen if I convert ( as my original plan was ) all my rapido and accumate couplers to M.T. ones.
    Thanks pgandw for the axle wipers suggestion, but I would like my couplers to work out of ther box.
    I don't use MT 1015/1016 couplers, but replaced the whole truck. Next conversion I 'l l purchase a truck without coupler and a separate 1015 coupler assembly. Thanks for the tip.

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