MTL couplers and the "inchworm" (slinky) effect

Mark Truelove Jul 15, 2021

  1. Mark Truelove

    Mark Truelove TrainBoard Member

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    OK there it is, I posted it. According to the site search, this is the first instance of "inchworm" posted here (or on a number of other train boards for that matter).

    When I picked up N scale again about a year ago, I knew that I wanted to start out with MTL couplers on everything. I hadn't really mastered the installs on my last attempt many years ago, but I remembered they were the gold standard and started with that in mind. (Back then, there weren't competing knuckle couplers yet, either - how things do change).

    Anyway, I've been at it making my Inglenook testbed reliable and operable completely hands-off (I needed to rethink magnet positioning before that happened), and it's fully loaded with MTL rolling stock and a switcher. After all my time in the hobby (both years ago, and now for about the last year) I'd never heard a report about a Kadee or MT flaw until I saw something in a video somewhere about a week ago, describing the "inchworm" problem and how it contributes to unwanted uncoupling. I was kind of underwhelmed and didn't even note the link or the site at the time, so I can't quote it. However, the delivery of the message was as if this was a long-known problem that model railroaders have been aware of for a long time (it should be, it's really easy to recreate and see for yourself).

    I'm still in that mindset where I'm thinking, there must be a fix for that if everyone is so aware of it, and so I started searching.

    I couldn't find anything. No references, fixes, I mean nothing. Not even the site where I'd just seen the video information for the first time is showing up in my searches. Nothing on this site either.

    I'm really bummed that I chose the Cadillac of couplers to use universally in my new train world, and they have this glaring flaw. Moreover, I'm freaked out by my inability to find any information about it that doesn't contain an insect ("MT Micro-trains inchworm couplers", etc.)

    Please let me know what you might already know about this phenomenon or any fixes, even just new sources of information. I'm really stumped on this, not a YouTube video to be found about it. :)

    Thanks!
     
  2. CSX Robert

    CSX Robert TrainBoard Member

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    I've never heard it called the "inchworm" effect. Search for "Micro-Trains slinky effect" instead and you'll find loads of information about it.
     
  3. Mark Truelove

    Mark Truelove TrainBoard Member

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    Brilliant and simple! And so much information too, as I knew there must be. Thanks.
     
  4. mtntrainman

    mtntrainman TrainBoard Supporter

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    Never had the 'slinky effect' cause any unwanted uncouplings. Also...There have been hundreds of possible solutions offered over the years. Even read an article of a guy who fashioned mini drawbars whereas he took the MT couplers off the cars and screwed the drawbars to each car in line with the coupler box screw. It stopped the slinky but it sure looked like a PITA to rail the solid line of cars !!:eek:
     
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  5. CSX Robert

    CSX Robert TrainBoard Member

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    Good point. I meant to mention that as well, as aggravating as it is to some(me included) I've also never heard of it causing uncoupling. There are some alternative couplers that do not have the slinky effect - Accumate, McHenry, E-Z Mate - but they all seem to have issues, whereas Micro-Trains for the most part just plain work.
     
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  6. WolfWorks

    WolfWorks TrainBoard Member

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    Here is how one well known modeler does it, he has an awesome looking layout
     
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  7. Mark Truelove

    Mark Truelove TrainBoard Member

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    I've been using my little Inglenook sidings to practice trying to get everything to near perfection. I first noticed the phenomenon when switching over the magnets, and yes, I did get plenty of unwanted uncouplings that I'm still trying to get rid of.

    So far, I like the velcro-under-the axle idea for a first attempt. I'll probably try that over the weekend.
     
  8. Mark Truelove

    Mark Truelove TrainBoard Member

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    I haven't watched the painting video yet, hopefully more goodness there.
     
  9. acptulsa

    acptulsa TrainBoard Member

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  10. CSX Robert

    CSX Robert TrainBoard Member

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    Ah yes, I didn't think about that but I can certainly see how slinky action over a magnet could cause uncoupling.

    Most of the soultions to the slinky action involve adding friction to your cars so that they don't roll as easily. I don't like that idea because I run long trains, but for a small switching layout it would probably work well.
     
  11. NtheBasement

    NtheBasement TrainBoard Member

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    I use magnetic uncoupling a lot. I haven't had issues with the slinky effect causing unwanted uncoupling but most of my magnets are not permanent. I recently installed an HO Rapido Railcrew remote uncoupler and like it enough to consider replacing my hinge-mounted magnets.
     
  12. John Moore

    John Moore TrainBoard Supporter

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    The only issue I have had with MT uncoupling has been related to being a bit to high or too low and once I corrected that it went away. And in the 1 to 1 world taking up slack or having slack run in is real. Thus the actual 1 to 1 world slinky effect.
     
  13. CSX Robert

    CSX Robert TrainBoard Member

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    This has been covered ad nauseam in other threads, but the Mcro-Trains slinky effect is not the same as slack action.
     
  14. Mike C

    Mike C TrainBoard Member

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    What about putting 2 springs in each coupler ?
     
  15. Doug Gosha

    Doug Gosha TrainBoard Member

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    Other than with uncoupling magnets, the only way the slinky effect can cause unwanted uncouplings is if the couplers themselves aren't working properly. In other words, the couplers aren't closing immediately if they get jostled by back-and-forth motion.

    Doug
     
  16. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    Many factors. Track (gauge, how well laid, clean/dirty causing uneven operation of the motive power, the operator), cars (light) weight. As already noted, coupler heights. I've installed drag (axle) springs on my lighter cars. In fact on all my cars, all brands. No unwanted slack action is possible.
     
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  17. JMaurer1

    JMaurer1 TrainBoard Member

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    I have drag axle springs on my cabooses to help minimize the effect.

    Are MT couplers perfect: no
    Are they better than or equal to anything else out there: yes
    Is there a better solution: no...not if you want operating couplers...at least not yet (some people are working on better couplers without the slinky effect but I don't believe anything has been officially released for sale yet)
    All we can do it try to minimize the problem and be thankful that we have something better than the Rapido coupler that still comes on some rolling stock (WHYYYYYYY!!!).

    Here's a short history of the N scale coupler:

    https://www.nscaledivision.com/information_on_couplers.htm
     
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  18. Mark Truelove

    Mark Truelove TrainBoard Member

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    Funny that, I recently bought a used Micro-Trains boxcar that came with rapido couplers on it. The reason I buy occasional MT rolling stock is so I can save myself one more experience of messing with the couplers. What am I missing here? Didn't Micro-Trains start out as a spinoff of Kadee, i.e. in the coupler business? (i.e. before manufacturing rolling stock)?

    I'm not actually worried about the boxcar or the expenditure at all. It's just about the weirdness of the logic here, given what I think I know so far.
     
  19. acptulsa

    acptulsa TrainBoard Member

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    HO used to have a similar problem. But then environmentalists found 31,740,829 completely unused horn hook couplers floating in the middle of the Pacific, and raised a stink.
     
  20. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    It was fifty years ago, when they started manufacturing N scale rolling stock. At that time most people were using Rapido couplers. So they offered cars with Rapidos and cars with their own brand of couplers. Theirs took off and after a few years they stopped offering Rapido equipped cars.
     

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