Sunday, October 20, 2019

Maintaining model couplers

I have posted comments from time to time in this blog about the various needs for maintenance of freight cars to make sure they operate as they should. This is potentially a really wide-ranging topic. Probably the broadest recent post like this addressed several kinds of maintenance issues (you can read the post at this link: ).
     My recent experience with the operating weekend at VanRail in Vancouver, British Columbia showed me some compelling examples of how well this can work. (For an overview of that event, you may wish to read the post about it, which is at: .)
     In particular, I was struck by the good operation at Mike Chandler’s layout, because he uses Kadee magnetic uncoupling ramps, often in layout locations that you really cannot comfortably reach from the aisle. This means that couplers must operate flawlessly, and they did. I came away with the determination to re-examine my own fleet and try to correct any couplers that are off in height or were even a little bit sticky or not free-swinging.
     Shown below is an example of couplers that almost line up perfectly, the one on the right being a Kadee #5. But even though a coupler pair like this will work fine on the main line, it many not behave as desired in tight switching locations, or in the presence of any trackwork shortcomings.

Below is a second example, this time showing two cars with #58 couplers, but here they are matching perfectly and accordingly will operate all right. It’s always best to strive for complete height matching, and I am working on my fleet to get there.

The cars above are a Westerfield AC&F reefer at left, and an InterMountain SP covered hopper at right.
     Coupler height is most easily adjusted with washers at the truck bolster, and that is what I usually do to make cars match the Kadee gauge as exactly as I can. (I have written about use of the Kadee gauge before, partly because I am surprised when modelers tell me they don’t even have one; for example, the post at: ). In my opinion, you simply cannot compromise on coupler height.
     Let me add some specifics having to do with the mixture of Kadee #5 and #58 couplers, like I have on my layout. I have said several times that I find that these operate very well together, provided that they are operating properly and that one recognizes the simple fact that the scale-head coupler necessarily has less gathering range and is less forgiving on vertical curves. But how about using the Kadee coupler gauge with mixed couplers?
     I contacted Sam Clarke at Kadee to ask him about this point, because I was uncertain how I should use the gauge with two different couplers such as the #5 and #58. He began by pointing out that the definition of coupler height is from the top of the rail to the centerline of the coupler. The Kadee couplers have a horizontal mold parting line that can be discerned on the coupler face (and on the coupler horn at bottom in this image), that locates this line for you.

     Sam went on to say that the best way to set coupler height is with the coupler center lines matching, such as  with the #5 and #58 combinations. But because they are close, he suggested that matching the top surfaces of the two couplers should also be okay, as long as you are consistent.
     One other point. Especially on the layout, you may need to search a little bit for good background to evaluate your couplers when gauging them. The photo below illustrates a less than terrific choice, using my old Kadee 205 gauge (there is a new 206 plastic gauge).

Putting a piece of white paper behind the gauge and car makes it far easier to see clearly what you are evaluating (the same is true, of course, at the workbench). Note also that the trip pin correctly clears the “shelf” at the bottom of the Kadee gauge.

     One last point: you will note above that the cars are not coupled to the gauge. Coupling them may lift one coupler relative to its rest position, so you need to move the car close to, but not coupled to, the Kadee gauge.
     I am working through my car fleet, a few cars every time I get the impulse, to set coupler heights to the gauge, and of course keeping notes as to which cars have been done. It might be an ongoing project you would like to attack also.
Tony Thompson


  1. Tony,
    I agree with your comments, but have one caveat: manually uncoupling a Kadee #5 and #58 can be a wee bit of a challenge at times. That has been my experience.

    Secondly, I have Kadees on 40+ year old cars that still operate perfectly. Soft pencil lead applied to all surfaces and slight adjustment to the older #5 copper spring is all that has ever been needed. For newer #5's, I still use a soft pencil lead on all surfaces.

    Biggest culprit for height issues are old clip springs that hold the couplers in place on a blue box Athearn. I have seen them loosen up a bit over time and slightly slip.

    1. Thanks, Lou. Regarding 5 and 58 couplers, I would observe that ANY coupler pair, whether mixed 5 and 58 or matched, CAN be a challenge to uncouple with a pick.
      I agree with you about pencil lead, or the old Kadee graphite lube in the "puff tube."
      And yes, that Athearn steel clip can indeed loosen, I think from wear on the "ears" molded on the Athearn coupler box sides.
      Tony Thompson

  2. I use a Bill Mosteller gage in addition to Kadee's tool. It's a machined cylinder that gives a go-no go reference for knuckle height and trip pin clearance. Made for the #5.
    We have mostly #5 heads on or club layout and have encountered the uncoupling problem mentioned above.