Couplers at Large!

Couplers at Large !

By Roger Heid


Since the dawning of model railroading, coupler issues have been haunting the community of model railroaders. When you are new to this hobby, you may not notice this, at first, but as you add more cars to your train, you will probably encounter some problems.

Before I go any further, I need to explain a few things. There are numerous manufacturers of model trains, primarily in Europe, US and Japan. Reynaulds Euro Imports (REI) obviously deals in products imported from, you guessed it, Europe. That’s where we start.

Besides that, adding more variety, there are also several different scales to consider, anything from G-Scale to Z-Scale.

HO is, by far, the most common scale used by model railroaders. Maerklin and Fleischmann are the oldest German manufacturers still in business today. Maerklin introduced their loop couplers already before WW II; Fleischmann featured a different design. Their couplers are not compatible, to this day.

Back then, it was very difficult, if not outright impossible, to convert couplers from one manufacturer to another, mainly because of the way they were designed. This issue did not matter that much. Once one started with a brand, one would usually stick with it. That’s history.

During the recent years, manufacturers like Maerklin, Trix, Liliput, Piko, Brawa, Roco and Rivarossi deliver their products equipped with the Maerklin style loop coupler, by default. If you started out with a European type train, this is most likely the type coupler you will encounter.

These couplers are designed for easy coupling by moving two cars together. If it hardly takes any speed for the couplers to engage, it is called a ‘Soft Couple’; if some oomph is needed, it is a ‘Hard Couple’. This is caused by one or both couplers being slightly out of alignment. This misalignment can be so bad that the cars won’t couple at all, no matter how hard you try, short of outright destruction.

The other problem you may encounter is an unintended disconnect while the train is running. This is highly annoying, as it just might result in some sort of collision or other unwanted side effects. Usually it is always the same two cars disconnecting from each other. The coupling between the two is too loose. This needs to be looked into, pronto.

Actually, you can fix both problems. Carefully study the intrinsic workings of these coupler mechanisms. You will notice that uncoupling is easily done by lifting the two prongs on the bottom simultaneously, using a wide blade screwdriver or a similar device. Now watch how these components react to each other during the coupling process. You will come to the conclusion that one or more of them need to be bent or peened to a degree. The use of smallish precision needle nose pliers is recommended. Be careful and patient.

Another thing to look for is coupler height. Some careful bending of the coupler mount will probably be required. Again, be careful and patient. Some manufacturers offer coupler height gauges in their accessory listings. Such a device can be very helpful in solving coupler related issues.

There is another cause for a coupler related problem, namely derailing. For instance, take a series of two or more, very long 4 or more axle freight cars being forced to negotiate a small radius curve. This will, most likely, result in a mechanical conflict between the buffers and the couplers. The distance between the cars is too short. The worst culprit is the newer Maerklin ‘Short Coupler’. The solution is the ‘Universal Coupler’ offered by Roco (# 40395), compatible with most all loop couplers. It will solve that problem.

This brings me to another issue. Some time ago, a technical commission in Europe established NEM. It stands for Norm of European Model railroads. At first, there was little collaboration with the NMRA (National Model Railroaders’ Association, established in 1935 in the US). Since the introduction of DCC (Digital Command Control), they have been working more closely together.

Anyway, for a number of years now, the product descriptions of European made locomotives and rolling stock have indicated that a given model has an NEM pocket. This means that couplers featuring the so-called swallow tail shaft can be installed into the pocket, regardless of manufacture.

For instance, if you wish to add a Fleischmann made rolling stock model to your non-Fleischmann collection, all you have to do is to order the Maerklin compatible loop couplers from Fleischmann, and you’re all set.

Some European manufacturers offer a variety of couplers different from the loop coupler. This is up for grabs. Your choice. Some of them are NEM compatible, some are not. All this depends on what your chosen specialty is.

At this point, I will briefly address the NMRA modelers. Those folks usually choose from a vast array of available Kadee knuckle couplers, as it most closely resembles the real world US standard coupler.

Maerklin is offering US prototype rolling stock of high quality. Lately, they have come with NEM pockets. Kadee offers knuckle couplers with varying shaft lengths, fitting in to the NEM pockets. However, varying NMRA style pocket heights between US made models may cause a problem with this.

Then there are the other scales. It is difficult to deal with all theses issues, in one session. I realize that I have not covered all the potential possibilities. I am hoping that other Forum and Blog readers will contribute more information by leaving appropriate comments.

2 Responses to Couplers at Large!

  1. Boris Gremont says:

    I have many old Markln passenger cars, still highly serviceable, with old type couplers (“pre NEM”). Where can I buy compatible conversion/retrofit couplers so that these old couplers can be replaced and converted into NEM-compliant couplers? Please advise. Thank you!!

    • Ernest Robl says:


      As the author of the above article no longer participates on this site, I will try to offer some thoughts in response to your question

      First, I do not operate Märklin equipment myself, but coupler issues are somewhat generic and not specific to any one manufacturer. I do own some pre-NEM pocket rolling stock, primarily from the Austrian manufacturer Kleinbahn.

      Second, it would help to know why you want to replace the couplers on your older rolling stock. I can think of some possible reasons, but there may be others:

        You may want to couple your older cars to more modern (yet era-appropriate) locomotives equipped with different couplers.
        You may want to have the cars operate closer together for a more realistic appearance.
        You may want to use current-conducting couplers for interior lighting or other purposes.

      I would not see any of the above reasons as justification for the serious surgery that would have to be done on the rolling stock to convert them to NEM coupler pockets. Remember that on modern rolling stock, the NEM pocket is typically part of a close coupling mechanism that varies the spacing between cars, depending on whether whether the car is on straight track or on a curve.

      Yes, you can purchase retrofit close-coupling mechanisms with NEM pockets. Roco offers kits with two different versions, designed for cars of varying lengths. But Roco warns that installation of these kits will likely require some milling of the underside of the car to get the equipment to fit. Such milling is probably best left to a skilled machinist.

      If you simply want to couple your older cars to a locomotive or car(s) with different style couplers, the best solution is a “coupling car.” This is a car equipped with different style couplers on each end. You can certainly get couplers that fit NEM pockets that will mate with older style Märklin couplers. This would just require investing in one modern (era-appropriate) car with NEM pockets — if you do not have one of these already. Then install the appropriate couplers on each end.

      Let me give an example. I use Roco universal couplers on my modern locomotives and on most of my freight cars. (These couplers offer some advantages in switching operations.) On my passenger cars, I mostly use Roco close couplers.

      So, for example, on one of my passenger trains, I plan to use a Kleinbahn auto carrier on the rear, as is the case on some prototype Austrian trains. (The Kleinbahn car has fixed non-NEM couplers.) The first passenger car has a Roco universal coupler on one end (to mate with the locomotive) and a Roco close coupler on the other end. All the intermediate passenger cars have Roco close couplers on both ends. But the last passenger car has a close coupler on one end and a Roco standard coupler on the other end — to mate with the fixed couplers on the Kleinbahn auto carrier.

      (Yes, Roco universal couplers can theoretically mate with Roco standard couplers and older hook-and-loop couplers from other manufacturers, but I’ve found that a Roco standard coupler works slightly better in mating with older hook-and-loop couplers.)

      So, if you absolutely want to have NEM pockets on your cars, yes it is possible to do the work. But it is probably more trouble than it is worth.

      Hope that helps.

      – Ernest

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