HO Scale Model Railroad Couplers

HO Scale Model Railroad Couplers

By Roger Heid and Ulrich Albrecht


In this blog, we will try to shed some light into couplers and the associated issues, primarily for HO Scale models. Let us reach as far back as the early 1950s in Germany. During those years, Fleischmann ruled in the HO 2- rail DC world, Maerklin was, and still is, the only manufacturer representing the HO 3-rail AC world.

Right from the onset, they were competitors. If you got started with model railroading, you had to decide which one to go with. There was absolutely no out-of-the box compatibility between the two. This included the couplers. Maerklin had their trusty loop coupler, aka Relex coupler; Fleischmann featured their proven claw coupler, still does.

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Maerklin Loop or Relex Coupler

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Fleischmann Claw Coupler

On smaller locomotives, such as the BR 89, the couplers on both ends were mere hooks, called hook couplers.

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Sample of a Hook Coupler

In the beginning, the way couplers were mounted to locomotives and rolling stock varied, depending on the individual models. Often couplers were not easily available as replacement parts. In some cases, a replacement required major surgery. This is now history.

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In the late sixties, Maerklin started to introduce a new coupler assembly that could be replaced without any tools. On the bottom of the car is a slotted prong; the coupler assembly was pressed onto that prong or stud. Two springy, fork-like spikes provided the centering of the coupler, thus functioning as a guide mechanism. On some less expensive motive and 2-axle rolling stock models, this system is still employed.

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Close Coupler Coversion for Motive Stock

Occasionally, especially after a replacement procedure, the couplers seem to be hanging too low. In most cases, this can be remedied by carefully forcing the two stud halves further apart, using a small screw driver blade. A close look at this affair will make this self-explanatory. Maerklin provides a coupler height gauge which comes in real handy, at times.


Coupler Height Gauge Maerklin 7001

About 15 years ago, Maerklin introduced the ‘Close Coupler’ to take the place of the ‘Loop Coupler’. The close coupler shortened the distance between individual cars, making the appearance of the train more real life like. For the above mentioned coupler mounting system, conversion couplers are available.


Conversion Couplers incl Uncoupling Tool

As far back as in 1979, the NEM coupler pocket started to show up progressively on more and more European made motive and rolling stock models. This made coupler related issues a lot easier to deal with. No matter what the coupler assembly consists of, there is always this box like pocket. These days, all European made motive and rolling stock comes with the Maerklin type loop or close couplers, by default, except Fleischmann. They still use their venerable claw coupler, but they provide other couplers as well.

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Sample of a coupler inserted into NEM Pocket

Henceforth, any coupler type of one’s choice could be inserted or replaced. Not all couplers are created equal. Some of them can actually cause problems. In respect to this, I have the following to say:

Instead of losing a lot of sleep over these problems, I developed my own approach. First off, you need to ensure that all cars, including the locomotive, do not uncouple while whizzing around on your track layout. If this happens, you need to take a close look at the coupler mechanism. Some peening and tweaking will have to be done to ensure the couplers do their job.

Along the line, you may have a certain train consist where you never change the individual cars around. Staying coupled together is really the only issue here.

On the other hand, you may wish to employ shift yard techniques, like concocting freight trains of varying consists. There you like to just bump one car against the other, thus coupling them together.

Unfortunately, this does not always happen. If it does happen, however, some cars may disconnect while the train is in motion. This can be frustrating, especially when you are demonstrating your trains to a visitor. When you are by yourself, this is less prone to happen. But if some friend or relative watches, it is bound to happen, isn’t it?

Now you need to troubleshoot individual couplers. You may need to replace some couplers. For instance, I do not like the couplers Brawa rolling stock comes with. From my experience, they are flimsy and break easily. I automatically replace them with Roco universal couplers. I just love those.

Ulrich has this to say:

Over the years, I have tested various types of couplers and came to the following conclusions:

The coupler has to provide a solid, quite rigid connection between the cars for the short coupling mechanism to work.  However, couplers also have to allow for a small amount of flexibility so that the cars can compensate independently for small unevenesses in the track.  If the connection is too rigid, even a small imperfection in the rail causes the coupler to act as a kind of lever between the cars the action of which can cause derailments.  In my experience, the Roco Short coupler and the Fleischmann Profi-coupler are too rigid.  On the other hand, the standard NEM coupler and the Kadee are too flexible so that reliable push operations are not possible with cars having short coupler mechanisms.

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Fleischmann Profi Coupler

The Marklin close coupler and the Roco universal coupler are ideal as far as rigidity and flexibility are concerned.  However, the Roco coupler couples on both sides and is quite flat.  This results in a firm, secure connection and no problems with the buffers.  The Marklin coupler engages only on one side, which leads to unwanted decouplings, and also is quite high.  Unless one has very large radii, the coupler interferes with the buffers.  Both of these couplers also connect to standard NEM couplers.  Here Marklin has a slight edge since the Roco coupler’s hook is open on one side.  On the other hand, the Roco coupler is available in a height adjustable version which works with a variety of connectors for Fleischmann and Roco rolling stock without NEM shaft.


Roco Universal Coupler


Roco Height Adjustable Coupler

In summary, the Roco universal coupler is by far the best coupler in my experience.  I have a few Marklin couplers left.  I usually remove the Marklin metal hook, and use the coupler at the front of steam locos like the 55 which I use in both directions.  Being black, it is kind of unobtrusive without its metal hardware.

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In addition, there are also the ‘Current Conducting Couplers’. They allow you to supply electricity from car to car needing only on pickup shoe. If every passenger car of a fairly long train has a pickup shoe mounted on the underside, the resulting drag factor could prevent the locomotive from being able to pull the train. The installation of these is best left up to the experienced modeler.

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Maerklin Current Conducting Coupler

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Maerklin Solid Draw Bar Kit


Roco 4 pole Conductive Coupler

Then comes an issue regarding the Maerklin Telex Uncoupler. There is the older style that goes way back to the analog days. I have two locos equipped so. This older Telex coupler works quite well with loop, close and Roco universal couplers. Unfortunately, they seem to have gone out of production.


The metal plate behind the hook lifts up freeing the loop

The new type I take with a grain of salt, to put it mildly. The mechanism is quite feeble and unreliable. If left turned on too long, the little coil inside may get fried, leaving the coupler useless. I have four locomotives that came with these new Telex couplers. On one of them, the couplers work well with the close couplers and the Roco universals. Loop couplers need to be precisely adjusted, most of the time. On the second loco, only the rear coupler works consistently; the front coupler either needs to be prodded or it decides to take the day off, possibly depending on the moon phase. On the other two locos, well, I decided to forfeit the feature, and I removed them. Roco Universals took their place. I do employ two Uncoupler Tracks. They always do the job, without fail.

These couplers can be repaired in some rare cases, but don’t hold your breath. Replacements should be done by a very advanced modeler or a technician.


Maerklin Kof with Telex Couplers

This blog is probably not covering every aspect of the coupler world and may not answer all the questions you may still have. But it is a good start to get to the bottom of some of the problems one encounters.

If you have something to add on, please, leave a comment. If you have questions, please post them in the Forum under the appropriate topic.

Thank you.


10 Responses to HO Scale Model Railroad Couplers

  1. Ernest Robl says:

    I use Roco universal couplers on my locomotives and freight cars and Roco close couplers between passenger cars. The end cars of passenger car consists have the Roco universal couplers to mate with the locomotives.

    When pushing modern passenger consists at speed (push-pull trains with cab cars at one end), you really need fairly stiff couplers and I found that the Roco close couplers worked better than the universal couplers.

    I have a test loop with some fairly tight radii and cross-overs and have tried out various coupler options on that.

    On the other hand, while visiting a large club layout in Austria, I was told that they had moved away from Roco universal couplers because in a derailment, the fairly stiff couplers often caused the entire train to derail.

    So, as with some other things in model railroading, you may just have to try various options with the equipment that you operate to see what works best for you. For example, I only run 1:100 passenger cars, so I cannot comment on how full-length 303 mm passenger cars perform with various couplers.

    I have a small number of freight cars that came with permanently-attached hook and loop couplers. Kleinbahn continued to make these even after most other manufacturers switched to NEM coupler pockets. These couple just fine with the Roco universal couplers.

    I have a Roco switcher with digital couplers on my wish list and plan to purchase that later this year. The Roco digital couplers are very similar to their universal couplers. But, again, I’ll have to try them out with my equipment to see how they work.

    Long-term, I also plan to try adding a digital coupler to an existing locomotive to see how that works out.

    – Ernest

  2. Jorge Sabater says:

    I have been using Fleischmann profi couplers for many years without any problems. Maybe they are rigid on tight curves but I only have very wide curves and no S curves. Vehicles can be pulled up out of the track with no impediment a hand uncoupling is a piece of cake, especially with two axle vehicles. I have many electric uncouplers but they never seem to be where you need them. They also produce an unpleasant noise by passing trains. Next time I will omit them. Best regards, Jorge.

  3. james adducci says:

    I would like to get everyone view on digital coupling and if this should be used unstead of the uncoupling track. I have Fleischmann track system and work on new layout and would like to omit the uncoupling tracks if possible

  4. Ernest H. Robl says:

    Digital couplers work best on locomotives, though they could be installed on some passenger cars — but I would not really recommend that. The latter would require that each of these cars have its own decoder to operate the uncouplers.

    There are many situations where you want to uncouple other than between a locomotive and the next car, particularly when switching freight cars. It is really not practical to install digital couplers on freight cars.

    I currently own one locomotive with digital uncouplers and plan to use it as a switcher within an industry. I may add digital uncouplers to other switch engines, though this is not a high priority.

    However, I still plan to use uncoupling tracks at some locations on the layout — and use a manual uncoupling tool at others. I find it impractical to have an uncoupling track at every possible location where I might want to uncouple cars.

    My priority for installing uncoupling tracks will be on tracks furthest back from the front of the layout and in locations that would be the most difficult to reach during normal operations.

    An important point is that if you use couplers with delayed uncoupling, such as the Roco Universal Couplers (or similar items from other manufacturers) this greatly helps your switching activity. With delayed uncouplers, you can activate the uncoupling over an uncoupling track, but keep pushing the cars down the track. When you stop, you can pull away without having to uncouple at that location.

    – Ernest

  5. Ciprian Sofineti says:

    Hello everyone! Would you please recommend me the best digital coupler for my six (three electric/diesel locos+three steam) locomotives? I’m switching to digital by Rocrail, will do mostly manoeuvring ,rebrussment ,passenger trains and freight as well. I’m planing to fit Lenz Silver decoders in my locos, so Krois close coupler seems to be the best over Roco, but I’d still ask for advice. Many big thanks in advance ! Cip.

  6. Jorge Sabater says:

    For delayed uncoupling I use a small wood board with the exact shape of the uncoupler raise platform in a fixed fashion and simply remove it after delayed uncoupling is completed. Put it anywhere any time, except on curves, and do away with the unreal noisy electric uncouplers. Jorge.

    • Jorge Sabater says:

      I forgot to explain how to raise the uncoupling platform. There are two different ways, electromagnetic and manual. For electromagnetic, install an uncoupling track under the table board. Glue a perpendicular shaft to the platform whose shaft will rest on the uncoupling track platform. The shaft should go through a bushing for reliable operation and to prevent wobblíng. Also, on either end of the platform add additional shafts and bushings to avoid disalignment of the uncoupler platform. Finally glue the bushings to the table board. For manual operation use a leaver and your finger. The uncoupler is removable as I mentioned before. Jorge.

  7. tony petres says:

    I purchased a Marklin Santa Fe passenger set 13 years ago. The couplers appeared to be the regular Marklin wire couplers that we have seen since about 1966. My problem is, although they look exactly like the standard Marklin couplers, the ones on the 2006 set that I purchased are much less stout and stable, so much so that just trying to hook a train together is an ordeal! Just won’t hold up or stay connected. Question. Can these inferior couplers be replaced easily? Looks to me like they can be popped out and replaced. Any ideas?

    • Ernest Robl says:

      If the couplers have the swallow-tail as depicted in the first illustration above, yes, they can be replaced relatively easily with the couplers of your choice. If you want to use couplers that are as close to the original couplers as possible, but somewhat sturdier, you could use standard Roco couplers. You can get these relatively cheap, as they are supplied on most Roco rolling stock — and many modelers use different couplers, thus replacing the original ones.

      Also, as mentioned above, the Roco universal couplers will mate with the standard loop couplers and may give you a more stable connection –one universal coupler to another.

      As you are apparently modeling American prototype, you could also get the Kaydee knuckle couplers that fit the NEM coupler pocket.

      As with most things model railroad, what works for one person may not work for another. Buying two to four couplers of a given type is relatively inexpensive. Try them out and see what works for you. (Remember, you can have so-called “coupler cars” with oe type of coupler on one end and another on the other end.)

      Just be careful not to break the mount of the coupler pockets as you are changing couplers. It’s best to hold the coupler pocket with tweezers or needle nosed pliers while you use other tweezers or needle-nosed pliers to release the coupler being removed.

      – Ernest

  8. Maerklin Current Conducting for HO Scale model railroad. Thanks for this information, subscribed.

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