Kadee on Märklin K-track

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What would make a fan of Märklin K-track think of using Kadee couplings? After all, a decision to go with this system means a lot of hard work just for starters.

Well, shunting is one consideration, but another is the high-quality electronics, which allow highly realistic operation. After extensive testing had shown that the usual products were not suited to my purposes, I was forced to look for a different solution. Kadee coupling
Kadee in detail

Why Kadee in particular

Apart from the fact that these couplings look exquisite, they allow precision shunting and advance uncoupling. Coupling at crawling speed is very satisfactory, even with light trains. Contrary to what most people think though, I would like to point out here that this coupling has basically nothing in common with a close coupling. In any case, I don't consider this to be of any importance, because satisfactory operation is what matters. This also applies for difficult shunting manoeuvres, even with a small track radius.

Installation tips

Unfortunately, nowadays most trains are supplied with link mechanisms, which do not exactly help with Kadee couplings, since link systems in conjunction with short couplings can result in a very stiff coupling connection, especially when going round curves. It's therefore better (though not essential) to remove the link mechanisms and attach the Kadee coupling directly to the underside of the carriage or to the bogie. The Kadee range offers a wide selection of different couplings.

Kadee NEM The type of couplings used for NEM shafts makes it easy to change over to Kadee. These couplings are supplied in various lengths to help tackle any installation situation.

One more tip at this point. This kind of shaft is rather thin, which means that when they are fitted there is a noticeable degree of play. However, this can be remedied by inserting underneath (between the NEM shaft and the coupling) a strip of metal, approx. 0.1 mm thick, which has been twisted slightly into a "V" shape. This acts like a spring to push the shaft of the coupling upwards. You can see a plate of this kind in the illustration above. The twists at the ends prevent it from falling out.

Clearance Another point to note with K-tracks is the distance between the top edge of the rail and the bottom edge of the coupling bracket. If you are operating with (two-wire) direct current, this distance is 0.8 mm (original Kadee information). But because with direct current tracks the contacts in the vicinity of the points protrude above the top of the rail, this 0.8 mm is not enough when operating with alternating current.

To prevent the couplings from locking up, the distance mentioned above is simply adjusted to 1.5 mm using the "original Kadee adjusting pliers" (illustration above). This does not affect the function in any way. The safeguards in my case, as can be seen opposite, are a coupler gauge and a 1.5 mm strip of metal.

One more tip in passing. In my experience, coupling No. 16 is not to be recommended (actually intended for European stock).

Now to a crucial problem, uncoupling

The above statement should not be taken literally. Because the exact opposite is true: uncoupling points using Kadee on H0 pose no problem at all with Märklin K-tracks. Part of the reason for this is that parts of the track are made from iron and can therefore transfer the magnetic force well. There is a brilliant way of achieving uncoupling points that are completely invisible and trouble-free (since there are no moving parts). I use two different approaches here.

Permanent magnetic uncouplers, although these are not practical in every situation, because under certain circumstances they can result in unintentional uncoupling when shunting.

Electromagnetic uncouplers, can be installed anywhere, silent operation, but the more expensive of the two solutions.

Regarding the permanent magnetic uncouplers

In this case, I use the Kadee Uncoupler No. 308, and install it according to the manufacturer's instructions under the Märklin K-track (no changes are required to the track).

The Kadee Magnet No. 308, consisting of a permanent magnet and matching steel plate. This helps to strengthen the magnetic field.
Permanent magnet

Regarding the electromagnetic uncoupler

Without doubt the ideal uncoupler. It can even be placed under the points. With this approach, I use the Kadee uncoupler "Gauge 0" (No. 810). This part is delivered as a kitset to be assembled in accordance with the operating instructions and then mounted under a K-track (here again, no changes are required to the track). Once the electrical side of things has been dealt with, again following the manufacturer's instructions, the electromagnetic uncoupler does its job.

A further point regarding this solution: Since uncoupler No. 810 was actually made for an "0" gauge track, the uncoupling magnet is now a bit too long. This will be noticed, especially when individual, short, two-axle carriages take on a life of their own during uncoupling because of the magnetic force. As a result, it may be a good idea to slightly modify parts of the uncoupler, as shown in the illustration below.

Electromagnet The individual parts of the Gauge 0 Kadee uncoupler (No. 810). To shorten the effective length of this magnet a little and thus remedy the problem described, two corners of the left-hand steel plate have been removed.

But the matter can be approached from a railway engineering perspective, by uncoupling more towards the end of the uncoupling point (light train beyond the magnet's range).

No matter what solution you are trying to achieve, before setting up magnets all over the set you should thoroughly test everything at one uncoupling point.

Uncoupling, but where?

Once the uncouplers have been installed, the whole mechanism can be covered with ballast in the usual way. To allow you to disassemble the magnets from below (whether permanent or electrical), and also to make it simpler to cover the track with ballast, I recommend laying a fairly stiff plastic sheet between the track and the uncoupler.

Another useful step to ensure you can find the hidden uncoupling point when operating the railway, is to mark the location with a lamppost, pole or similar.

The results fit the bill perfectly. Invisible, noiseless and even electrical if you want.


Kadee couplings are very delicate products. Extreme care should be exercised when handling them to ensure a perfect function. I recommend using the right tool from the start to make the installation. It is also important always to use the type of coupling that is suited for the particular train. It does not pay to compromise. This way, you will avoid disappointments that take away all the fun of the exercise.

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