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Couplings

Micro-Trains couplers

An alternative style of coupling is the "Micro-Trains" coupler that is common on American models. It is the N gauge variant of the "Kadee" coupler. A Micro-Trains coupler is a variant of the "knuckle" coupler and it operates in quite a different way. It is physically smaller than the standard UK coupler, although it is fair to say that both are disproportionately large compared with might be found of a real train!

The Micro-Trains coupler is magnetically operated, but in a different way from the Peco coupler. It is also controlled by a piece of iron wire, but it moves laterally not vertically. To couple two pieces of rolling stock together, simply drive one into the other and the couplings will join. They will then stay connected and reliably so (picture a).

To uncouple a Micro-Trains coupler, the train must be reversed while the coupling is over a magnet. (That can be a permanent magnet, or an electromagnet). This releases the pressure from the connection, and the iron wires are attached towards the rails. When that happens the two couplings separate laterally, toward the rails. The train can then be moved apart: see picture (b).

micro_trains_couplers

If the train is then pushed together while still over the magnet, the coupling does not mate. Instead it goes together in a way that allows the train to move but does NOT couple (picture c). This allows that coupling to be moved to a different part of the track without re-coupling. For a shunting operation this is useful: the train can be separated where the magnet is, then moved to where the rolling stock needs to be left.

The end result is a coupling that couples reliably, and uncouples reliably. It is less obtrusive than the "UK standard" coupler. Here's one installed to a UK carriage. You can see clearly the black "knuckle" coupler, and the gold coloured iron wire that operates it.

installed_microtrains_coupler

Websites with advice on using these couplings

Using Micro-Trains Couplings

There are fundamentally two types of Micro-Trains couplings: body mounted, and truck mounted. The former mount to the body of the wagon / carriage / locomotive (as would happen on the real thing). The latter mount to the bogie, so as to allow operation on tight radius curves. There are different versions available in both types, distinguished by the length of the coupling rod (shank) from the model to the knuckle. In general, operation on small radius bends will require longer coupling "shanks". Diagrams showing the different variants are available.

These couplings are widely used on American models, with an extensive range of variants to cover different model types and coupling mountings. However none of them are explicitly designed for UK image rolling stock. Consequently some degree of modification will be involved. This means being brave!

Read more: Using Micro-Trains Couplings

Fitting Micro-Trains couplers to UK stock

The couplings are readily available in UK through specialist suppliers. Firstly, begin by getting the starter set (part number 1050). It includes so many useful bits and pieces that its cost will be more than repaid after installing a few couplers.

 

Installing a Micro-Trains coupler conversion

Micro-trains supply an extensive range of conversions to add couplings to N gauge rolling stock. Sadly none are specific to UK models. Luckily, they are sufficiently similar that the same conversion kits can be used. The no. 1129 kit converts a Rapido coupler pocket with a "medium" length shank coupler. This seems to be OK for the bogie oil tankers and reduces the coupled distance slightly (to 8.3mm buffer to buffer).

  • Remove the bogie from the model. It is held in by a plastic pin that simply prises out.
  • Remove the existing coupling and its spring. Using a scalpel through the turns of the spring can help keep it from flying out.
  • To get the height right (mine are lower than standard) I needed to cut away the bottom of the pocket (marked).
  • The sides of the opening at the front need to be chamfered using a knife. The Micro-Trains leaflet illustrates this.
 oil_bogie_no_coupling
  • Open the coupling packet, being careful with the content. There are four items: a small sprue with the coupler itself, a small spring, the iron wire and a cast metal insert. The insert will stop the coupling from moving vertically, but leaving it free to move side to side.
  • Cut out the two parts of the coupling from the sprue, and clean all flash off the metal insert. Its inside surface must be smooth.
 micro_trains_coupling_parts
  • Assembler the coupler shank, following the diagrams in the kit. Make sure you get the iron wire on the bottom of the coupling! The second part of the shank assembles over the wire, and the two parts need to be handled as a pair using tweezers.
assembled_micro-trains_shank
  • Insert the metal insert into the bogie's pocket, and using tweezers put the spring inside it. Buying spare springs is good insurance! For the coupler height I use it will need to be almost flush to the bottom of the bogie and must be level.
 oil_bogie_no_coupling
  • The tricky part: lift the insert, and using tweezers inser the coupler shank into it. I find it easiest to be looking into the bottom of the coupling pocket. Get the shank the right way up!
 oil_bogie_with_new_coupling
  • Use a small blob of epoxy to secure the metal insert into the bogie pocket. You will need some clever arrangement to set the coupling height for this operation.
  • After the glue has set, check the height of the coupling. Mine shown here is a little too low.
 oil_bogie_coupling_height_check
  • Adjust the iron wire so that it just grazes a 10 thou shim placed on the rails. Bend to adjust; be careful not to damage the shank. Trim the excess wire at the top.
  • Here is the finished product! Check that it moves freely from side to side, and returns to the centre. Check its height is OK so that it doesn't foul on buffers etc (this is why I'm using a lower height standard).
oil_bogie_finished

 

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