The layout of the sidings beyond the station at Little Bazeley is a variation of Alan Wright's Inglenook Sidings shunting puzzle. The choice of a very loose 1964-1969 modelling period, being the very last years of the British steam/diesel transition era, just about allows for comparatively short standard wheelbase stock of 10'-0" (3m). Scaled down to 4mm scale 00 gauge, this translates into goods wagons about 3.2" (8cm) long, i.e. short enough to allow for the capacities needed for an Inglenook Sidings setup within the given space of 4' x 1' (120cm x 30cm).

The warehouse setting is left fairly unspecific as to who exactly receives and ships what, which allows for a fair variety of freight stock to be used. The shunting puzzle is fully workable within the limits of the baseboard on the basis of the original Inglenook rules.

Shunting Order
for Little Bazeley Sidings

1. Form a departing train consisting of 5 out of the 8 wagons sitting in the sidings

2. The 5 wagons are selected at random

3. The train must be made up of the 5 wagons in the order in which they are selected




One essential aspect of operating a shunting layout is the choice of couplers and the uncoupling system to go with them. Since the late 1990s manufacturers have acknowledged the importance of reliably working couplers by either having their products factory-fitted with such couplers (as in the US, where magnetic couplers in the mould of the Kadee system are now almost standard fittings) or by providing coupler pockets in accordance with the NEM 362 norm, allowing modellers to substitute the factory-fitted couplers with a different coupler of their choice by simply plugging this into the pocket.


  Ever since developed by Tri-ang in the late 1950s, the tension lock coupler has been the standard device used on British 00 scale models. Consisting of a fixed loop bar and a raisable "fish-hook", they are foremost and above all designed to perform automatic coupling.

This is achieved by pushing the hook through forward motion over the loop of the next vehicule's coupler; once the hook drops again, the two items of rolling stock are securely coupled and, thanks to the barbed form of the hook, interlocked - in fact so much so that uncoupling becomes a major problem, even when taking stock off the rails.

In general, tension lock couplers are therefore regarded as being both unsightly and operations-unfriendly, and only suffered because ready-to-run UK models offer no alternative.
As can be deduced by the way a tension lock coupler works, uncoupling can only be achieved by way of lifting the hook sufficiently in order to allow the loop to pass under it again - and this will only work when the couplers are not under tension (hence their name), i.e. the rolling stock is standing still.

The "classic" way of achieving this is by using a sprung ramp between the rails. When a train passes over it, the couplers are interlocked through the tension and depress the ramp. However, if the train stops, the ramp will lift the now loose coupling hooks, splitting the consist at this point.

The problem is that this works fine most of the time but not all of the time, and unwanted uncoupling increases as the speed of a train passing over the ramp decreases - as would of course be the case on a shunting layout such as Little Bazeley.

The answer to this problem is to have an uncoupling ramp which is not permanently "active", i.e. which is raised to push up the hooks only when rolling stock standing over it is intended to be uncoupled. A number of home-made systems, ranging from basic to highly complex, have been developed by numerous individuals, and there are even commercially produced motorized solutions which are push-button activated.


Peco uncoupling ramp (above), Gaugemaster uncoupler (below)

This allows for remote uncoupling, but only at the exact location of an uncoupling device, as tension lock couplers immediately recouple once the hook is no longer raised, making "delayed uncoupling" (i.e. pushing an uncoupled wagon to a point beyond the uncoupling device) impossible without modification to the couplers.

This is one of the major features and advantages of magnetic uncoupling systems such as used by the well-known Kadee / MicroTrains couplers, which (together with their much sleeker appearance) accounts for their growing popularity with UK prototype modellers. This is further heightened by the now de facto standard of NEM 362 coupler pockets on 00 scale models which allow for easy swapping of couplers equipped with a swallow-tail end.



Unfortunately, the NEM 362 specifications are mostly adhered to by manufacturers with regard to the pocket and coupler shafts but interpreted rather loosely in terms of the distance to the railhead (which NEM 362 sets out as 8.5mm with a tolerance of +/- 0.2).

The negative effect this can have on UK models fitted with Kadee couplers is illustrated here: two pieces of rolling stock from the same manufacturer (Bachmann UK) using the very same NEM 362 Kadee couplers provide no guarantee that the couplers will line up correctly.

The different heights at which the coupler pockets are located are clearly visible in this random example.

This results in a call for some major surgery in order to achieve reliable uncoupling as Kadees (as well as other magnetic buckeye couplers) tolerate little to no misalignment in height between two couplers. But even if all is well adjusted (and Kadee even produces a special purpose vertical and lateral gauging tool to serve this end), full reliability is not guaranteed. Again, uncoupling is usually the bigger problem, leading to the strange "Kadee dance" when a locomotive can be seen pulling rolling stock back and forth over an uncoupling magnet because the two couplings just won't separate. This is why a growing number of modellers remove the trip pins (which the magnets should force sideways) on their Kadee couplers and prefer to uncouple them manually, thus using the couplers only for the sake of better visual appearance (examples are the BR Springburn Yard layout (there's a youtube video showing the pinless Kadees during shunting moves) or the GWR/SR Hintock Branch 00 scale layout).
One big advantage of the Inglenook concept as operated on Little Bazeley is that uncoupling moves only take place in one direction (as all of the sidings point the same way) and that the actual position of the freight stock is of no importance as long as the maximum number per siding is being respected and no points are blocked.

So, it was back to the traditional tension lock couplers for Little Bazeley as I really could not be bothered with the major hassle of fitting and adjusting Kadee couplers even on as few as the 8 cars necessary for the Inglenook operation (even less so as Kadees are the most expensive option by far) when reliable uncoupling was not assured.


Kadees require magnets for uncoupling, and there is an alternative to the "activated uncoupling ramp" approach for tension lock couplers which makes use of magnets too. First described by Brian Kirby in December 2008 on rmweb.co.uk, this method modifies the narrow Bachmann tension lock couplers (which feature a coupling hook made of non-magnetic material) by adding a bent iron staple to the hook. As the rolling stock passes over a magnet, the hook is pushed upwards as the staple is being drawn down by the magnet.

Putting the concept to the test using rather coarse staple samples (they are bent so that the inward leg rises back against the wagon floor in approximately a 45 degree angle) the setup worked fairly reliably, especially when using fairly large (i.e. thick) iron staples - finer examples took more finetuning until they were attracted downwards by one of the two magnets (one for each coupler) between the track.

In comparison to any self-made raisable uncoupling ramp (which can run into unexpected re-alignment difficulties when lowered back to in-between the tracks), the Kirby method has the advantage of working faultlessly once all the couplings are set up properly.

Just how much time and effort one is prepared to invest in the "setting up" of couplers and uncoupling devices is a matter of taste and possibly also modelling skills. Personally I found that adding the staples to the counterarms of the coupling hooks took quite some time and effort, yet reliable uncoupling on Little Bazeley during extensive test runs was not assured. Whilst certainly due to the flaws and shortcomings of the setup and not of the method as such, I felt what I really wanted was an uncoupling system which echoed the simplicity of the layout itself.
"Simple" and "prototypical" usually don't go together, but in this case I found that the way shunting was performed on British Railways in the 1960s gave me the idea on how I was going to uncouple rolling stock on Little Bazeley Sidings.

Now of course BR didn't use tension lock couplers. But the main tool used when working with hook-and-chain couplings was a shunting pole which allowed the employee (called a shunter) to reach between wagons to fasten and unfasten couplings without having to physically place himself between the rolling stock (and thus reduced the risk of accidents). The shunter shown in a 1950s BR in-house poster can be seen carrying such a shunting pole in his right hand.

And this is where Sid comes in.

Sid is, of course, short for Sidney, the regular shunter on runs to and from Little Bazeley Sidings. But then Sid could also be seen as an acronym for "simple device" - for uncoupling, that is.

In reality, Sid is a figure from a Preiser set of track workers (#10418) and glued to a thin wire with a 90 degrees hook at the end which effectively acts as a shunting pole. I got the basic - and ultra simple - idea of the hook from a youtube video and then simply added Sid as a slightly tongue-in-cheek decoration. Just like the shunter on the BR poster, he uses his pole to uncouple rolling stock at Little Bazeley Sidings.


Most uncoupling systems primarily try to avoid having the infamous "big hand from the sky" appear. But the "look no hands" approach has some very noticeable flaws when used with tension lock couplers. No matter whether it's the traditional sprung ramp or a magnetic device that does the uncoupling, rolling stock will always be uncoupled and remain at the very same spot (i.e. where the uncoupling device is located). This is because delayed uncoupling (where couplers are separated and do not recouple if the wagons are pushed forward after the uncoupling) is rather impractical with UK tension lock couplers (although possible using a modified Kirby system, as shown in this youtube video).

The ultra simplistic way of uncoupling tension lock couplers which Sid brings to Little Bazeley seemed much better suited for a shunting puzzle. The only modification to the original youtube idea needed to ensure reliable uncoupling was to remove the hooks from the couplers facing away from the bufferstops at the sidings - this way, the hook only needs to lift one single hook and instant re-coupling is minimized (which I found to be a frequent occurence with both hooks in place).


Seen here is the single hook coupling setup (left), the paperclip wire hook inserted between the two loop bars (centre)
and finally the uncoupling of the two goods wagons by the simple lifting action of the wire hook (right).

  After initial tests I went for something just a wee bit more elaborate - a small 1.5mm Allen wrench which fits the purpose just perfectly. Attaching Sid the shunter with superglue really only serves cosmetic purposes...

The big advantages of having Sid do the uncoupling, basically, are:

a) no visually obtrusive uncoupling devices,
b) only very minor modification of ready-to-run stock required (removal of one single coupling hook per wagon),
c) uncoupling is possible anywhere on the layout,
d) extremely cheap uncoupling system (as low as the cost of a single paperclip if going for a truly basic tool approach)

The major disadvantage for many will, of course, be the big hand from the sky involved in the uncoupling, but I have found that ultimately this bothers me a lot less than a hands-free magnetic uncoupling system which doesn't work reliably.





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Page created: 07/JUN/2004
Last revised: 15/NOV/2015