Alex Jackson Coupling

This coupling was developed by Alex Jackson in the early 1950's. He managed to design and develop a coupling that cannot be commercially exploited in that you must make it yourself from wire. As a result it is cheap and providing you follow the design carefully it is a reliable coupling.

Details of its construction appeared in the January 1960 Model Railway News written by John Langan who used the coupling on his "Presson" layout. Those who saw it would marvel at the shunting that went on without the hand from the sky being involved in the process. It was used regularly by the Manchester EM group including Sid Stubbs, Norman Dale and Norman Whitnall. More details of its manufacture and use appeared in the Model Railway Journal numbers 55 & 56 and it is these articles that are probably more easily obtainable today.

Since the 1960's there have been some developments in the design on the coupling especially related to bogie stock and frequently there is someone who has used the idea to develop his own version of the coupling. What is apparent is that the design that Alex developed all those years ago is still a great way to couple stock together.

Who was Alex Jackson?
The late 1940s and early 1950s was a period when many developments were taking place in the hobby following its revival after the war. At that time, Alex F. Jackson, despite poor health, gave much encouragement to many fellow modellers by his brilliant approach to the problems of mechanisms, good running, track work, and true scale modelling. He first worked in a scale of 3/8" to 1 foot and his garden railway, running off 100 volts ac supply was a source of enjoyment to all who visited him. Many also remember his unfortunate cat which never seemed to learn to keep off the track when a running session was in progress - with surprising results!

A fine example of one of his locomotives in 3/8in scale may be seen in the March 1948 Model Railway News. Later, Alex changed to 4mm scale and immediately adopted EM, 2 rail, using split axles, metal wheels and insulated frames for locomotives, with hub insulation of metal wheels and axles for rolling stock. Here again we were shown the advantages of using the higher than usual voltage of 24V DC which was quite revolutionary at that time. This of course meant home built motors which he used with heavy flywheels, to obtain smooth and controllable running which can still be compared with the best of today. No gimmicks in the controls either, just a plain resistance wire controller. His attitude to modelling and an example of his construction methods may be seen in the description of his 4mm scale LNWR 0-6-2 side tank locomotive in the MRN for June 1950. The photograph clearly shows the early version of his coupling for which he became so well known. Alex died in October 1952 after a serious operation, when he was in his early thirties, and the hobby lost not only a most distinguished exponent of our craft, but an enthusiastic leader who by his example helped to raise the standard of modelling to a level which we still appreciate today.

Thankfully he developed a simple coupling ingenious in its design which is now used worldwide by many modellers in several scales. It is widely known as the AJ coupling and is a fine memorial to this pioneering modeller.

The coupling
Alex first demonstrated the coupling at a meeting of Manchester Model Railway Society in February 1949. We still receive enquiries for information about the coupling, and although very little change has been necessary on the magnetic version, we now present a revised description of this ingenious mechanism. Let us emphasise that we, following the traditions set by Alex, truly believe that our hobby is about making models rather than purchasing them. This coupling is very much a home-made item and is not available for purchase.

The coupling is in regular use - we know that it works for us and many others and that our claims for it are justified, but it must be emphasised that whilst it is capable of satisfactory operation in the hands of careful modellers it is not suitable for very rough handling, and accurate maintenance of all angles and dimensions is essential for faultless operation.

By accurate setting in the first instance, using the simple aids to be described, and maintaining this setting from time to time, the coupling will operate faultlessly and indefinitely. Its main advantages are:
1. It is unobtrusive.
2. It is quiet in operation and very mysterious to the onlooker.
3. It is reliable if properly made.
4. It is extraordinarily cheap.
5. Couplings are identical at each end of the vehicle, so that turning a vehicle end for end does not affect performance.
6. No mutilation of wagon headstocks or attachment to buffers is necessary.
7. The pull for uncoupling, being downwards ensures that the vehicle is kept upon the track.
8. The electro-magnet may be energised by a push button on the control panel before a wagon reaches it with the certainty that it will uncouple as the wagon passes through the magnetic field
9. Uncoupling while moving, with the loco. pushing and buffers under compression with couplings slack, is positive and the magnet will operate only one coupling at a time
10. Only one uncoupler is required per fan of sidings.
11. After being uncoupled at the magnet location, vehicles may be parted and left at any position on the layout. This allows realistic shunting to take place.

The hook

The ingenuity of the coupling lies in the design of the hook as shown. Each feature of this is important and plays its part in the action of coupling and of uncoupling. The method used for forming the hook was devised by Norman Whitnall and referring to Fig. 1 it is essential to bend the wire back along the top of the nose with the tail coming down on the right side of the shank when the coupling is viewed end on. This 'handing' is important so that wagons will couple with each other and also with those already in existence. This way of bending the hook shape produces a strong hook which tightens upon itself when under load and is therefore capable of handling long trains. The hook does not require to be soldered but the tail should be stoned smooth to ensure that it is free from burrs.   The material used to form the hook is 0.011inch diameter spring steel wire (32 SWG or 0.274mm) sometimes referred to as music wire. This is easily available from a music shop in the form of guitar strings and the picture shows a common variety.

Bending the hook
At first sight it might appear a difficult task to bend the special shape of hook consistently but by the aid of a simple jig as shown this may be performed easily. It also shows the sequence for forming the hook.

First cut a piece of .011in. (0.274mm) diameter spring steel wire about 90mm (3.5in.) long, making sure that it is quite straight and that you have stoned all burrs off the wire ends. Insert one end into the 5mm deep hole of the jig and bend the wire at right angles. Fold this bend tight upon itself using pliers or the jaws of an instrument vice. Now insert the doubled end into the 2.25mm deep hole in the jig and bend the projecting long wire to the combined angles of 30 degrees and 45 degrees as in Fig. 3 (bend No. 3) . A simple template may be made to check this but with practice it can be judged quite well by eye. With the double portion still in the jig, bend the tail to the combined angle of 60 degrees and 60 degrees as shown in Fig.3 (4th bend). These angles do not have to be accurate to the last degree; it is sufficient to judge bends of 1/3, 1/2 and 2/3 of a right angle.

Flexibility
To obtain the required flexibility for positive operation within the magnetic field, the coupling wire is only 0.011inch diameter and needs an optimum length of 65mm (2.5inches). It is anchored at the end of the wagon farthest from the hook as shown in Fig. 4. The fact that the vehicles are really pulled from the end remote from the coupling makes it desirable to fix the end of the coupling wire as near to the centre line of the vehicle as possible in order to minimise the turning moment.

With all this in mind, let us examine in detail the action which takes place when coupling and uncoupling.