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Couplings

August 22, 2011

At the present time I am using 3mm scale B&B couplings on my Broad Gauge stock. When these work well they are very good but I find they have e tendency to uncouple if the track or baseboard joint is uneven and some are a real problem to get them coupled. This may be down to the way I have assembled them, which I find a fiddly job.

The standard [or narrow] gauge stock has 3mm scale Sprat & Winkle couplings which I used when they were running on 12mm track. I do not like these couplings now as they need a permanent magnet instead of an electro-magnet and to use the delayed uncoupling the train has to stop over the magnet, back off to let the hooks drop then push forward. All a bit of a hassle.

At a recent exhibition I was talking to a member of the Scalefour society who demonstrated some Alex Jackson couplings. I had always thought that these were really too complicated but having seen them in close up and had them explained this myth was dispelled. I also saw on a friend’s EM layout that he was using them attached to the paddles of Sprat and Winkle couplings. This made me think and I decided to see if I could do similar and get them to work in 3mm scale. This now is the result of my experimentation.

I downloaded an excellent article on the couplings from the Manchester MRS web-site and purchased the Palantine jigs for bending the wire hooks, which I have found excellent in producing the standard hook. As I have so many Sprat & Winkle couplings I decided to se if I could use the paddle as a counterweight  and mount the coupling making it hinged. I initially tried mounting the coupling in the usual place for a S&W coupling but the length of spring wire for the coupling was too short and therefore too stiff. I then tried mounting the coupling in the middle of the wagon to give a longer length of wire. I needed to add some lead weight to the paddle to get the coupling to return to normal. Initial trial showed that the coupling would couple up but on trying to uncouple I couldn’t get the tails of the hook to disengage. I think this was due to the length of the tail and the fact that there is less height for the hook to drop than in 4mm scale. I found that shortening the tail by 0.5mm didn’t affect the ability for the coupling to engage but did allow it to uncouple over the magnet. I have fitted six wagons so far and trialed them on the layout with good effect. So muck so that I have now decided to take the plunge and fit all the standard gauge stock with this coupling.

The pictures below show how I have adapted the Sprat & Winkle coupling and how I mount them on a wagon. I have also shown a jig I made to hold the wire hook in the correct position whilst it is soldered to the paddle.

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The dropper to operate the coupling is made from a paper clip and is mounted just forward of the axle. I found this position gives the best operation of the coupling. The paddles are mounted on wire hooks soldered to a piece of copperclad which is then glued to the floor of the wagon.

My next job is to mount them to a coach bogie but as yet I have no bogie stock!

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