Ask Phil - What is a Sprat & Winkle coupling?

29 October 2020
In your recent podcast, you mentioned something called a "Sprat & Winkle" coupling? What is is and why would I want to use them? Andrew, London

While 4mm scale ready-to-run models are always fitted with tension-lock couplings, when you build a kit, this isn't the case.

When I started modelling seriously, everyone at my local model railway club used Sprat & Winkles, and since they seemed to know what they were doing, I followed suit.

A Sprat & Winkle is a tension-lock coupling, just like the ones found on RTR models. This means that when the train is being pulled, and the couplings are in tension, the hook can't move because it's wrapped around the coupling bar and so, "locked" in place. When the train is being pushed, the couplings are in compression and stock can be uncoupled.

With RTR couplings, this usually involves an uncoupling ramp between the rails. These need to be quite large and very visible.

The Sprat & Winkle turns the coupling upside down and, because the hooks are brass and bars are steel, they are also a lot thinner and less visible. Uncoupling is achieved by attaching a steel chain to the arm. This is pulled down by a magnet under the track. It can be right under it and completely invisible. This works so well that layout owners usually have to produce a mark so operators know where the magnets are!

If we look under the wagon, you can see the arm is counter-balanced by a brass paddle. When the chain isn't being pulled down, this lifts the arm back to the normal position.

Exactly how the couplings are attached to stock tends to vary between builders. I like to bend a staple to fit through the paddle and push these through holes in the wagon floor.

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Talking about the floor, I fit mine behind the bufferbeam, because that's the easiest thing with a kit-built wagon such as the one on the right. For RTR wagons, like the left hand one, I cut a hole in the chassis so I can get at the wagon floor. If all your wagons are RTR, then they can be fitted below the bufferbeam to avoid making a hole.

Coupling bars can be stuck across the buffers with superglue, or you can make a U-shaped piece of wire that fits to the bufferbeam. The only important thing is that all the bars are the same height so a little gauge made of a block of wood is a good idea.

For locos, we just fit the bars and not the hooks. This works well enough and takes a couple of minutes with the added benefit that it leaves the bufferbeam clear for detail.

Is all this worth it? Well, I like the invisible uncoupling magnets and the less-obtrusive couplings, so for me, it is. They are also very easy to fit to kit-built models, which many of mine are.

The choice of couplings is a very personal one and every modeller is different. Just find something that works for you. Normally, I'd suggest going to a show, watching a few layouts and asking people what they are using a why, but that's a little tricky these days.

If anyone missed our podcast, you can find it on YouTube

And the name "Sprat & Winkle"? The couplings first appeared on Derek Munday's model of the LSWR Meon Valley Line decades ago. The prototype enjoyed the nickname "The Sprat & Winkle Line", so when he made the couplings commercially available, the name stuck.