Shuttle-units: what you need to know

TriAng shunters with shuttle unitSit back and let your model railway run on autopilot with a shuttle controller. MRE investigates these handy little devices.

I’ve been thinking about another little box layout. This is really a storytelling model diorama but it’s set around a railway track and for extra interest, I want to have a small shunter (I purchased a Tri-Ang R353 Yard Switcher to this) trundling back and forth along the track. It’s too small a layout for DCC and having to stand there and stop, reverse and start, and DC system would get dull real quick.

Tri-ang R353 Yard Switcher

My lovely ‘new’ TriAng R353 for use on a shuttle-controlled layout.

After a bit of thinking, I’ve decided to use a shuttle unit.

These little electrical circuits control a train’s movement along a section of track automatically pausing it at each end with a definable pause before reversing direction, thus creating an endless loop.

They can be used for point-to-point operations, such as a train moving back and forth between two stations, and simulating the operation of a branch line – as will be the case on my layout – or industrial siding.

With a shuttle unit, you can set your train to run at a particular speed and then let it go, freeing you up to concentrate on other parts of your layout or just sit back and enjoy watching it.

Along with automatic reversal, many other options are available to provide a wide range of possible applications. Randomised wait times, signal control and the ability to slow and speed up the train as it stops and starts are amongst the features available (in the BLOCKsignalling SSR-1, SAS1 and Gaugemaster GMC-SS1 respectively).

The Gaugemaster unit comes in a clean, user-friendly, box while the BLOCKsignalling unit, pictured above, is a naked circuit board so will need mounting. I’ll screw mine to the underside of the baseboard so went with the BLOCKsignalling unit but if presentation and ease of use are important, the Gaugemaster unit is recommended.

They’re also relatively easy to install.

How to connect shuttle units

Typically, in the case of DC systems, they have two sets of input connections: from a power supply, around 12 to 14V DC, and the track power feed from the DC controller. For output, are the two wires to the track. The unit itself is powered by the first supply and passes the current from the DC controller to the track, changing the polarity – and hence the direction of travel – as needed.

A mechanism for detecting/stopping the train at either end of the track is also needed, and for this diodes are typically soldered to the rails although some use reed switches or infrared to detect the loco, such as with the SimpleShuttle and IRDOT-1 from Heathcote Electronics.

As said, I’ll be using one of the small simple layout I’m thinking about at the moment. If you’re building one like this or want to add automatic running for your railway layout, shuttle units are what you’re looking for. They are easy to install, affordable, and can make a big difference in the functionality and operation of your layout. Give them a go, they’re simple to wire up and let you sit back and enjoy the layout hands-free.

I’d love to hear how you use your shuttle units, please add a comment below if you’ve got one.

Founder of ModelRailwayEngineer, Andy Leaning

Andy is a lifelong modeler, writer, and founder of He has been building model railways, dioramas, and miniatures for over 20 years. His passion for model making and railways began when he was a child, building his first layout at the age of seven.
Andy’s particular passion is making scenery and structures in 4mm scale, which he sells commercially. He is particularly interested in modelling the railways of South West England during the late Victorian/early Edwardian era, although he also enjoys making sci-fi and fantasy figures and dioramas. His website has won several awards, and he is a member of MERG (Model Railway Electronics Group) and the 009 Society.
When not making models, Andy lives in Surrey with his wife and teenage son. Other interests include history, science fiction, photography, and programming. Read more about Andy.

Afflliate disclosure:The links on this page may take you to carefully selected businesses, such as Hornby, Amazon, eBay and Scale Model Scenery, where you can purchase the product under affiliate programmes. This means I receive a small commission on any orders placed although the price you pay does not change. You can read my full affiliate policy here. I also sell my my own ready to use, pre-made and painted buildings and terrain features. browse the range.
  1. I am looking to do a shuttle tram system. So it would have two track that go along both lanes of the road. At each end, both track would come together with a switch so that when it returns it stays on the right side of the road. Do you know of any shuttle controller that can handle this – they all seem to assume single track with switches for multiple spurs at the ends, rather combining track. As an extra bonus, it should be able to handle two trams passing each other.

    • Hi Jenny, I’m not aware of any off the shelf system that will do this; as you say, most are designed for simple single track back and forth operation. It could be done with servo controlled points, sensors and an Arduino with some programming but that’s quite involved. Andy

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