Starting Out: Cab control, testing and ballasting

Bernard Gudgin and Michael Watts are experienced teachers and trainers. They have several decades of modelling and exhibition experience across the gauges from T (scale 1:480) to 16mm live-steam (scale 1:19), as well as narrow-gauge. They are often seen at exhibitions where they provide free advice to newcomers and returnees under the brand name of Oxford TRAINing.

Even on a small layout you may want to move more than one locomotive at a time. For example, you may want to shunt in a goods yard while a passenger train arrives at a station. This is most easily achieved using something called Cab Control.

Spreading ballast by hand is quick, easy and effective when you have had a bit of practice. Always try everything first – in this case with a spare bit of track! A piece of thin card folded as shown here with a smallish amount of ballast will be easy to tap into place. Put on less rather than more, and then only add a top-up where necessary. Work down between the rails first and then along each of the shoulders. A dry finger can push most of the stray bits into position between the sleeper centres, and a short rule can be used to tidy up the outer edges. Here’s a section of Hornby Set Track with Peco ballast being tapped into place. A yard of 16.5mm gauge track will take less than 10 minutes to place the ballast. Slightly smaller than scale-size ballast is easier to apply, and it tends to look more realistic – this is probably to do with the brain’s perception of small scales.

It follows exactly the same principles of wiring and switching that we have already described but it gives more flexibility in operating your layout, but you do need two controllers (cabs) – one to drive each locomotive – and this is then called two-cab control. The operation of your points and their power supply remains exactly the same as with a single controller.

You can have cab control for any number of locomotives all operating at the same time, but the switches become a bit more complicated and maybe your layout is not that big – and you have not got enough hands!

We have previously described how each of the separate track sections of your layout is powered via switches – either on or off. Each track section has its own switch between the (one) controller and its section. As a result you can apply power to only those sections that form the route for your train. Any locomotives on other sections remain electrically isolated and hence unpowered. This is the situation for one controller – that is one-cab control.

If you want to operate two locomotives at the same time, each on different track sections, you will need to add a second controller so that you now have two cabs – hence the term two-cab control.

Each controller operates one locomotive on its route over sections of track selected by switches. But you do now need to change each of the section switches to a different type – from single-pole on/off type to single-pole double-throw centre-off type.

A couple of low-cost home-made devices for low-voltage testing only. Left, a bulb in a socket with a couple of lengths of wire, and right, a similar arrangement with a dry cell included. It is practical to put a crocodile clip on the end of each wire so that a quick semi-permanent connection can be made at least at one end – or you may run out of hands! The bulb for the left-hand device should be a 12V one or you may blow a lower-voltage one from testing power on your tracks, which could be up to 12V. The battery-powered device needs only a 1.5V or 2.5V bulb that lights up sufficiently brightly from the 1.5V dry cell when used for continuity testing. You will find, by Murphy’s Law, that the wires are always too short for your needs – make them long – at least 3ft in total – and then they will get tangled up!

These are the same physical size but the dolly now has three positions. This gives you the additional facility of a centre-off position when no track section is connected and so is electrically completely isolated from either of the two cabs – useful when checking wiring, and valuable to completely isolate a locomotive on a particular track section.

These switches are the same physical size as before, but have three contacts on the underside, and cost very little extra. You will be able to upgrade your previous control panel to two-cab control fairly easily by just replacing the track section switches, adding a second controller and a bit more wiring.

For the full article, see September’s edition of Modelling – available now!

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