As well as interior lighting for the passenger coaches, I have fitted head and tail lights to the majority of the fleet. For my multiple units, these are automatically switched according to the direction of travel – so much easier with DCC. I know that this is, strictly speaking, not prototypical, since it is the driver’s job to select the appropriate lighting for the direction of travel. However, for the modeller, it can help to confirm which way the train will move off when the head and tail lights are automatic.
For a bit of fun, I have equipped some of my driving cabs with lights that can be selected by a function call. These are selected by F1 or F2 for cab 1 or 2 respectively and this also helps to confirm which is “forward” for a multiple-unit.
• The first train I added lighting to was my APT set. More here ...
• After learning how best to do it and what not to do, my next was easier. This was the Midland Pullman set and the work is described here.
• Lighting for passenger coach rakes and goods brake vans is described here.
I am still thinking about fitting running lights to my steam engines. This is because I would need to change the physical positions if I allocated the engine to a different class of train and that would complicate the wiring. However, the Duchess and the Britannia are only likely to be used on express passenger services (Class 1), so this might not be an issue for them. There is also the problem of the tail lamp when running light, because this should be removed when hauling a train. I will have a similar problem with my diesel headcodes. However, the “prototype for everything” philosophy means taking advantage of the fact that was not unknown for locomotives to carry the wrong head codes. I even saw a DMU drawing into a station where I was waiting one morning carrying an illuminated red tail light above a front buffer. The guard became highly agitated when I mentioned it to him!
Opinion is divided about having the head and tail lights controlled automatically for direction. After thinking about it, I have decided not to have my locomotives’ head and tail lights under automatic directional control. This is because, when shunting or backing onto a train, the unprototypical switching back and forth would be very obvious. “Forward” is clearly identifiable even for a diesel engine by such features as the cooling fan grills, so directional lighting is not necessary to identify direction of travel. It is a straight forward task to reconfigure the white and yellow wires to be non-directional and to respond to F1 and F2, with a corresponding reallocation of the other functions. With a little cunning, I can achieve independent control of the tail lights at both ends with only one extra function wire.
For those who want to have automatic directional switching of the headlights at each end, the white and yellow wires are used to give directional control. For a locomotive, the tail lights should only be illuminated if the engine is running light and this can be arranged to operate under the control of a single button. Two other function output wires can be remapped to give directional switching for the tail-lights at each end so that these can be switched on when running light and off when hauling a train. The tables below use F4 because F1 and F2 are allocated for cab lighting and F3 for passenger coach interior lighting.
For the TCS T6X decoders, the green and purple wires are mapped to F1 and F2 by default and are used for the cab lights. The following CVs are amended for the tail-lights:
| CV | Value | Result | Output |
|---|---|---|---|
| 39 | 32 | Brown wire to F4 | Rear tail lights |
| 40 | 32 | Pink wire to F4 | Front tail lights |
| 53 | 0 | Brown wire on forwards only | Rear tail lights |
| 54 | 16 | Pink wire on reverse only | Front tail lights |
For the TCS T4X decoders, no cab lights are provided and the following CVs are amended for the tail-lights:
| CV | Value | Result | Output |
|---|---|---|---|
| 35 | 32 | Green wire to F4 | Rear tail lights |
| 36 | 32 | Purple wire to F4 | Front tail lights |
| 51 | 0 | Green wire on forwards only | Rear tail lights |
| 52 | 16 | Purple wire on reverse only | Front tail lights |
It is apparent that not all DCC systems are made equal and compliance with NMRA standards is anything but consistent between makers. One thing I’ve noticed from a number of YouTube videos of people’s layouts is the different behaviour of directional lighting. Several decoders seem to switch off their head and tail lights when the loco comes to a stop, or switch the lighting from “reverse” to “forwards” even though the controller has not been reversed. Some decoders don’t respond as they should at zero speed and a surprising number of command stations can’t produce a zero speed reverse packet (every speed packet includes a direction bit). The combination of NCE control and TCS decoders that I have chosen always reflects the direction selected by the controller, even when stationary, which gives a far more realistic effect.