In Part 1 of this series on reverse loops I covered reverse loops on analogue layouts. This is brilliant if you are controlling your layout for analogue, but what about those using DCC control? That’s where this article comes in. As previously explained, a reverse loop on any layout will cause a short when connected up as opposing rails connect. This may not seem like an issue when using DCC as it operates on alternating current, but in reality it is exactly the same problem as with analogue layouts. This is because the two rails are constantly switching between positive and negative - and although both sides are doing this, you will find that with a reverse loop the short still occurs. This is down to the fact that the two rails are switching consistently to the opposing polarity as the other rail. In brief, you do still get the same problem as you do in analogue.
In the previous article we showed you how to wire up a reverse loop to allow the track formation to work on analogue. The diagrams shown can be used to wire the DCC controlled track in the same way, the downside being you do still need to stop the train. This of course defeats some of the purpose of operating in DCC. There is a simple solution however, and that is to install an Auto-Reverse module.
These modules do exactly as their name suggests, they automatically reverse the polarity of the reverse loop. As with the analogue wiring you do still need to isolate the four rails of your point. This is easily done by using plastic rail joiners. Once installed the rails no longer cause a short. That’s step one done.
Step two is simple, connect your Auto-Reverse module into the circuit. If using the Gaugemaster DCC40 Auto-Reverse Module simply connect the unit as shown in the digram below. Once installed, welcome to the world of automatic polarity change on your DCC reverse loops.
The Gaugemaster DCC40 Auto Reverse Module is designed and built to the NMRA standards and should work with the majority of digital controllers. It is unfortunate however, that because of the design of some of the more basic systems, it does not work with all of them. Some systems operate in a slightly different way to many of the other systems on the market, and because of this the DCC40 is not suitable when using either of the Hornby or Bachmann systems.
Although you can't use the DCC40 with these systems, it doesn’t mean that reverse loops cannot be overcome in the same way. All you simply need is the Reverse Loop module produced by the relevant manufacturer. If you are using any of the Bachmann systems you would need to use the Bachmann (B36-525) E-Z Command Reverse Loop Module and the Hornby (R8238) Reverse Loop Module if you are using a Hornby digital controller. The Hornby reverse loop module is installed in a similar way to the DCC40. The wiring diagram is shown below:
Unfortunately, at the time of publication, I have been unable to find a copy of the instructions for the Bachmann E-Z Command Reverse Loop Module and am unable to provide a diagram for the installation. Hopefully this will be included at the start of part three of the reverse loop series. If you do need a Bachmann E-Z Command Reverse Loop Module for your layout, be sure to consult the instructions provided with the unit prior to installation.
That concludes part two of the article on Reverse Loops, keep a lookout for part three in a forthcoming issue of Right Lines. The third and final instalment of the series will cover the more advanced situations where a reverse loop occurs, for example if two reverse loops are present on one circuit and those pesky track arrangements known as triangles.
Part 3 coming soon...
JAMES HICKMAN explains Reverse Loops on digital layouts.