KB599: Can AR1 be used to set up automatic back and forth operation?

This article was last updated on Aug. 7, 2011, 3:26 p.m. | Print Article | Leave Feedback

Q: I am building a new DCC layout that will include a logging spur that is simply a single long piece of track with no loop.

I want to have a train go back and forth on this track which automatically reverses when it gets to each end.

While the AR1 was designed for reversing loops, can it be wired to simply reverse a train on a straight piece of track?


A:  Not in the way that you intend.

One of the interesting problems with DCC is that we often still think in terms of DC, where the track polarity is switched to reverse locomotive direction. The AR1 is a device that detects a short circuit at a reversing section and corrects the track polarity to allow for automatic reverse section operation.

When you want to change the direction of a specific locomotive, you must send a command to the decoder inside the locomotive.  This is not handled by any Digitrax automatic reversing device like the AR1 or PM42.  

For your application, you would need to set up detection at both ends of the track and set up a computer program to automatically send the change of direction command to the decodert when it is detected.  This could be done with BD4, DS64 and a computer program such as Railroad & Co.

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