Need advise for wiring reverse loop staging area....

[irishRR]

Hello all. I am building a reverse loop staging area that will sit underneath my layout. I have wired a single track reversing section with no problems, but I am wondering about a few things. First, a picture:

20190727_235150 by John Collins, on Flickr

So, as you can see, I plan on making a gap after the first turnout, making the entire loop the reversing section. If wired correctly, is a single automatic reversing module capable of controlling the polarity for all of the staging tracks within the loop? I have used the Digitrax AR1 auto reverser for my other reversing section with no problems, but it is a single stretch of track, not multiple tracks with turnouts.... Also, if I have trains sitting on the staging area tracks, will this risk doing any kind of damage to the individual decoders in the locomotives? Am I able to wire this thing like I would a normal reversing section is ultimately what I am asking. I would love to hear from anyone who may have done this on their own layout. Thank you for your time. Cheers!

-John Collins

[richhotrain]

John, that setup is really no different than a single track reverse loop. It just requires the same precautions for a single track reverse loop.

One, you need to be sure that one train is not entering the reverse loop as another train is exiting the reverse loop. Two, the area inside the gaps should be longer than the longest train that might occupy the reverse loop.

Multiple tracks within a reverse loop are perfectly acceptable.

Locomotives sitting idle or moving inside the reverse loop are also perfectly acceptable without any risk of damage to their decoders.

Lastly, a single auto-reverser is used in this type of setup.

Rich

[irishRR]

Thank you so much. I had my suspicion that it would work, but I just didn't want to learn any expensive lessons "the hard way"....

[peahrens]

richhotrain

Locomotives sitting idle or moving inside the reverse loop are also perfectly acceptable without any risk of damage to their decoders.

It helped me earlier to understand how this works.  Let's say a Loco "A" is moving forward within the section while another Loco "B" comes into the section.  If the entering Loco B crosses the gap when the track polarities are opposite of what is needed, the first wheel hitting the gap creates a momentary short.  The auto reverser senses that and flips the polarity of the loop immediately such that the entering Loco B very quickly sees matched polarities at that gap and can continue.  

Loco A that was already in the loop keeps going forward even though the loop's DCC polarity has flipped.  That happens because the decoder has earlier been told to provide the motor wires forward (DC polarity) voltage (at speed "x").  When the reverse track DCC polarity is flipped by the auto reverser, Loco A's decoder simply does what is needed to still provide the same DC voltage (speed control) at the same (not reversed) DC polarity to the motor wires.  So loco "A" just keeps going along as it had been doing.

You will find some similar examples in the following that covers a multitude of reversing section types:

http://wiringfordcc.com/track_2.htm#c4

 

[richhotrain]

Paul, let me just add a bit of clarification to the commentary that you offered in your example. For the benefit of those readers unfamiliar with the operation of a DCC-powered reverse loop, in your example both Loco A and Loco B will continue to operate without interruption when Loco B enters a reverse loop that is occupied by Loco A even if Loco B enters the reverse loop when the polarities are reversed at the point of entry. I believe that was the point of your reply, and I agree with you.

Rich 

[rrinker]

 Somewhere there's another thread on this exact thing - because this is exactly what my layout looks like. Large dogbone, with loops at each end containint concentric tracks that will be my staging.

 Simple way, single AR, whoke loop is a reversing section. There are no issues with sitting locos having the power changed under them as the AR does its job for a loco entering or leaving the loop. Wiring for the 'shank' of the bone is simplified - you can have as many crossovers between the two tracks as you want without worrying about more reversing sections. You just need to make sure the feeders are in the correct order.

 The only negative in this is that you can't have a train enter staging from the main at the same time a train leaves staging on the other main. So another thought I had was to gap the loop right in the middle, since each of the loop tracks is logn enough to hold 2 full trains of the length I expect to be able to run on my layout. Then one can exit while another elaves since only one of those would actually be crossing the reverse section gap and trigger the AR. The downside is, it would absolutely require that trains be parked in staging in a particular way, none across the midway gaps, and never have a train longer than half the length of each track (I run all metal wheels, so illumination or not doesn't matter, though one of these days I plan to put decoders in all my cabeese for a flickering oil lamp interior lighting plus lighted markers). One possible workaround is that the PSX-AR reversers have a setting that allows two of them to be used back to back. If it's reliable enough, that may be an option. Or else I just have to set up operation so that nevr will be one train exiting the visible part of the layout at the exact same time another needs to enter the visible part.

 Third option I don;t think got mentioned previously, just thought of it now. Instead of cutting the staging tracks in half lengthwise - use two reversers, one powers from teh eastboung switch and 2 of the 4 tracks, the other powers from the westbound switch and the other two tracks. Now a train can leave from track 1 or 2 at the same time another train arrives on track 3 or 4. The only issue is keeping track of which staging track to occupy, and when.

                                    --Randy