# DCC reverse loop wiring help needed!



## RonK9977 (Oct 4, 2019)

Hello!
I have an auto reverse board and I not sure where to put it and the GAPS in the track to make my situation work so any help would be great...In my diagram (sry it is poor) you see that you come from the main line to the GREEN loop and go around it...Then to go back to the main line you have to go through track section "A" which turns the train around so you can go back the way you came by opening the switch to go back down the MAIN line entrance way you came...

From what I have seen so far in researching what you would do is isolate/gap the "A" section and put the reverser there BUT this section IS SHORT (1.5 feet maybe) so this section will be shorter than any train that will come through. And that's the problem. 

Can anybody tell me how to wire this to work?
THANKS!
Ron


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## mesenteria (Oct 29, 2015)

This short length won't be a problem as long as any electrical pickup axles are within the A section of track....AND...you stagger the two gaps a bit so that no two metal tires cross them both at the same time. As long as the gaps, across from each other at each end of the reversible section, are staggered about 1/8", and the locomotive (and tender if it's a steamer) are between the two sets of gaps, you'll be okay.

And yes, you make the reverser switch the polarity or phase only to the gapped length, the diagonal. You get input from a DCC system if you're running DCC, but the outputs connect only to the two rails comprising A. In DC, mate the polarity feed the same was as the outer loop at the inputs of the reverser, and wire the outputs to the two rails that are gapped, the diagonal.


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## OilValleyRy (Oct 3, 2021)

I would gap where the bottom turnout meets the left side of that loop, where the top turnout meets the right side of the loop, and where A track meets the bottom turnout. That would accommodate multiple locomotives, lighted caboose, lighted passenger cars, etc which you may currently have or may someday decide you’d like to add.


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## gregc (Apr 25, 2015)

won't there be a problem with longer trains with cars having metal wheels that don't fit within the connecting the oval?

wouldn't it be better to include part of the oval, possibly the around the bottom right corner? so yes, there would be 3 sets of gaps: the 1st indicated in the diagram top left of section A, a 2nd just to the left of the bottom turnout leading to section A on the oval and a 3rd on the right side of the oval, an appropriate distance from the 1st gap.


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## RonK9977 (Oct 4, 2019)

mesenteria said:


> This short length won't be a problem as long as any electrical pickup axles are within the A section of track....AND...you stagger the two gaps a bit so that no two metal tires cross them both at the same time. As long as the gaps, across from each other at each end of the reversible section, are staggered about 1/8", and the locomotive (and tender if it's a steamer) are between the two sets of gaps, you'll be okay.
> 
> And yes, you make the reverser switch the polarity or phase only to the gapped length, the diagonal. You get input from a DCC system if you're running DCC, but the outputs connect only to the two rails comprising A. In DC, mate the polarity feed the same was as the outer loop at the inputs of the reverser, and wire the outputs to the two rails that are gapped, the diagonal.


Wow staggering the rail lengths on the gaps! I will try this and get back and tell everybody what happened!
THANKS for all replies!
Ron


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## gregc (Apr 25, 2015)

mesenteria said:


> you stagger the two gaps a bit so that no two metal tires cross them both at the same time.


why?


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## Lemonhawk (Sep 24, 2013)

Like Gregc, I wonder why you need to stagger the gaps? If you fill the gaps with plastic, its unlikely that metal wheels would trigger the reverser independent of gap stagger. Only a locomotive with several wheel pickup would trigger the reverser again independent of the gap stagger?


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## DonR (Oct 18, 2012)

I also wonder at the reason for staggering gaps (insulated joiners) in
a reverse loop situation. The reason for the gap is that if the 2 rails
touched there would be a short. (Both Left and Right rails would do this) When EITHER metal wheel spans
the 'gap' there is the 'trigger' short for the Reverse loop controller to match phase (polarity). After the
'match' the 2nd wheel spanning a 'gap' in the 'other' rail would not short thus the
train continues to run.

Don


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## RonK9977 (Oct 4, 2019)

Well I finally got it all wired up and it works great!
Now I can turn the train around to go back down the long incline on the back of the layout the same way it comes up to my elevated section of track.
I did it like Mesenteria said 1st post and it all works just fine
Here is a pic of where the "A" section is and the red tape is where the gaps are staggered 1/8" from side to side on each gap! I used a PSXR auto reverse board for the reverser.

































Short Video of it working! turn up sound on bottom right corner......

Cheers and thanks for all advice!
Ron


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