Question on Wiring Theory

[KB02]

As I am rebuilding my layout, I am still building to the basic philosophy of continuous running; basically a big loop. I am building everything with the premise of a double main line like I had before. Previously, I had the double main line wired with the rails closest to each other on the same polarity - squishing the "loop" like a dog bone. This makes cross overs a pain in the butt to wire up with isolators and reversers and reversing sections every place I wanted to swap sides.

Polarity wise speaking, and in model railroad terms, it wasn't really a double main, but two independent lines that happened to be next to each other.

In the attached image, if I used reversers in the sections in green, I could make all of my double main line section matching polarity (right rail positive, left negative) thus simplifying the wiring of any cross over I wished to use, correct?

Pretty sure I'm right on this, but it would be great to get some confirmation before I change my wiring plan. Not really sure why I never thought of this before.

This isn't my actual track plan, just something I drew up quick to illistrate the theory.

 

[KB02]

Yes, could be the whole loop. My thinking is that I would like to add in a double cross-over and/or a few other cross overs through out the modules that I am building and with tracks dedicated to opposite directions the process would be complicated. Just running reversers would simply that, wouldn't it?

Are there any track planning software programs out there that can configure polarity issues?

 

[timlange3]

KB02, the loops at each end would be your reversing sections. I would isolate the loops from turnout to turnout for both loops. You will need two reversing controllers for DCC, one for each loop.

 

[KB02]

The reverse section could be at any point within the loop as long as the section is long enough to hold any consisted locos, though, right?

I think I've pretty much answered my question on this one. By running auto reversers on/within the loops, I am essentially turning a Dog Bone layout into a Double Loop layout.

I ran a quick experiment on my layout and used one of my modules with a simple double main (no turnouts). I isolated one of the tracks and installed an auto reverser. The next module was not yet wired up yet, so I hotwired it to the section of track that was still wired normally, except I wired the double mains as side by side, not opposite. (Neg, Pos, Neg, Pos from top to bottom as you look at it instead of Neg, Pos, Pos, Neg). I ran a train across the sections and the reverser kicked in like it was supposed to and the loco ran straight through. Then I added a simple turn out to the end of the double mains (sort of like a wye), and the loco had no problems switching tracks.
The only problem I can foresee would be if I ran Distributed Power and the length between locos is less than 4 feet (the length of the section powered by the reverse circuit). Then again, if I'm running DP, why would I have a train that short?

Thanks for letting me sound this one out. Sometimes I just need to say (type) something out loud before it makes sense in my head, you know?

 

[jward]

Looking at the setup as drawn, the reversing loop on the right could be handled entirely by the contacts on a switch motor like the Tortoise, or an Atlas Snap Relay wired in parallel with a twin coil motor.

 

[dennis461]

The reverse section could be at any point within the loop as long as the section is long enough to hold any consisted locos, though, right?

Long enough to hold lead loco and lighted caboose!

 

[timlange3]

Jward, that is true, but you will have to stop the train once it is fully in the reversing section before you actually flip polarity. Stopping means no power at all in the section. If you are using DCC then a DCC auto reverser will do the job without having to stop the train. With DCC you could put block detection on the main and diverging routes and automate the turnout throw too.

 

[jward]

Jward, that is true, but you will have to stop the train once it is fully in the reversing section before you actually flip polarity. Stopping means no power at all in the section. If you are using DCC then a DCC auto reverser will do the job without having to stop the train. With DCC you could put block detection on the main and diverging routes and automate the turnout throw too.

The setup I have pictured works with DC or DCC. On DCC it eliminates the need for an autoreverser. If you want to run on DC without having to stop in the reversing loop, you could replace the Snap Relay with a 3 amp bridge rectifier. The AC terminals would connect to the main track, and the DC to the loop itself. You would have to be careful using this method, as it effectively makes the loop a one way track. If it were wired for clockwise operation you wouldn't be able to run anti clockwise around the loop.
\