I’m in in the process of building out Dave Frary’s Pennsylvania RR plan featured in the Jan-Sept 1993 publication of Model Railroader, built out the plan in AnyRail and now ensuring I have all the wiring figured out since the original plan was DC based and my intent is to go 100% DCC. I also plan to be the only one operating the layout and will have at most 3 trains operating concurrently, probably more like no more than 2. As I’ve been reading up on wiring I’ve come across a number of folks talking about reverse loops and the implications to segmenting the plan into insulated sections. I have attached a copy of the plan which shows (in red) what I believe are the embedded “reverse loops” (wherever the train would effective get turned around) and in blue, where I understand I can contain the insulated section which will need an auto-reversing mechanism. My questions to this very experienced group are as follows:
Am I correct in my understanding and if so is the section in blue the one place that I have to address the polarity issue raised by the reverse loops?
Outside of having isolation to help detect shorts and controlling the polarity issue created by the “reverse loops”, do I need to do any other power isolation?
Any recommendations on a DCC controller and any additional boosters (not sure I even need one with a layout this size)
I’m also interested in using an IPAD to run the layout and wondering what the latest and best thinking is on that topic
I appreciate any advice that anyone has, thank you.
when using metals wheels, reerse loops need to be longer than the longest train otherwise shorts can occur simultaneously at both ends when the wheels span the gaps
both rails need gaps at either end
at the top right there are 2 reversing loops, one train could be entering the outer loop counter clockwise while another train is entering the inner loop clockwise. gaps in 4 tracks to the right of the turnouts
similar in the lower left, again 2 reverse loops, gaps in both tracks below the cross-over at the far left as well as to the right of the turnout at the top left
As greg indicated, you have four reverse loops in that track plan.
To avoid a dead short, each reverse loop needs to be completely isolated from the other reverse loops and from the adjacent non-reversing sections of track.
I have something similar on my layout, and I use four PSX-AR units to control the four reversing sections on my layout. The newer version is the PSXX-AR. These are auto-reversers that also act as circuit breakers to protect the rest of your layout in the event of a short inside one of the reversing loops.
My DCC-powered layout is controlled by an NCE PH-Pro 5 amp wireless system. There are other fine DCC systems as well. There are smaller systems with less power such as a 2 amp system, but I would recommend a 5 amp system plus four auto-reverser units such the PSXX-AR. That would provide all of the power and the protection that you will need. A second booster would not be needed.
The section in blue in your track plan is actually a non-reversing section, as explained subsequently. The four loops are reverse loops although it is interesting to note that these loops do not fold back onto themselves. Rather, each loop folds back onto the loop aside it. The result in each case is a meeting of rails of opposite polarity.
I will leave any discussion of iPad use to run the layout to others.
I refer to the three sections of track circled in Green as “non-reversing sections”. For illustration purposes, I have noted the wiring protocol as positive (+) and negative (-), dividing the track into top and bottom rail for polarity purposes. My suggestion would be to wire these three non-reversing sections the same way with matching polarities.
In the following illustration, the yellow circles indicate where mismatched polarities meet in the two loops on the right side of your track diagram. These two reverse loops must be completely isolated by insulated gaps and separate wiring from the non-reversing sections.
Each of your four reverse loops should be controlled by its own auto-reverser. Power to the input side of each auto-reverser should come from the wiring that powers the non-reversing sections. Any and all feeders inside each reversing loop should be connected to the output side of its respective auto-reverser. Each reverse loop should be completely gapped and isolated from the other reverse loops and from the non-reversing sections. Be careful not to connect feeders from the non-reversion sections to any of the auto-reversers.
Incidentally, the reason that you cannot address the polarity issue raised by the reverse loops in that track section that you colored in blue is because the four reverse loops fold back onto sections of track with opposite polarity no matter how your wire the blue track section.
This is my first layout since I was a child and given my age, I’ve decided to thoroughly research this layout rather than experiment with building a few less permanent ones first.
With that said, I sent back to the Model Railroad article I referenced and I think I’m seeing a disparity between it and what you two are saying. It seems to reference 3 possible “reverse loops” (or as they say it “places the train turns around”) and a difference in wiring. I may well be confused (I probably am) or possibly there is something about the era of that article that makes a difference. I’ve copied 3 pictures from its pages that reference this topic. If I could ask if one or both of you could straighten me out, that would be great. As I’m sure you know better than I, I want wire this right.
I have a layout with a complex track plan that has a number of reverse loops, two of which “do not loop back on themselves.” The gentlemen posting above are giving you excellent advice on how to block and wire the four reverse loops in your track plan.
There is a question about iPad control of the layout. My layout is S scale and I do not use DCC, I use AC with Legacy for track power and engine control. My layout has no physical controls, it is 100% controlled and operated from touch sensitive track plans on an iPad. I am also 100% satisfied with the layout operation using the iPad. I actually have three iPads so I have two for visitors to use as well as myself.
The iPad system is the Lionel LCS, Layout Control System. It works with any train control system, there are several S scale operators who use LCS with DCC. It is not my intent to push this system, just bring it to your attention.
Below are screen shots of four of the seven iPad screens that control my layout. Just touch the turnout to throw it, touch the bulb icon to turn block power on or off, touch the Fire icon to align preset layout routes. It also controls all the layout lighting and accessories. Should you have any interest in the details they are at www.control.lionel.com.
John, you are completely right. It is a DC layout with block wiring, 10 blocks in all, and cab control. Completely different animal than a DCC-wired layout. There are actually four reverse loops in that DC layout. What Andy Sperandeo was referring to when he wrote that article were three distinct “turning” points, two of which were in the middle of the crossovers, an added source of complexity in that particular layout.
Thanks again for imparting your advice. Very impressive you all put so much thought into your replies. I guess you all agree I have 4 reverse loops as Rich has laid out visually. I got confused when the article talked about the section in blue (or close to that) as the only area being what needed to be isolated. I’m going to ignore all of it and listen to what you have all advised.
Rich, to make sure I understand your suggestions … because there are the four reverse loops and the crossovers are not part of the problem in reversing polarity, I should place insulators right at the 4 yellow locations you indicated (before the switches on the reverse loop side I assume to avoid a problem). then run power to each of them separately. I’ll do research on wiring the auto-reverse switches, I assume they are placed in the isolated sections.
A couple of clarifying questions if I may …
The rest of the layout can be wired to the same power district unless I want further short management, correct? And all sections can share the same bus correct just different sub-busses to the isolated sections.
Just to be clear that’s all I have to do to address any polarity issues in the plan?
Wiring the auto-reversers is fairly straight forward. An auto-reverser receives power on the input side from two wires leading from somewhere on a non-reversing section. The output side of an auto-reverser sends power through two wires to track inside the reverse loop. If you decide to use more than one pair of feeders inside the reverse loop, simply gang them together or use terminal blocks.
I use 14-gauge solid wire for my buses and 22-gauge wire (stranded or solid) for the feeders. In your situation, you could use a single main bus for the three non-reversing sections and run sub-buses to each of the auto-reversers to power the four reverse loops. Each auto-reverser (e.g., PSXX-AR) is designed as a circuit breaker to protect a “power district” which in your case will be the reverse loop.
The non-reversing sections of track will be protected by the booster or, alternatively, you could add a circuit breaker, such as a PSXX unit, to create a 5th power district. If you want to really divide your entire layout further into power districts, you could make each yard its own power district by adding even more circuit breakers, but that is likely unnecessary given the size of your overall layout.
Guys, thanks a lot, big help in wrapping my head around this topic.
I’m going to wire it as suggested and isolate then add auto-reversers right at the locations Rich advised.
One follow-up question this comment from Greg if I may … “again, consider the needs when one train enters one of the loops CW and a 2nd train enters the other loop CCW”.
Greg, could you explain that just a bit more in terms of any additional steps I should be taking. Again, my intent is to run 2 maybe 3 trains at most at the same time.
to hopefully make it clear, if you were unsure why they are 2 separate reverse loops that require 2 separate auto-reversers… That each loop my have opposite polarity from the other
even when 2 trains were to enter from the same direction, cw/ccw, one may be leaving while the other is entering and the loop polorities will be opposite one another
it’s odd that such a small track plan has 4 reversing loops requireing 4 AR ($$$)
some simplificaiton an reduce it to 1 reverse loop and less $$$. i think the following would work with one reverse loop being the upper straight section including the turnouts at either end
Cost can be an issue for budget conscious modelers because an auto-reverser can be expensive. A set of four auto-reversers will add up quickly.
But the beauty of a DCC auto-reverser with circuit breaker capability is that is automatic, no manual intervention required.
If cost is an issue, there is a much less expensive alternative and that is a manual approach without circuit breaker protection.
You can install DPDT switches that are thrown manually to prevent shorts. With bi-colored LEDs wired in-line to visually identify polarities, your fingers replace the automatic response of an auto-reverser. The disadvantage, of course, is that it requires manual intervention.
I am in the process of constructing a fairly large two-level HO layout. The layout will have 8 reverse loops when completed including a turn table.
Track power is provided by a NCE 10-amp DCC radio system. I have a separate power buss for powering turnout motors using a Tam Valley 3-amp DCC booster.
I have three different auto reversers which all work seamlessly. I started with two older DCC Specialties PSX-AR’s and a DCC Specialties Frog-AR. To reduce costs, I am now installing Tam Valley Dual Frog Juicers on the remaining reverse loops.
