Hi Gang. This is a question about logic and which way is better / easier, not about the wiring itself.
I have now moved over to modeling N scale on our Club N Scale layout. It is a layout that would fit in a double size garage, so is on the large size. The mainline track plan is a folded Dog Bone type. That is, the mainline is double tracked with a loop on each end, and the tracks don't connect together at the loop ends. This double tracked mainline winds around the layout and passes itself quite a few times. The layout is getting scenery but there are not many folks working on it at the present time (most are working on the Clubs HO layout) and the wiring can be changed as I see fit. The layout is DCC.
The problem is, that when some mainline crossovers were put in, no thought was given to the polarity being opposite on the parallel track. (The layout is actually wired as one big circle.) Thus, when you try to take a locomotive from one main to the other, everything shorts out. There are gaps between the turnouts at the crossovers now so the layout isn't shorted all the time. The mainline runs, and runs fairly well.
Now, there are two ways to fix this. One is to make an isolated section of track at each crossover, that includes one of the turnouts, and wire this section as a reverse loop would be, using an auto reverser. This would have to be done for every mainline crossover on the entire layout. The second way is to isolate the loops on each end of the mainline, and make them each a reversing loop with auto reversers. Then rewire one side of the entire mainline to match the polarity of the other line. That way, there will be no polarity conflicts between the two parallel tracks.
Right now I know of three crossovers between mainlines that would have to be modified. There is also a third loop on a branch line that may be involved, but I am not sure yet. (I am still getting my feet wet on the layout and it's track plan.) If I was wiring it from the very beginning, I would have wired both loops as reversing sections. But to make this change now is going to be a major undertaking, and there does seem to be a way out using the reversing sections at each crossover.
So; what would YOU do, and WHY.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Without a track plan, it is difficult to take a hard and fast position on this, but I would opt for isolating the two loops as separate reversing sections for a lot of reasons. But, the most important reasons would be (1) economics, cheaper to buy two auto-reversers than one for each crossover and (2) simplicity, easier to isolate and identify the two reversing sections at the ends of the layout than to maintain reverse polarities on a number of crossovers. In addition, if you follow the conventional wisdom to create a reversing section longer than the longest train, it would seem far easier to follow this advice on the two loops of the dogbone than it would be to isolate sections of track on either side of the crossover.
As an aside, one thing that surprised me about your post is that no one thought about the reverse polarity issues on the parallel tracks when the crossovers were installed and wired. A track plan should always be drawn with polarities in mind and the rails color coded, but that is water over the bridge at this point.
Rich
Alton Junction
richhotrain As an aside, one thing that surprised me about your post is that no one thought about the reverse polarity issues on the parallel tracks when the crossovers were installed and wired. A track plan should always be drawn with polarities in mind and the rails color coded, but that is water over the bridge at this point. Rich
Yea. This also surprised me too. I found it when I tried to use a crossover. The double track mainline winds around like a pretzel.
Thanks Rich. What you suggest does make sense and would be the best, but it sure is going to take a lot of work to rewire one of those tracks all the way around. I'm actually leaning the other way because it would be less work, but I have to find out how many crossovers there are. I also haven't actually looked under the layout at the actual wiring yet, and that may make a difference too.
Anyone else want to chime in?
I would agree with Rich, make the two end loops the reverse sections, and no insulated gaps at the crossovers along the main (unless they are turnouts that require such things - that wouldn't change from DC to DCC). Two autoreversers, one at each end. Isolate enough of each loop such that the longest train will fit. And take care wiring the feeders for the shank of the bone so there aren;t shorts caused by that. If using sy white and red for the bus wires, it shoudl be white to the rail nearest the aisle, then red for the other rail of that track, then white for the outer rail of the second track, and red for the rail closest to the wall.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
gandydancer19 What you suggest does make sense and would be the best, but it sure is going to take a lot of work to rewire one of those tracks all the way around. I'm actually leaning the other way because it would be less work, but I have to find out how many crossovers there are. I also haven't actually looked under the layout at the actual wiring yet, and that may make a difference too.
What you suggest does make sense and would be the best, but it sure is going to take a lot of work to rewire one of those tracks all the way around. I'm actually leaning the other way because it would be less work, but I have to find out how many crossovers there are. I also haven't actually looked under the layout at the actual wiring yet, and that may make a difference too.
I assume that a you mean that a lot of work would be involved to rewire one of those tracks because of the number of feeder wires involved. One solution might be to cut the bus wires just before each end loop and reverse the connections. Although the colors of the bus wires would thereafter be mixed, it would save all of the work involved in severing and reattaching the feeders.
OK, this morning I drew up a simplified track plan. (below) The small circle on the left under the larger loop is a branch line. I also know that I may have to do some rewiring on it too. (No crossovers, staging tracks, yards, or industry sidings are shown on the plan below. They are a non issue at this time.)
Also, having thought about everything last night, The key factor is: "How is the DCC Bus run?" And that I don't know yet. If there is a bus for each track on the mainline, yes, the easiest would be cut it at the ends, connect it to the bus next to it (the other track) and put in auto reversers on the loops. (I would also have to cut the other bus at the ends as well in order to isolate the loops.)
What I have been thinking is that there is one bus that follows the double track mainline and both tracks are connected to it, but opposite track connections from each other.
But again, the FACT is that I actually DON'T KNOW how it is wired because I haven't looked yet. So, I guess my question was a little premature at this point in time.
Rich and Randy, thanks for your replies and input so far.
Elmer,
I am betting that, based upon that track diagram and the fact that the crossovers are shorting, the outer rails all are wired the same way and the inner rails are all wired the same way. For example, all of the outer rails may have blue feeder wires to a blue bus wire and all of the inner rails may have red feeder wires to a red bus wire.
I doubt that there is more than one set of bus wires for the layout. There would be no reason for it considering the track plan.
I printed a copy of your track plan and treated the track as if it were the outer rail. Using a red pen, I traced the corresponding inner rail. That made it seem clear that your layout was wired that way. Reverse polarity occurs at the center point of the crossover.
Isolating the two loops as separate reversing sections is the answer. Then, sever the bus wires at the ends of the loops and reverse the connections. That would be the simplest solution to your problem.
I agree. Thanks.