Eventually my layout will be a folded dogbone with two levels and the staging loops one over the other. Straight forward until I mention that this is a PRR corridor layout six tracks wide through Philly with three tracks in each direction. At two points on the lower level there are crossovers that go from track one to track six and back again. Since the six tracks are basically three loops I have been advised to make the polarity on all six tracks identical and use polarity reversers on the loops which I understand completely. Here is where I am getting the brain cramp. For now the railroad will only be one level so if I am thinking correctly all tracks being a total of six loops should be wired with identical polarity and there should be no problem with crossing over for now because they will always be in phase. Right???
If you don’t have any reverse loops, then you don’t need reversers. If these are all dogbone loops and you can’t come back on yourself, then you’ve got no reverse loops.
If it’s easy enough to isolate the individual loops, then I would think that a simple circuit breaker for each one would be a good idea, but you don’t need the expense of a reverser. Of course, some, maybe all, reversers act as circuit breakers, too.
Without seeing your track plan and being able to visualize what you’re talking about, it’s difficult to say; but if your crossovers are in a location where trains will be running in opposite directions of each other after going through the end of the dogbone, then you do in effect have reverse loops and must use auto-reversers and insulate the track to prevent shorts.
One way to figure it out for sure is to imagine yourself sitting in the engineer’s seat of a locomotive going around the layout, and assuming that the right-hand rail is positive. If you go around the end loop of the dogbone, is the positive rail the same as it would be if you approach through a crossover? If not, you have a potential short.
If the track plan has nothing more than either cross-overs or diamond-style crossings, you have no reversing section. Once you add even 1 tiny centimeter of track where the loco can run 180 deg from its previous direction after doing a loop or a three point turn (a wye), you have a reversing section. So, you’ll have to trace rails and see if any double back onto themselves. You can probably find a lot more on this, plus diagrams, at Tony’s in the DCC section since he sells autoreversers and would presumably illustrate for the prospective buyer why they are needed in the first place.
That’s what I thought. When I go to the two levels the three westbound tracks will become the three eastbound on each level necessitating the reversers but not now which is good news. I will still make the staging a block to facilitate the change if and when it happens. Thank you.
All the crossovers between #3 and #4 tracks will short out.
If you make three loops of track and squeeze them together in the middle where it looks like 6 tracks, any crossovers between the two inside tracks will form a reversing segment and cause a short when a train goes over them.
The solution is to make BOTH ends of the six track segment reversing sections or NOT to put crossovers between tracks 3 and 4 (the two inside tracks). You can have all the crossovers you want between tracks 1-2-3 and between 4-5-6, but the 3-4 will short out.
If you choose to make the ends reversing sections then wire all the tracks in the middle so all the rails closest to the aisle are + and all the rails closest to the wall are -.
If you choose not to put crossovers between 3 and 4 , then wire the outside rail of every loop to the + and the inside rail of every loop to the -.
Dave H.
You should not wire things so that a train can pass directly from one reverser-controlled section to another. If you do that, both reversers will flip at the same time, leaving the polarity mismatched, but with the opposite sense. The reversers may keep “fighting” each other until you remove the train crossing the gap.
Maybe my description isn’t too good. The layout will be six tracks wide as is/was the PRR and will be around the walls. So each side of the room will have six tracks for a total of 12 if they were side by side. The crossings will be traditional track to track crossovers not crossing from 1 to 6 or back again in one move. That is why all tracks have to have the power connected identically. Since this is a 30’ x 35’ area building one level will take some time let alone two so initially I am just going to make the staging area connect the whole first level in a big loop. Later a helix will replace this connection as well as two reversing staging loops (one on each level) to create the dogbone. When that happens the following will occur. The three westbound tracks will enter a staging yard that will be built as a 180 degree curve so track 3 & 4 will be the same track as will 2 & 5 and 1 & 6. At that time since all the visible railroad will be wired to allow the crossover of trains the staging area will require reversing modules for each pair of tracks. The only time I will need the reversers is when the staging gets connected so the trains turn around and come back on the appropriate track going the other way on the same level. initially it will just be a roundyround.