Hi all. I'm planning out the wiring for my staging yard, and ran into a question I can't quite figure out.
My staging yard has a reverse loop on one end for which I plan on using a Tam Valley Dual Frog Juicer to control the polarity reversing, as I have those on hand from the previous version of the layout. The issue is that in order to accomodate my longest mainline trains, I want a reversing section at least 8 ft long, and I don't have the room to push the crossover that creates the reversing loop out of the loop. I can get close which creates a reversing loop about 6 ft long, but that limits my train lengths to less than what the rest of the layout was designed around.
Can I include the crossover turnouts within the reversing loop? I'd have to wire them to the output of the dual frog juicer powering the reversing section instead of the bus, but I don't know how that might affect the abiity of the juicer to catch the wrong-polarity situation. I'm not sure why it wouldn't work, but I've never tested it. If this is a workable solution, I then have a reversing section about 9 foot in length, which would be ideal.
This is on a DCC N scale layout with Digitrax DCS210, and staging yard on a separate power district from the main level but not currently boosted. I've run reversing loops before, just never with a need to have anything within them until now.
Thanks,
Jason
-Jason
Feel free to include whatever track arrangement you need in order to accommodate your longest imagined train. As long as that length, turnouts and all, is fully gapped AND can only be fed power by the reverser's outputs, you should be good.
The idea is that any one gap, anywhere on the layout, can be reversed if needs be. That's what the reverser must monitor and switch when there's a conflict under any one metal tire. Conventionally, we in the hobby prefer that the reverser only manages a small, but necessary, gapped length while the rest of the layout gets 'normal' DCC power from the bus.
Two things to remember:
The decoder doesn't care what's happening under it as long as any change takes place fully, in a very few milliseconds.
Technically, you don't have to include the entire train length in the reversed section. From my understanding, you only need to avoid having two metal tires crossing two gaps concurrently where there is a conflict at both of them. Then you will confound the reverser. Digital Specialties, in their instructions for the PSX-AR, says when your trains are perforce going to be longer than your gapped and reversed section, you should make two (2) pairs of gaps at each end of the reversed section, and not just the single pair of gaps. You space each pair just a couple of hairs wider in separation than the longest truck, say a three axled heavyweight passenger car. This creates about 1.75" of dead rails at each end, unfortunately, but that should not bother most locomotives at all. Meanwhile, outside the reversed length, you have metal tires that are drivers and truck wheels that either don't need reversing or they don't care.
jkovacs5I want a reversing section at least 8 ft long, and I don't have the room to push the crossover that creates the reversing loop out of the loop. I can get close which creates a reversing loop about 6 ft long, but that limits my train lengths to less than what the rest of the layout was designed around.
there's must be more to this because a train obviously can't go back through a turnout if the back end hasn't cleared the turnout
greg - Philadelphia & Reading / Reading
Hi all. Sorry for the delay; my old MRR subscription was under a compromised email account so I switched it up to my normal email, but I'm going through the first-posts moderated delay again.
Mike and Greg are correct, and I didn't fully describe the track organization. The reversing loop isn't a balloon off of a single turnout, but rather at the end of double-track mainline. The turnout I reference is the crossover. If I didn't have the crossover, I'd not have a reversing section, just an oval. (Well, not at all an oval in plan, but electrically it'd be a simple oval.)
Technically, that crossover isn't from mainline to mainline, but mainline to a stud ended siding which enables the reversing action. The issue is compounded in that the two mainlines do not enter the staging yard parallel, like they are on the main deck of the layout. So one of my mainlines will be wired in with the same polarity with all the yard tracks (say, A rail away, B rail close), while the other mainline is arriving mid-yard reversed (B rail away, A rail close). If I didn't have the crossover, no problem, the off-polarity main would just continue around the turnback curve to the ladder and it'd be happily aligned with the other mainline, but I'd loose my method of reversing my engines. But that crossover would have to be within the reversing section; if not, I'd create a dead short.
However, I figured out an alternative that I'm happy with. The reversing route is purely to reverse the directions of locos, but for the rest of the consist that isn't an issue. So instead of putting the reversing section on the mainline, I've confined it to that spur track connecting the off-polarity sections. It's more than long enough to handle my longest motive lashups (I have a couple A/B sets of F3s that I someday want to run as an ABBA set, although I haven't done so yet. Not that an ABBA set need to be turned around, but it's by far the longest lashup I'll ever need), but too short for all but the shortest consists. Managerial dictates will confine that track to motive power only. This also keeps the wires from Frog Juicer reverser to rails at just one pair of feeders, which is about as ideal as can be.
Guess I just needed to write out the problem to see a solution I hadn't considered before. Thanks for your help! And good to know from the first reply that trackwork within the reversing section is not a problem as long as it's all capable of being powered through the reverser. I won't need it now on this build, but good to file away for the next.
One thing to be aware of is the current capacity of the auto reverse circuit. While you can do a lot of things within a reverse loop or crossover track, you may find the auto reverse circuit is somewhat limited.
My crossover reversing track has a 5-stall roundhouse on one end and a six-track yard on the other. I have kill switches so the roundhouse stall tracks are not normally live, and usually use only one switcher in the yard, so I keep my current demands low.
It takes an iron man to play with a toy iron horse.
Thanks Mike. Mine is also shelf around the room with wireless throttles, but Digitrax in my case. Agree 100% that not everything needs automation; I don't even have Tortoises installed yet (Peco, so wire sprung turnouts) so at present everything I do is manual. But my room is not large, and manually managing it isn't really an issue.
My reversing section is definitely short. I think it's now all of 24", as planned (ran out of rail joiners, so it hasn't been roughed in yet. Hopefully will have a chance to lay in the connecting trackage and test the reversing section by the end of the week). As I said, long enough for my longest conceivable engine lashups, but that's about it.
Hi Mr. Beasley,
Current draw within the loop was something I was a little worried about, but I don't think I'll have an issues. The staging yard deck is on a second power district and being a lone wolf operator, it normally wouldn't have anything running on the whole deck except for the engine/consist traversing the reversing section. My other motive power will be hostled on stub-ended engine tracks after dropping their strings in the main yard, and I can turn off those off with simple SPST switchs (which will also take care of all the extraneous noise of the auto-engine starts at layout power-up).
EDIT: Hey, it looks like I'm finally out of posting detention!