I am rebuilding my layout and want to incorporate a reversing loop. Normally, this would not be a problem, but I would like to turna 10 car passenger train. Because of the length it would extend over the line that connects both sides of the oval. I realize that I would have to isolate part of my mainline to include the length of the train. I understand the concept in going in one direction, but not sure what I would need to do in going the other direction.
[#welcome] to the forum. Your posts are delayed in moderation for a bit.
This is a case where a visible track plan would be helpful. Posting pictures in this forum is unique and you have to follow the directions here
It sounds like you’re talking about a simple oval with a single revering track bisecting it. What you’ll have to do is divide th elayout into at least three blocks, the reversing section and two blocks on the oval, each “half” where it is divided by the reversing track. That way you can swap the polarity if each half of the oval to match the polarity at the two ends of the reversing track.
Hello All,
DC or DCC?
This makes a huge difference in how you can switch polarity.
In DC you will need a manual solution while in DCC you can use a manual solution or automate the process.
A track diagram always helps.
In a polarity reversing section only the electronic components need to be isolated in the section.
Unless the cars or caboose have electrical components; lights, axles with resistors for detection circuits, then only the motive power has to be in the section when the polarity shift occurs.
For example: If only the locomotive(s) is/are the only “electrical component” in the train, no matter how many cars being pulled- -even with metal wheels- -the entire length of the train doesn’t need to be isolated in the polarity reversing section.
If however, you have a caboose or passenger car(s) with lights or rolling stock with resistors installed on the wheels for block detection, then those components need to be factored into the length of the polarity reversing section.
Keep the questions coming and…
Hope this helps.
What you describe is not a reversing loop but a reversing section. A line crossing from one side of a loop to the other looks like it creates a reversing loop but it really doesn’t. It looks like it creates two “loops” back to back but it really doesn’t.
Also, if you build only one such crossing track you can turn a train once but then you can’t reverse it back again unless you actually reverse the train back across the connector. You would be better with two crossing tracks. Single crossing tracks will be annoying quite quickly. If you need to you can use a diamond or 90 degree crossing track piece to allow one reversing track to actually physically cross the other in order to squeeze two crossing tracks inside one oval. You still have to deal with the problem of train length as you obviously can’t physically cross part of a train though another part.
Metal wheels will spark and pit rails and wheels if you have a train longer than the reversing section. This is because you can only match polarity at one end of the reversing section at a time. You should make sure the entire isolated part of your reversing section is longer than your longest train. The reversing section can include one of the turnouts forming part of the crossing track.
You can make the reversing section as long as you like until you reach the second turn
The Atlas Wiring book shows a few cases where only two blocks are required. Why do you see three as the minimum?
You can do it with two blocks even if you have two crossing tracks.
Three allows more options for control but technically two blocks are enough. You change polarity in the “other” block while the train is in the so called “reversing section”. Actually, both blocks are “reversing sections” in a two block system.
Atlas uses one Twin switch to control polarity. Two DPDT integrated into one switch.
wouldn’t reversing the mainline polarity reverse it in both blocks?
Here we go again, if everyone would just ignore Laststpikemike maybe he will go away. He just enjoys mudding up every topic he can.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
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Aging is not for wimps.
Two blocks, two DPDT. The powerpack reversing switch is no longer used. Like the Atlas 220 situation discussed on another thread. Atlas Twin switch doesn’t depend on common rail, or at least I don’t think it does.
Folks, we don’t even know if the OP is operating in DC or DCC, and we cannot be sure at this point what his layout even looks like.
Rich
We need to know if this will be DC or DCC before we go much further.
I’ve built these crossovers on ovals, and if I had it to do again, I would extend the insulated sections outward, beyond the turnouts for the reversing section so that parts of the oval would actually be parts of the reversing section. This lengthens the reversing section.
I have run trains with illuminated cabeese and passenger cars. I run miy reversing crossover with DCC. It’s a fast, solid state one, and tolerates the rapid changeovers at the end of the train well.
Physically the reversing section is constructed the same way for DC or DCC. The only difference is how you reverse the “polarity”.
Quoting the Atlas Wiring book is not and cannot be muddling things up.
You are free to advocate ignoring my posts but you should refrain from inaccuracy when doing so.
With all due respect.
While we are awaiting the PO to pony up a few more details and get through moderation, I had thought that metal wheels would trigger a short across the gap.
JJD has a different opinion.
If he is correct, why isn’t there a short in that situation.
I do not think you can include both turnouts in one block unless you create three blocks.
So, given that difference, we need to know whether he is operating in DC or DCC.
Good question. I have four reversing sections on my layout. All of my rolling stock has metal wheels.
None are resistored and none of the rolling stock is lighted. Yet, metal wheels on each and every piece of rolling stock are detected by the controlling PSX-AR.
Rich
That was my initial thought because he specifically stated his train would be longer than the reversing section. After thinking about it more, he could extend one end of the reversing section out onto the loop, although that could cause issues if he ever wanted to operate a shorter train within the reversing section while also operating one seperately on the loop.
Well no because the wiring is also the same. You can manually reverse “polarity” in DCC in the same way as for DC. The difference is only which switch on the Atlas Twin switch you throw. For DC it must be the one that controls polarity in the section the train is not in (unless you stop the train and really why would you?) whereas for DCC it doesn’t matter.
The OP only asked about train length and whether and how far to extend the reversing section beyond a turnout. The real issue is the OP doesn’t seem to yet realize he actually wants two reversing connecting tracks, not just one.
Good point. The third section could be controlled by a selector type block control switch assigning the “extension” piece to either the reversing section or the main loop as required.
It would help to know the dimensions we’re dealing with.