Reverse Loop ????????


Sharecropper

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Can someone please explain a reverse loop wiring situation? I have a reversing loop in my track but I'm not exactly sure how to wire it, or isulate the track section. Do I need any type of special switch for this?
 
The reversing (insulated both ends, both rails) section should at least be long as the locomotive(s)and tender (if steam). If you use lighted passenger cars, then this section should be at least the length of the train. Otherwise, the passenger cars will keep trying to cause a reversal or short as each contact wheel crosses the gap while other cars are in and out of the exit side.
 
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There is also the setup with a bridge rectifier in line with the power to the loop. You simply reverse the train with the throttle while it is in motion and it keeps moving without stopping. I have a diagram somewhere if I can only dig it up. Someone may have one handy?
 
Sorry...... I forgot to mention this is a DC system. I have considered switching to DCC. Would I have the same issue if it were a DCC setup?

Reggie
 
Reggie, I use DCC and with it I use an electronic reverser for all my reversing loops. Mine is a simple reverser only and sells for $32 while some with combinations breaker/reversers/stationary decoders can cost around $50 and more. Some larger layouts have boosters that have built-in reversers.

An automatic electronic reverser senses a short at the track gap when the loco's wheel is on the gap and the polarities are opposite in the reversing section. It very quickly (milli secs) flips the polarity to match the lead-in track. Then as the train moves out of this section, the same happens at the exit.
 
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Reggie, consider switching to DCC now. The reverse loop is a good example. With DC, you need to not only see that you get the wiring right but you have to worry about locomotive and train length, as Rex indicated. Even if that all works, you have to remember to throw that toggle switch before the train come out of the loop or it's short city. Then you have to throw the toggle back again once the train is clear of the loop. Instead, you can just spend $32, hook up two wires, and never have to worry about the reverse loop again. Unless you like to do lots of wiring, chasing down shorts and spend most of your time throwing toggle switches instead of running your trains, DCC is the answer. Just ask Rext how much fun it would be to have the whole gang of us over if his layout was wired for DC. :eek:
 
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Yeah Reggie, DCC is great and really one of the main reasons I returned to the hobby.

When I had Jim and the Gang over for an Op session, they ran in all directions on any track and all I had to do was keep them from running into each other :D.

DC would have been a real pain in the rear having to throw rotary switches for routes and allow only one train on a section of track,... worst of all, I probably wouldn't have had the session because I would still be doing all the wiring. ;) :)
 
Aha, I found the page (by George Schreyer) I was thinking of:
http://www.girr.org/girr/tips/tips3/reversing_tips.html
If you want to reverse while in the loop you'll need a dpdt switch to do it. You can also wire in a bi color LED to indicate polarity for entering the loop.
Our train club used the bridge rectifier setup at the CNR training school layout in Gimli MB and it worked slick!
 
I've done DC layouts in the past with DPDT switches. It's not that big of a deal to throw switches, it depends on how often the train comes through.
 
Not a reverse loop , but I have a reversing " Y " , with DCC I bought and installed a reversing controller , don't have to worry about anything , it takes care of it for me. Nice thing to have.
 
I think I will start planning for DCC before I go any further with my layout.
That is a good move to make and I guarantee that you will be happy with the operations.

I have five electronic reversers around the layout and they are smooth, automatic, and don't forget. Several I have were bought from Tony's Trains for $32ea.:) Easy installation: two wire to main track power, two wires to the reversing section rails.
 
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My new layout has two reversing loops. I have an Atlas 220 controller, which looks like it will control one of the loops, but it looks as though I will need a second one for the other reversing loop. The electronic reversers you speak of, can I use them with DC? (I cannot afford to go to DCC yet)What are the brands and model numbers of the reversers? I looked at Tonystrains.com and several other places, but could not find any info on them. Please help! Thankyou!
 
No, they are DCC only. I don't know of an auto system for DC, maybe magnets on locos and reed switches under the track, controlling some relays.

Ken.
 
Sorry...... I forgot to mention this is a DC system. I have considered switching to DCC. Would I have the same issue if it were a DCC setup?

Reggie

Yes. The situation in DCC is exactly the same as DC. The reverse loop will cause a short if not handled, and needs to be as long or longer than a train etc. (metal wheels bridging the gap can cause a short and the DCC system will shut down fast to protect itself from shorts)

One thing that is more convenient in DCC is that you can use auto-reversing electronics that flip the polarity when they detect a short.

On a simple return loop, you could also power the switch and if you're using a motor-type switch machine you can use contacts on the switch machine to throw a relay so the polarity changes based on the position of the switch. If you have multiple other tracks or switches coming off, then that doesn't work since that's based on the alignment of a particular switch.
 
Easy installation: two wire to main track power, two wires to the reversing section rails.

Just a nagging little question from me. With the DCC reverser module, when the short is detected the polarity of the rails in the loop are reversed, am I right or wrong?

Although I've little done about getting a new layout up and running I did receive my Power Cab, so there's no turning back now. Next I'll have to order a few decoders. Still have no idea of what I want to do about a plan so I may put up a drawing of the space available with a couple of ideas that are rolling around in my empty head.
Cheers
Willis
 
yes thats right Willis, the main stays the same the loop is reversed.

I hate that empty head feeling....... I just pinched a layout from MR mag:eek:

Ken.
 
Thanks Ken, I guess I'm still thinking in DC keep forgetting that decoder has rectifiers so in itself it's indifferent to polarity.
I believe I post a sketch of the available area I have, it'll be around the rooms or a folded dog bone type but I'll be wanting 28 or 30 inch Radius for the mainline. This time gotta get the steamers running. Maybe someone will toss a scrap of intelligence in the empty space then I'll add a little fertilizer and who knows it might grow into something :D

Cheers
Willis
 
No, they are DCC only. I don't know of an auto system for DC, maybe magnets on locos and reed switches under the track, controlling some relays.

Ken.

Ken, your suggestion for using some relays sparked an idea. I really dislike the Atlas 220 controller I tried using because of having to flip two switches back and forth on every loop and worrying about turnout controls. So, I picked up pencil and paper, sketched the double reversing loop portion of my layout, and after some brainstorming, finally came up with a wiring schematic that I thought would work. So, I gave it a shot and it worked!!!:D I used 4 SPDT relays, fed the common on all four with power from the cab. They reverse polarity of the entire layout section while at the same time turn on and off two separate isolated blocks. The train enters the loop from the mainline and stops at a block of dead track. I activate all four relays from one switch. The "dead" block becomes live and also switches polarity of the mainline, at the same time, removing power from a block in the next loop. The train moves back onto the mainline until it enters the next loop, stopping at the next "dead" block. I then deactivate the relays from the one switch and the whole process starts again. Eventually I would like to eliminate the switch for controlling the relays and use your idea for magnets and reed switches. And possibly turnout control...
 
sounds interesting, I'm happy it's working for you.
I used reed switches and magnets from Fisher & Paykel refrigerator door switches on my old DC layout. one at each end of the loop on the main to make the loop polarity correct, and two in the middle to switch the main while the train was in the loop. Fully auto!!

Ken.
 
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