Reverse Loop ????????

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#1
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?
 

CBCNSfan

Registered Member
Staff member
#2
Well SC maybe this will help
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When a loco is coming out of the loop then the polarity of the main track has to be reversed, this is done with a double pole double throw (DPDT) switch.
If you are using DCC it is much simpler because it can be done automatically by the system.
So I guess the question now is are you using DC or DCC?

Willis
 
#3
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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Rico

BN Modeller
#4
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?
 
#6
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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UP2CSX

Fleeing from Al
#7
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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#8
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. ;) :)
 

CBCNSfan

Registered Member
Staff member
#9
OH! my I feel another what to buy DCC thread coming on :D

Seriously Rex and Jim are right, if you have Reverse loops DCC is the way to go.
I had two reverse loops with 3 tracks each and the whole system DC with power routing was controlled by these few switches
Click-->

When things went wrong, well it was a devil of a time to trace out the fault, in fact after the last fault, I dismantled the whole thing to start over again. I ordered my first DCC system Saturday past, so besides rebuilding there's no turning back now, DC will be a thing of the past. There's a link in my signature to my layout before the destruction :D

How large is your layout? Do you have a track plan or photos of it?

Cheers
Willis
 
#11
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.
 
#13
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.
 
#14
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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blue92rs

Cheaper than therapy!
#15
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!
 

NZRMac

In Training Down Under.
#16
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.
 
#17
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.
 

CBCNSfan

Registered Member
Staff member
#18
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
 

NZRMac

In Training Down Under.
#19
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.
 

CBCNSfan

Registered Member
Staff member
#20
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
 



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