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 Wiring reverse loops?
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Author Previous Topic: Ruh Roh ...  Atlas ... HELP!!! Topic Next Topic: Cannon and Proto SD50  


Posted - 2005 December 02 :  10:06:39 PM  Show Profile
Updated this to say I'm looking for specific recommendations on where to gap for reverse loop wiring on this layout, regular DC with Atlas components. Thanks:

Edited by - B_A_R on 2005 December 05 10:20:24 AM

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Monster Railroad

Posted - 2005 December 02 :  10:46:55 PM  Show Profile
I dont know if this will work which someone will clarify it, but Maybe you can use a Digitrax or Lens reverse loop module and it will do it automatically? Lets see if that is possible guys for DC?

Southern California Desert Rail Division

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Posted - 2005 December 02 :  11:18:09 PM  Show Profile
heres a link to some of the basics.
what you need to do is basically isolate the loop from the rest of the track,
then after the loco enters the reverse loop, you need to reverse polarity on the main, before the train comes back out.
this is important since the train coming back out is now facing the opposite direction.
a quick search for "wiring reverse loops" will pull up many pages that may also be helpful


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Posted - 2005 December 03 :  02:14:30 AM  Show Profile
I don't think the DCC reverse loop circuits will work. They work by detecting a short and flip polarity on that section of track. In DCC this is fine but in DC the train will change direction. There should be a way with Atlas parts that you can do it. Check out one of their wiring books.


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Posted - 2005 December 03 :  1:58:53 PM  Show Profile
Hi BAR! For a reversing loop that feeds and returns on the same track, that means a train enters and leaves the loop on the same line, you put in an isolated section of track. This needs to be big enough to hold your largest loco, including the tender (for steamers) if the wheels pick up current. This section of track gets it feed from a switch/electrical, switch off, and the loco stops when on the isolated bit. Change the point/switch, alter the direction on the controller, switch the current back on to the isolating rails and the train continues.


Oh for the days when coal was king and steam ruled.
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Posted - 2005 December 03 :  3:11:15 PM  Show Profile  Visit RDG-LNE's Homepage
None of the DCC reverse section units will work with DC. For DC you still have to use two DPDT switches or the the equivalent.


My railroad photos are here

The Schuylkill & Ontario Ry. Co.

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Posted - 2005 December 03 :  9:47:20 PM  Show Profile  Visit BRVRR's Homepage
Can't see your photo, but the Atlas wiring book has complete instructions on installing reverse loops on DC systems. None of the currently available Automatic Reversing Modules (ARMs) for DCC layouts can be used for the purpose on DC systems. If you use lighted passenger cars or lighted cabeese, the reverse loop should be long enough to hold your longest train to prevent short circuits. Since I can't see the picture, I can not be more specific. With a photo or schematic of the layout and control system I could be more helpful or post/send the appropriate pages from the Atlas book.
Good luck,

Remember: It's your railroad.
See my layout & web site here:

Edited by - BRVRR on 2005 December 03 9:51:24 PM

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Posted - 2005 December 03 :  11:27:31 PM  Show Profile
Atlas' "Controller" should do the job. If memory serves me correctly, it has two cabs direction switches; a cab selector switch; and a reversing section switch.

I used it on the "Great Eastern Trunk" (around 1989) in a 5' x 12' version. It worked very well. Great layout to break in those old Athearn grinders

Tom Austin
Centralia IL

Edited by - MoPac1 on 2005 December 03 11:29:16 PM

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Posted - 2005 December 03 :  11:59:00 PM  Show Profile  Visit jward's Homepage
here are a couple of options you may want to consider.....

all of them involve a reversing section that is COMPLETELY ISOLATED from the rest of the track. in fact, any reversing section must be isolated in this manner, by gaps in BOTH rails at BOTH ends of the section.....

the first, and simplest to wire is to use a 4 amp bridge rectifier. the AC terminals are hooked up to the common rail, and the block switch for that section. the DC leads go to the 2 rails of the reversing section. the advantages of this method are:
1. you have only the reversing switch on the power pack to worry about. simply throw it while running through the loop and you will automaticly be at the correct polarity coming out the other end.....
2. the wiring is greatly simplified over all other dc solutions, comparable to a dcc auto reverse unit....

the only disadvantage is that you can't back up while in the reversing section. the rectifier keeps the train moving in the same direction regardless of the way your direction switch is thrown.

the other solution you may want to consider, if you enter and exit your reversing section over the same switch, such as the stub tail track of a wye, is to use an atlas snap relay, or deluxe under table switch machine.

the contacts are the same on both of these. the 3 on the end are wired the same as a switch machine with the red/black/green wires. along the body of the relay are 2 sets of contacts marked common, a & b. you wire the common terminals to ryour common rail, and the block switch. wire thea terminal to the b terminal on the opposite side of the relay, and do the same for the other a and b terminals. the wires should cross each other in an x....then wire both b terminals to the rails of your reversing section.

the advantage of this method is that every time you throw the switch leading into this section, you reverse the polarity of the reversing section. but you must remember that any train in the section MUST be stopped when you throw the switch, or else it will reverse itself instantly. you must also flip the reverse switch on your power pack before you start moving again, to avoid backing up.

both of these methods eliminate the second reversing switch that seems to cause so many people trouble.. i have used both on previous layouts and they both work well.

Jeffery S Ward Sr
The unofficial EMD homepage.

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Posted - 2005 December 04 :  4:31:25 PM  Show Profile
Thanks everyone.

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Posted - 2005 December 04 :  10:38:13 PM  Show Profile
b a r,
always glad to help,
you have an interesting plan,
and i was just wondering,
how are you blocking it?


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Posted - 2005 December 05 :  10:23:32 AM  Show Profile
Originally posted by sam

b a r,
always glad to help,
you have an interesting plan,
and i was just wondering,
how are you blocking it?


Thanks,but my trackplanning skills are severely limited. Anyway, it's really just for continuous, display-type running. I just planned to isolate the two main ovals, unless you've got a better suggestion. So you know, it's two 4x8 tables, with #4 turnouts on the lower loop and some #6 elsewhere.

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Posted - 2005 December 06 :  02:07:22 AM  Show Profile  Visit jward's Homepage
since i was just now able to see your track plan, here are my recommendations for wiring....

you have 2 tracks that cross each other. these should be your reversing sections. gap them on either side of the crossing, at the frog end of the first switch you come to. gap both rails here. you should end up with 4 sets of double gaps. since these reversing sections will be rather short, i'd advise wiring them through bridge rectifiers per my previous post. you can get these at radio shack for a couple of bucks apiece. once they are installed you will only be able to run through the reversing sections in one direction, so mark which end you will need to enter them. a cheap plastic signal makes a good marker that doesn't draw attention to itself....

Jeffery S Ward Sr
The unofficial EMD homepage.

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