Return loop wiring

[sailor38]

Returning to the hobby after 20-plus years. My memory cells are failing me, I think. Here's the problem:
I am using a DPDT Ctr Off switch for the return loop. I have wired an X pattern on the four corner terminals. I have wired the leads from the track at the top,
let's say yellow on top left and blue on top right. I have wired the leads from the rectifier on the bottom corners. No connections at all to the middle two terminals. Here are my observations: I know I have power in the loop and also on the mainline. The loco will run into the loop from either turnout but will not exit. Also, it doesn't matter which position the switch is in, the direction does not change. The loco even runs in the center off position. (I have tried reversing the leads at the end so that yellow is on one side and blue on the other or that they are on opposite sides. It doesn't make any difference.)
Conclusion: Either the switches are bad (I've tried a couple) - not that likely but possible, OR my wiring is incorrect - far MORE LIKELY.
Can someone help? [?][:(][8]

[cacole]

The wires from the power pack need to be connected to the center terminals on that toggle switch so the polarity is reversed when you change the switch from one position to the other. The way you have things wired now, the switch is having no effect at all on anything because the power is just passing through the X wiring connected to the end terminals. Leave the X wired as you have it now, but cut the wires from the power pack and resolder them to the center terminals. This way, power is fed into the switch through the center terminals, and then goes to the track according to which way the switch is thrown.

[Anonymous]

I can get you part ways......wire get soldered in corner then goes to the opposite corner and gets soldered. like an X, and then a wire is soldered to each center prong......from this point out I don't recall where they go. That will work on the switches.....

[NZRMac]

If your running DC your Loco will go backwards in the loop, if your reverse switch is connected to the loop and not the mainline, when you flip the switch.

If you have DCC it will continue on but may pause a little while the switch is in the middle position.

[mcouvillion]

If I remember correctly for DC, when you enter a loop as described above, you must stop the train before exiting the loop, then change both the position of the toggle switch and the polarity switch on the rectifier (throttle) for the train to be able to exit the loop without having a problem. Correct me if I am wrong, but I think this is essential. You can't just go blasting throught the loop then change the polarity of the loop and have the engine keep on moving forward. You also have to change the polarity of the track entering the loop so that the train will go in the opposite direction when it exits the loop. You must do both polarity changes while the train (engine) is stopped in the loop.

Mark C.

[sailor38]

Thank you all so much. Connecting the power pack leads to the center posts of the DPDT switch did the trick... kinda. The thing is, I don't remember having to stop the loco in the loop and throw both switches in the opposite direction.
Maybe I'm just dreaming but I thought all I did in the past was throw the toggle while the loco was moving through the loop. Just dreaming? Anyway, for the record, the reversing switch is wired to the mainline, not the loop.
Thanks again![:D][%-)]

[NZRMac]

If your loop track is wired straight to the rectifier, and the main is thru the DPDT then you should be able to thro the switch while your train is in the loop, without stopping.

Ken

[Jacktal]

Please anyone correct me if i'm wrong but you will have to have both loop and main line rigged with polarity reversing switch.One R-S will allow you to reverse the polarity of the loop in advance so that your train can enter without stopping,and,while your loco is within the loop,you will need another R-S to reverse the main's polarity so that your train can exit without stopping.Since you can't reverse the polarity while your loco is on one circuit(either main or loop) without having it changing direction,you will have to be able to change polarity on either upcoming part of the trackwork to match it with the section the train is on.

[cacole]

Whether you want to reverse the polarity of the main line or the loop, both ends of the loop must be insulated from the main line. If you reverse the main line, you must always enter the loop from the same direction or the polarity will be wrong and the engine will short out. If you have the switch connected to the loop, you must stop the locomotive while you're in the loop, reverse the toggle switch, and reverse the direction control on your throttle. Reversing the main line as you have it now wired is the best way, because you don't have to stop the train as it goes around the loop. Just make sure both ends of the loop are insulated, and always enter the loop from the same end. Confusing, isn't it? This is precisely the reason that Lionel decided to change from DC to 3-rail AC power. Even DCC hasn't solved this problem, but there are automatic reversers available that replace the toggle switch when you are using DCC.

[sailor38]

AHA!!!!!!!!!!!!!!!!!! Mr. Cole you are soooooo right! Now I remember that you must enter the loop from the same end to avoid having to throw both switches. You have saved me hours and hours if not days of grief. Thank you so much for the refresher course. Maybe I shouldn't wait twenty-odd years between layouts.
[banghead] [bow][tup]

[bogp40]

Wired as cacole suggests:
You can enter to loop from any direction. The reversing loop polarity is set to whatever block entering from, while in the rev block you reverse polarity on the rest of the layout controlled by your cab. Always keep the entire train within the block before revesing polarity. Metal wheelsets can arc and pit going over the rail gaps during quick intermitant shorts.(not a real operational problem in DC but will shutdown/ trip for DCC)
Bob K.

[NZRMac]

With DCC you can reverse the loop polarity with the train in the loop. I'm using 4 reed switches and two 3PDT relays.
The first reed sw is on the main which sets the loop entry polarity the 2nd reed sw in the loop is unused in this direction.
The third reed sw in the loop changes polarity of the loop ready for train to leave the loop.
The forth reed sw is on the main and sets the loop polarity for entering loop from other end.

I've glued a little magnet to the underside of the loco.

The circuit works really well, because the relay changes so fast theres no
pause or light flicker on the loco at all.

Ken

[mcouvillion]

After reading the responses following my first response, and considering the option of entering the loop from either direction, you might consider installing LEDs at the gaps between the main line and the loop. You could disguse them as dwarf signals. Esentially, connect a red LED across the gap on one rail and a green LED from one rail before the gap to the other rail past the gap. What you would get is a red indication if the polarity is opposite on the same rail across the gap, and green if the polarity is different on the two rails. If you place a dwarf on either side of each gap, you will always know whether your polarity is right before crossing the gap.

Mark C.