Large Scale Central

Reverse Loop

Track and Trestles
#21

Greg Elmassian said:

Yep, of course all the other locos on the mainline will now take off in reverse!

I know, Todd is probably only running one loco at a time on the track, so reversing the main line does not matter. (for those who do not know, reversing the “polarity” of the rails does not change the speed or direction of a DCC loco)

Greg

True. But it makes no difference whether you use one 4pdt switch, or two dpdt switches, or one dpdt switch and switching at the TE, you still have this caveat.

At least the 4pdt is the most convenient and you wouldn’t even need to stop the train in the loop.

#22

Todd Brody said:

At least the 4pdt is the most convenient and you wouldn’t even need to stop the train in the loop.

I don’t think making the switch on the fly would be tolerated by the motors too well. Electrically you are correct, but there will be a split second where there is no power to the rails giving the motor a jolt. I’d still stop.

#23

Greg Elmassian said:

Whew, sure am glad I run DCC! One autoreverser hooked to the loop, powered from the main, done.

Greg

Yes, and with on-board battery I don’t need your fancy electronics; I just drive around the loop however I want. BUT - The O.P. is asking about track power so we are all just trying to help; not try to change his religion.

#24

Daktah John said:

Todd Brody said:

At least the 4pdt is the most convenient and you wouldn’t even need to stop the train in the loop.

I don’t think making the switch on the fly would be tolerated by the motors too well. Electrically you are correct, but there will be a split second where there is no power to the rails giving the motor a jolt. I’d still stop.

Really no longer than a relay throwing, or momentarily passing over a dirty/insulated section of track for that matter and this happens on all kinds of things all the time. I’m betting most motors would be fine.

And, this basically makes it “fool-proof” as you can’t get the polarities out of alignment creating a short by accidently throwing one dpdt and not the other or failing to reverse the TE current.

Also, if you set your track up in “blocks,” you can use the switch to reverse the current only to the appropriate blocks while leaving other blocks/loops on that same TE alone (i.e., they don’t reverse).

#25

Whew! If I had known it was that hard, I would not have done 2 reverse loops with a single track, bi-directional mainline. But then again, by having 2 reverse loops, I may have simplified my situation. The power from my TE goes right to the loops, and the relay control only reverses the polarity of the mainline. So while a train is in a loop, the relay changes the polarity of the mainline, and then train never even has to slow down.

#26

That’s a good way to do it David (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Todd B, please go ahead and build that, test it and report back.

#27

Daktah John said:

That’s a good way to do it David (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Todd B, please go ahead and build that, test it and report back.

If I had a loop of track at my disposal, I would.

#28

I often do run more than one train on my RR at a time though with the train engineer when I hit “emergency stop” they all stop.

I also have several areas where I can park a train on a siding.

This loop was going in any way and the reversing part was an after thought to provide more interest. Most trains will still take the bypass route but it will be fun to run one up the mountain and have it reverse now and again.

Since the reversing part won’t be an every day thing I don’t mind stopping the train and flipping switches.

#29

I think if you hit the switch fast, it would be fine, i.e. agreeing with Todd B. It would be good to make sure it is break before make, but I believe it would be in a switch that “large”.

Greg

#30

OK, I’ll concede on that point; but I still think it’s a bad idea. What if you hit that switch by accident when the train is high-balling on the main outside the reverse loop - KA BANG. Model trains don’t do “Bostons” like a '57 Chevy Hydromatic. Two switches (one being on the power pack) much less chance of a screw up.

#31

I guess you are not familiar with “Todd’s Theorum of Screw-Ups”

“The ability to screw something up is proportional to (2 to the “nth” power) - 1 where “n” represents the number of interactive components involved.”

So if you have two components to deal with, you have three chances to get it wrong and one to get it right. If you have three components to deal with, you have seven chances to get it wrong, and one to get it right.

But some people are “more astute” than others so there is an “Lc-Factor” (Learning Curve) or “Kh-Factor” (Knuckle Head) used as a multiplier that can change over time. This factor can have a value of zero (i.e., the guy never screws up) to one (i.e., for three interactive items, will get it wrong seven out of eight times), but with some people, I think the factor may even exceed one (i.e., even if you give them something that is working and fool proof, they will find a way to screw it up).

#32

Todd, yes. On the club’s Wye there is a toggle switch to reverse the polarity in the one leg. I occasionally forget to throw the toggle when the locomotive is in the leg. But one member forgets to throw the toggle all of the time. Either he doesn’t switch it so the locomotive can enter that leg, or he doesn’t switch it so the locomotive can exit that leg. Then the DCC booster just shuts down and everyone’s trains slam to a stop. This can cause derailments on other people’s trains. So I would say that his factor is infinite, since he never gets it right. But, since he is the club president, and he assisted with the construction of the Wye, I cannot say anything.

#33

Todd H.,

i had return loops with single main lines in analogue DC.

you can keep it simple and reasonably cheap, using either manual operation, or automatic “block” traffic.

do you want to use the mainline for just one train at a time, or for various trains with a passing siding?

#34

David Maynard said:

Todd, yes. On the club’s Wye there is a toggle switch to reverse the polarity in the one leg. I occasionally forget to throw the toggle when the locomotive is in the leg. But one member forgets to throw the toggle all of the time. Either he doesn’t switch it so the locomotive can enter that leg, or he doesn’t switch it so the locomotive can exit that leg. Then the DCC booster just shuts down and everyone’s trains slam to a stop. This can cause derailments on other people’s trains. So I would say that his factor is infinite, since he never gets it right. But, since he is the club president, and he assisted with the construction of the Wye, I cannot say anything.

Have you thought about turning the switch sideways at the club. I have mine like that so I can see it easily and don’t need to think too much. If the switch is flipped to the left it means the train is entering or leaving on the left track on the WYE if right then to the right. Simple.

On my turntable I use a colour code. I have a blue tack on one side of the bridge and a red on the other. There is a red and blue tack next to the DPDT switch. Engine enters the turntable the colours need to match up. Simple.

Korm my RR is one large continuous loop and this reverse loop is being added to provide some interesting fun on occasion. If I need to turn a train I use the WYE.

#35

Todd Haskins said:

Have you thought about turning the switch sideways at the club. I have mine like that so I can see it easily and don’t need to think too much. If the switch is flipped to the left it means the train is entering or leaving on the left track on the WYE if right then to the right. Simple.

On my turntable I use a colour code. I have a blue tack

Todd, but that IS the way the toggle is mounted, right up on top, beside the track in question.

#36

OH maybe you should try the coloured tack idea.

#37

My wye doesn’t require that any switches be toggled. The tail section is controlled by the LGB EPL attached to the turnout. The two lead in turnouts also throw the wye turnout into the proper position. Everything operates automatically.

When you want to use the wye, you toggle the appropriate turnout on the mainline and this also throws the wye turnout to that direction setting the polarity on the tail section. When you throw the mainline turnout back to the mainline, the wye turnout remains as it is (foolproof).

You pull your train into the wye and there is diode protection at the end, so the train stops automatically before departing the end of the track (foolproof).

To leave the wye in the other direction, simply toggle the other turnout on the mainline to the wye. This simultaneusly throws the wye turnout and the polarity reverses. The engine now gets current though the diode and the train proceeds out the other direction onto the mainline (foolproof).

You can toggle the wye turnout and reverse the current to the tail section independant of the two mainline turnouts (i.e., toggling the wye turnout has no effect on them). This way you can work within the wye (toggle trains back and forth to “interior” sidings) without effecting the mainline.

Once the train is back on the mainline, throw the mainline turnout back to the mainline (wye turnout ignores this) and reverse the power to your train to a forward direction on the mainline.

#38

Back when I was running track power I had considered using bi-color LEDs on both sides if the gap to visually indicate that the polarity was correct (colors match), but I never really needed it so it was never implemented.

#39

David, I think we went over this before, but remind me… you have a DCC booster? Then you must have a dcc system… and you don’t use an autoreverser?

Sounds nuts…

Greg

#40

Greg says:

I know, Todd is probably only running one loco at a time on the track, so reversing the main line does not matter. (for those who do not know, reversing the “polarity” of the rails does not change the speed or direction of a DCC loco)

This is only true for DCC power, a DCC equiped loco on DC/Analog track power will reverse with polarity reversed.