autoreverser placement

[jim81147]

So I have basically a folded dogbone and want to put a crossover in . Where would the autorverser be placed ? would I isolate the crossover itself and put it there?

 

[PMW]

Not sure that would work. I’d think you’d have to isolate a section big enough section for your longest train and wire the AR to that section or possibly sections.

I’m sure people with a better grasp on this will weigh in.

 

[timlange3]

I think folded dog bones are interesting. Logic would say the track in the middle is a two track mainline, electrically we would like to isolate the two tracks from each other. In this case, I would go with logic and isolate the loops at each end. You will need two auto-reversers for this.

 

[jim81147]

Paul , you are correct , there would have to be some lead in to the crossover on both tracks . Tim , if I draw my plan out without the crossover there is no issue . Since the crossover creates the problem , in my simple mind isolating the crossover and lead in would solve the problem but I will be the first to admit that wiring can be confusing for me.

 

[migalyto]

If you post a track plan we can then tell you exactly where to gap and place the auto-reverser.

 

[jim81147]

you will have to excuse the crudeness of the drawing but it make the idea . Black and pink are the rails and green is the crossover location. I have omitted yards and sidings for clarity.

 

[Toolbelt]

isolate a section big enough section for your longest train

I've read that phrase before, but was unsure whether they meant longest powered locomotive........ or train (including freight cars)? My gut is telling me it's the longest locomotive (by wheelbase), but just need confirmation.

 

[Canalligator]

I have a folded dog bone with a crossover near each of the loops on the ends. I split the power across the center of the crossovers. If you’re careful, you can just wire your reverser, using the turnout switch and not require an auto reverse at all.

 

[Canalligator]

That wasn’t explained well. The crossovers are near the ends of the straight part in the middle. I’m emulating a double track main with it.

 

[Rico]

Hmmm I started typing out my answer but now I’m not so sure.
I'm pretty sure as Tim suggested you’d isolate the end loops.
Two single crossovers might simplify the issue.
I’d contact the manufacturer for their input, if you do please share the answer!

 

[Iron Horseman]

Paul , you are correct , there would have to be some lead in to the crossover on both tracks . Tim , if I draw my plan out without the crossover there is no issue . Since the crossover creates the problem , in my simple mind isolating the crossover and lead in would solve the problem but I will be the first to admit that wiring can be confusing for me.

Is your double crossover a pre-built piece or are you going to make it using 4 turnouts and a crossing? If pre-built what brand and what rail gaps are built into it? In your post above, what is the 'lead in' considered to be? In my mind there are 4 leads to the double crossover.

One way to think of it is as if there are two reversing loops as below. The red line is one, and the blue is the other. The gaps (insulated joiners) would then be as shown with the yellow on black and pink rails - this would be required in that spot (often a commercial double crossing will already include these). Then another set in orange on green rails - these could be moved to the other side of the crossing, one or both sets.

 

[PMW]

I've read that phrase before, but was unsure whether they meant longest powered locomotive........ or train (including freight cars)? My gut is telling me it's the longest locomotive (by wheelbase), but just need confirmation.

I believe it means your longest anticipated train including freight cars (if they have metal wheels). I also think there's a work-a-round for that too but don't ask me to try to explain it. I had enough trouble with my "simple" reversing section

 

[jim81147]

my crossover is built up - 4 turnouts and a cross . My interpretation of lead in a piece of flex on each side of the turnout . The switches are peco streamline insulfrogs . I had read that "the longest train " included all freight cars because of the possibility that a car might have sound or a lighted interior or such .

 

[Toolbelt]

I believe it means your longest anticipated train including freight cars (if they have metal wheels). I also think there's a work-a-round for that too but don't ask me to try to explain it. I had enough trouble with my "simple" reversing section

But assuming the freight wheels are insulated from each side, and mounted to a plastic car body, is that still an issue? If I'm pulling 37 cars around my 4 x 8 layout, the reverser section would represent 60% of my track.

 

[Toolbelt]

a car might have sound or a lighted interior or such .

yes that would make sense. But for regular freight cars with insulated axles and plastic bodies, I can't see how they'd be a factor?

 

[Iron Horseman]

my crossover is built up - 4 turnouts and a cross .

That is good more options. A thing to remember is that Peco insulfrog turnouts are power routing. Is the crossing double insulated, that is both sets of rails passing through are 100% insulated from the other set?

My interpretation of lead in a piece of flex on each side of the turnout.

Hmm trying to get my head around that one. With that scenario where are you putting the gaps? Seems a complication with it is that even with no locomotive involved changing one set of the turnouts to "cross" would trip the auto-reverse. Changing the other likewise, changing them both... um, don't know I would have to draw it out. Or were you thinking of putting an auto reverse on each of the 4 leads? Then introduce the locomotive. What if it hits the section at the exact time the turnouts are thrown.

I had read that "the longest train " included all freight cars because of the possibility that a car might have sound or a lighted interior or such .

Even metal wheels. The smaller the gaps in the rail the bigger the potential problem.

 

[Iron Horseman]

yes that would make sense. But for regular freight cars with insulated axles and plastic bodies, I can't see how they'd be a factor?

It is the metal wheel itself possibly jumping the gap between the two electrical blocks.

 

[jim81147]

Horseman , I am not sure I follow what you are asking/saying . As I said my grasp of wiring is not that great . The way it is right now , I have insulated joiners on both sides of the crossover on the short loop side . I had planned to go somewhere on the other side of the layout and isolate about a 6 foot section , then put reversers on that isolated section and the loop below the crossover . When I started thinking about it today I had to draw it out to make sure I was thinking correctly and when I did I saw that without the crossover , it appears to me I would need no reversing . Is that correct as you see it ? But I do want a way to change directions on the track , hence the crossover . Thats where I thought that maybe building a block that contained the crossover and some tangent track and putting a reverser on that block might be what I needed . I confuse myself just writing it out

 

[diesel]

Just catching up here, but if you have insulating joiners on both sides of both ends of the short loop, connecting the auto reversing device to the short loop itself should be enough if you have DCC. The crossover may have its own caveats and conditions, but may be a red herring so far as the reversing loop is concerned.

Without DCC, coming out of the loop, the train would short again on the fixed main loop polarity and can't reverse because it would reverse the locomotive. But DCC is polarity agnostic, so a short would cause the reverser to trip again, reverting to the normal polarity which matches the maiin loop. But in that case, the train direction is under DCC control and the train will just continue through the crossover to the main loop.

I say this without having tried it. Probably, two reversing devices were suggested earlier because of this... if you are running DC you would absolutely need two reversers.

The way the reverser logic works is:
If a short is detected, reverse.
If the short is still detected, there is a system fault like a track or wheel short. Indicate a fault.
If the short is not detected, the reversal was successful.

 

[ctclibby]

Have a go at this. Diesel is correct, but a pix is worth $$$.

This is only for the DogBone loop. If you wish a double cross-over somewhere in the middle. Whole new can of worms. You would need 2 reversers; one on each side and 1+ Train length on Both tracks on Both sides of of the double cross-over.

I am not sure about cutting gaps of a manufactured double cross-over and/or diamond. That could be a can-o-worms.

Oh, and you could swap out the diamond in the Passing Siding version with a double-slip.

Hope this helps.

L8r