# Double Dogbone Auto reverse questions



## johnfm3 (Sep 30, 2016)

I bought a layout a few months back and I have been making changes to it, the most recent being installing a NCE DCC Twin system.

The layout was originally a DC system, which was a multi level large loop with the elevation change was done along the back side. The upper level has a way to make a small loop where the out going line can cross over to the incoming line again.

Now with me on DCC, I am thinking of making changes and having a single main line and making the the upper and lower loop setup as return loops. Basicly a dog bone layout (If I recall the terminology correctly) The reason for this is the inner track curve is too tight for my large passenger cars to travel thru. So I am thinking of eliminating the inner track and only have a single line go between the 2 levels.

If I go this route, where do I install the auto reverse module(s)? And should I plan on buying 1 per section (2 loops and the 1 main line)? Tech 4 because then I also have the train yard area.

What are the other concerns when thinking about doing this?

The 3 rail segments will be about the same length.

John


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## johnfm3 (Sep 30, 2016)

After a little more looking, Do I just put the auto reverser on the single mainline track?

My train yard is accessed by the lower loop.


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## flyboy2610 (Jan 20, 2010)

Could you post a photo or drawing of your layout, and where you were planning to have the reverse loops?


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## johnfm3 (Sep 30, 2016)

flyboy2610 said:


> Could you post a photo or drawing of your layout, and where you were planning to have the reverse loops?











This is a horrible representation of my layout. But it gives the just idea of what I have. My layout has much smoother corners. Green is base level. Red is top level. And Yellow is transition between the 2 levels.

I want to make the yellow where they parallel into a single main.

Here are real pictures of the layout.

















John


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## johnfm3 (Sep 30, 2016)

here is a quick 2 min video showing a train on the layout running the full loop.


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## CTValleyRR (Jul 26, 2014)

As drawn, you don't have a reverse loop. Even if you combined those two yellow tracks, you still wouldn't.

A reverse loop is created when a train leaves a turnout on one leg, and can trace a path to ckmme back into the turnout on the opposite leg, while continuously moving forward.

As drawn (and as proposed), your train always travels either clockwise or counter clockwise. If instead of merging the yellow "mains", you took the inner one diagonally across the center and joined the green about where the sidings are, THEN you would have a reverse loop.


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## johnfm3 (Sep 30, 2016)

CTValleyRR said:


> As drawn, you don't have a reverse loop. Even if you combined those two yellow tracks, you still wouldn't.











I just drew my layout and explained what was needed to make the layout a double loop layout.

Here is the same layout after combinding the yellow tracks to a single main line as I explained.

Now you have a red and green section which come back to the same turnout making them reversing loops. And the red section as a way to stay on itself.

The yellow is still the transition in elevation and its also the single mainline. The blue is a place holder for the train depot.


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## mesenteria (Oct 29, 2015)

johnfm3 said:


> ...
> 
> If I go this route, where do I install the auto reverse module(s)? And should I plan on buying 1 per section (2 loops and the 1 main line)? Tech 4 because then I also have the train yard area.
> 
> ...


The base unit of the DCC system sends signal and power to the reverser's two inputs. The reverser, mounted close to your reversing section, has outputs that are wired directly up to the rails within the gaps at either end of the reversed length of rails. The turnout servicing the reversing loop must be gapped at both exits.

Depending on the length or rails, you might wish to have the reverser's outputs supply a sub-bus if you'll need several feeder wires here and there. Feeder wires from the rails will be soldered to bared wired along the sub-bus.

Both lengths of wire and lengths of rail degrade the signal because of resistance. The resistance of the wire depends on its construction and dimensions, but voltage drop will attenuate the signal and raise the signal-to-noise ratio to the point where the short detection built into the main station won't work. (Google 'DCC quarter test). So, if your runs are getting long, you might need a booster, maybe two.


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## flyboy2610 (Jan 20, 2010)

After your modifications, both the red and green loops become reverse loops. For the red loop, I would put insulating rail joiners on both rails of both routes through the turnout about 12" past the turnout. I would do the same for the green loop.
I've never installed an auto-reverser, so I can't help with it's placement, but I would imagine that installing it about midway through the loop would be the best.


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## DonR (Oct 18, 2012)

Yes, as has been noted, your changes do create two
reverse loops. However, you could consider them
'main line' and designate the yellow section as
a reverse loop which would require only one auto reverse unit.

However, I'm a little 'nervous' about that possibly, tho, as it makes possible the situation where two trains could access the isolated reverse section at the same time and that would result in phase chaos. 

It would be best to isoolate the entire RED loop with
insulated joiners in both rails at the turnouts to which it is connected. 
The RED crossover turnout far right needs no insulated joiners.

The GREEN loop would be different. Place insulated joiners right of the
lower green turnout, and 2 or 3 feet right of the upper yard turnout.
Thus, the BLUE yard becomes part of the YELLOW main. 

You would need two reverse loop controllers. One would
output to the RED section, the other would output to
the GREEN section. Both would take the main track bus
power feed for input. They are totally automatic and
are usually 'hung' under the section they control. You
could use any brand reverse controller. The YELLOW and
BLUE sections take power from your main bus.

Don


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## johnfm3 (Sep 30, 2016)

DonR said:


> ... However, you could consider them 'main line' and designate the yellow section as a reverse loop which would require only one auto reverse unit...
> 
> Don


Don, I thought about this as well.

Here is the unit I am looking at buying...
DCC Specialties PSX-AR Auto-Reverse Circuit Breaker w/ Tortoise

https://tonystrains.com/product/dcc-specialties-psx-ar-power-shield-auto-reverser-circuit-breaker

If I put reversing loops on Red and Green sections, leaving yellow and blue sections on main power, I have a problem arise if the green loop track power reverses while a train is leaving the loop onto yellow mainline and another train is leaving the blue section yard into the green loop. Unless I add a third auto reverser for the blue yard area. An then it becomes a situation as too how to configure the Blue and Green reverse's delay settings so they dont try to change at the same time.


It may be better to leave the green and blue section on main power and reverser units on the yellow and red segments. The placement of the reversers and configuration is where I am going to need help.

This is going to be difficult to decide on how to deal with it.

John


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## johnfm3 (Sep 30, 2016)

So the price difference between the DCC Specialties dedicated circuit breaker and the auto reverser with circuit breaker is small enough that I may just buy 4 auto reverers.

Has anyone used these and tell me if the Auto Reversing feature can be disabled so it only functions as a Circuit Breaker?


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## DonR (Oct 18, 2012)

John

You are correct, that a train leaving the blue and entering
the green would create an electrical conflict with another train
leaving the green and entering the yellow. One thought
I had was to include the entire blue in the green isolated 
section. You would have two trains running
in the green iso section at the same time, This is
not normally recommended, but in the situation of
your layout I don't see a problem.

Lighted passenger cars would be a factor but I notice
that yours are not lighted. Lighted car trucks spanning
the insulated joiners would be the same as a loco.

There also could be the possibility of a 2nd train entering
the red iso section while the first train is in it. As with
the green, so long as only one loco is spanning the
insulated joiners there is no problem.

The worst solution, tho, is to make the yellow the only
iso section. The likelyhood of 2 locos spanning the
insulated joiners is much greater there.

In the end, much care must be used to prevent 
two locos from spanning the insulated joiners at the
same time. The result of this conflict would be to
set off your main controller circuit breaker.

As to your selection of reverse loop controller, any 
one on the market would work fine...you may find
some that are less costly. Since you need two that
could be a factor.

Don


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## johnfm3 (Sep 30, 2016)

So does a Auto Reverser stay in its last state, or does it revert back to a Normal state prior to when it reversed polarity?

Does that question even make sense?

John


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## DonR (Oct 18, 2012)

John

I fully understand your question. It does
make sense.

Here is how the Reverse loop controller works:

When loco wheels span the insulated joiners there
is a 'short'. Instantly, the reverse controller reverses
phase (polarity) of the iso section and the loco continues
without so much as a blink of it's headlight. When
that same loco reaches the 'exit' of the iso and it's
wheels span the insulated joiners it AGAIN reverses
phase, thus matching the main phase and the loco
continues on.

So, yes, the reverser does hold the 'last state (phase change)'
until it is next triggered.

When you consider the above, you will understand why
it's important to prevent locos from spanning the
insulated joiners at both ends of the iso section at
the same time.

Don


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## CTValleyRR (Jul 26, 2014)

DonR said:


> John
> 
> I fully understand your question. It does
> make sense.
> ...


And it doesn't have to be the SAME loco, either. Two different ones simultaneously would do it.

You best bet is not to have two sections of track with reverse loop controllers abutting one another. Separate them with a section of normally-powered track.... with all sections longer than your longest train, if possible.


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