Auto Reverse


jmartin26@...
 

Like many others seem to be i am pretty new to DCC, having been in G scale for many years and then inactive for a number of years. I think i have read the answer to my question several times. Unfortunately, i keep confusing myself and coming up with different answers. I have posted a picture of a portion of the layout (auto reverse or pass through). My question is does this scenario constitute a reverse loop. I could not understand how it could but then read (very possibly i misunderstood) that this is a reverse loop. i then decided to just accept this at face value and proceed. However, the more i thought about it the more confused i became. I used the simple test i read somewhere about following the track to determine if the rails every changed polarity and they do not. I also saw that this may be a crossing and not a cross-over which may have caused my initial confusion. If there is any value in it i laid pieces of wire, for purposes of the picture, along the track to show how i plan to wire the mainlines, and really all the way through the loop. I am ready to start wiring, after purchasing PSX devices. The loop end, there is also a slightly larger one at the other end of the layout, will be its own power district but at this point i am very unclear on the need for a PSX-AR vs. an additional PSX1.

Thanks for any help you can provide
Jim


Don Weigt
 

Jim, your tracks cross, but at no place can the train return to its origin going in the reverse direction. This is NOT a reversing loop! Either a reversing loop or a wye requires one or more turnouts. You have zero here, so not a reversing connection, as long as that's a simple crossing and the rails through each route aren't connected to the rails through the other.

Another way to check is to roll a car or loco or imaginary one through the route and see if there's ever a way the wheels on the right rail ever end up on the left rail of the same track section. If so, then no matter how convoluted the tracks, it's a reversing loop. If the wheels never swap rails, then there's no reversing loop or wye.

Don Weigt

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Don Weigt
Connecticut


Blair
 

Jim
Don is correct.  The definition of a reversing section is that a train "returns on the same rails it came from".  By that definition, you have no reversing section as long as that is a crossing, not a crossover, slip or double slip.  Change that simple crossing to any of those turnout types, and you've introduced a reversing section, dependent on the setting of the turnout.
Blair


Don Vollrath
 

Your picture by itself is not a reversing loop. But 1) you are just asking for future issues when you have parallel mainline tracks with opposing polarity of the tracks. Any crossings or crossovers further ahead will cause reversing polarity problems 2) there may be a polarity issue at the crossover you show depending on how it is constructed.

DonV


Wil Davis
 

What you show is not a problem depending on whats on the other end.  If it is a standard loop everything is fine.  If they come together at a turnout you have a reversing loop.

Just my .02,
Wil


jmartin26@...
 

Thank you all. That was my original thought but then I think I read too much and got thoroughly confused. I read another message just before I posted this that seemed to confirm as well but since I could not locate the pictures to go along with the post I decide to ask just to be certain. 

 


Lawrence Varady
 

Don't mean to hijack this topic but I have similar question on AR1 requirements and wiring for this diamond crossover.

https://groups.io/g/w4dccqa/album?id=269711

Thanks


Lawrence Varady
 

Here is some info:
I would like help on determining how to wire AR1'(s) for my layout.
I am using an Atlas 2564 DEAD FROG crossover.
I will not be running any lighted cars or more than a 2 Loco consist thru this crossover.
Crossover track colors indicate Power Districts, BUT all power is from an NCE Power Cab system, no boosters.


Don Weigt
 

Hasn't this been discussed before? I know I've looked at that track plan previously...

You are making this more complicated than needed. But, there is no "right" answer. There are several choices, depending on track lengths, train lengths, how many trains will be on the layout, how many moving at any one time, and how you want to run trains.

Terminology: The 2564 is a CROSSING, not crossover. It has fixed routes, no moving parts, no points, only four frogs. The two routes through the crossing probably are isolated from each other. I say probably, because the Atlas website has so little technical information.

You can test if the two routes are isolated. Temporarily power one route through the crossing, run a loco there to test it, then without changing where the power is connected, try running the loco on the other route. If the loco has power on both routes, then the two are connected electrically, and will limit the wiring choices.  You can also check this without power or a locomotive if you have an Ohmmeter and know how to use it. Test that you have continuity when you touch the two meter probes together, and both to the same rail, then test that the rails on one route through the crossing are not connected to the rails on the other route.

I'd wire the entire layout without any reversing, except I'd insulate both rails of all four tracks where they meet the two turnouts on the right edge of the simplified drawing. Connect that right side part or left side of your layout, whichever has the fewer trains running at once, to your auto reverser and you're done.

If you have a "nested" auto reversing section in the right side, then fix that track phase (hard wire to your track power) and put the auto reverse on the left half of the layout. In that case, I'd wire the crossing tracks to the right side of the layout, and gap both rails of all four tracks going to the two turnouts on the left side of the drawing, to have more track with fixed phase and less auto reversed.

Ideally, you want as much track fixed phase as practical, and as little auto reversed as needed for the way you want to run your railroad. So, if those crossing tracks are as long as you longest trains, or if all the cars have plastic wheels so you only need to worry about power to the locos, then fix the phase of the entire layout EXCEPT the two crossing tracks from the turnouts at the top to the turnouts at the bottom, gapping both rails of those tracks where they connect to the turnouts. You should only need one auto reverser for the two routes, unless you really intend to have one train entering one route while another is passing through the other route.

So, you have choices to make. Think about how you want to run your trains, which choice gives all or most of what you want with the least complexity. Build your railroad, wire it that way, and run it.

You probably will find how you run your trains will change over time. I'd suggest waiting a while before scenicing everything, in case you decide to modify which parts are auto reversed and need to change where the insulated gaps are in your rails. One way to avoid or minimize that, is to gap both rails anywhere you may later want reversing tracks to meet fixed power phased tracks. You'll need more track feeders that way, but it will save you work and annoyance in the future, should you decide to change how it's wired.

And one last thing: test, test, test! Don't build the whole railroad, apply power for the first time, and try to find any shorts or other problems. As soon as you have your first block or section of track down, power it up and make certain it works. It's fun to see trains move on new tracks. Every time you add more than a few feet of track or turnouts, test again. Then, if a problem is found, it's probably in the small amount of trackwork you just added. You don't need to spend a lot of time looking at other parts of the railroad.

Don Weigt
Connecticut

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Don Weigt
Connecticut


Jim Betz
 

Lawrence,
  A crossover, in an of itself, does not constitute a reversing section.  The only way to know if you
have a reversing section is to take a car and "run" it over the layout thru all possible paths (can
be done virtually on your plan).  If the car can come back over the same piece/section of track
going the other way then you have a reversing section (more than one?).  Even then the cross
over doesn't have to be the reversing section (it can be much larger and somewhere else).
  Although the AR-1 is made by NCE ... if you are going to run sound, lighted passenger trains,
or consists ... you will probably prefer the PSX-AR to the AR-1.  The AR-1 was designed a LONG
time ago and before the advent of sound and does not do well for trains that are drawing more
current.  Even if you don't intend to run any of the above ... if I were you I'd still use a PSX-AR
because once you've run a couple of sound locos you are unlikely to "go back".  ;-)
                                                                                                                                    - Jim in PNW