Wiring a auto reverser for a wye.

[Hawghead]

Got the wye installed just waiting for a couple of switch machines to finish the installation as I ran out of slots in my in my Octopus and I don't want to buy another one just for two servos.  Any way I know I'm going to need an auto reverser and am pretty sure I'm going to use the Digitrax AR-1.  What I'd like to know is how I need to hook it up.  Below is a drawing showing the AR-1 hooked up to the tail track and the AR-1 hooked up to one leg of the wye.  It seems to me either option A or B would work but I want to be sure. 

Thanks in advance,
Scott

[Hawghead]

Opps I just saw it.  Option B would only work going around the wye in one direction.

Scott

[nickelplate759]

Opps I just saw it.  Option B would only work going around the wye in one direction.

Scott

Not sure about that, but it depends on where your gaps are.  Is option B only powering the side of the wye between the two turnouts?
If so, it will work (add feeders where you have Option A), but as always remember that your entire train (or at least all the parts of it that conduct electricity) must fit in the block controlled by the AR1.   If both ends of your train cross the ends of your reversing block at the same time you'll have a short.
If you put the AR1 where you have Option A that can't happen - which in my mind makes Option A preferable.  It's one less mistake someone like me can make.

[peteski]

To me it looks like gaps are on both routes coming out of the turnouts. There are thin lines across those tracks.

[nkalanaga]

I had that same issue, many years ago, with straight DC.  All I did was insulate the trail track and its turnout from the rest of the wye, and connect a rotary DPDT switch as both electrical reversing and turnout throw.  The turnout was in a closet, a little awkward to reach, so it was thrown with fishing line and two fishing sinkers.  The large sinker pulled the throwbar to the normal position, the fishing line raised it when the rotary switch was turned, and the small weight pulled it to the new position.

In your diagram, "option A" would do the same thing, if the tail track and its turnout ere wired as a separate block.  Depending on how the turnout is thrown, you might be able to use switch machine contacts, or a manual switch, and avoid the auto-reverse completely.

[reinhardtjh]

I would go with Option A.  If it's truly just a tail track then you are sure that your train (engine) will fit wholly within the section being reversed and avoid the possibility of something shorting as George (NicklePlate759) points out.  Option B does not provide that guarantee.

[eric220]

If this is just an equipment turning wye, why not isolate on the diverging leg of both through turnouts and make the whole of the legs and tail track the reversing section? Also, unless there’s been a major redesign, I’d advise you to steer clear of the AR-1s. I had a malfunctioning AR-1 take down my whole layout.

[mmyers]

What switch machines are you using? The auxiliary connections on a Tortoise switch machine could be used to correct the phase. No AR needed. John Berger had a loop on his layout/module controlled this way. It worked perfectly.

Martin Myers

[Hawghead]

Thanks for all the help guys, (guys, can I still use that term?  )

Eric
Yes, the wye will only be for turning engines (one at a time).  You're saying eliminate the gaps in the diverging routes of the tail track switch and let the auto reverser power both routes coming out of the tail track switch from the tail track, correct?  I was going with the AR-1, because of all the electronic reversers it seemed the most simple to use.  Any thoughts on a better choice for the auto reverser?

Peteski,
Each of the turnouts will be isolated from the legs of the wye, I did it this way when installed it as I'd seen diagrams that said it was necessary and I figured if it wasn't I could always use additional power feeders.

George,
You're right it would work if I added jumpers to the tail track and the one leg of the wye, but if I can do it with just reversing the tail track then I'll go that route (KISS principle)

Martin,
In this area I'm using https://www.n3ix.com/quadln_s-loconet-servo-decoder-family/quadln_s-accessories_servos/ for two reasons.  One, I needed to offset the switch machine from the hole is the sub road bed because, as luck would have it the hole wound up right next to a cross member in the bench work.  These allowed me to mount the switch machine to the side and just put two 90 deg bends in the throw wire.  Additionally because they move the throw wire side to side instead of pivoting it, they're great for where the sub roadbed is very thick, like in this case where it's 1" foam over 5/8" plywood.

The next thing I'm wondering about is powering the frog on the turnout for the tail track.  The switch machine has a micro lever switch on it and I was thinking I could just make the inputs to that switch the output of the auto reverser.  That way when the tail track changes "polarity" the frog would also.

Thanks again,
Scott

[peteski]

Scott, Digitrax AR-1 is actually not fully electronic.  While there are some electronics on it, it uses a slow old-fashion relay (over 100 year old technology) to change the polarity of the track  output.   Most other brands use transistors for much faster parity change.  Those are fully electronic.  From what I read in the Interwebs, the AR-1 is not all that good in use.  Eric mentioned that in his post here.

If this is only for a single loco (short electrically live train), then if you are planning on using switch machines which also have an electrical switch built-in, you could get by not using a reverser at all. Also mentioned here earlier.

[John]

Don't over engineer this thing .. You can get by with one AR-1 .. either one A or B should work - put double gaps where I drew the black lines .. you also need to have power routing for the frog on the Y turnout

You could also just use a toggle switch if this is rarely used ..





https://dccwiki.com/Reverse_Sections

https://dccwiki-prod1382-images.b-cdn.net/images/1/14/Reversing-triangle.png

Application Example 2: Reversing Triangle or Wye
AR1 connected to reversing triangle

Whereas reversing loops are rare on full-sized railways, triangular junctions, or wyes are quite common. The AR1 can also be used for these. The triangle may connect to a separate line (as in full-sized practice) or may simply be a convenient spur siding.

A wye was often used to turn a locomotive where a turntable was not available.

The track feed connects to the AR1 input just as in the reversing loop case. The AR1 output feeds the spur. The two double gaps on the right (before the turnout) are essential to isolate the different power phases.

It is important to note that it is not possible to make any other feed connections to the spur other than via the AR1 unit.

The double gap on the main line marked with an asterisk () is required if the turnout has a live frog.

[eric220]

John and I are recommending the same thing.  Gap as shown, and the reverser will adjust the polarity to match whichever leg of the wye the locomotive is traveling over.

I'd use a solid state reverser like Tam Valley's.

[Hawghead]

John,

I think I'm gonna go with your suggestion and just let the tail track power the two legs of the wye from the output of the auto-reverser.  I will have to un-gap the frog of the tail track switch as I'd gaped it when I built the turnout.

Eric,

Thanks for the link, I didn't know that Tam Valley still made the dual frog juicer.  After the pandemic TVD stopped producing some of their products because of the supply problems and I thought the dual frog juicer was one of them.  Just ordered one to use as the auto-reverser.

Scott