I want to install a PSX-AR in a double track reverse loop. When using the loop, either track can be used as a siding. Do I need to install two PSX-AR or one will work?
Depending upon the exact track design and the placement of your gaps, one PSX-AR should be sufficient since it is unlikely that one train will still be entering the loop as another train is exiting the loop.
Just place your gaps inside and as close to the beginning of the loop as possible. Same for the turnouts which begin the siding inside the loop.
Rich
One reverser will get you by IF there would never be a chance of one set of gaps being crossed by locomotives OR cars with electrical pickups at the same time any of the three other sets of gaps were being crossed.
If your second track is strictly a siding you may not have to be concerned but if there were ever a chance of trains moving on both tracks simultaneously, sooner or later you will probably create a short that the auto reverser can not compensate for. In that case you would need an auto reverser for each track of the double track loop.
Passenger cars with lighting pickups crossing the gap will cause it to short as well if more than one gap were bridged so you have to keep that in mind, too.
Hope this helps, Ed
If it is unlikely to have a train on both tracks of the double track loop, why would it be double track? The fact that it is double track implies that it is indeed likely. If it is possible to have trains on both tracks at the same time I think you should use 2 PSX-AR’s.
You don’t need electrical pickups to trip the AR. All you need is a metal wheel.
I’m just sayin’ if you run passenger trains they will bridge the gap (85 feet worth!) and they will short IF they happen to be bridging the exit gap at the same time a train may be crossing the entrance gap.
I agree with you that if this is truly double track then two ARs are called for.
Rich is making a point that without any kind of track plan to look at we are just speculating here.
#1 rule in using any auto reverser. Only one set of gaps can be crossed at a time.
Thanks, Ed
Good point.
Is it like A or B? A needs only one AR, B needs 2.
My best guess is that he is referring to his reverse loop as shown in A.
That was the basis for my initial reply.
Rich
If it is, indeed, a double track entering the loop, which we don’t know without further comment or a track plan from the OP. From his original post, it sounded to me like a single track entering the loop then branching into a siding around and inside the loop.
If, instead, it is B, then where are the crossovers placed to make one or the other track a siding?
Rich
While not directly relevant to the OP’s question, it points out how sometimes you want to change the square hole to a round one if you only have a round stick to put into it[;)] In other words, careful design often used for DC control offers a few advantages if this will be a DCC powered layout while limiting the possibility of conflicts described above already. Some thought needs to be given to how the OP intends to use the loop.
In a case like this, I recommend using track design to limit the possibility of having two sets of gaps crossed at the same. Here it’s example A. While two trains might be moving within the reverse loop behind the gaps, it’s physically impossible to cross two sets of gaps because there’s only one set.
That’s how my Chama staging loop is set up. The loop is big enough so it’s seperated into 4 blocks, with each loop track being gapped internally to the loop. This is because I built for DC control originally.
Depending on the available visibility and other goals for such an arrangement, making it one way helps further limit the possibility of conflicts. In my case, the loop is hidden under the main part of the layout and monitored by CCTV. There I made the exiting turnout from the siding that brings the two tracks back together power routing to feed the two blocks that lead to it. That way motive power can’t advance to the second block in each track unless that turnout the merges them back together is set to allow the train to pass. Alternatively, you can run trains into those tracks when they are dead and use that for a safe, no-spark “capture zone” that’s very helpful if this was DC and still useful with DCC.
I am the only one who operates the Chama loop, so all the power switches are conventional “throw and stay” type. If it was going to be operated by multiple people with less experience and habit than myself, then making the power switches spring-loaded so they must b
Hi,
I understand that my question lacked precision. Here is the exact sitation:
Actually the Turtoise that controls Switch A determine the polarity of the loop. Turtoise that controls Switch B will allow the current on one track or the other (remmant of the DC wiring).
So my questions are :
Can I keep the wiring as it is (allowing current on only one track at a time)?
Do I need one or two PSX-AR?
If only one PSX-AR, should I place it between switch A and the gap?
Thank you.
You can not keep the wiring as it is. The PSX-AR has it’s own requirement.
You only need one.
It is not placed “between” anything.
You will need both rails of both tracks gapped just past switch A before the other two switches. Your DCC bus will feed the main, and the PSX-AR will attach to the bus and feed the loop. Whenever a gap is spanned (creating a short), the PSX-AR will detect the short and switch the polarity of the loop to match. It will also throw the Tortoise to line up in the direction the train is comming from. You don’t care which way the switch is thrown when you are entering the loop.
The two loops are concentric, and don’t cause a conflict in phase/polarity where they meet their access points; the two turnouts. You could have this arrangement at each end of a loop of track and you wouldn’t need a reverser. So, when already inside the potential conflict zone, the one turnout that forms your reversing loop, there is also no conflict for the two sidings. Therefore, as Carl says above, you only need to worry about the conflict, and that takes place ‘west’ of the two tracks and their turnouts, where the loop pinches. That is where you need your gaps. The single reverser will reverse all the tracks, including the siding, when it detects a fault.
I understand that:
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I leave intact the gaps East and North of A;
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I bridge the two gaps North of B;
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I wire the PSX-AR on both rails immediately South of B;
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I discard any other wiring.
Thank you everyone.
I don’t see why you only want power to one track at a time.
But that aside, you only need one PSX-AR and only two sets of gaps, one set at each end of the turnout that forms the loop.
Everything inside those two sets of gaps is wired to the output side of the PSX-AR.
Rich
Rich,
In my last reply, I indicated that I will probably bridge the gaps North of Switch B then feeding both tracks simultaneously. Beside that, I like to use the blocks inherited from my previous DC wiring. Almost all the insulated blocks are automatically controlled by a Turtoise switch machine, some with toggle switch. The locomotives I don’t intend to use during a session can then sit on an unpowered section of track. In fact It saved me a lot of reprogramming when I inadvertently made some programming on “programming track mode” on the main.
If I had wired the layout for DCC in the first place I would have probably made different choices but I am happy with what I get as I get the best of both world.
Guy,
In your diagram, I can see that you’re set-up is nearly identical to mine, down to the need to convert it from DC. I’ll explain a little bit more as to why it makes it easier to operate for staging by making it one way. As far as I can see, other than perhaps a minor relocation of gaps, all the wiring can stay the same.
First of all, my reversing section is ONLY the track with Tortoise A and the arm that reaches towards and through Tortoise B (including both power-routed extensions leading to it), powered coincidentally enough thru a PSX-AR. I’ll call the first, “loop” turnout past A as Tortoise C and it is also part of the reversing section.
Tortoise B is also in the reversing section but the gaps for it are however far you make them into the loop with the power routing feature of the contacts.Your diagram shows them relatively short and close to B, but on my loop they’re actually about half way around the loop so much longer than in your diagram.
Thus, I used the Tortoise’s contacts at Point B end only to switch power on the two tracks that lead into it. That creates the “capture and emitter” half of the loop.
I gapped the loop internally about half way around it. You have probably already done that with your DC wiring in some fashion so that if the Turnouts C and B are set to different tracks it won’t short. But gaps are easy enough to move if they need to be adjusted. The main issue is to make the distance between wherever you locate the gaps BEFORE the train gets to B and BEFORE the train enters/exits the loop at A longer than your longest train.
The contacts on Tortoise C are used just far enough to get past the frogs. Presuming that you already have leads to the two tracks leading out of C, simply cutting a set of gaps right past it (if not already present) and hooking up the remainder of the first half of the loop to full time power now that you’re on DCC will set it up as the “receiving” end
If the Tortoise for A is already controlling the loop polarity, you don;t even need the PSX-AR. In fact this is the PREFERRED way to do it - rather than have a short automatically corrected by the device, prevent the short in the first place. To avoid dropouts of sound, and also to keep the Tortoise from handling too much current, have the Toirtoise contacts drive a relay.
Even the gaps at the bottom can stay, and Tortoise B would control which track was live, same as it does now. But all power feeding this must come fromt he relay on Tortoise A.
Yes, this is a contrarian view, but I see no reason why it wouldn’t work. And save the cost of a PSX-AR. This is a ‘simple’ balloon loop, with the extra siding inside it, which really doesn;t change anything. For such loops, you can avoid the short altogether by controlling the loop track polarity through the switch motor.
–Randy
Another alternative is to use a PSX-AR and forget about the Tortoises on the two turnouts inside the loop by just using Peco Electrofrog turnouts. You can throw the points with your finger and keep the inner loop unpowered when the points are set for straight through.
Rich
There’s something I’m missing about using the Tortoise contacts to reverse the loop polarity.
Of course, as the train enters either leg of the loop rail A must be ++ and rail B must be – now once the train is fully in the loop, you are going to throw the switch and the Tortoise is going to change the polarity on what? The loop is occupied by the train. You don’t want to change that polarity. You want to change the polarity of the remainder of the layout since you just made a westbound train out of an eastbound train and it is still moving forward.
From what I see the train will continue around the loop but when it encounters the main line rails you will have the short. Or am I missing something?
The old Atlas controller had an east-west switch. The trick was that the polarity DIDN’T change while the train was in the reversing section but you changed the polarity of the rest of the layout (or the cab that your train was assigned to) in old DC days.
I have three reversing sections on my layout. 2 use the PSX-ARs and one has a Digitrax AR-1 and they all work “seamlessly” in the background without even thinking about them.
Just curious, Ed