I have designed this HO layout attached and know that I have one (or two?) (or more?) reversing loops. I plan to use the digitrax AR1 http://www.digitrax.com/products/autoreversing/ar1/
but can not figure out where I need to gap and insulate and where to wire the AR1s. Any help in figuring this out is VERY much appreciated!!!!
Many thanks!
Bernard
You have several choices and since what you have posted seems to be a schematic rather than a scale drawing, it's hard to say where the best place to put the gaps would be. You could put them where the + signs are or you could put them at both ends of the crossover tracks. If you do the former, the end loops are the reversing sections. If you do the latter, the crossovers are your reversing district. How you plan to operate your layout should also figure into the decision as to where to place the insulated gaps to create the reversing sections.
edit: You could get by with just one reversing district if you put insulating gaps on the top between the end loops and the crossovers. You would also need to an insulated gap in each of the crossover tracks. Again, how you intend to operate the railroad could dictate the choice of where the reversing section(s) should be.
I agree with jecorbett. Tell us what the dimensions of that track plan are. A lot depends upon the length of those straight runs.
Each crossover is a reversing section, but you could gap it so that both crossovers are one reversing section.
As jecorbett points out, the two end loops could be the reversing sections, but this will require different gapping and a different placement of the feeder wires.
We need to know more.
Rich
Alton Junction
Thanks for your comments and yes this was a schematic. Sorry should have be clearer. This ais a part of a much larger layout. Each 'loop' is 30 feet+
The concept was to be able to bring trains in on the north main and switch on the south main so that they came back out on the north track. Is this doable?
Gaps should go just below the lowest turnout enclosed by the circle and just below the curved turnout in the lower right corner on the other end of the loop.
However, it might be a good idea to move the second set of gaps to the left, down around the curve, if you intended to ever use that section of the main for a switching lead.
Mike Lehman
Urbana, IL
OK, what you have is a dogbone which is what I have. My end loops are stacked and I have staging yards within the loops, but schematically and electrically it is the same. I simply gapped off the entrance and exit for each loop. That creates two reversing sections. Unless I am misreading your diagram, it looks like you have only one place where there are crossovers. You could create a single reversing section there. You would gap both the crossover tracks and then on one main or the other, place another gap some distance (at least a train length distance) from the crossovers in both directions. The track within those gaps is your reversing section. From your diagram, the simplest thing would be the main nearest the aisle. Keep in mind if you ever add crossovers elsewhere, that is going to create another reversing section. Since I have a number of places on the layout where there are crossovers, the simplest thing for me was to make the loops the reversing section.
jecorbett's right. I missed the top left loop.
However, I wouldn't make the reversing section at the crossovers for it. I would put them way over in that loop itself in the upper left, long enough to hold the longest train. That way everything in between doesn't need to deal with the reverser cycling all the time.
Thanks! So do I have one or two reverse loops and do I need one or two AR1s?
I say two.
I think the AR1 is like my PSX ARs and will support more than one reverse loop provided only one train crosses gaps at a time. I have a narrowgaueg line to support, but yours looks more like mainline running. I think such a restriction is likely to impact your ops. However, presuming the AR1 is like my PSXes, you could temporarily wire it to both, then later on add the second. Just be careful to use it properly in between.
mlehman I say two. I think the AR1 is like my PSX ARs and will support more than one reverse loop provided only one train crosses gaps at a time. I have a narrowgaueg line to support, but yours looks more like mainline running. I think such a restriction is likely to impact your ops. However, presuming the AR1 is like my PSXes, you could temporarily wire it to both, then later on add the second. Just be careful to use it properly in between.
Great. I will get 2 AR1s.... as I plan to have multiple operations and trains.
Now I am afraid that I am still not at all not clear as to where to gap and wire them?
At this point only the bottom loop section to the turnouts is built. I am working my way up and over. I want to add the AR1s sooner than later and can add them into the bottom section now. If they go at the loop in the top left then I'll have to wait.
Can anyone help with more specific locations to gap and where to put the AR1s?
Before I answer that question, let me ask what brand of turnouts you intend to use. The reason that matters is that some brands, like Walthers(Shinora), have to be insulated at the diverging ends so you could kill two birds with one stone and put the insulated gaps at the nearest turnouts to the loops. If you are using Atlas which has insulated frogs, it doesn't much matter. I might still put the gaps where the turnouts are. There is nothing wrong with a reversing loop being fairly long.
For this section (including the turnouts as shown on the Schematic and circled in RED) it is all atlas code 100 and the turnouts that create the switching between the two mainlines are Atlas #6s. For the rest of the layout it will all be code 83 and i was planning on using Peco Insulfrogs.
I'm not too familiar with Peco but if the frogs are insulated, they should work like Atlas.
With that type of turnout, you have a lot of flexibility as to where to put the gaps. You want to make certain the loop is going to be longer than the longest train you might operate so that one end isn't exiting the loop while the tail end is still crossing the gap at the entrance.
You need an insulated gap both going into the loops and exiting from them. Looking at your plain, on both loops, I would put the gaps somewhere between the loops and the nearest turnout, both entering and exiting. Just don't make the reversing section too short. Longer is better. If you think you might someday add a crossover track near either loop, those crossovers can't be part of the reversing section. In that case you would want the gaps closer to the loops.
Yes, Peco Insulfrogs are like Atlas and are not power rotuging and provide power through all legs. No gaps needed for the turnouts, so gap placement for the loops is going to depend on train lengths.
Electrofrogs are power routing and need gaps on the diverging frog rails.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I read through this thread very quickly, so I may be forced to retract everything that I am about to say.
But I only see a need for one AR-1.
First of all, you need gaps between the connecting turnouts of each crossover. That will prevent shorts caused by reverse polarity.
Now, each mainline can operate straight through without any difficulty. However, as soon as a train crosses over from one mainline to the other mainline, a short will occur. To prevent a short, place gaps further up and down on the left side mainline, far enough apart so that the entire longest train is inside the gaps. The reversing section becomes the left mainline between those gaps on the mainline and the gaps dividing the crossovers. The green circles represent the gapped rails.
So, only one AR-1 is needed. Use Atlas turnouts if you can because they are already gapped and they are not power routing.
If you use Peco turnouts, use Insulfrogs since they are already gapped, but they are power routing, so additional feeders may be needed to avoid dead sections of track. Avoid Peco Electrofrog turnouts if at all possible. I have nothing against Electrofrogs, but they do require more gapping and more wiring.
To wire the AR-1, run a pair of feeders from the bus wires to the input side of the AR-1. Any and all feeders from inside the reversing section should be connected to the output side of the AR-1. No feeders inside the reversing section should be connected directly to the bus wires. No feeders from outside the reversing section should be connected to the AR-1.
Thanks Rich. I think this actually may make sense to me...Finally! So to recap... I have a dogbone style layout with two loops (one top and one bottom). Only the bottom has a crossover between the two. I am running DCC and using Atlas turnouts. You are suggesting that one AR1 gapped as per your diagram should work. One question.... Is it the length of track BETWEEN the north gap in the left mainline and the south gap in the left mainline the area that needs to accomodate the length of a train?
trafficdesign Thanks Rich. I think this actually may make sense to me...Finally! So to recap... I have a dogbone style layout with two loops (one top and one bottom). Only the bottom has a crossover between the two. I am running DCC and using Atlas turnouts. You are suggesting that one AR1 gapped as per your diagram should work. One question.... Is it the length of track BETWEEN the north gap in the left mainline and the south gap in the left mainline the area that needs to accomodate the length of a train?
The length of the reversing section needs to take into account the possibilty of a train crossing over from the right side mainline onto the left side mainline. This would be true with trains moving from north to south as well as trains moving from south to north.
Edit Note: This would also be true for trains moving in either direction from the left side mainline to the right side mainline. So, the proper way to locate the left side mainline gaps is to measure from the gaps placed in the middle of the crossover.
Say that your longest train will be 10 feet. The left side mainline gaps should be placed 10 feet away from the crossover gaps in either direction.
jecorbett OK, what you have is a dogbone which is what I have. My end loops are stacked and I have staging yards within the loops, but schematically and electrically it is the same. I simply gapped off the entrance and exit for each loop. That creates two reversing sections. Unless I am misreading your diagram, it looks like you have only one place where there are crossovers. You could create a single reversing section there. You would gap both the crossover tracks and then on one main or the other, place another gap some distance (at least a train length distance) from the crossovers in both directions. The track within those gaps is your reversing section. From your diagram, the simplest thing would be the main nearest the aisle. Keep in mind if you ever add crossovers elsewhere, that is going to create another reversing section. Since I have a number of places on the layout where there are crossovers, the simplest thing for me was to make the loops the reversing section.
jecorbett raises an interesting point. If you ever decide to add another crossoever up or down the mainline in the future, you would create another point of reverse polarity. So, you need to think ahead here.
Considering the overall design of your track plan, I don't see where or why you would later add more crossovers, but if that is a possibilty, then you could adopt an alternate wiring plan and treat each end loop as its own reverse loop. That configuration would require gaps at the entry and exit points of each loop and an AR-1 for each reversing loop.
In that case, where each loop becomes a separate reversing section, there would no longer be any need to place gaps between the turnouts that make up each crossover. There would also be no need to place gaps in the left side mainline up and down from the crossovers. However, in that instance, all of the feeders outside of the two end loops, must be wired the same way, in phase, to prevent dead shorts.
If I were you, I would just treat the two crossovers and the adjoining section of left side mainline track as the reversing section, and that would only require one AR-1.
THANK YOU Rich. I will do exactly as you suggested and make the left main the reversing section. I do not anticipate adding more crossovers as the goal was to turn trains as they came out of my fiddle yard (near the south loop).
There is NO problem with creating mainline gaps 10 feet south of the gaps in the turnouts, but will there be a problem gapping 10 feet north with the current track arrangements and turnouts?
BTW you have of way of explaining things that I understand. I really appreciate your clarity.
i admit i have no experience with auto-reversers and am puzzled why the lower end of the dogbone loop isn' t isolated and treated as the reversing section instead of isolating just a section near the turnouts.
Wouldn't moving the insulated gaps at the bottom of the figure to the other side of the main (really just further way, around the dogbone) make the entire lower dogbone part of the reversing section? The top most gaps can also be moved closer to the turnouts (possibly between the turnouts) which would keep the wiring shorter (see 2nd edit comment below).
i tried illustrating this. In the figure i put a slash through the insulated gaps that should be moved and added an orange dot to where they should be moved to. Similarly the red slash and dot indicate where i think the top insulated gap could be moved to.
(how would you isolate things if there were just one cross over)?
edit: added 2nd figure
edit: moving the top insulated gaps shown in the figure on the right would result in a short without additional gaps.
it appears that each crossover requires a reversing section. The reversing section for each has no common track with the other. But because of the way Rich positioned the gaps, both reversing sections can be controlled as one! Hats off to Rich!
greg - Philadelphia & Reading / Reading
I'm not going to disagree with Rich that this can be done with a single reversing section, but I do want to throw a caveat in to think about. It doesn't ncessarily mean you shouldn't put the reversing section in the middle, just consider if it will work with your ops as envisioned...
The thing about automatic reversers is they tend to like one train in the reversing section at a time. If you get more than a single train, either entering or leaving, things can get confused. This is usually not a problem with loops, as they tend to be at the end of the line and thus tend to get trains one at a time simply by virtue of that location.
A reversing section right in the heart of the busiest part of the layout might be a handicap when trying to observe the one train at a time rule, even if long enough to accommodate the longest train. This is because that train will have to enter or leave the reversing section and no other train can enter the reversing section until it's completely clear of the previous train to avoid baffling the reverser.
If that sounds like a limitation, it may be a case for going with two reversers and using a section of the loop at each end for the reversing section instead. If it doesn't, then Rich's solution will save you a few bucks and work just fine.
trafficdesign There is NO problem with creating mainline gaps 10 feet south of the gaps in the turnouts, but will there be a problem gapping 10 feet north with the current track arrangements and turnouts?
What is the distance from the center of the top crossover to the turn west at the top of the track diagram?
And how long will your longest train be?
greg, you could it the way you proposed but what I would be concerned about with that arrangement is the greater possibility that two trains would be inside that bottom reversing loop at the same time, or on entering as one is exiting. The reason for my solution is that the reversing section would be just long enough for one train and without the practical possibilty of another train entering or exiting the reversing section at the same time.
If there were only a single crossover, he would need three sets of gaps instead of four.
mlehman I'm not going to disagree with Rich that this can be done with a single reversing section, but I do want to throw a caveat in to think about. It doesn't ncessarily mean you shouldn't put the reversing section in the middle, just consider if it will work with your ops as envisioned... The thing about automatic reversers is they tend to like one train in the reversing section at a time. If you get more than a single train, either entering or leaving, things can get confused. This is usually not a problem with loops, as they tend to be at the end of the line and thus tend to get trains one at a time simply by virtue of that location. A reversing section right in the heart of the busiest part of the layout might be a handicap when trying to observe the one train at a time rule, even if long enough to accommodate the longest train. This is because that train will have to enter or leave the reversing section and no other train can enter the reversing section until it's completely clear of the previous train to avoid baffling the reverser. If that sounds like a limitation, it may be a case for going with two reversers and using a section of the loop at each end for the reversing section instead. If it doesn't, then Rich's solution will save you a few bucks and work just fine.
Mike, I think in the OP's situation, there is a greater likelihood of two trains in the reversing section if it is one of the loops, as I indicated to greg. In my proposed solution, trains can pass each other on the mainline without any issue since only the one on the left side mainline would be entering or exiting the reversing section. On the other hand, it is not likely that one train would be entering the reversing section, as proposed, while another train is using one of the crossovers because of the possibility of a collision. This would be particulary true if the reversing section were just long enough to accommodate the longest train. I would not be concerned in the least placing the reversing section in the heart of the mainline.
rich
i think your solution is best.
The top and bottom insulated gaps can be moved further away, but moving them all the way around the loops back to the turnouts just creates a too short "non-reversing section".
i guess there's nothing to prevent two trains crossing the reversing section gaps creating an impossible state for the auto-reverser.
I think this is much easier to understand if there were only a single crossover.
Rich,
My thoughts on this were because I wasn't sure about what the planned ops were. I was thinking of a train using one of the crossovers while another train was pulled up close to use the other pair of switches. It would have to stand well back of the turnouts or it would be in the reversing section depending on which line the trains were on.
Then there was future ops. The top part of the layout seems well-developed, but I wondered if the sparseness of the lower right area and the loop back to its left was due to the intent to use it for expansion later. That might add track to the area to the left of the crossovers that might result in complications with the reversing section being adjacent. But that's future/unknown stuff and one can always rewire and cut new gaps if needed. Your solution works for the current track arrangement in that area.
gregcI think this is much easier to understand if there were only a single crossover.
greg,
Very true, but then you would only have reversing in one direction.
mlehman gregc I think this is much easier to understand if there were only a single crossover. greg, Very true, but then you would only have reversing in one direction.
gregc I think this is much easier to understand if there were only a single crossover.
And that would be bad because?
mlehman Rich, My thoughts on this were because I wasn't sure about what the planned ops were. I was thinking of a train using one of the crossovers while another train was pulled up close to use the other pair of switches. It would have to stand well back of the turnouts or it would be in the reversing section depending on which line the trains were on.
Mike, I do see your point, and it is valid. I will take the liberty to expand upon it. A train traveling south on the right side mainline has now completed the bottom loop and is headed north on the left side mainline about to crossover onto the right side mainline. A train headed south on the left side mainline would have to stop before crossing the uppermost gaps to avoid conflicting the AR-1 as the northbound train crosses the gaps on the lower crossover.
That said, safety rules would mandate that the southbound train on the left side mainline not get too close for fear of a head on collision. So, the OP should mark the mainline gaps with signals or other markers so that trains do not proceed beyond that point.