The thing is, most reverse loop examples show the most trivial kind - the diverging leg of the turnout loops back to the straigh tleg of the same turnout. Ineed on such a simple arrangement it would be impossible for one train to enter at the same time another was leaving - or even impossible for having a train longer than the loop, unless you really like to smach your trains up.
Most people wuickly recognize such arrangements as reverse loops. But in the realities of a more complex layout design, you can sneak in a reverse loop and not initially realize it. A more complex track arranagment that just so happens to have one path where the direction of the train can reverse back on the same section of track it came from is a reverse loop evne if most of the time the trains take an alternative route, and needs to be planned for. Those can actually be some of the hardest ones to configure, becuase technically the 'reversing section' may be very small - but then you have the clear possibility of longer locos and cars with metsl wheels crossing the gaps on both ends at the same time.
Wyes are the same way. Yes, include one of the turnouts and theoretically there's no way two locos could occupy the same track, crossing both ends of the isolated section at the same time, unless they were on a collision course. But - what if instead of a simple single track around one leg this was actually a larger section of the layout, with maybe even a passing siding in the middle? Then you could easily have a train entering from both ends at the same time, in a completely legitimate operation.
That's why such tricks as drawing the plan with both rails and coloring each one differently without lifting the pen are useful. If the red rail runs into the black rail - you have a reverse loop somewhere. The tricial designs pretty much sort themselves out. The more complex ones - that's where you need to plan it both from an electric perspective AND an operation one.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
WardR What happens if 2 locos go over different reverse loop gaps at the same time, you will have a short? Isn't this why reverse loop gaps are cut at a turnout, so theres no way of 2 locos entering same time?
What happens if 2 locos go over different reverse loop gaps at the same time, you will have a short? Isn't this why reverse loop gaps are cut at a turnout, so theres no way of 2 locos entering same time?
Sometimes, it is poor planning. Sometimes it is unavoidable. Two locos will enter or exit or simultaneously enter and exit the reversing section. Or, a single train will both enter and exit the reversing section at the same time. The result is a short.
Rich
Alton Junction
RoadCopper Also re main bus wire Q&A, I ran it basically as a loop under remaining track just to shorten the length of feeder wires up to tracks. I know wire is costly but I think shorter feeders is also important.
Also re main bus wire Q&A, I ran it basically as a loop under remaining track just to shorten the length of feeder wires up to tracks. I know wire is costly but I think shorter feeders is also important.
Good point, RC.
Gents - thanks for the input. I will likely only be running one loco at a time so length is smaller. I know that size matters....
I took Rich's idea and have pulled main bus wire out from under that section, run new bus wire of different colours only under that loop section.
I think I will add double gaps at all locations as suggested as I am using Kato Unitrack and can isolate using their gap joiners easily.
Andy
Yes, that's correct. Fewer gaps are easier to install and keep track of. And if the only trains being run are ones with a single locomotive that fits within the reverse section, then it should be ok. That's why it's important to know the length of the reverse section vs the length of the powered eqipment to be run.
David
db200 Rich, Actually, when you look at RoadCooper's diagram, it has a wye, with one leg of the wye completing the reverse loop. The best place to put double gaps is on each end of that leg (the track with the circle above the double circle). This assumes that any locomotive consists or strings of powered rolling stock - lighted passenger cars, etc. - will not be longer than that leg. If there are plans to run powered equipment that may bridge both gaps at the same time, then the double gaps will have to be placed somewhere else. But putting the gaps somewhere else may mean having to add several sets of gaps, not just two sets as described here. That's why placing them on that one leg is best. If any powered equipment to be run will fit entirely in that leg, no other gaps are needed. David
Rich,
Actually, when you look at RoadCooper's diagram, it has a wye, with one leg of the wye completing the reverse loop. The best place to put double gaps is on each end of that leg (the track with the circle above the double circle). This assumes that any locomotive consists or strings of powered rolling stock - lighted passenger cars, etc. - will not be longer than that leg. If there are plans to run powered equipment that may bridge both gaps at the same time, then the double gaps will have to be placed somewhere else. But putting the gaps somewhere else may mean having to add several sets of gaps, not just two sets as described here. That's why placing them on that one leg is best. If any powered equipment to be run will fit entirely in that leg, no other gaps are needed.
David, I agree that would work with just two sets of gaps, but the reversing section appears to be so short that reverse polarity problems might still occur as a long train crosses gaps at both ends.
Although my arrangement calls for four sets of gaps, it does leave plenty of room for longer trains.
I am not sure what you mean by "best" by placing the gaps on only one leg unless you are suggesting that it is easier to keep track of fewer gaps.
To answer RoadCooper's questions:
Q1) You can connect the bus wire as a loop, but there's really no need to. It would kind of be a waste of wire. If you think about it, that's what the rails on the track sometimes do - they form a loop, so it's ok. But you need to think of the power bus as a tree - the main bus wires are the trunk and the feeders are the branches that go out to where the rails are.
Q2) Yes. Connect the main bus to the rest of the loop, if you place the double gaps as described above (at each ends of the track with the circle above the double circle).
Q3) The input to the AR1 is from the main bus wires as described in the instructions. If the reversing section is fairly long, then the output wires can be installed similarly to the main bus - that is, with a larger gauge wire with several feeders going to the track. BUT NOTE that the output of the AR1 should only feed the reversing section and it MUST be isolated from the rest of the layout. Hence, the double gaps must be placed at each end of the reversing section as described above.
RoadCopper Being a newbie to layouts, wiring, trackwork and such, all this is so intimidating. I have another dilemma as part of this whole reverse loop issue. I am running a DCC system from an NCO ProCab. I am using Kato Unitrack. I have the Digitrax AR1 Reversing Decoder ready to be hooked up. Here are the questions (and bear with me, I am new to this...someone once said only the question NOT asked is stupid!) Q1) Main bus wire - can it be installed as a loop that joins back on itself or just should it go out and end at the other end and be capped off with Marrettes? Q2) As one above said, the main bus goes to the AR1 per the instruction sheet. But do I connect the main bus elsewhere in the loop? As I write this, I think not but not really sure. That would defeat my AR1, correct? - Not sure if I can explain my layout trackwork but here I go. My mainline runs in a returning loop that will eventually become a full around the room loop. For now the benchwork does not extend that far, so it is more or less point to point. As the loco goes on the mainline moving e.g. EASTWARDS it comes to the main loop at a switch. If it takes the left wye, it enters my loop. It travels into the llop (there is one small stub siding for industry there) but then as it rounds the loop it is now heading WESTBOUND at the bottom of the loop. It has not reversed direction at this point. It then encounters a switch as is comes out of the loop - it has two options at the switch. Option 1 is to stay on the left wye and continue on to the end of the line as it stands today to the current end point. Taking the right wye here would create a reverse loop. Option 2 is to enter the right wye and immediately can then take another left wye to enter a passing siding. NOTE: Still no reverse in direction yet. If it was to take the right wye at this point, it enters back to into the loop where it could go round and round forever if I choose. Note that I could use this as a backing up point as you will see in a minute. Option 3 is just past the Option 2 switch where at the switch it takes the left wye where it is now heading back to the original entering switch or Option 1 and it becomes the reverse loop to change direction back to the entry mainline track going the opposite direction. (If I can attach some drawings, I will). Q3) So the main question here is where to install the insulating rail joiners and where do I attach the AR1? HELP !! BTW - my LHS suggested I go with the DCC and Unitrack to speed layout and trackwork construction. It did that but created other issues. He is not the best at explaining in newbie terms how to get it all working.
Being a newbie to layouts, wiring, trackwork and such, all this is so intimidating. I have another dilemma as part of this whole reverse loop issue.
I am running a DCC system from an NCO ProCab. I am using Kato Unitrack. I have the Digitrax AR1 Reversing Decoder ready to be hooked up.
Here are the questions (and bear with me, I am new to this...someone once said only the question NOT asked is stupid!)
Q1) Main bus wire - can it be installed as a loop that joins back on itself or just should it go out and end at the other end and be capped off with Marrettes?
Q2) As one above said, the main bus goes to the AR1 per the instruction sheet. But do I connect the main bus elsewhere in the loop? As I write this, I think not but not really sure. That would defeat my AR1, correct?
-
Not sure if I can explain my layout trackwork but here I go. My mainline runs in a returning loop that will eventually become a full around the room loop. For now the benchwork does not extend that far, so it is more or less point to point. As the loco goes on the mainline moving e.g. EASTWARDS it comes to the main loop at a switch. If it takes the left wye, it enters my loop. It travels into the llop (there is one small stub siding for industry there) but then as it rounds the loop it is now heading WESTBOUND at the bottom of the loop. It has not reversed direction at this point.
It then encounters a switch as is comes out of the loop - it has two options at the switch. Option 1 is to stay on the left wye and continue on to the end of the line as it stands today to the current end point. Taking the right wye here would create a reverse loop. Option 2 is to enter the right wye and immediately can then take another left wye to enter a passing siding. NOTE: Still no reverse in direction yet. If it was to take the right wye at this point, it enters back to into the loop where it could go round and round forever if I choose. Note that I could use this as a backing up point as you will see in a minute. Option 3 is just past the Option 2 switch where at the switch it takes the left wye where it is now heading back to the original entering switch or Option 1 and it becomes the reverse loop to change direction back to the entry mainline track going the opposite direction. (If I can attach some drawings, I will).
Q3) So the main question here is where to install the insulating rail joiners and where do I attach the AR1?
HELP !!
BTW - my LHS suggested I go with the DCC and Unitrack to speed layout and trackwork construction. It did that but created other issues. He is not the best at explaining in newbie terms how to get it all working.
Road Copper emailed me a copy of his track diagram which I am including here with his consent. This is the right side of his layout. I drew circles to identify the locations of suggested rail gaps. The double circle locates the point of reverse polarity. Any other suggestions?
Seeing the track plan I would still not isolate the sidings but feed them from the reverse loop bus, not the main bus. You are just introducing several more areas where the AR-1 has to interact when metal wheels cross the gaps. As I said in my earlier post, I don't separate the sidings from the reverse loop bus and I don't have any problems. I keep about 5-6 sound locos on these sidings.
-Bob
Life is what happens while you are making other plans!
RoadCopper Probably - give me an email to send it to.
Probably - give me an email to send it to.
Road Cooper,
Check the Conversations section of the Forum. I sent you a mesage and an email address.
CSX Robert PennCentral99: I don't think Rich was referring to me to post a pic, but here's an artist's misconception (crude drawing) of my reversing section.... The black lines are fed from the main. The red lines are the insulated rail joiners. The green section is the reversing section controlled by the AR1. The black dash line is the power from the main to the AR1, the green dash line is the power from the AR1 to the reverse section. As per other posts, I did not need insulated joiners at 2 & 3, but this is how I did it and never had a problem. BTW, this track plan/layout has been dismantled. I moved and have a 10' x 10' room where I will be building a 2-level, around the room, 24 inch shelf layout with a new track plan. I am glad you haven't had any problems with your layout wired like that, but here is why it is better to not wire the spurs and sidings to the main bus. You can not have metal wheels cross two reversing section boundaries that are of oppostie phase at the same time. By having spurs or sidings that connect to the reversing section connected to the main bus you increqase the chance of this happening.
PennCentral99: I don't think Rich was referring to me to post a pic, but here's an artist's misconception (crude drawing) of my reversing section.... The black lines are fed from the main. The red lines are the insulated rail joiners. The green section is the reversing section controlled by the AR1. The black dash line is the power from the main to the AR1, the green dash line is the power from the AR1 to the reverse section. As per other posts, I did not need insulated joiners at 2 & 3, but this is how I did it and never had a problem. BTW, this track plan/layout has been dismantled. I moved and have a 10' x 10' room where I will be building a 2-level, around the room, 24 inch shelf layout with a new track plan.
I don't think Rich was referring to me to post a pic, but here's an artist's misconception (crude drawing) of my reversing section....
The black lines are fed from the main. The red lines are the insulated rail joiners. The green section is the reversing section controlled by the AR1. The black dash line is the power from the main to the AR1, the green dash line is the power from the AR1 to the reverse section. As per other posts, I did not need insulated joiners at 2 & 3, but this is how I did it and never had a problem.
BTW, this track plan/layout has been dismantled. I moved and have a 10' x 10' room where I will be building a 2-level, around the room, 24 inch shelf layout with a new track plan.
I am glad you haven't had any problems with your layout wired like that, but here is why it is better to not wire the spurs and sidings to the main bus. You can not have metal wheels cross two reversing section boundaries that are of oppostie phase at the same time. By having spurs or sidings that connect to the reversing section connected to the main bus you increqase the chance of this happening.
Yeah, I agree. It will work either way, but it would be better to include those two sidings or spurs as part of the reversing section. That could be easily done by removing the gaps at 2 and 3. If only the gaps at 1 and 4 are retained, that would be sufficient to completely isolate the reversing section including the sidings and spurs.
Incidentally, if that were done, then any feeder wires to the tracks forming the two sidings ot spurs would need to re-routed to the output side of the AR-1 rather than to the main bus wires.
PennCentral99 I don't think Rich was referring to me to post a pic, but here's an artist's misconception (crude drawing) of my reversing section.... The black lines are fed from the main. The red lines are the insulated rail joiners. The green section is the reversing section controlled by the AR1. The black dash line is the power from the main to the AR1, the green dash line is the power from the AR1 to the reverse section. As per other posts, I did not need insulated joiners at 2 & 3, but this is how I did it and never had a problem. BTW, this track plan/layout has been dismantled. I moved and have a 10' x 10' room where I will be building a 2-level, around the room, 24 inch shelf layout with a new track plan.
richhotrain HaroldA:I am adding a reverse loop to my RR which will eventually contain turnouts, sidings and other trackage within the loop. I am using a Digitrax AR1 to handle the polarity change. My logic is telling me that everything within the loop needs to be separate from the rest of the layout so my plan is to run a track bus from the AR1 to the loop then add feeders as needed to power everything in this section. Am I on, pardon the pun, the right track? The instructions are a little ambiguous. You are operating in DCC, correct? Rich
HaroldA:I am adding a reverse loop to my RR which will eventually contain turnouts, sidings and other trackage within the loop. I am using a Digitrax AR1 to handle the polarity change. My logic is telling me that everything within the loop needs to be separate from the rest of the layout so my plan is to run a track bus from the AR1 to the loop then add feeders as needed to power everything in this section. Am I on, pardon the pun, the right track? The instructions are a little ambiguous.
You are operating in DCC, correct?
There's never time to do it right, but always time to do it over.....
Power for the inner sidings come from feeders from the main bus. I didn't show that wiring, I was focusing on the reversing section.
Inspired by Addiction
See more on my YouTube Channel
So how do you get power to the inner siding? I see insulated joiners at "2" so is there a separate feed wire there? Same at "3"?
If you look at your layout here and considered the green section as my main loop, and considered your AR1 lines as my full main loop coming back into the mainline loop, it approximates my issue. Not sure if that makes sense. And going out the switch at 3 mimics my mainline towards your 'cola mine' but not joining it. And "4" is my passing siding.
Yes DCC using NCO ProCab
HaroldAI am adding a reverse loop to my RR which will eventually contain turnouts, sidings and other trackage within the loop. I am using a Digitrax AR1 to handle the polarity change. My logic is telling me that everything within the loop needs to be separate from the rest of the layout so my plan is to run a track bus from the AR1 to the loop then add feeders as needed to power everything in this section. Am I on, pardon the pun, the right track? The instructions are a little ambiguous.
RoadCopper Would love to post but don't know how. I have some jpgs of track layout
Would love to post but don't know how. I have some jpgs of track layout
Can you email them?
I have four AR-1s on my layout.
The wiring is fairly straight forward.
A pair of feeders from the main bus wires attach to the input side of the auto reverser. Any and all of the feeder wires from inside the reverse loop attach to the output side of the auto reverser. No feeders from the main bus wires should be attached to the rails of any track that forms part of the reverse loop.
Neither one of you probably want to hear this, but track diagrams would help immensely.
Can each of you post one?
HaroldA Thanks - going back to my original question - sidings and other track need to be isolated from the loop and powered from the bus coming from the booster and not the AR1. If I understand what you are saying, sidings powered from the AR1 will cause locos to changed direction - not a good thing. Makes sense.
Thanks - going back to my original question - sidings and other track need to be isolated from the loop and powered from the bus coming from the booster and not the AR1. If I understand what you are saying, sidings powered from the AR1 will cause locos to changed direction - not a good thing. Makes sense.
That's what I did for my reversing section and have not had any problems. I did not experiment with the sidings not isolated to see how the AR1 would respond. Another suggestion: it helps to place the gaps for the reversing section about a loco length away from turnouts (isolated frog). Also, depending on how much track is in your reverse section, you may need to install additional feeders so the AR1 gets a good "jolt" to activate.
However, according to farrellaa, his sidings and other track are not isolated and does not have a problem.
If the sidings are connected electrically only to the reverse loop they do not need to be isolated. The only sidings that would need to be isolated would be those that connect to the loop at one end and to he main at the other. In that case, they would need to be isolated from one or the other, your choice. But then these are not really sidings, they are crossovers. Phase (polarity is a DC thing) will be swapped in the sidings when the AR1 operates and match the loop phasing. Engines with decoders will not change direction. The decoder will make the engine go in whatever direction it has been told to go.
Engines without decoders will change direction so they really should not be used on a layout with DCC reversing sections. Once the phase is swapped in the loop, a DC engine sitting on a siding that is isolated from the loop will never be able to leave the siding.
Martin Myers