Hey guys - I’ve been a lurker for many a year now, and have gleaned much from the wisdom that abounds here. With some outside help, and with the advice and thoughts I’ve read on here, I’ve put together a track plan that is actually in the final stages of construction - I have about 50% of the roadbed and track laid. And it just dawned on me that I have a return loop in my layout! [D)]
If possible, I’d like some clarification on the decision I’ve made regarding where I need to insulate for proper operation. I’m running (or will be running, I should say) DCC, and so obviously an auto-reverser is now in store as well. The section that I’ve indicated is the section marked between the 2 red dots, and that’s the track that I think I should isolate and connect the auto reverser to. It’s also approximately 36 inches in length, and from my understanding of how reverse loops work in DCC, the length should be sufficient for the engine consists that I’ll have.
Your thoughts are greatly appreciated! (And while I’m not explicitly looking for advice on the layout itself, any other generally constructive thoughts you may have would be welcome.)
Next, you have correctly identified the reversing loop. My only thought would be that if there is a lot of traffice in that section (since it’s near the yard) is that you may want to move the reversing section over to another part of the loop. If it’s a light traffic area in its current location, you could leave the reversing section where it is.
Third, I like the track plan. Looks like you built it for train watching and making/breaking trains.
Your upper dot should be on the diverging route of the turnout just above it. There is no reversal between your two dots…the reversal takes place between the lower dot and where I think you should place it. Between the two dots the polarity stays constant on each rail. If you place the upper dot two tracks higher, you will see that the reversal actually takes place, running clockwise, when the train meets that one turnout.
You are right that the reversing loop needs to be as long as your longest consist. But to play it safe I think it needs to be as long as you longest train. Why? If you want to use a pusher or if you will run cars with metal wheels there is a possibility that one locomotive is over one end of you reversing block and a car wheel (or the pusher) is over the other end. The locomotive and the car wheel will connect the blocks with fixed polarities to each other via the reversing block and the boosters over current protection might shut down. If the last car is a pusher it will most certainly do it.
My suggestion is to have the reversing block between the two switches above the upper dot and move the right switch to the right so a complete train will fit in between the switches.
Just my [2c]. I haven’t had any use for a reversing loop myself so I can’t verify this in real life.
After i wrote the above I took another look at your layout and found that the real reverse loop is the outer track in the loop to the left of the dots. Use the whole or most of that loop as a reversing block.
Nof has it right. The loop needs to be longer than your longest train. A metal wheel on the caboose is sufficient to bridge the gap, and if an engine is crossing the other gap at the same time, you’ve got a short which the auto-reverser can’t resolve.
I would move the right-hand dot up to the diverging route, and the left-hand dot to the left another 3 feet, and put it on both tracks just on the loop side of that first crossover. If you’re using the main there as part of the yard, though, where you might have an engine backing out of the yard, it might be better to move the insulators all the way over to the left side of the loop, again on both tracks. This will avoid the problem of a conflict between a train entering the loop at the top and a switcher pulling out of the yard at the same time at the bottom of the plan.
Interesting. I hadn’t considered making it as long as the longest train. But I see why that makes sense. So taking the advice here, I have two options, and both options involve moving the insulation on the right hand side to the the diverging path of the upper switch. I can then either have the insulation at the beginning of both curves, or just after the crossover. Here’s an image of what my options are:
I believe I’ll have roughly 150 inches of track if I go from the blue dots to the diverging route on the switch. That’s a little over 12’, which means a couple of engines and approximately 10 or 11 cars, depending on length? And going with the “blue” option seems to make more sense, as you guys pointed out, for switching operations in that lower yard.
Thanks for the tips, gentlemen! I appreciate it! I’m sure I’ll be back for more as this progresses.
If you look carefully, you will see that both turnback loops are actually reversing loops. At first I was going to suggest adding the crossover that would make the upper turnback loop a reversing loop for extra operating flexibility, but I see that it’s already there - just past the entrance to the lower reversing loop, by the red dot.
Since you actually have reversing loops at each end of your dogbone schematic - a common thing to do - you can wire each loop as a reversing section, or you can wire the common center portion as the reversing section for both loops. The first is simpler to understand, the second takes less wire
Another thing in favor of using 2 reversers in this situation is the circuit-breaker feature. I’ve got 2 Tony’s PS-REV units from www.tonystrains.com. Tony has an updated reverser now with a different name, but they are fundamentally the same. I can’t speak for all reversers, but the PS-REV’s also include a circuit breaker. This effectively isolates the loop from the rest of the layout, and thus allows you to keep running trains elsewhere if you develop a short in the loop. This is useful both for operations and for troubleshooting. FYI, everyone who has Tony’s reversers seems to like them. For one thing, they’re all solid-state, so they respond quicker than those reversers that are relay-based.
Fred, I guess I’m still not seeing it. I see the split you’re talking about right beneath the left hand dot (the switch to the immediate left of the bottom most yard line, right?), but those two rail lines converge in the upper right corner of the layout before getting to the upper loop. I can’t see how I can reverse a train in the upper loop. Am I still missing it?
Though, I do see the wisdom of having the capability to reverse a train in both loops, and is likely something I can easily add, if I don’t already have it.
The crossover beneath the left hand dot does in fact complete the reversing loop at the top of the layout. The 2 lines do not converge in the top right corner, but in fact become opposite parts of the top left turnback loop. Trace the lines carefully.
I was originally going to recommend that you add a crossover in the top right to allow this reversing, but since you already have the capability, you may want to leave well enough alone. As it stands, your 2 reversing loop entry points overlap each other. You cannot go directly from one reversing loop to the other, which is probably a good thing.
Oh! I see what you’re saying now. That’s super tricky - without being intentionally so! Thanks for your patience in helping me understand where it was. Now I’m totally lost at where to insulate. I’m not opposed to running lots of wires, but seeing as how I’ve had a hard enough time realizing, and then finding, the return loops, simpler is probably better. I’m assuming the blue dots I placed earlier are still accurate. How would you recommend insulating the top loop, seeing that that loop is potentially very large? Or is it fairly simple and I just essentially insulate the top looping, somewhere around the 9’ vertial mark on both sides of that loop?
I am going to disagree with everyone but you. I was told by someone aobut 4 years ago on how to find a reverse loop/track. I had to print out your picture to check it for sure. What I did was start a the top of your layout and traced along the outside of the track like I was running my finger on the outside rail.
As I come around I stay on the outside all the way around the layout. That outside track is just one big loop. Then I started on the switch on the right where it comes from the outside track towards the inside track. I followed this down to where it meets the outside track again and it is just like a passing siding.
Now comes the tricky part. I started again on the rail just above the right red dot and took the inside loop, tracing my finger on the outside rail. As I follow it around it matches up with the inside rail after the left red dot (LD).
If you take the switch that is 2 away from the LD and travel to the outside loop this is just like a passing siding. If you take the switch 1 away for the LD the outside rail is still the outside rail which is like a passing siding for the outside track.
Where you have your 2 Red Dots is the only section that is reversing. If you insulate it at that location then it will work.
Try what I have done and you will see it. This is the only sure way to know where reversing section are unless you run and engine around.
I recommend the latter. KISS. There are ways to use just a single reversing section, but it must include the entry turnouts for both reversing loops, and must be a train length long. It would take some analysis to determine where to put the boundaries and insulating points. Again, I recommend just isolating an appropriate length of each loop and calling it good! I believe (could be wrong) Tony’s solid-state DCC auto-reverser has terminals for 2 separate reversing sections built in.
I have scanned a copy of your trackplan, without the shading colours, and added two red and three blue dots. The reds afford you a nice long loop for one of your two concentric reversing loops, and the three blue dots afford you either a longer or a shorter reversing loop on your outer loop. But there are two, and they are effected at the turnouts beside which the rightmost dots are placed. Trace them out with two fingers simulating the left and right rails, and you will see what I mean.
Believe it or not, you’re both right. However, the key here is to recognize that both of what we’re calling “reverse loops” traverse that short section between the original red dots. Remove that section, and you break both of the reverse loops.
However, from a practical standpoint, you can’t do that. That section is just too short. I’ve got a short crossover reversing section on my layout, and I have trouble with it every time I run a passenger train with illuminated cars. And my section is longer than the original between-the-dots one under discussion.
So, I’d go with 2 reversers, one where the blue dots are, and the other one on the top loop. The top loop is so big that the placement is pretty arbitrary.
Reversers, by the way, can handle a lot of track and locomotives. I think Tony’s are rated at 5 amps. So, don’t be afraid to put passing sidings, industrial sidings and even whole yards on your reverser circuit.
The outside loop does not reverse. There is no way that a train on the outside loop will ever get on the to the reversing section unless it backs up onto a track that takes it to the reversing section.
Every time I look at this thing I see something else. Anyway, yes, the outer loop is a reversing loop after all. Look way up at the wye junction at the upper right corner. Note the orientation of the power on the left and right rails. Now continue on the outer loop, around the curve, and come back to where I have the blue 2. At that point, it has effected a reversal, even though it has not closed with its oncoming route. Trace it and see. It is tricky, but because the loops travel elecrically in the same direction, due to the way one enters either loop, when the two tracks converge, both have effected a reversal. Even now, I still get a nagging doubt, but my fingers tell the story. Either that, or that early wye is going to be problematic. It really depends on how you orient yourself electrically at that wye. The inner track, to its left, is going which way? And if so, how does that diverging track from the wye get oriented in the loop and back at the turnout where I have the blue long. Or, how about the turnout to its left, since one of us thinks the power orientation is contrary on those two loops beginning way back at the wye. We can’t have it both ways is what I am saying.
I thought I would interject a couple of thoughts into this very interesting discussion…
First, just because you have to reverse to change direction doesn’t mean there isn’t a reversing section. It is just a wye in disguise.
It is just as valid to put the reverser on the part that seems not to be the reversing section, and it could be a big piece. The objective is just to prevent shorts.
Now I’m going to see if I can figure out how I would try to handle it…
There is only one reversing section on this layout. Technically it is between the two red dots. It has been stated that it would be wise to have a longer reversing section. I will agree with that.
To get a longer reversing section you will need to have one end where the left red dot is. You will also need insulated rail joiners at the track connection just below the same dot on the other leg of the switch. The reason for this is the track that connects here is aligned the same as the outer loop which runs the entire outside track which does not reverse. When it goes through this switch it changes polarity based upon the other track which is coming from the outside track but changes polarity at this point. You will also need insulated rail joiners on the next switch traveling right to left from the left red dot on the leg that joins the inner loop and the outer loop for the same reason as above. The other end of the reversing section should then be right before the sidings/spurs.
These locations for the insulated rail joiners will prevent any shorts because of reversing.
I think I have a way that works ok, but my head is hurting, so I could be wrong [:P]
I need four sets of gaps to isolate the section:
Anywhere between the two red dots.
On the short section below the left hand red dot.
On the crossover to the left of the left hand red dot.
Anywhere on the inner loop at the bottom left, between the crossover in #3 and the turnout where the inner and outer loops join. Where kind of depends on train lengths. Try to figure where it work to be least likely to have one train enter and exit at the same time, or even two different trains. Remembering that there are four ways into and out of the section.
