I am thinking about purchasing a DCC system. I have a decent sized DC layout I want to convert to DCC for my father for the ease of not dealing with what switch to flip for the reverse loops. My system has a reverse loop at each end of the layout. One is more of a switching yard the other is just a straight up reverse loop.
Im trying to wrap my head around how the reverse loops work?
Does the polatiry change only in the reverse loops or does it flip the main track?
It was hinted upon when I sent a diagram to a reseller that I really need to remove a reverse loop to work properly.
Just wondering,
Rodeoboy38
Rodeoboy38Does the polatiry change only in the reverse loops or does it flip the main track?
It depends on how you wire the layout and reverser(s) up. If you had two reverse loops separated by say a single track mainline, you could wire it up to the mainline so the polarity reverses on the mainline. But normally you would use one reverser for each reverse loop, and just wire them up so the reverse loop tracks are the ones that reverse polarity.
The big difference with an automatic reverser and doing it with a toggle switch is the automatic reverser reverses polarity in a fraction of a second. As soon as the engine's wheels enter the reverse loop and the detector senses a mismatched polarity, it flips the polarity in the reverse loop without the engine's progress being affected. Same way when leaving the reverse loop; if the polarity doesn't match, it changes it immediately.
Not to change the subject ,but will the auto reverser work with straicht DC?
Thanks T.C.
Rodeoboy38 Im trying to wrap my head around how the reverse loops work? Does the polatiry change only in the reverse loops or does it flip the main track?
The answer to your question, does the polarity change only in the reverse loops or does it flip the main track?, is determined by where you treat the location of the "reversing section(s)".
Not all loops are reversing loops unless the loops fold back onto themselves. For example, in a "dogbone" layout, there is a loop of track at either end of the layout with a mainline in between, but neither loop folds back upon itself, at least not at the very end of the loop. So, in that instance, the mainline could be the reversing section if you so choose.
Once you choose whether the mainline or the loops become the reversing sections, the polarity only flips inside the reversing section, but never in the non-reversing section. This is accomplished by gapping each reversing section to isolate it from the non-reversing section and wiring the track inside the reversing section to the auto-reverser.
Rich
Alton Junction
T.C. Not to change the subject ,but will the auto reverser work with straicht DC? Thanks T.C.
No - none of the DCC autoreversers work with DC. Period.
You CAN make a DC autoreverser, but the problem is the polarity controls the direction that the train travels in, so with DC you change the main whuile the loco is in the loop. OK - sounds simple - but any other train already on the main will suddenly reverse. Fine if you are only running oen train at a time.
There are commercial DC reversers - usually work via ir beam break sensors across the track of the loop. When the beam is broken, it triggers the device to flip the main polarity so the train can exit the loop.
The method of handling a reverse loop with DC works fine with DCC - it's just that DCC has easier (and easy to implement automatic) methods.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinkerThere are commercial DC reversers - usually work via ir beam break sensors across the track of the loop. When the beam is broken, it triggers the device to flip the main polarity so the train can exit the loop.
I will have one reversing section on my DC layout.
The track plan and operating scheme will call for the train to stop when it is on the reversing section to always set out or pick up a freight car. I have found planning a situation like this into the operating scheme makes the reverse loop operation pretty simple.
Stop the train. Your first reverse is done with the polarity switch for the reversing section. All subsequent direction changes are done with the throttle direction switch.
Then when you pull out of the reversing section the polarity will be correct.
This is the least obtrusive way I have found to handle a reversing section on a DC layout.
-Kevin
Living the dream.
Interesting thread.
Here's my question.
If the mainline is, in essence, the reverse loop any DCC locos running on mainline are NOT affected. Correct?
I like this idea, if so, as the mainline is plenty long enough for any length train I may run. My trains usually run longer than a simple return loop blob.
danno54 If the mainline is, in essence, the reverse loop any DCC locos running on mainline are NOT affected. Correct?
danno54My trains usually run longer than a simple return loop blob.
Unless all your cars use plastic wheels, you'll want to be sure your train isn't exiting the reversing section while part of it is still entering it. Metal wheels can bridge the gaps, causing problems.
Rodeoboy You've come to a great place to ask questions. I thought I had reversing loops figured out then asked a question here and it is now simpler than I thought.
I don't think anyone has mentioned that an auto-reverser has limited power available inside its controlled section. So, the size of the reverse loop should be kept relatively small. Yes, you can wire your whole layout to be inside the reverse section, and only the actual loop outside it, but you may run out of power in the main layout.
Some DCC systems allow you to run a DC locomotive as "Engine 0" while maintaining most DCC functionality. You will find that the DC engine will not traverse the reverse loop, though. It may short out at one end of the other, or it could actually ping-pong between the ends.
It takes an iron man to play with a toy iron horse.
As Digital Specialties explains in their instructions for the (no longer available?) PSX-AR of 14 years ago, you can create staggered double gaps at each end of whatever length of track you decide to reverse (it can be anything, anywhere). As long as the pairs of gaps are spread sufficiently to encompass an entire rolling stock truck that has pickups (Walthers heavyweight passenger cars come to mind), you can have a reversed section of pretty much any length. Anywhere.
So, I hope our OP understands that he can elect to reverse either loop, both loops, or the mains between them, as he sees fit. If he elects to reverse only the main, whatever happens inside the loops remains in the loops, and the reverser will only act to deconflict phase incompatibility when the lead item crosses whichever pair of gaps and meets the incompatiblity.
Thanks for the replies to my question, I think I will stick to my toggle switches for now. My layout isn't that large and I have LED'S to tell me if the current is correct.
T.C.
T.C. Thanks for the replies to my question, I think I will stick to my toggle switches for now. My layout isn't that large and I have LED'S to tell me if the current is correct.
Schematic of the track plan helps - unroll all the curves that are there for looks or because there is a wall in the way. And/or use two color hilighters to trace over each rail on the plan and if the two colors end up in contact then you have a reverse loop.
The two sided car is great when the track is already laid, and pretty obvious when you run it around the layout.
With a single track main, it's usually not difficult to find a reverse section that was created. With double track - some people make the track plan way more complex than it needs to be. Rather than 2 reverse loops at the ends of each main, just loop them together and put a crossover. The you end up with just the two end loops as reversing sections, and you can add any number fo crossovers along the main and never make another reverse section. It usually the most efficient use of available space as well - as Armstrong demonstrates in Track Planning for Realistic Operation. Loops take a lot of space, especially with larger more realistic curve radii. So rahter than waste 2x space, stack the loops one on top of the other and get 2x loops in 1x space.
Thanks for all the replies. Im glad it sparked some conversation on the subject. Now I'm pretty confident that I can leave my reverse loops in without issue.
Thanks to all,