Another Reverse Loop Question

Discussion in 'DCC & Electronics' started by jesso, Mar 20, 2008.

  1. jesso

    jesso Member

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    Ok, I know, I know, another reversing loop question.

    I am making up my layout and I wanted to know if this would work. This diagram isn't quite the same shape and scale but it works out the same. Is it possible to get this diagram to work with DCC? Where would I put insulted rail joiners and which sections do I wire together?

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  2. steamhead

    steamhead Active Member

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    Hi....The two "angled" sections between the lower & upper tracks (on either side of Inglenook) need both rails at both ends to be insulated (I am supposing that off to the right the upper & lower tracks join at some point). These need their own power feeds via an automatic reversing controller or a DPDT reversing switch. The rest of the layout can be wired as "one".
  3. Chesticus

    Chesticus New Member

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    First of all, the last post is correct. You can block off the two angled sections of the layout and put in reversing loop modules. That having been said, I have the same basic concept that you have, and I have been having troubles. You might want to go and read my post "reversing loop problems" and see what some of the people there have been saying.

    Some of them are saying that if you are going to block off these two sections, you do not want the train length to be longer that the length of the blocked off sections. If you are like me this may be impractical. But I am still working on it.

    But even with all of the troubles, it really is a cool way to run trains

    Chesticus
  4. Gary Pfeil

    Gary Pfeil Active Member

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    Actually, you do not have to make the two angled sections reverse blocks. This is the first reaction from those of us who are used to dc wiring. However, if you wire the two parallel tracks connected by those angle sections in the same polarity (ie, both north rails black, both south rails white) then just the curve at the left end becomes a reverse block. This section is often much easier to make a train length long. Assuming that at the other end of the layout the top and bottom "mains" are connected by another similar 180 degree curve, that one is a reverse block as well. This is how I wired my layout, in order to have crossovers whereever required without having polarity problems. I hope this was clear.
  5. 60103

    60103 Pooh Bah

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    You could make a single reverse block containing the two angled sections, the two turnouts that join them to the upper track, and a length of the upper track each side of those turnouts, to make up your train length.
    But I would probably go for running the reverse block around the loop at the left end. Probably from the left turnout on the angled bits around to the turnout "to lower level". Include the whole of the turnout "to upper level", i.e. gaps beyond the frog on the curved track, but neither of the turnouts at the end of the block.
  6. Gary Pfeil

    Gary Pfeil Active Member

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    Another thing to keep in mind: A dcc reverse block can extend in length to include parts of other routes which are not themselves part of a reversing section of track. The fact that a train traverses a section of track controlled by a reversing module even tho it is not running thru the part of that block that actually reverses a trains direction will cause no problems. If polarities match across gaps, the module does nothing. The only thing to remember is that you want the reverse section to only ever have one train at a time crossing it's boundaries, to prevent flipping the polarity back and forth, just as can happen when the train length is too long.
  7. jesso

    jesso Member

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    I guess I should have included more. The entire layout will be a continous loop where this is just one side of it. It will eventually be a u-shaped layout. In fact this section won't be the first part, but this section will be where the reversing could happen, the other side of the layout will have no way to turn around a train.

    If I made this loop on the reversing module, i believe then the rest of the layout would have to be a reverser as well, if I understood Gary correctly. Wouldn't that make the wiring on the rest of the layout fairly difficult?

    Also, am I understanding that a metal wheel crossing over the insulated rail joiner is the problem? Does anyone make longer insulated rail ties or do people hand make ones that work better?
  8. Gary Pfeil

    Gary Pfeil Active Member

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    Not the rest of the layout Jesso, but another section, most likely the other "end". My layout is probably schematicly similar, I have a double track main with turnback loops at each end, essentially a circle. The loops are reverse sections, and the double track between are wired with the same polarity so crossovers do not present a change of polarity. So each end can change polarity, but the track between does not.

    Yes, any metal wheel crossing a gap where the rail has opposing polarities is a problem. As has been written here and the other threads, it is possible to make a reversing section longer than a train, you just extend the block to include enough trackage to accomodate the train. Obviously, if the reverse loop comes back to the same turnout it entered, the train can't be longer than it. In other cases, you can extend the block.

    I just recently installed Tony's power shields on my layout. I tend to buy stuff long before I actually use it, when I pulled out my power shields bought years ago, I found a reversing unit as well. It does also protect in the same manner as a power shield, so I used it as one, not needing the reversing function. So, you could use a reversing module for each block of your layout if you so desired, but why spend the money. I do think tho that the power shields and reverser units are close in cost, but again I bought mine years ago, when they were still Tony's, not whatever they are called now. Pretty sure they are still Tony's but were always made by NCE and now maybe someone else? Or given a new name.

    Let me know if this all makes sense!
  9. jesso

    jesso Member

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    Ok, here is the rest of the layout (shortof) as I am a little confused as to where to block it out. Yes I know it is quite the spaghetti bowl, but I like spaghetti. I guess my main problem is that I am still in a DC frame of mind.

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  10. Gary Pfeil

    Gary Pfeil Active Member

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    Nevermind what I said before. Because of the arraingement on the bottom part of your plan, I feel the best place to put a reversing section is centered at the back to back turnouts on the top track, yjr diverging routes of which are the tracks you label reversing lines. The one reverse block will include both reverse lines, and a portion of the main (top line) extending as far as the longest trrain you will run, in both directions.

    The problem will be that the non reversing section nect to the reversing section needs to be longer than your longest train too, as one route you can run will lead right back to the reverse section. My scanner isn't working or I would post your plan with gaps to make it easier to understand what I'm trying to say.

    I would gap at the bottom of the right side revese line, before the turnout at the bottom. If you are running a train down that line from the top main to the bottom and then around the right end loop to go back from where you came, the next gaps need to be before the turnout at the top which you had just run thru. The section of track around the right end loop need to be atrainlength long, but not a reverse block. The left side reverse line will not have gaps before the turnout at the bottom, but rather extend on the bottom main as far as your longest train. It can include all the turnouts on that bottom main. The trailing point turnout which goes to what looks like a yard should be gapped on the diverging route. The next two turnouts can have gaps placed a train length away from the gap to the right of the turnout on the top. A drawing would be priceless!

    Bottom line is this: The top loop needs to be three blocks, all a trainlength long. If your drawing is near scale, it looks like the shortest block, and therefore the one which dictates train length, will be the right side turnback section. It's maximum length would be from the right hand side of the turnouts on the top track, around the loop to the gaps in the right side reverse line. So a similar length block on the left side loop would do. All the rest of the trackage on the main circle can be the reverse block, don't worry about the fact that some trains running thru the reverse block are not using the two tracks you labelled reverse lines, it just doesn't matter.

    Hopefully someone else might post a drawing for you.
  11. Gary Pfeil

    Gary Pfeil Active Member

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    Hi Jesso, Got my scanner working and thought I'd post your drawing marked up. Don't know if you've already solved your problem satisfactorily. I drew in some gaps, I called two of them "X" and two others "Y" You have two reversing tracks, the two diagonal lines on the top oval. Since they can not be used at the same time, you can make them into one reverse block. I noted just 3 blocks as A, B and C You can of course go on and divide the remainder of the layout into blocks as you wish, or not. For the purpose of this discussion, B is the reverse block, and A and C are blocks to either side of it. Note that block A is seperated from the rest of the layout by the reverse block (except for the connections to upper and lower levels)Therefore, while you must be sure to wire the balance of the layout (the lower oval) correctly (note the 1's and 2's written around the plan to indicate polarity)which rail is 1 or 2 in block A won't matter, as it abuts the reverse block. However, those connections to other levels must match thise levels.

    OK, basically you need to be able to gap the blocks in such a way as to make all three blocks a train length long. Since the plan is not to scale, you will probably need to move gaps one way or another. But notice that travelling from one gap X to the other must be atrain long, but can include trackage not needed for reversing a train. When you run though this trackage (block B trackage) with a train not reversing itself, it will not cause any problems. Also, going from gap Y to the other gap Y must be a trainlength long. Blocks A and C must be a train long too.

    I hope this all makes sense.

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  12. Gary Pfeil

    Gary Pfeil Active Member

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    Note that to the right of the bottom gap X I have drawn two gaps to isolate the yard area, which is part of block C. These are essential, but gap X itself can be moved to the left to include the turnouts to other levels if you need the length. Just gap the diverging routes as I did in the yard. The same thing holds true with the upper gap Y, it can move left to include that turnout. But make sure block A remains a train long.
  13. jesso

    jesso Member

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    Thank you for doing the diagram. Ok, I understand what you are saying on where to block it, but I am still trying to unlearn my DC thinking on this. Here is my thoughts as I am still confused on it. A train is traveling on the outside track of block C heading towards point X. The train goes through the middle of block B towards the other point X. As it crosses into Block A wouldn't the polarity of A be the opposite direction? I am sorry that I am such a nooby on this.
  14. Gary Pfeil

    Gary Pfeil Active Member

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    As the train crosses the gaps into block A, block B changes its polarity to match that of block A. What a reverse module does is change the polarity of its block to match that of any adjacent block you cross into. That is the reason we keep saying the block needs to be a train length long. Otherwise, wheels crossing gaps at both ends at the same time cause the module to flip back and forth.
  15. jesso

    jesso Member

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    Ok so when the train goes from a to b, the reverser changes the polarity of b. When it goes from b to c, correct me if I am wrong, the reverser changes the polarity of b again to what c is and since it is dcc, the train continues in the same direction? Am I understanding that correctly? Hopefully this is my last question. Thank you for putting up with me.
  16. jesso

    jesso Member

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    I was just looking at my track plan and both A block and B Block will easily be over a foot longer than any yard track or siding, so your idea works into the plan great. Thank you!
  17. Gary Pfeil

    Gary Pfeil Active Member

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    Yep, you got it. Block B will always have its polarity changed to match whatever block you are entering/leaving. If the polarity already matches, the reverser does nothing. If the reverse module you choose works properly, you won't ever notice a thing.
  18. 60103

    60103 Pooh Bah

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    Jesso: the polarity of the track in DCC has nothing to do with loco direction -- loco direction is determined by the chip in the loco.
    If your trains are just gong around the oval, the polarity of the reverse loop will be the same as the oval. If you have a train crossing one of the diagonal lines, you don't really want one coming around the other way. The reverse section should only get flipped when a train exits it (and get flipped back by the next train through).