I am new to DCC and am building a new layout. I am confused about the locations of gaps in the track. I have three crossovers that I know are creating a reverse loop, depending on how they are thrown. I have attached the layout. Crossovers are at A, B and C. The gaps I am going to place are at D locations. Most of the blue mainline curves are 30-32"R for reference. I could use some input on other gap locations. Thank you.
The only time you create a reversing condition is when crossover "B" is reversed. The other two do not. So I suggest you put gaps at either end of the single track, and in the middle of crossover "B" (between the two switches) to make that your reversing section (remember it needs to be long enough to accomodate your longest consist/train if rear cars draw current).
Thank you. Crossover "B" was where I thought the reversing section was created, just was not sure about the other crossovers. So, let's place gaps in the middle of crossover "B" and then gaps 6-8 ft each side of that crossover making two separate sections. Then which sections would get auto-reverse module(s)? One of these or both?
OK. I just read the reply again. We are only talking about one section, not two. My mistake. Does it make more sense to have a particular end of the single track gapped, over the other end? I am thinking of gapping the east end.
I should have said each end of the single track. You will need 3 gaps in this case - each end of the single and in the middle of the crossover. The single track is your reversing section.
Now I understand. I would be placing the gaps at the ends of the single track, at the head ends of the turnouts. Can the gaps be placed after the turnout at one end, as long as both tracks at that end are gapped? I could gain a few feet of reverse section if I gap somewhere after the turnouts.
You could do that. I would place the gaps somewhere logical, such as right in front of the C crossover. That way if you have a train waiting on one of those tracks while another is reversing, you know it's all in the reverse section if it's clear of crossover C. (I gather you are using metal wheels on your cars? Otherwise this would not be necessary and probably disadvantageous.) Finally, in the "advice you didn't ask for" category: Why not face crossover B in the opposite direction. That way you would be able to reverse trains moving either direction, rather than having two reverse loops that go the same direction. Just saying...
Welcome to train board edfeets, just looking at your track plan and I see that there is another reversing loop besides the one that Harron points out. The red track makes a reversing loop at the lower right. This will require rail gaps at the entrance to the loop and the exit from the loop. That is, gap the diverging track and the straight track so that the whole loop is isolated from the rest of the layout and controlled by an auto-reversing module. The blue track is a similar proposition, the crossovers at A and C do not need gaped but you do need to gap B in three places as Harron suggests. This will split your layout into two blocks. I would also gap the rails between A and C on the outside track opposite the crossover at B just to be on the safe side. It will make wiring easier, e.g. the left loop controlled by: Main wiring buss, the right loop controlled by: Auto-reversing buss. I hope this helps. Another observation, trains travelling in a clockwise direction can reverse direction but trains travelling in an anti-clockwise direction must backup through the crossover to change direction. Just my own opinion, but I would like to run trains and reverse them in either direction. That aside I like your track plan, it looks like a lot of fun.
I agree with Cleggie in that there is at least two reversing loops. I also think you maximise the operating capability if you think of the main loop as being two reversing loops back to back. Because I am making it more complex I have drawn a picture to explain my thoughts. I see the option to make 4 blocks (see diagram as 1-4). Block 1 is the new reversing loop which Cleggie described. Block 2 is to allow one train to traverse the single line from B south towards C. Block 3 is to allow one train to traverse the single line from "z" towards B. Block 4 is everywhere else. This enables trains to operate throughout the layout and lowers the chance that a train parked awaiting access to B would sit on top of a gap and short across it. If you only have a single train or convince yourself that you wont park trains on the gaps then you wont need to break the layout into so many blocks. Also if you are using metal wheels on your trucks I would suggest that you ensure that all trains (engine plus all trucks in the train) can fit entirely within a block else the gaps will be shorted at one end of the block by your engine and at the other end by a truck. This means that block 3 needs to be lengthened (perhaps by moving the transition from single to double track back towards "z"). However if all the wheels are plastic (and you never buy the next new "must have" with metal wheels) then forget this paragraph. This seems good advice to me as well. In essence a really interesting problem - I hope I havn't made it more confusing. enjoy your layout - it looks great.
Chas, I think you are making it more complicated than it is. As we described, the simplest way is to put a gap in the middle of the B crossover and create one reversing block on the left side of it.
Ok, I think I need to make this clear and point out where the problem is in your crossover, why and where you need to gap the track. Firstly, the crossovers at A and C don't need gaps and here is the reason why. Provided you wire up your parallel tracks as in the pic you should have no problem. Be careful because I have wired up feeders to my main power buss and got the polarity wrong, it's easy to do. Whenever I do any track wiring I always write black by one rail and red by the other then trace each rail and write on the benchwork or subroad bed black or red. Now this is the BAD BOY, if you trace the rail through the crossover the red rail joins up to the black rail and vice versa. This is exactly the same situation that you have at crossover B. The solution to the problem is to gap the rails, in the middle of the crossover and at either end of your turnouts. This then cuts your layout into two sections one would be powered from your main power supply, the other from your auto-reversing module. Ok, you have a parallel track that I have left out of the picture this is because there is no potential short curciut as indicated by the first pic. However you should gap the parallel track between A and C at a point opposite B to completely separate your two power blocks. Does this make sense? Now you maybe able to wire the other reversing loop to your auto-reversing module and control both reversing loops from the one module. It all depends on how you run your trains. You can't have a train tripping the reversing module on the red loop at the same time as a train is passing through the B turnouts. So if you are careful it is do-able. Otherwise you will need two auto-reversing modules.
Ken, Thanks for the very clear explanation about how to figure out where a reversing loop might happen. I never thought of drawing a different color line, but that makes sense. Thanks Steve
Cleggie - Excellent stuff and great pictures - I now understand completely what you are recommending. I agree with your thinking about the gaps you have drawn excluding one train from touching the gaps at the outside of B while another train is proceeding through B. This makes excellent sense. In regard to “However you should gap the parallel track between A and C at a point opposite B to completely separate your two power blocks. Does this make sense?”. There may still be a risk that a train is crossing this outside gap (at a point opposite B) when another train also goes through B. I’ve looked for an easy answer and can’t see it yet. If you can convince me on this one then I will concede. Ben - fair cop - I'm for making it simple. Could you please draw a picture so I can see what your recommendation looks like? I often find I'm making the wrong conclusions from text descriptions cheers Chas
See attached.... The red gaps are pretty much necessary as drawn. The orange gaps in front of the C crossover are where I would put the other end of the reversing section, so that I could run long trains through the reversing section and still have the option of using metal wheels. One could stop there, but after looking at this some more, I might actually go one step further. There is still a danger that one train could be going through the reverse on the inside track, while another approaches the C crossover on the outside track. This would cause the reversing section to want to be both ways at once, which of course isn't possible. From an operational standpoint, the second train shouldn't have to stop at C; it should be allowed to continue until it approaches the single track section. The solution is to put in the green gap, and make the outside section an 'X-block', controlled by a relay. The turnout labeled in the picture controls whether this outside track is part of the reversing block or part of the main block. If the turnout is lined for the outside track, then the relay switches the power for that track to the reversing block, so that a long train can run all the way to C and be entirely in the reversing block. If the turnout is lined for the inside track, then the outside track is switched to the main block, so that a train could travel from C to the turnout without causing the problem mentioned above. Hopefully if the original poster shows up again now, he won't be thoroughly confused!
Oh... Hmmm... you are right, there is a problem. Solving this one is not easy. I have looked at other ways of gapping the track but they all have the same potential for a short when running two trains. The only way to avoid this is to do away with the parallel track between A and C but that will cut into the opperating potential and I don't think that is a good idea either. Hopefully there are others who are scatching their heads and maybe able to come up with an answer.
What would be the issue if you did this: The blue lines represent the isolated reverse loop sections. the lower right "D" is a no brainer but the "B" section does take some thought. If gaped the way I figure (gaps shown in black, reverse sections shown in blue lines) there is ample room to get an MU through the cross over without causing a short. What am I missing? Brain
You only missed that the original poster asked for advice on how to achieve a longer reversing section. Perhaps because he has lighted passenger trains or is worried about metal wheels. What you suggested is exactly what Harron suggested in the first reply in this thread. But thanks for the picture!
Possible layout change. Finally back online. Wow! Lots of great information and ideas here. Just what I was hoping for. I was very interested in the comment about the trains not being able to reverse from both directions and have been giving that a lot of thought. I believe I have a solution, but not sure if it will work out OK. I did not want to turn around crossover B, so looking at several of my earlier 9 layout revisions I noticed one of them using the inner loop at the left side of the layout as a reversing loop. That revision had the curved turnout next to crossover A actually coming out of crossover A and having both diverging tracks going to the inner loop, one clockwise and the other counter-clockwise. The outer loop continues to be connected to crossover B. I have attached another picture of it. I guess the questions are: Can two trains be running in a reverse section when the autoreverse is tripped? What is the opinion of the change? What about gaps? Thank you for your inputs, Eric
Hey! Nice to see you back! I like the change, myself. On the gaps, you will still need an additional gap near the B crossover, as both I and Arctic train drew. As for extending the section to the C crossover as I suggested, or doing the "X-block" with a relay, keep those ideas on the back burner in case the shortness of the reversing section becomes an issue. I think you've got quite an interesting layout, btw, what with the option of both continuous running or running point to point in a couple different ways. Plus a good amount of industries and such. Just what I like in a layout this size. Now that I'm paying attention to the whole track plan, though... A couple more pieces of unsolicited advice (sorry, I can't help it): 1)In the leftmost industries section, I think you need a run-around, or else you'll find yourself unable to spot cars in one direction or another. 2) Unless your yard is merely for staging, you'll probably want a longer yard lead. Lot's of advice on track planning on those issues to be found here if you look back through previous topics.
Just a little history on this layout. It started as the Pennsy Middle Division as shown in 1993 MR and later in a follow-up book. I was planning on building it as shown in the mag with only minor modifications and had actually purchased much of the track and structures, and started benchwork. And then it happened. I started reading MR articles on layout operation and soon realized that the Pennsy layout was lacking two important elements - industrial spurs and a staging yard. The basic shape is the same, but I added the staging yard, that does actually extend a little further, and took out the small yard in the center of the left loop and replaced it with some industrial spurs. Much of this inspiration is due to David Popp's articles and his Naugatuck Valley layout. That complicated track spur is on purpose, but is also only preliminary. A lot depends on how the structures fit. Any Engineer working those spurs will need to plan his moves carefully. I appreciate all the advice and suggestions. I will have to re-read all the posts several times to really understand some of them. Hope to finish laying track within a few weeks, just before Summer. Eric
