I am reconstructing an N scale layout that will have double main lines with loops on each end to help trains turn around, somewhat like a C shape table top, with the loops being hidden. My question is, is there any reference someone has, whether it be in MR, or a website, that has a track plan for a loop, where the train obviously turns around but comes back on the opposite track? Also, I know the wiring has to be done special for loops due to double polarization of the electrical feed, but does it need to be done twice for 2 loops?
Any help would be great!
Thanks,Joe
What type of wiring are you planning DC or DCC? It will make some difference on your wiring.
In DC you can have a loop at each end of two parallel tracks and as long as you do not cross over you do not need special wiring. I am not familiar with DCC, but I do know that to reverse direction via a loop that comes back on itself, there is a special unit you buy. Again, if you do not cross over you do not need to have it. You can have two loops and connect them and as long as your trains do not change directon on the same track when they return, there is no special wiring. Wish I knew how to draw you a diagram. Sorry! Maybe someone else can.
If you go to the top of this page to Store, then to Kalmbach Publishing, Books - they have a section on wiring. One book I think is on wiring DC and there are several on DCC. Your LHS may have one in stock.
Good luck,
hi joe
i do not understand your first question about a trackplan for a loop.
In 102 Realistic Trackplans you can look at plan 35 (Bald Eagle Branch of the PRR), with one partial hidden loop. If you study the trackplan thoroughly you find no reversing loops; so you don't need any special features.
We use the word loop often, but alas in two completely different situations.
A double track mainline with end-loops without crossovers is in fact a simple oval or loop; no special features are needed. (these plans are called a dogbone)
If you have a single track loop to loop design, both loops are reversing loops. And yes at both ends you need special features, if you want to change polarity automatically.
On the plan at the left you should omit the crossover...then the plan is in fact a oval in disguise.
With the crossover and reversing loop added you'll have polarity issues.
You could insert a drawing of your plan on here, so some one can have a look at possible wiring issues
paul
I'm sorry.. steinjr I thought he meant something else.
I removed my comment. It won't happen again. Thanks.
I could have sworn he asked for any help.
Then again, you really don't know what he actually meant.
Keith --
You seem to be talking about a helix (a spiral to gain elevation), whereas the original poster seems to be talking about a reversing loop (tracks that go out from one branch of a turnout, and come back to the other branch of the same turnout, allowing a train - shorter than the length of the reversing loop ... - to continue in the opposite direction on the single track at the foot of the turnout).
Totally different kind of animal. In the context of reversing loops, it makes no sense whatsoever to talk about how to make thin subroadbed for helixes (or helices, or however you form the plural of helix) ....
Stein
Paul,
Thanks for the diagram. What I think I want though are two switches at the end right before the loop so I can isolate both mainlines alone so I can run two trains at different speeds. If I use the idea you have in the diagram it would allow for two trains, but they would have to be stopped and started together, or running at the same speed.
It may not make sense, if not I can draw a diagram.
Thanks,
Joe
jbdbackfan Paul,Thanks for the diagram. What I think I want though are two switches at the end right before the loop so I can isolate both mainlines alone so I can run two trains at different speeds. If I use the idea you have in the diagram it would allow for two trains, but they would have to be stopped and started together, or running at the same speed. It may not make sense, if not I can draw a diagram.
Probably would help. I think part of the problem might be that you seem to be mixing parts of several different questions at the same time - double mainlines, reversing loops (maybe) and controlling several trains independent of each other (probably in DC, since it is a trivial exercise in DCC).
Wait - are you simply asking about this way of arranging the tracks ?
If so, you don't need any special wiring for this.
Is your question really about how to control two trains independent of each other ?
I think a diagram would help a lot in making us understand what you are really asking about.
Smile, Stein
cowman In DC you can have a loop at each end of two parallel tracks and as long as you do not cross over you do not need special wiring.... Again, if you do not cross over you do not need to have [special wiring for polarity issues]. You can have two loops and connect them and as long as your trains do not change directon on the same track when they return, there is no special wiring. Wish I knew how to draw you a diagram. Sorry! Maybe someone else can.
Hi. I drew a layout schematic some time ago that illustrates several aspects to this question. This is based (loosely) on the double-track downtown mainline that provided access to Houston Union Terminal (now th site of Houston Astros/ Minute Man Stadium).
The double track is actually two sides of an oval of track (I could say "loop" but that might be confusing because it is something different from a reverse loop. And the British use the word "loop" to refer to a passing siding.) I envison it as running counterclockwise, ie right-hand running. Anywhere there is double track, trains normally would run forward on the track that is to their right, like driving on a two-way street or a divided expressway. Trains actually run forward in only one direction around the (disguised) oval but they seem to change direction because they disappear to the north and come back running south...but on the southbound track. That balloon shaped shape track at the north end of this plan is not a reverse loop, because it sends trains the opposite direction on a different track, not the same track.
But what about the track arrangement at the bottom, south of Double Track Junction. (There is/was a real Double Track Junction by that actual name on the Houston Belt & Terminal, though not in this exact schematic location.) That IS a reverse loop, isn't it? Well, no, no more so than the turnback curve at the top. A train running south on its right hand track can take the turnout in either direction at Double Track Junction, and it will come out running north on the right hand track. And it will run on the right hand track whichever route it takes around the "apparent reverse loop," that is, the right-hand track for THAT route. It actually functions as a passing siding, and it could be used to hold one train while allowing another to pass through.
Now, what about the passenger station on the wye? Wyes have polarity situations, don't they? NOT THIS WYE! Notice that the south leg of the "wye" into the terminal comes off the southbound track. The north leg crosses the southbound track with a sharp angle crossing and attached to the northbound track. Running a train into the terminal on one leg and coming out on the other does NOT cause the train to run in the opposite direction on the SAME track...it routes it over to the other direction track. I rode the Amtrak/Santa Fe Texas Chief in and out of this station several times artound 1973. The train would head out around the south leg and go southbound past Double Track Junction on its way to Chicago. The train heading in from Chicago would be running on its right-hand track, the northbound track and would run PAST the north leg, then BACK into Union Station. This would put first-class passengers closest to the depot, the locomotives would be on the far end away from the station where passengers would not have to walk past it, and the train would be oriented to head out for the next trip, though it would need to be serviced and fueled, etc.
This layout was designed to concentrate on the passenger action. Congress Yard was about two or three blocks east of the wye. It is used here primarily as a holding place for freight trains, and freight trains woiuld have to be always pointing "north" in the yard to run the correct direction around the loop, providing a background to the passenger operation.
I hope this is as clear as Houston gumbo mud!
cowman In DC you can have a loop at each end of two parallel tracks and as long as you do not cross over you do not need special wiring. ... Again, if you do not cross over you do not need to have (special wiring). You can have two loops and connect them and as long as your trains do not change directon on the same track when they return, there is no special wiring. Wish I knew how to draw you a diagram. Sorry! Maybe someone else can.
I tried to upload this diagram which DOES show "apparent" reverse loop AND wye with no polarity "issue." This is based on Houston in 1960s and 70s...
I spent 20 minutes writing an explanation but when I posted it, it disappeared. Maybe I can get back after fixing supper. Controlling trains individually is a separate issue from reverse loops. If wiring this for DC cab control, I would divide the line into blocks...soundbound track one block from just north of the freight shed switch to just south of Double Track Junction (one both routes). Each of the two tracks around Milby Street would be a separate block... northbound track from just south of Double Track Jct. to just north of Tap Junct switch a block...Block from just north of Tap Junct to just south of Congress Junct. ....Block from just south of Congress Junct.to just north of Freight Shed switch-- maybe this block cut in the middle. Separate block through Congress Yard. Separate block inside Milby Street. Separate block in the passenger terminal. Each of these blocks with a selector so it can be controilled from either two or three different cabs (power packs).
Plus on-off blocks for each passenger station track, for each Milby Street track, and each of the three parallel Congress Yard tracks. The on-off "satellite" blocks are not fed directly from a power pack but from whatever is connected to the main block where the on-off block is located.
leighantBut what about the track arrangement at the bottom, south of Double Track Junction. (There is/was a real Double Track Junction by that actual name on the Houston Belt & Terminal, though not in this exact schematic location.) That IS a reverse loop, isn't it? Well, no, no more so than the turnback curve at the top. A train running south on its right hand track can take the turnout in either direction at Double Track Junction, and it will come out running north on the right hand track. And it will run on the right hand track whichever route it takes around the "apparent reverse loop," that is, the right-hand track for THAT route. It actually functions as a passing siding, and it could be used to hold one train while allowing another to pass through.
Mmm - trying to picture this in my head. This (see drawing below) is in principle what is happening at Double Track Junction, right?
Seems to me like this is a reversing loop (electrically)?
What am I missing? Oh - now I see. Te upper mainline track actually has B-A on it's rails, not A-B. That also works out on the turnback curve on the other end of the layout:
Pretty nifty way of doing it!
That's overkill. If the return loop is simply a place for the train to turn back on itself, then the loop itself doesn't need to be double tracked. Unless, you want to create a staging track within the loop, then it's a simple matter of making a siding out of the otherwise single track loop.
This accomplishes two things. 1, it gives you a place to park a train, or to have one train disappear from the scenery part, and have another appear in it's place (the staging function) or,
If the loop remains a part of the scenery, it creates the illusion that the double track continues through the loop without the bother of all the complex trackwork and wiring that Stein shows.
I modified the earlier posted image:
You'll still need a reversing circuit if you have the straight double track to the right wired in parallel, but that's not difficult to do, and if you're using DCC, an auto reverser will make running through the reverse section seamless.
Lee
Route of the Alpha Jets www.wmrywesternlines.net
OVERKILL ?
as always it depends on what you want.
As done as designed it could represent a junction of two double tracked routes.
If done in your way its a double tracked STAGING loop.
Its time, imho, for the OP to make clear what his question is.
Paul
Thanks for the help everyone.
The double track junction is exactly what I was looking for. This would allow me to park a train in the loop while allowing another train to run continuously on the same exact line correct?
The question is, for the double track junction what needs to be wired special if I have two of these on each side of the layout.