||Planning Considerations: Reversing Loops
Reversing Loops and Sections Considerations
Track plans that wind around themselves with large numbers of crossing tracks and turnouts usually have an inordinate number of subtle and not so subtle reversing sections and loops.
We call this type of track plan a spaghetti bowl plan for obvious reasons.
Reversing loops and sections are the cause a lot of wiring nightmares and "strange" operation as well as driving up the total number of individual boosters.
This is because these loops and sections must all be identified, isolated and then fed by an appropriate autoreverse booster.
However, even with autoreversing boosters there are limitations and restrictions that govern their use.
1. Identify every single reverse loop and section.
This is very important and sometimes difficult if your layout is of the spaghetti bowl variety.
2. Once you have identified these loops and sections, do your best to get rid of them!
Eliminate reversing loops and sections as much as practical.
Doing so will save you lots of labor and headaches since layout wiring becomes much simpler.
3. If you have a reversing loop or section, it is mandatory that your longest train fit completely inside the loop or section.
The autoreversing feature will not work if this rule is not obeyed.
4. Use only locomotives featuring all wheel pickup.
Offset pickups, commonly found on older steam and diesel locomotives will not work properly with the ZoneMaster autoreverse booster.
5. Reversing sections that are part of a wye must be long enough to hold the loco or consist without any block gaps being bridged by the loco wheels.
How To Identify Reversing Sections And Loops
The easiest method is to begin with a "straight-line diagram" of your track plan.
Similar to the appearance of a dispatcher's panel, this type of diagram straightens out the physical curves but preserves the order and direction of all turnouts.
The track is represented with a single line.
To start, pick a reference or starting point.
It can be anywhere although a yard or mainline town is a good place to start.
Label the starting point with a unique name or letter.
In the example, A is used as the reference point.
Now break the circle and straighten out the lines.
Now imagine yourself in the locomotive cab observing the track ahead of you as you proceed in the forward direction.
At each turnout you come to, give it a unique number record if it branches right or left.
When you find yourself back at position A, you can indicate this with A at the end of the straight line or include a line indicating the track that took you back to the starting point. Now follow all the branches and continue with the diagram.
If at any time you find yourself now going in the opposite direction, you have just come through a reversing area.
Here's a simple loop with two sidings.
Although the sidings appear to be on the same side of the main line, they are not.
The straight-line diagram makes their physical orientation to the main line obvious.
Below is a more complex plan and it has a reversing loop.
The traditional diagram that follows the layout bench work and terrain makes the reverse loop difficult to identify.
Converting the track plan to a straight line diagram makes the reversing loop easy to identify.
Use a different color to identify the loop in the straight line diagram.
Turnouts #5 and #6 mark the loop's boundaries.
Once the reversing sections are identified, booster selection and wiring is easy.
Download the ZoneMaster and ZoneShare installation manuals for more information and wiring.
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