Wiring help with fiddle yard throat

[westernwill]

Would it be possible for your up route from the helix to bypass the fiddle yard completely.

 

Then the RLM would just be protecting the down route.

 

Otherwise I agree with Chris on the potential problems.

[96RAF]

If you view the helix as two simple loops of track as drawn below then they can be ignored as a reverse loop and isolation concentrated on where the actual reversal is located...after all a helix is just a straight piece of track coiled into a spring.

 

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[paul.b]

Hi all

I have been at this all weekend trying to come up with some sort of soulition to this issue, the only thing I can think of will not get rid of the problem totaly but reduce the entry and exits to the RLM is to put the helix and whole lower level on the RLM this will reduce the IRJ`S to where the RLM meets the main layout......any thoughts on this

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[Chrissaf]

You will get a 'short circuit' doing that.

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Go back to basics. You had to put in the RLM because of your throat pointwork being part of a WYE reverse loop (not shown on your drawing above......see your original image on page 1).

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I have replicated the original layout design from Page 1 as schematic A below. The RLM was required because of the WYE Reverse Loop on the right that you included in the original layout design. The WYE is part of the main DCC Bus.

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If you remove the Helix side IRJs and incorporate the Helix and lower loop as part of the RLM protected section. Then that whole section creates a traditional reverse loop because of the throat cross-over pointwork, this creates a short circuit on the left hand side Helix loop......see image B below.

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In C below, just as a cerebral thought exercise I have moved the original IRJs to the end of the new lower loop to overcome the short generated in B. But this makes the issue even worse because the original RLM protected section now covers an even bigger area of layout track. Thus there is more scope to have more trains inside the protected RLM section, thus greater opportunity to have a train entering and leaving at the same time. To minimise the opportunity for two trains leaving an entering the RLM section at the same time, then the protected RLM section needs to be as physically small as possible, but larger than your longest train.

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In an ideal world, A RLM protected section of track should only have one single entry point and one single exit point and just big enough to accomodate a single train. This is impossible to achieve with your complicated cross-over fiddle yard throat pointwork, which due to its design has to have two entry and exit points (as in image A).

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The only way you could totally resolve the issue is to remove the WYE (take out the vertical part of the WYE shown on the drawings). This would then convert your layout topology to a 'dogbone' design. Once that it is done, the throat cross-over points are used to form the new main Bus. The Helix and lower loop are then connected via RLM1 and the original upper level loop (with the WYE removed) is connected to further RLMs as necessary. This results with each individual RLM sections only having a single entry and exit point.

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A simplified overview schematic of what I am describing is shown below. In reality, the upper level loop on the right is actually a series of inter-connected loops in your design. Each one of which would probably need its own RLM section. As you can see, this starts to get complicated, plus you loose the WYE feature function (if that is important to you):

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Review the 'Dogbone' RLM designs in my downloadable RLM Design document that I have previously giving you a link for.

[paul.b]

Hi all

I will have to have a re-think on the lower level and the helix, I have opened up  a right can of worms that is  causing more headaches than expected. I thank you all for all your advice and help, Im not giving up on this just going to try and redesign this into a workable option

Regards paul

[Chrissaf]

Paul, if you could achieve something like this......then problem solved.

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Say something like this for example:

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Notice that the connections into the existing loop can (optionally) be external to the actual WYE side links (denoted by the red triangle). As indicated on the lower mid left hand side of my grey track addition. For all intent and purpose, the Helix and lower loop is a 'passing loop' off the main loop from a layout topology point of view. Thus it is not creating any additional reverse loops by connecting in this manner.

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[paul.b]

Hi Chris

this is as close as i could get to that at the moment 

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regards paul