Track wiring advice

[CHOOPER]

Apologies for the appalling drawing of the track layout; what is the correct way to wire this layout up for DCC so I dont get a shortcircuit in the circled area due to the reverse loop? 

Many thanks

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[Flashbang]

Hi

You will need 6 x Insulated Rail Joiners (IRJs) Hornby part number R920 fitted where the red lines are shown cutting across the rails 2 IRJs are fitted at each location in place of the metal rail joiners (Fishplates). Plus a DCC Reverse Loop Module Hornby part number R8238.

There must be no other rail feeds to the reverse loop section which I've shown in Brown only the two wires from the Reverse Loop Modules output.  The Reverse Loop Module Input is taken from the DCC feed coming from the DCC console or tsken from anywhere along the DCC fed rails which I've shown by a red and black arrow.

 

To note. A reverse loop should always be longer than the longest complete train to travel over it. That is a loco and all carriages or wagons should fit inside any entrance and exit IRJs.

 

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[Fishmanoz]

Flashbang, while it's not possible to be certain due to the non-scale layout drawing, I suspect your solution is not optimal. The reason is for the opposite of the limitation you've noted on length of the reverse loop.  The reverse loop limitation not mentioned is that only one train can enter or leave a reverse loop at any one time.  If more than one enters or leaves, the poor old RLM has to keep switching track phase back and forth continually trying to keep up with the phase needed as each train is crossing the entry and exit IRJs.

 

So while not certain in the layout as drawn, I suspect there will be far too much track length in the isolated section suggested such that a train might be entering/leaving at the top of the crossover at the same time as one is leaving/entering at the bottom.  If so, a shorter loop will be needed.

 

And while I've yet to figure it out fully in my head, I suspect you have to consider this to be 2 reverse loops, one to the left of the crossover and the other to the right.  The only way to treat it as one is to have a single isolated section within the crossover and the crossover is too short to do that here.  You can see what I mean by visualizing the layout "unsquashed" into a more conventional oval with a long crossover from bottom left to top right.  Then it looks like a more typical reverse loop layout and has enough length in the crossover to include the single isolated section there.

[Chrissaf]

I have to agree with Fishy, regarding not being an optimal solution. The schematic as drawn by the OP is 100% a copy of the example I use for a 'Dog Bone' layout in my "Reverse Loop Tutorial" PDF document.

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Downloadable on this link (when the page opens, click the document name in the top left corner to initiate the download):

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https://btcloud.bt.com/web/app/share/invite/TAIW63ObNS

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I would direct the reader to Chapter 6.2 with particular focus on Fig 8 on page 23, that demonstrates precisely what Fishy has described in text. If the OP's schematic is simplified i.e. only a single loop is drawn but the actual layout has two loops (or more). Then the documented solution needs to be replicated on each loop that exists. For example a twin loop dogbone would utilise 4 x RLMs.

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Note that the Hornby R8238 RLM is now obsolete and stocks on retailer shelves are in short supply. No information is available as to whether Hornby plan to introduce (later) a new improved replacement under a new R number or not. Other brands of RLM are available and documented in my downloadable document above. I recommend any RLM that gives adjustable trigger current levels at about the 2 Amp level (this assumes one is using the Hornby 4 Amp P9300 controller power supply).

 

 

 

[96RAF]

Much the same answers as were posted on another forum to the same drawing.

[Flashbang]

The very simple answer (as some point out that actual length of the loop is unknown) is to just move the lower pair of IRJs back (to the right) and into the loop more, thereby reducing the reverse loops overall track rail length!

However, the rule of ensuring a complete train still fits inside between any entrance and exit IRJ remains, so the loops actual rail length IRJ to any other IRJ needs to be slightly longer than the longest trains length,