Insulating breaks and frog switchers - where?

[Lacathedrale]

I've had a station throat plan knocking around my head for a little while, but I'm quite terrified about how I would wire it up - does anyone have any thoughts on where to set up insulating gaps and switched frogs?

 

[jim.snowdon]

One approach to this is to set the whole of the S&C layout on paper, draw in isolation breaks at all four corners of every crossing and give them an identifying letter. There will be feed and return connections to each of the two tracks on the right, Mark these as A+, A-, B+ and B-.

Give every point end a number, remembering that some of them will work as pairs, and decide which will be the Normal position for each one.

 

 That will have laid the foundations for the next stage, for which some ordinary squared paper will be useful. Mark it out, from left to right, with a column for the routes (track A to track B, for example), every point end and every crossing. Now, in the first column, write in every possible route (from/to). Then, for each route listed, determine which point ends need to be Normal or Reverse - many will not matter as they are outside the route selected. (For the unfamiliar, Normal and Reverse relate to the position the lever would be in in a lever frame.)

Trace through the route and note down for each crossing whether it should be connected to A+, A-, B+ or B-. It may seem laborious, and in a complex layout it is, but it is logical and thorough. What will emerge is a matrix that will let you work out, for every point end, which crossings need to be connected to which rails. It will also reveal which crossings operate in common and can thus be electrically connected (and isolation gaps removed).

 

Apologies if the explanation seems a bit long winded, but it's one of those processes that is easier to do than explain.

 

Jim

[Lacathedrale]

Thanks @jim.snowdon - so when you say 'crossing', you mean the common crossing assemblies of the turnouts, and the middle of the diamond?

[jim.snowdon]

Correct. Every single crossing, at least to start with. It will simplify down once you go through it as you will find some groups of crossings that are always the same polarity and can be joined together electrically, like the triangular groups in the middle of the scissors crossover.

 

Jim

[AndyID]

I think this is the minimum number of breaks although you need to be careful when using either crossover that nothing is fouling the points in the other crossover that might bridge a break at the frog. If that's a concern you need a few more breaks.

 

Two of the frogs (crossings) at the three-way are connected as they can always have the same polarity. You might need a little bit of relay or diode logic to control them.

 

Edited December 15, 2019 by AndyID
Saw a problem! Revised diagram.

[dessire_luvals]

On 15/12/2019 at 04:19, AndyID said:

I think this is the minimum number of breaks although you need to be careful when using either crossover that nothing is fouling the points in the other crossover that might bridge a break at the frog. If that's a concern you need a few more breaks.

 

Two of the frogs (crossings) at the three-way are connected as they can always have the same polarity. You might need a little bit of relay or diode logic to control them.

 

 

I would put a lot more breaks in this to keep things more logical. 

 

I have used the letters and numbers model to record everything but I do that alongside a very simple drawing with black and red for sections of rail that are always the same polarity and each frog as a section that has to be switched.

 

i think wiring this would be relatively simple with a single changeover switch on each point motor. If you look a route “top left to bottom right” you have 6 sections in my model that need changing. Use each point motor switch to change the polarity + to - or vice versa.  You can do the same “bottom left to top right” if you are willing to have the single slip have the normal route to be “bottom left to bottom right”

[AndyID]

1 hour ago, dessire_luvals said:

 

I would put a lot more breaks in this to keep things more logical. 

 

 

Without a diagram it's impossible to know whether that would be more or less logical but adding additional breaks weakens the mechanical rigidity of the formation.