Wiring a handover or link section

[ikcdab]

I have read a fair bit about link sections on here. That is, a section of track that can be joined electrically to either (but not both at the same time) of its neighbours. 

Therefore, where you have two operators, one of them can drive a train into a link section, then the other can take over and drive it out. The sort of thing you might have between a branch line and main station with separate control panels for each and a link section between them.

Clearly, if you only want one switch, it is easily accomplished with a single DPDT switch. But what I need ifs for each operator to have their own switch, rather like the staircase lights are wired with a switch top and bottom either of which puts the light on or off. But of course different. When either operator operates their switch, they take control of the link section. Or perhaps they both have to cooperate and operate their switches together, but in any event, they each have one.

I have seen such sections referenced in this topic below, but I cannot fathom out how to wire it up. I can see that it's a combination on two way switches in some way.

Can anyone provide a simple diagram?

Thanks

 

 

[cliff park]

I would say go for a relay, 2 pole changeover contacts. One operator switches the relay for him, the other operator releases the relay for him to take charge. Either use relays that self latch or use one with additional contacts to latch it.If you used a 4 pole c/o you could use the other pole to light LEDs at each station to show who had control.

[Pete the Elaner]

Use the control panel to assign a controller to the section, not the other way around. You can't have both competing this way.

 

You won't need the link section at all. Work out where the train is going, then all points & set each section (Sounds like you have 2) along this path to whichever controller you choose (I prefer the one you want to use on the receiving section). Once the train has cleared section(s), you can set these to another controller.

This is known in the UK as cab control, which is a term you may have heard. I believe the US has a different term for it.

It also means that if a controller develops a fault, you can control everything with 1.

 

A complication comes where you have a single or double slip. This needs to have its own section, but it is something you soon get used to.

[John ks]

If you are happy with common rail return then this should work

Both controllers must be fed from different power supplies

In practice if you cant control the link section then throw the switch at your end

Like 2 way switching ( Staircase lights) the position of the switch has no relationship to the light being on (In Oz Switch down = light on)

 

 

John

 

[John ks]

 

On 16/04/2020 at 18:44, cliff park said:

If you used a 4 pole c/o you could use the other pole to light LEDs at each station to show who had control.

Here is the circuit that goes with Cliff's description

 

 

Three There are 2 push button switches, the LH one is NC & the RH one is NO

Unlike my previous drawing this one can use the same power supply

If the power supply is 12V DC then it can also feed the LEDs

John

Edited April 26, 2020 by John ks

[ikcdab]

1 hour ago, John ks said:

If you are happy with common rail return then this should work

Both controllers must be fed from different power supplies

In practice if you cant control the link section then throw the switch at your end

Like 2 way switching ( Staircase lights) the position of the switch has no relationship to the light being on (In Oz Switch down = light on)

 

 

John

 

Fantastic, exactly what I was after. 

Many thanks

[DCB]

I would have a push button at each end.  Press once for control.

A point motor with an accessory switch would make an inexpensive passive latching change over relay but would have no centre off facility so a section switch for the section would be needed and probably done best by a switch on each panel.   If no off position is required feed the point motor accessory switch from the adjacent tracks instead of the panel.  If you don't want common return use two accessory switches, and if you want a warning light you could add a further switch or three.

I actually have a change over section where you have to hold the button down to energise, but its not idea for this application.

Edited April 17, 2020 by DavidCBroad

[AndyID]

On 16/04/2020 at 05:44, John ks said:

If you are happy with common rail return then this should work

Both controllers must be fed from different power supplies

In practice if you cant control the link section then throw the switch at your end

Like 2 way switching ( Staircase lights) the position of the switch has no relationship to the light being on (In Oz Switch down = light on)

 

 

John

 

 

 

 

A slight variation also for common return:

 

 

 

This versions uses two double-pole changeover switches. As drawn neither controller is feeding the section. Either of them can "grab" the section by closing their switch (down). That prevents the other controller from feeding the section. If A and B try to grab the section at the same time neither of them will be connected to it

 

With this arrangement it's a bit easier to tell whether or not a controller is in control of the section.

 

[Michael Edge]

This is unnecessary complication, there's no reason why it shouldn't be possible to have both (or all) link switches on at the same time. I would always recommend using common return wiring anyway, one rail is common to the entire layout and all section breaks are in the other one. It has to be used in conjunction with on/off/direction switches on all controllers. Normally control position A would switch (SPST in one rail) on the link from his last section to the link with section B then stop but B can take over running the train with his link switch as long as both direction switches are facing the same way, A can (must) then switch his off. If there's nobody at B then link switches can be on at both ends of it (all intermediate sections on) as long as B's controller switch is in the off position. A can then use the same procedure to drive through B on to C - and so on round the layout, no matter how large. This is the electrical equivalent of switching out a signal box with all intermediate signals cleared. It gives complete flexibility of control, allowing one controller to connect a whole complex layout if required but it does depend on every operator remembering to switch all links off after use.

[AndyID]

12 hours ago, Michael Edge said:

This is unnecessary complication, there's no reason why it shouldn't be possible to have both (or all) link switches on at the same time. I would always recommend using common return wiring anyway, one rail is common to the entire layout and all section breaks are in the other one. It has to be used in conjunction with on/off/direction switches on all controllers. Normally control position A would switch (SPST in one rail) on the link from his last section to the link with section B then stop but B can take over running the train with his link switch as long as both direction switches are facing the same way, A can (must) then switch his off. If there's nobody at B then link switches can be on at both ends of it (all intermediate sections on) as long as B's controller switch is in the off position. A can then use the same procedure to drive through B on to C - and so on round the layout, no matter how large. This is the electrical equivalent of switching out a signal box with all intermediate signals cleared. It gives complete flexibility of control, allowing one controller to connect a whole complex layout if required but it does depend on every operator remembering to switch all links off after use.

 

And how do you prevent one controller damaging the other controller when the operators make a mistake?

[Michael Edge]

There's no damage with anything I've used, you just get an overload and/or cutout trip. We've only been using this system in the Leeds club for about 50 years though.

[AndyID]

8 minutes ago, Michael Edge said:

There's no damage with anything I've used, you just get an overload and/or cutout trip. We've only been using this system in the Leeds club for about 50 years though.

 

No problem with old-fangled resistance controllers but I'd recommend caution with modern solid-state controllers, and they are not cheap.

[Michael Edge]

It's probably more than 40 years since we used resistance controllers, when I mentioned 50 years I didn't mean we hadn't changed anything. No damage so far to my knowledge - certainly not on my own layouts.

[DCB]

On 21/04/2020 at 07:46, Michael Edge said:

This is unnecessary complication, there's no reason why it shouldn't be possible to have both (or all) link switches on at the same time. I would always recommend using common return wiring anyway, one rail is common to the entire layout and all section breaks are in the other one. It has to be used in conjunction with on/off/direction switches on all controllers. Normally control position A would switch (SPST in one rail) on the link from his last section to the link with section B then stop but B can take over running the train with his link switch as long as both direction switches are facing the same way, A can (must) then switch his off. If there's nobody at B then link switches can be on at both ends of it (all intermediate sections on) as long as B's controller switch is in the off position. A can then use the same procedure to drive through B on to C - and so on round the layout, no matter how large. This is the electrical equivalent of switching out a signal box with all intermediate signals cleared. It gives complete flexibility of control, allowing one controller to connect a whole complex layout if required but it does depend on every operator remembering to switch all links off after use.

 

No reason at all if you use the right kit.  I used to connect two controllers to the same line when double, triple or more heading with power hungry Triang Transcon locos.  I had fishplates glowing red hot on one occasion.  Robust kit that Triang.  Trouble is some controllers don't have an off position where the transformer is isolated from the track and back feeding 19 volts or so doesn't do them a whole lot of good. 

Even with the right kit the train will either stop with no controller feeding it or go like a bat out of hell with both feeding it if you don't synchronise switching one off and the other on.  That's why my suggestion disconnects one controller as it connects the other in the time it takes to throw a point.

Edited April 26, 2020 by DavidCBroad

[Michael Edge]

I was assuming that the controller had a two way centre off switch - all the ones I have used do.

[Suzie]

There are a couple of solutions not yet mentioned which might be more practical:-

 

1. If the track is used in only one direction, then the transfer section can be fed by a diode from each controller (assuming common return wiring, use a pair of diodes otherwise) to block the controllers being connected together, and no switches will be needed. Clearly if trains are being passed both ways this will not be possible.
2. Decide which controller will be the master. Use a 2-way push-button at the master position to allow the master controller to connect to the transfer section when the button is pressed. When the button is released the push-button will connect to the slave controller.

While it is possible neither of these solutions meet the original spec of 'landing light switch' operation, they will be a lot more intuitive to use in the absence of full cab control wiring.

[t-b-g]

We have done something like this on one of our layouts. The link section is fed and switched from a relay.

 

The relay has two on/off single pole switches, wired in parallel, to power it. So if both switches are off, the relay switch ensures the link section is attached to station A. If either switch is on, the relay makes the link section switched to station B. If both switches are on, it is linked to Station B.