Cab control wiring for a terminus

[No. 800 Maedbh]

I'm currently building a terminus as part of a larger layout. I want to use Cab control for it, but not quite sure about wiring it all up.

Track plan is loosely based on Cyril Freezers Hungerford Bridge with some compromise for space. Track is laid loosely, with some parts down to show the layout more than anything else. All points are insulfrog.

 

Any assistance would be greatly appreciated!

[Dungrange]

Cab control is no different for a terminus layout than it is for any other part of a layout.  You divide the track into sections such that all points are fed from the toe end.  The track feed(s) for each section are then connected to the common terminals on a double throw or multi-position switch.  The other terminals are then connected to your two (or more) controllers, such that when the switch is in the left position, the left controller is attached and when in the right position, the right controller is attached.

 

If you are using common return wiring, then the switches can be single pole, but if you're not using common return, then they will need to be double pole (so that you can switch both feed and return to each section).

 

https://www.brian-lambert.co.uk/Electrical_Page_1.html is a good beginners guide to sectioning, discussing common return and types of switches.

[Chimer]

I would sectionalise it like this:

 

Assuming platform 1 at the top, and each platform road is a separate section (haven't got enough distinct colours):

 

Arrivals to P1 need blue and P1 sections switched to the same controller;

Arrivals to P2, P3 and P4 need blue, green and P2, P3 or P4;

Arrivals to P5 and P6 need blue, green, gold and P5 or P6.

 

Departures from P1 need P1, green and brown;

Departures from P2, P3 and P4 need P2, P3 or P4, green and brown;

Departures from P5 and P6 need P5 or P6, gold and brown.

 

And personally I would use IRJs on both rails at every section break and wire it using DPDT switches, but lots of people would go for common return and SPDTs.

 

Hope this helps?

 

 

 

[Jeremy Cumberland]

8 hours ago, Chimer said:

I would sectionalise it like this:

 

Assuming platform 1 at the top, and each platform road is a separate section (haven't got enough distinct colours):

 

Arrivals to P1 need blue and P1 sections switched to the same controller;

Arrivals to P2, P3 and P4 need blue, green and P2, P3 or P4;

Arrivals to P5 and P6 need blue, green, gold and P5 or P6.

 

Departures from P1 need P1, green and brown;

Departures from P2, P3 and P4 need P2, P3 or P4, green and brown;

Departures from P5 and P6 need P5 or P6, gold and brown.

 

And personally I would use IRJs on both rails at every section break and wire it using DPDT switches, but lots of people would go for common return and SPDTs.

 

Hope this helps?

 

 

 

I suspect  @No. 800 Maedbh wishes to use the biottom brown line for shunting while using the top brown line for a departing train, so an additional section will be needed for the bottom brown line, from the points on the left up to the orange double slip.

 

If  @No. 800 Maedbh wishes to use the top brown line for shunting while a departing train uses the bottom brown line, then the top brown line will also need a separate section, from the points on the left up to the green double slip.

 

I expect you'll want isolated sections at the ends of each road that can accept an incoming train, to isolate the incoming locomotive while you bring in another locomitive to shunt the train or to pull it out of the station. These aren't part of cab control, but they will still have switches on the control cabinet, with just an on off function. Use an insulated rail joiner on one rail only, and use a SPST on-off switch (you can use other types of two-position switch and not connect the unwanted terminals).

[Dungrange]

59 minutes ago, Jeremy Cumberland said:

I suspect  @No. 800 Maedbh wishes to use the bottom brown line for shunting while using the top brown line for a departing train, so an additional section will be needed for the bottom brown line, from the points on the left up to the orange double slip.

 

If that were the case, I think there would need to be a trap point / headshunt to ensure that the shunting train couldn't run onto the departing line (unless the limit of shunt is greater than a certain distance from the point) - I think that distance is either 100m or 440 yards between the limit of shunt and the clearance / fouling point depending on period.

 

1 hour ago, Jeremy Cumberland said:

If  @No. 800 Maedbh wishes to use the top brown line for shunting while a departing train uses the bottom brown line, then the top brown line will also need a separate section, from the points on the left up to the green double slip.

 

As above, I think such a movement would only be permitted by the signalling if there were enough length to incorporate the overlap distance between the limit of shunt at the clearance / fouling point.

 

9 hours ago, Chimer said:

And personally I would use IRJs on both rails at every section break and wire it using DPDT switches, but lots of people would go for common return and SPDTs.

 

I'd do the same.

[Jeremy Cumberland]

2 hours ago, Dungrange said:

If that were the case, I think there would need to be a trap point / headshunt to ensure that the shunting train couldn't run onto the departing line (unless the limit of shunt is greater than a certain distance from the point) - I think that distance is either 100m or 440 yards between the limit of shunt and the clearance / fouling point depending on period.

To be fair, @Chimer hasn't quite drawn it as the Hungerford Bridge plan, which has a crossover from the bottom road to the up (or down) main.

 

Although in my own models (which I admit are mostly in my imagination rather than actually built) I aim for a degree of realism in trackwork, signalling and operation, and wouldn't dream of omitting trap points where they were needed, I don't think most railway modellers are interested in such things. The important thing for most of us is to have a layout that is fun to operate, and it is hard to think of trap points adding to the fun. Furthermore, they can barely be seen from an ordinary viewing distance. Also, since there appear to be no goods sidings in the plan, I am not sure that a trap would be needed on the bottom road anyway, unless it was used for storage of vehicles in which case it would be need to be trapped at both ends.

 

The middle road wouldn't have a trap point of course, but the middle road might have a starter immediately before the crossover, which would act as a limit for shunting moves if the bottom road were being used for a departing train.

Edited May 9 by Jeremy Cumberland

[Chimer]

2 hours ago, Jeremy Cumberland said:

I suspect  @No. 800 Maedbh wishes to use the biottom brown line for shunting while using the top brown line for a departing train, so an additional section will be needed for the bottom brown line, from the points on the left up to the orange double slip.

 

 

My assumption was that the bottom line is there to allow departures from platforms 5 and 6 simultaneously with arrivals into 2, 3 and 5.  But an extra section for that line would add flexibility.

Edited May 9 by Chimer

[No. 800 Maedbh]

On 07/05/2024 at 10:17, Dungrange said:

Cab control is no different for a terminus layout than it is for any other part of a layout.  You divide the track into sections such that all points are fed from the toe end.  The track feed(s) for each section are then connected to the common terminals on a double throw or multi-position switch.  The other terminals are then connected to your two (or more) controllers, such that when the switch is in the left position, the left controller is attached and when in the right position, the right controller is attached.

 

If you are using common return wiring, then the switches can be single pole, but if you're not using common return, then they will need to be double pole (so that you can switch both feed and return to each section).

 

https://www.brian-lambert.co.uk/Electrical_Page_1.html is a good beginners guide to sectioning, discussing common return and types of switches.

Many thanks for the info and the link, very useful!

On 08/05/2024 at 23:19, Chimer said:

I would sectionalise it like this:

 

Assuming platform 1 at the top, and each platform road is a separate section (haven't got enough distinct colours):

 

Arrivals to P1 need blue and P1 sections switched to the same controller;

Arrivals to P2, P3 and P4 need blue, green and P2, P3 or P4;

Arrivals to P5 and P6 need blue, green, gold and P5 or P6.

 

Departures from P1 need P1, green and brown;

Departures from P2, P3 and P4 need P2, P3 or P4, green and brown;

Departures from P5 and P6 need P5 or P6, gold and brown.

 

And personally I would use IRJs on both rails at every section break and wire it using DPDT switches, but lots of people would go for common return and SPDTs.

 

Hope this helps?

 

 

 

 

On 09/05/2024 at 07:48, Jeremy Cumberland said:

I suspect  @No. 800 Maedbh wishes to use the biottom brown line for shunting while using the top brown line for a departing train, so an additional section will be needed for the bottom brown line, from the points on the left up to the orange double slip.

 

If  @No. 800 Maedbh wishes to use the top brown line for shunting while a departing train uses the bottom brown line, then the top brown line will also need a separate section, from the points on the left up to the green double slip.

 

I expect you'll want isolated sections at the ends of each road that can accept an incoming train, to isolate the incoming locomotive while you bring in another locomitive to shunt the train or to pull it out of the station. These aren't part of cab control, but they will still have switches on the control cabinet, with just an on off function. Use an insulated rail joiner on one rail only, and use a SPST on-off switch (you can use other types of two-position switch and not connect the unwanted terminals).

Thanks to @Chimer, especially for the diagram, and @Jeremy Cumberland, both comments are very insightful. 

On 09/05/2024 at 08:57, Dungrange said:

 

If that were the case, I think there would need to be a trap point / headshunt to ensure that the shunting train couldn't run onto the departing line (unless the limit of shunt is greater than a certain distance from the point) - I think that distance is either 100m or 440 yards between the limit of shunt and the clearance / fouling point depending on period.

 

 

As above, I think such a movement would only be permitted by the signalling if there were enough length to incorporate the overlap distance between the limit of shunt at the clearance / fouling point.

 

 

I'd do the same.

 

On 09/05/2024 at 10:17, Jeremy Cumberland said:

To be fair, @Chimer hasn't quite drawn it as the Hungerford Bridge plan, which has a crossover from the bottom road to the up (or down) main.

 

Although in my own models (which I admit are mostly in my imagination rather than actually built) I aim for a degree of realism in trackwork, signalling and operation, and wouldn't dream of omitting trap points where they were needed, I don't think most railway modellers are interested in such things. The important thing for most of us is to have a layout that is fun to operate, and it is hard to think of trap points adding to the fun. Furthermore, they can barely be seen from an ordinary viewing distance. Also, since there appear to be no goods sidings in the plan, I am not sure that a trap would be needed on the bottom road anyway, unless it was used for storage of vehicles in which case it would be need to be trapped at both ends.

 

The middle road wouldn't have a trap point of course, but the middle road might have a starter immediately before the crossover, which would act as a limit for shunting moves if the bottom road were being used for a departing train.

I plan to have a headshunt on the bottom brown line, as on the Hungerford Bridge prototype. Freezer envisioned it as follows.

 

 

[Jeremy Cumberland]

34 minutes ago, No. 800 Maedbh said:

I plan to have a headshunt on the bottom brown line, as on the Hungerford Bridge prototype. Freezer envisioned it as follows.

From the description, you'd definitely want the bottom road to be a section of its own, which can extend all the way up the headshunt. The middle road can probably remain part of the brown section.

[DCB]

Hi  I got  brain freeze reading  all the above.  Overthinking underdoing     Feed the pinch points is my doctrine.  

Three trains can run simultaneously so three  controllers and I would use 4 way two pole rotary  switches  with an OFF position for each feed

[No. 800 Maedbh]

4 hours ago, DCB said:

Hi  I got  brain freeze reading  all the above.  Overthinking underdoing     Feed the pinch points is my doctrine.  

Three trains can run simultaneously so three  controllers and I would use 4 way two pole rotary  switches  with an OFF position for each feed

Rotary switches do seem to be the way to go for switching between controllers, though trying to figure out how to wire them fries my brain!

[Suzie]

I guess the key question that I don't think has been asked is how many cabs?

 

My initial thought would be two since I don't think you would realistically have much work for a third running train, so I would just feed each of the terminal roads on the right via a 2-way centre off switch (single pole for common return, or double pole otherwise).

 

If using three or more cabs it would be required to use rotary switches to select the cabs so you could retain an off position to isolate a train, but this might not be required if the arrival roads have loco isolators at the end. A lot is dependant on how you want to operate the terminus.

 

Key to finding a solution is to know how you want to operate, and make the sectioning simple using power routing via the points to  avoid having to change an excessive number of switches every time you move a train. By feeding the terminal roads, when starting a movement you just have to select the cab on where you are starting, and if going to a different terminal road select that as well, and just drive - remembering to switch the roads back to off when you have finished the movement.

 

Common return wiring will be your friend in eliminating a lot of physical wire in the wiring, but can be a bit tricky to get your head round.

[cliff park]

I would also suggest bringing all the feeds to the control area via chocolate blocks or similar so that they are easily accessable, to make changes in the light of running experience. It can be very annoying to realise that it would all work better if only you could split that section, or take it out of that section and add it to a different one. If you have to crawl about upside down to do this it doesn't get done. Then it becomes less fun to operate.

[kevinlms]

1 hour ago, Suzie said:

I guess the key question that I don't think has been asked is how many cabs?

 

My initial thought would be two since I don't think you would realistically have much work for a third running train, so I would just feed each of the terminal roads on the right via a 2-way centre off switch (single pole for common return, or double pole otherwise).

 

If using three or more cabs it would be required to use rotary switches to select the cabs so you could retain an off position to isolate a train, but this might not be required if the arrival roads have loco isolators at the end. A lot is dependant on how you want to operate the terminus.

 

Key to finding a solution is to know how you want to operate, and make the sectioning simple using power routing via the points to  avoid having to change an excessive number of switches every time you move a train. By feeding the terminal roads, when starting a movement you just have to select the cab on where you are starting, and if going to a different terminal road select that as well, and just drive - remembering to switch the roads back to off when you have finished the movement.

 

Common return wiring will be your friend in eliminating a lot of physical wire in the wiring, but can be a bit tricky to get your head round.

I tend to agree about the number of controllers, it does seem that a 3rd controller would rarely be required. Would it be simpler to ignore it, but at the same time, wire as per Cliff's suggestion, so that it could be added without making major alterations, if later operating experience made the 3rd controller desireable?

 

As for common return wiring, if DCC is never going to happen then that's OK to go with common return. If DCC is a possible addition, then it's better to NOT use common return.

[Chimer]

For just this terminus, I can't see a need for a third controller either, but it is going to be "part of a larger layout", so maybe three or more operators might all need to be able to "drive" down the branch now and then.

 

Whatever, if rotary switches are used, adding further controllers even at a later date is simple until you run out of connections, remembering you need to leave one unused as an "off" position.

 

Because the key to cab control wiring is to understand that the switches, whatever the type, are "owned" by the track sections not the controllers - i.e. the single side of each switch is linked to one track section, the other side to multiple controllers.  Meaning several track sections can be switched to the same controller at the same time, but a single track section cannot be switched to more than one controller at once.  Apologies if that's labouring the obvious, but it is a bit unusual for the single side of a switch to be the output, which is effectively the case with cab control.

Edited May 12 by Chimer