Scissors (elec)trickery

[Ian Smeeton]

It has been very quiet on PSJ for the last couple of months, lack of mojo the main culprit, but when the mojo has been in the room, I have been working away at the electrics.

 

The discovery of a 1949 map showed a scissors crossover in use in Paisley St James Yard, and three were duly constructed, two being immediately scrapped as they were no good!

 

The third survived, and is now on the layout.

 

The next stage is electrifrying (the layout, not me) everything.

 

I have the second most boring job in the world which gives me an awful lot of thinking time, but even thinking for eight hours at a stretch, I have not been able to ponder my way through eletrifying the scissors crossing.

 

 

Traditional DC, operation of turnouts by wire in Tube from DPDT slider switches. Additional micro switches could be sourced, although I don't have any at the mo.

 

Is there any kind soul out there who would be able to give me some guidance.

 

I have had a hunt around the net, but haven't found anything I understand (yet)

 

Regards

 

Ian

 

 

 

 

 

 

[Sol]

Read this page

https://brian-lambert.co.uk/Electrical_Page_3.html#Bookmark5

 

Ron

[Sol]

and this

 

and

http://www.stciers.me.uk/home/track_wiring/scissors.htm

[Ian Smeeton]

Thanks for the above.

 

I will have a good study of the methods.

 

Regards

 

Ian

[Silver Sidelines]

I took the easy option and used a 'insulfrog' diamond.  The rest of the trackwork is electrofrog, spot the nylon joiners for cab section breaks.  It would be a neat project to carve up the diamond to bring the tracks closer together.#

Ray

 

[Sol]

like this one .

 

Edited March 10, 2019 by Sol
added another link

[AndyID]

 

You could try this. There are really only two "states". All straight or all crossing. You can set the points for other combinations but none of them make much sense.

 

I'm assuming you are using live frogs. There are six of them (indicated by the circles) but you only need to gang the diamond's frogs from two of the turnout frogs.

 

(from a former Paisley Buddy)

 

 

 

 

 

 

 

 

 

 

 

Edited March 10, 2019 by AndyID
JPG might be better

[Izzy]

Hi Ian,

 

This is how I would do it.

 

 

Use one set of points (A1/A2 shown here) to set the crossing polarities, otherwise using B1 & A2 both routes have to be set for crossover to get the correct polarities for either route, A1/A2 or B1/B2. Then, without any interlocking disipline myself to only set one cross route at any time with the other pair of points set straight, so the right polarities exist for the route chosen.

 

Hope this helps,

 

Izzy

Edited March 10, 2019 by Izzy

[Suzie]

There are three states in practice which makes the wiring a bit more intuitive:-

 

• All straight
• Crossing bottom left to top right
• Crossing top left to bottom right

I am assuming that you will feed both routes from one end and not require power routing and that you can operate the two points of each crossover with a single switch. DCC would have made this a lot easier, but you should be OK.

 

Note that the frogs of points 1 and 3 are connected together as are the frogs of points 2 and 4 to make life easier.

 

I could not do it all with DPDT switches, so you might have to add a microswitch to point 1 to get the extra pole.

 

If you need power routing you will need extra poles for that too. Wiring is common return with the black feed being the common.

 

 

[AndyID]

Ian's scissor crossing is in a goods yard. I'm not sure he's going to need that much complexity

[Suzie]

1 hour ago, AndyID said:

Ian's scissor crossing is in a goods yard. I'm not sure he's going to need that much complexity

 

If it is 'one engine in steam' then all four feeds will be the same and that will simplify things a lot. Context is all!

Edited March 10, 2019 by Suzie

[AndyID]

58 minutes ago, Suzie said:

 

If it is 'one engine in steam' then all four feeds will be the same and that will simplify things a lot.

 

If Ian promises to never foul the points he can make it even simpler and go with a two-state (all straight/all crossing) version in which case he won't need any additional switches

[Ian Smeeton]

I promise to never foul the points, however, the scissors may have to be operated by one of 3 controllers.

 

Normally the yard controller will be in charge, however, at times, either the down or up main controllers may have to be used to dispatch or recieve trains.

 

I do have a cunning plan for this.

 

Or (being Scots) a punning clan!

 

The methods shown above all seem to have their merits, some more than others, but being three pints of Pedigree down, this afternoon, I think that further consideration may have to wait fro sobriety, whnever that occurs.

 

Gentlemen, thank you for your help, and I propose a toast. Please raise your glasses...

 

Success to Temperance!

 

Regards

 

Ian

[pH]

11 minutes ago, Ian Smeeton said:

 ... but being three pints of Pedigree down ...

 

Lucky you! Incidentally, should it be "three pints down" or "three pints up"? 

[Suzie]

1 hour ago, AndyID said:

 

If Ian promises to never foul the points he can make it even simpler and go with a two-state (all straight/all crossing) version in which case he won't need any additional switches

 

The issue for this method is that the diamond frogs will need to be set depending on which way you are going through the crossover - that is why there are three states and not two.

[Ian Smeeton]

39 minutes ago, pH said:

 

Lucky you! Incidentally, should it be "three pints down" or "three pints up"? 

 

Judging by the comments   & looks from Mission Control, I am 3 Pints Down,

 

And Overdrawn on Brownie Points.

 

Regards

 

Ian

[AndyID]

1 hour ago, Suzie said:

 

The issue for this method is that the diamond frogs will need to be set depending on which way you are going through the crossover - that is why there are three states and not two.

 

And you are absolutely correct!

 

You might getaway with two states for the points but the diamond's frogs must be set according to the route.

[Suzie]

1 hour ago, AndyID said:

 

And you are absolutely correct!

 

You might getaway with two states for the points but the diamond's frogs must be set according to the route.

 

Your diagram will work, it just needs a few more insulated gaps than my method. The discipline of only setting one crossover at a time still applies.

[AndyID]

33 minutes ago, Suzie said:

 

Your diagram will work, it just needs a few more insulated gaps than my method. The discipline of only setting one crossover at a time still applies.

 

LOL! I talked myself into believing it won't work. That's true if you throw all the points but, as you say, it does seem to work if you treat it like two crossovers and only use one at a time.

[Izzy]

I don't know how Ian is considering powering the track, but I would split it into five separate pieces, each point and the diamond, and then have them as three sections, two straight routes plus the crossing, the routes individually switched on/off and the crossing powered from both of them. In this way, and with the frogs powered as I suggested earlier, only the DPDT switches Ian mentioned earlier would be needed - just one side actually - to switched all the frogs. I am out today, but if it would help I can post the wiring dia later. I always like to try and keep wiring as simple as possible.

 

Izzy

 

[Ian Smeeton]

2 hours ago, Izzy said:

I don't know how Ian is considering powering the track, but I would split it into five separate pieces, each point and the diamond, and then have them as three sections, two straight routes plus the crossing, the routes individually switched on/off and the crossing powered from both of them. In this way, and with the frogs powered as I suggested earlier, only the DPDT switches Ian mentioned earlier would be needed - just one side actually - to switched all the frogs. I am out today, but if it would help I can post the wiring dia later. I always like to try and keep wiring as simple as possible.

 

Izzy

 

 

Yes, please.

 

This is the hardest part. After I have wired and run this, the single slip and diamond for the yard entrance should be a doddle.

 

Regards, and thanks to all for the input.

 

Ian

[Ian Smeeton]

Hopefully I can upload the .box file here for Izzy.

 

No, .Box files not allowed.

 

There is the screenshot lfurther up the thread, though, if that is any use.

 

Regards

 

Ian

 

 

[Grovenor]

13 hours ago, Izzy said:

I don't know how Ian is considering powering the track, but I would split it into five separate pieces, each point and the diamond, and then have them as three sections, two straight routes plus the crossing, the routes individually switched on/off and the crossing powered from both of them. In this way, and with the frogs powered as I suggested earlier, only the DPDT switches Ian mentioned earlier would be needed - just one side actually - to switched all the frogs. I am out today, but if it would help I can post the wiring dia later. I always like to try and keep wiring as simple as possible.

 

Izzy

 

If Ian's scissors is built as per the Templot plan he showed then this approach is not practical, it needs to be looked at as an integrated whole to avoid the need for rail gaps in very awkward places. The required wiring has already been provided by Suzie.

See

Regards

[AndyID]

7 hours ago, Grovenor said:

If Ian's scissors is built as per the Templot plan he showed then this approach is not practical, it needs to be looked at as an integrated whole to avoid the need for rail gaps in very awkward places. The required wiring has already been provided by Suzie.

 

 

I agree. Putting breaks at some of those locations would be difficult.

 

I think there is a way to do it with 2 two-pole switches but it's getting late here and I could be talking nonsense. I'll post it tomorrow if it still seems to make sense.

 

[Suzie]

2-pole switches will require breaks around the four point frogs (eight of them) so that you can just link the crossing frogs to the point frogs and have one pole per point frog.

 

I tried very hard to rework it but DPDT + TPDT is the best I could get either way while maintaining the structural integrity as far as possible with breaks just on the crossing frogs.