Scissors Crossover in EM Gauge

PaulR

Western Thunderer
Hi All,

As part of my next project I'd like to build a scissors crossover in EM Gauge with DCC. I feel OK about constructing it but my mind becomes completely befuddled by the logic of the wiring and electrical breaks.

Does anyone have a clear diagram with the breaks and wiring marked in - it would save my brain!

Thanking in anticipation,

Paul
 

James Spooner

Active Member
Hi Paul,

I have built, what is effectively a scissors crossover, in EM and using DCC, on my layout, Elmham Market (although it is heavily disguised in the goods yard). Remember that DCC uses positive and negative in exactly the same way as DC, so to an extent that is a bit of a red herring.

I am sure there must be many ways of doing it but my solution was to pair the points so there is a master and slave for each route. I used Fulgurex point motors as they have two pairs of switches and are quite kind on the points, but Tortoise or DCC Cobalt motors work equally well (and I have been using Cobalts as the Fulgurex’s fail). Then isolate the frogs on the diamond crossing as if it were two live frog points back to back and wire it so the polarities are controlled by the polarity switches on the points that feed into it (you will need to sit down and draw your wiring diagram for the diamond so you know what frog you are wiring to which point as the polarities might seem a bit counter intuitive).

The diamond then becomes a second slave to the master point controlling the route. The next bit is critical. If both master points are directed towards the diamond you will get a short. The way around that, which I adopted, is to introduce a form of electrical interlocking (again using the extra switches on the point motors) so that if one master point is directed towards the diamond, the other is neutralised and cannot move (and vice versa). You don’t want to create a conflicting movement anyway, so this isn’t an issue. I hope that helps but very happy to try to explain better if all I have created is fog!

regards

Nigel
 

PaulR

Western Thunderer
Thank you for that advice Nigel, especially the last bit which hadn't actually occurred to me. I'll take your cue and try drawing out a wiring plan. I'll be using Cobalt motors so I presume that they also have capacity to employ electrical interlocking.

I'll let you know how I get on!

best wishes,

Paul
 

Lancastrian

Western Thunderer
Paul,

This is what I have set out for a project later this year.
1655819713055.png

This is DC based, but as Nigel says, it will be the same for DCC. Two 4PCO relays driven with a 5v supply switched by points 6A and 8A.

Ian
 

Stephen Freeman

Western Thunderer
I think I do have a copy of the GOG manual page for this but obviously can't post it here, I think there may be something of use in either the EM or S4 manuals, if you have them. A bit of route setting is needed.
 

Phil O

Western Thunderer
I have built a half scissors on Pottery Quay, I use a double pole centre off switch to operate the servos and a micro switch on the servo to change the polarity of the common crossings. The off position on the switch sets the turnouts to normal, using one pole for reversing one turnout, with switch in the up position operates one servo and the other pole and the switch down the other servo. Linking opposite turnouts on the diamond should work ok.
 
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