Wiring a Single Slip

[60526]

Once upon a time I would have probably been able to solve this but the grey matter is somewhat confused at the moment. I'm replacing some mechnical point polarity switching with microswitches, problem is that the existing wiring has been played around with, so I am confused.

The attached sketch shows a single slip, the lines run from the arrival line into platform 4, platform 3 to departure and platform 4 to departure. Each point rod has a microswitch connected to it, these being for points 19 and 20.

The setup is as follows

A (arrivals) to P4, point P20 is set straight and P19 is set on the curve

P3 to D (departure), P19 is set straight and P20 is set on the curve

P4 to D, both P19 and P20 are set on the curve.

The points are controlled by lever and cord, and all I can work with is 2 microswitches, I know relays might be the best option but not at this time. How do you wire it up?????

 

If anyone can help it would be appreciated.

[Suzie]

Try this:-

 

 

I have assumed that the microswitches are in the coresponding position to how the track has been set.

 

 

[tebee]

That doesn't quite work - if both sets of blades are in the bottom position - so that the slip is effectively a diamond crossing, its possible to take the ARR->PL4 route and the PL3->DEP route.

 

The wiring as shown would work for the PL3->DEP route but not for the other.

 

I think it's impossible to do this using just the micro-switches.

[60526]

Excellent, yes it does work. Both sets of blades are never in the bottom position, When the line is routed A to P4, P20 is switched to straight, but P19 is also switched to the curved position.

 

I better explain further, this is for Borchester Market. If you've read some of the threads on RMweb you'll know that the team has had a few problems with the original wiring. Progressively we're working our way through potential problems. In this case it is around the main station approach, it's been intermittent but behaved itself at the Ally Pally exhibition recently. However during a running session in it's shed last weekend the problem re-occured, so with the layout appearing at the Roding Valley Group exhibition at Leytonstone next weekend I decided to do something about it, problem was that our chief sparks Ray has been busy this weekend, hence my request for help, and I'm over the moon that somebody from RMweb came back.

 

Anyhow the original concept was by Frank Dyer, "Suzie" well done for solving it, I'll add you to the list of honary members of the Borchester Market Group.

 

Regards

Charlie