Lionel 027 electric Switch Wiring Question

This is somewhat tricky, as you only want it to switch for a specific direction of travel.  It could be done with logic, I'm thinking a couple of relays or electronics.

 

Yes. You can do it with one relay. In this case, you can use an A-C relay, and do not need to provide D.C or a slow-release capacitor.  Or you can use a D-C relay and a diode.

 

You will need to create 2 separate insulated outside rail sections in the mainline track approaching the switch. Call them A and B. They need to be separated by one regular section of track.

 

The first one (A) goes in front of the track switch, about three sections before the switch, and is wired in parallel with the anti-derail section of rail on the switch itself. That will create the impulse that will swing the switch to the diverging route. We will call the wire that interconnects the insulated rail A and the diverging route switch coil the "diverging wire"

 

The other insulated track section (B) goes between section A and the switch, also in the main line.  Section B is wired to a relay ("B") that will operate whenever a train is on section B.  One side of the relay coil goes to section B and the other side of the coil goes to a constant hot post on your transformer.

 

Relay B has one break (normally closed) contact in series with the diverging wire.

 

Sequence of Operation:

 

Train approaches switch, and A section throws the switch to the diverging route.

 

Train travels around the loop, and approaches the trailing end of the straight entrance to the switch. 

 

The anti-derail feature of the switch senses the train, and throws the switch automatically to the straight direction.

 

The train now travels across section B and operates relay B.

 

The break (normally-closed) contact of relay B in series with the diverging wire now opens the diverging wire, and prevents the diverging choice from happening until the last car of the train leaves the interlocking, at which time the switch is thrown back to the diverging route.  This prevents the exiting train from "picking" the switch.

 

You can also do this with a 153C contactor, if you don't want to use a relay, but your operation will be more precise with the relay.

 

>direction of travel>------- section A------- regular section--------section B---------switch (diverging track)-----------loop----------entrance to straight side of switch-----------section B (again) --------- section A (again) ----------> exit the interlocking, train goes to the other end of the layout-------->

         

 

 

 

Arthur.  that is exactly the advice I was looking for.  thanks so much for taking the time to spell it out so succinctly!  I'll be  giving it a  shot in a few weeks and will post some vid

You're welcome.

 

There is one thing you might consider, which I neglected to mention...

 

As the train approaches the straight switch entrance, after having gone around the loop, if the train is going fast, I wouldn't completely rely on the anti-derail feature, I would recommend that you add another insulated section, right up close to the switch, and wired as we did for Section A, except that it will operate the switch to the straight direction. This is just some added security so that you won't have an embarrassment.  

 

Note that in this whole scenario, you don't even need to use a switch controller, since the whole operation is automatic and hands-free.

 

If you need a diagram, you're SOL, unless I can fax it to you. I am a Luddite who does not know how to draw a circuit and get it to you over the interweb.

Hi Art,
For a Luddite, you are up on your urban slang.

Interweb. LOL.

Most appropriate written use of the term I have seen.

"Upon further review..."

 

You will need to make insulated section "B" two sections long* (insulated outside rail on two pieces of track, insulated pins at each end, metal pin connecting them in the middle.)

 

This will ensure that if you run a rail car with a long wheel-base that it does not over-reach the insulated section and allow another car ahead of it to operate section "A" by mistake during the time that the train is exiting the interlocking.

 

*or, at least, longer than the longest rail car that you intend to have in the train.

 

As you can see, this type of control project is simple in theory, but as you start to explore all the possibilities, you need to rethink some of the practical applications.

 

Making relay "B" a slow release would allow just one short section of control track, but that requires that you use a D-C relay with a capacitor.

 

Once you get a mock-up built, I would energize the track, but just manually push a car up to the switch, then through the loop, and out the "exit" to ensure that we have our sequence correct.

Arthur pointed out the problem with going too fast and if you are using postwar 1122 switches and the train is going too slowly, because those switches operate on track voltage, you may not have enough voltage to completely turn the switch points which would also likely cause a derailment.  I don’t have any modern O27 switches so I don’t know if you would have the same problem with them.

 

BTW, if the length of the track between the switches is longer than the train you are planning to run, then you could automatically throw the switches without using any relays, just by using insulated rails on the track section adjacent to the common leg of each switch.  I did something similar to that and that is how I discovered the problem with insufficient voltage mentioned above. 

 

HTH,

 

Bill

If the switches are more than 1 train length apart, just one wire connecting the diverging route binding posts of the two switches will work.

In reference to Mr. Arthur's statement about "...to draw a circuit and get it and send

it over the interweb" wouldn't using a scan do a drawing work?

 

Or is there another way? 

 

Anyway, I always enjoy your posts, Arthur, always.

I was thinking along these lines myself, since I've done it.  But unless I'm misreading Rob's statement, the distance BETWEEN the switches is irrelevant. 

 

I'm mentally picturing a simple example.  Switch 'L' is on the loop on the left and switch 'R' is on the loop on the right.  The engine/train enters the left loop on the divergent route, loops around, and 'forces' switch 'L' into the straight route (since the switches are non-derailing).  At the same time, if the 2 switches are wired together, that action causes switch 'R' to the divergent route. 

 

When it exits the right loop, switch 'R' goes straight and at the same time switch 'L' goes curved.

 

Basically when one goes straight the other goes curved.

 

Sorry if I mis-read your answer Rob, but I still don't see the need between the switches.

 

- walt

Rob:  You are correct, he would not even need insulated rails as I suggested if his train is shorter than the distance between the switches.  Why overcomplicate it with relays or insulated rails! 

 

But if he wants to let it run unattended, he needs to make sure he has enough track voltage to throw the switches.  This could be a problem if he's running a modern can-motor locomotive and often means adding more cars to slow down the train!

 

Thanks,

 

Bill

I did mis-read.  I didn't FINISH reading his post where he describes using just one wire.

 

My method requires connecting the straight post on one to the divergent post on the other, and duplicate the other way.

 

- walt

So Happy with all of the responses. I'll actually be running a PS2 trolley so track voltage shouldn't be an issue. I will do some exprimenting until i find the ebst solution