Modifying whistle relays

I'm a bit confused. Will you be activating the whistle relay by pushing a conventional whistle control on a transformer?

Will the contacts of the relay be used to power a coupler?

If so, them I see no need to isolate the frame of the relay. If you wish to isolate the contacts, to provide a floating contact closure with no ground reference, I'm pretty sure (haven't looked at one in 30 years or so) that you can derive the wires going to the two contacts.

Can you tell us why you need to have the frame floating and not grounded to the frame of the car?

Can you expand upon the circuit you have in mind?

As a conventional whistle relay is wired, it already activates when DC is detected, while its relay is across the track power, and its contact feeds track power to the whistle motor. Just substitute the coupler coil for the motor in the above sentence, 

Look at a parts diagram for the 2330, 2340 and 2360 GG-1. There the whistle relay is isolated from the frame. Two things to keep in mind for these locos. First the relay is mounted upside down. To accommodate this the contacts are spring operated. Up side down or right side up does not have impact on insulating the relay from the frame. Second thing is the service manual shows the insulation paper in the wrong place. It goes between the relay and the bracket.   Many of the later stream locomotives isolate the relay bracket from the frame by attaching the relay to the plastic whistle body. 

I’m trying to set up this circuit using a post war whistle relay. I am modifying a 624 so that I can open the couplers by using the whistle button on a transformer to uncouple the engine anywhere in the freight yard. 

The whistle contact is not isolated from the relay frame. When the relay is activated it makes a path to ground through the relay frame. 

Hence why I am asking about insulating the relay frame from the loco ground and providing a dedicated ground wire from the tail end of the coil to ground. I just don’t know if this is a common modification or if I should look at a different relay where the contacts isolated from the relay and I can wire hot through them without sending hot to ground when the contacts are closed. 

There is no reason that I can think of that would require that you isolate the relay coil from the frame of the loco. As I said above, just substitute the coupler coil, as a load, energized by the relay contacts, for the horn in the loco.  

Each coupler has two wires. One is grounded. The other is waiting for "hot" from the track to operate. The relay has a switched "hot" lead that goes to the horn. Take that hot wire from the relay contact that normally goes to the horn, and re-route it to the coupler hot lead. 

The coupler coil is grounded and is not easily lifted.  The movable contact on the whistle relay is also grounded. To get the whistle relay to operate the coupler, the relay frame needs to be insulated as indicated by the OP. Lionel makes the two parts needed to do this. They are shown in the parts list for the two motor GG1. One is a fiber shoulder washer and the other is a fish paper insulation sheet.  Both are still available from parts dealers. The bracket that supports the relay may have to have the hole slightly enlarged to accommodate the shoulder on the insulating washer. 

David Johnston posted:

The coupler coil is grounded and is not easily lifted.  The movable contact on the whistle relay is also grounded. To get the whistle relay to operate the coupler, the relay frame needs to be insulated as indicated by the OP. Lionel makes the two parts needed to do this. They are shown in the parts list for the two motor GG1. One is a fiber shoulder washer and the other is a fish paper insulation sheet.  Both are still available from parts dealers. The bracket that supports the relay may have to have the hole slightly enlarged to accommodate the shoulder on the insulating washer. 

I had the same idea in mind but I was going to use some thin paper gasket material I have handy to do it, with the same idea over making the center hole over sized in the arch bracket I made to keep it isolated. That was what I considered “easy”. The hard part I had in mind was the removing of the end of the relay coil that goes to ground then extending it (or unwinding it slightly) and making a way to connect it to ground so the relay still operates on a whistle signal and operates the coupler. I do wish they were 2 wire couplers then I would leave them hot all the time with a ground to operate but Lionel didn’t make it that easy for me. 

Forgot about that issue.  On the GG-1 whistle relay there is a third contact plate in that stack of brass contacts and insulation screwed to the relay frame. Both ends of the whistle relay coil go to those contacts. One is then connected to the center rail and the other to the locomotive frame. Adding an additional contact to that stack is easy if you have a scrap relay to strip the parts off of.  The problem is the screw, which has an odd ball thread on it, and you might need one that is slightly longer. Again, you should look at the GG-1 service manual pages. This is shown in the wiring diagram for this locomotive. 

   Just use paper or plastic under the frame and a nylon nut and bolt to hold it.

Never mind. The isolation kills the coil being active.

Use the whistle relay as is, and trigger a second ac relay that is isolated on it's points.

I rememeber the other magazine did a article on this exact topic a few years ago and also there was this discussion on their forum. Here you go......

http://cs.trains.com/ctt/f/95/p/168736/1854296.aspx

That link just loops back to this page Yardmaster. Can you elaborate on what was done?

Sorry about that!

Fixed it!

Thanks for all the tips everyone. I used the second relay I had in case I messed it up but it worked fine the first time. 

I insulated the relay frame with some gasket paper then took the tab for the coil out of the contact stack and ran that to the frame. I attached the center pickup to the screw and put the coupler wires to the tab on the contact. It works great. I need to get my freight yard up and running now. It’s half way through the layout stage and doesn’t have power yet.