Push button wiring for Lionel O27 uncoupler tracks

In short, there are two buttons because the activate the control rails in distinct ways.

Diagrams and explanations are in the Lionel Service documents which Olsen's kindly hosts:

http://www.olsenstoy.com/searchcd31.htm?itm=689

Here, the uncouple button, when depressed places hot power to both the left and right control rails. The unload button passes power to the right control rail and ground to the left control rail.

It would appear to me that the K-Line track only provides the simpler uncouple operation.

The "Unload" button powers up the control rails for operating cars that use sliding shoes.

The "Uncouple" button powers up the coil to uncouple cars with plunger type mechanisms, and powers up the control rails to uncouple cars with coil type coupler mechanisms.

If you only want to use the uncouple coil part of the track, a Single Pole, Single Throw - Normally Open (SPST-NO) switch can be wired to the coil (right-most connection on the track) and a constant voltage source post of a transformer. That will allow you to uncouple cars with the track power off.

Larry

I fervently hope your wires are in better shape than the ones I have are. These were flexible and the insulation fine when I was a child, but not so much now.

Cut a 1"-2" hole in the door and stuff the excess into it, cover the hole with controller or turnout, or stuff with moss, etc..

It can't be one button and retain full features. The rails work two ways, so one rail might have common or hot feed depending on your action choice.

You'd neep 2 momentery dpdt buttons/toggles.

To uncouple only, yes,...

if you jump L&R rails together at the track, then one lead off those to a #90, etc, then from #90 button to the tracks power terminal (center rail or transf. constant volt or other phased transformer, etc)

@Adriatic posted:

You'd neep 2 momentery dpdt buttons/toggles...

Or one DPDT center off momentary toggle(or other style, to your liking).

I’d forgotten about the control rails, since I don’t use them. I also didn’t realise that the live rails differed for some cars. 

Ok, so I can simply disregard the “Operate” button and just use the “Uncouple” button, and that will uncouple any coupler (including the handful of solenoid type couplers I have in use) and operate the only accessory cars I have (two coal tipper cars). I can use the K Line uncoupling Track the same way, apart from uncoupling solenoid couplers (which I don’t tend to do anyway) 

I don’t know why I didn’t think of simply stuffing the cables through a hole in the board, and covering it with the controller. Obvious, when you say it. I can also simplify the conduits for track droppers into a single conduit along one side, by doing that.