PW Coil Couplers

It grounds in the middle of the coil on the tube the coil is wrapped around. This tube is usually crimped on the back to support the fiber board that the other, outer, end of the coil is attached to.  The coupler is crimped to a steel strap or plate that connects to either the truck frame or axles.

Thanks for the input. So where does the ground in the middle of the tube go to?   Does it ground at some point to the wheels? Shouldnt I have continuity from the shoe through the coil to the wheels?

The coil should be grounded on one end or it wouldn't work.

@Train Nut posted:

Thanks for the input. So where does the ground in the middle of the tube go to?   Does it ground at some point to the wheels? Shouldnt I have continuity from the shoe through the coil to the wheels?

The accessory shoe rails on the uncoupling track are energized with center rail power when the uncouple button is pushed. This power goes through the rivet in the accessory shoe. The top of the rivet is contacted with a copper spring which conducts power to to the fiber plate on the rear of the coupler. One end of the coil wire is wrapped around this spring. The return path varies a little depending on the type of truck.  The coil wire is wrapped up between the coil and the tube it is wrapped around. That tube contacts the coupler body. The coupler body is crimped to a plate that hangs on the axles. Wheels on the axles contact the outside rail. There are lots of contact points that might be a problem.  I would use a wire to probe the various joints to see where conductivity is being lost.

Well my only conclusion is that they're both burnt out. I have continuity from the rivet on the shoe to the brass spring to the input of the coil on both trucks, but nothing when I touch the wheels or any metal will complete the circuit.  Seems odd that they're both bad.

Can you provide a picture of the back of the coupler?

@David Johnston posted:

Can you provide a picture of the back of the coupler?

I have continuity on both trucks from the shoe to the coil where the red arrow is. 

Touch transformer power to the solder lug on the coupler and the end of the coil wire where it is grounded. The coupler should operate. If it does not, chances are the coil is bad.

Larry

Forgive my ignorance. I've never messed around with coil couplers other than replacing springs.

Where does the coil ground? I was thinking any metal or the wheels would be ground.  It can't be the crimped part on the fiberboard.

In your middle picture there is a silver disc next to where the copper spring attaches to the fiber insulator. That is where the coupled grounds.

@David Johnston posted:

In your middle picture there is a silver disc next to where the copper spring attaches to the fiber insulator. That is where the coupled grounds.

That is crimped to a fiber board. How would it to make ground? 

The coil wire where your red arrow is pointing needs to be connected to a metal part of the truck. (Make sure the insulation is scraped off the wire for it to make electrical contact.) Touching power from the transformer to the pickup shoe (or the solder lug next to your red arrow) and the metal of the truck should activate the coil and open the coupler.

Larry

From what I can see that wire is soldered to the lug and then goes to the coil. 

@Train Nut posted:

That is crimped to a fiber board. How would it to make ground?

If you turn the truck over you will see where the coupler is crimped to the plate that is attached to the axle. That  silver disc is just a good place to get good contact to the coupler body. The crimp between the coupler and the bottom plate is one place you can loose the ground contact.

@David Johnston posted:

If you turn the truck over you will see where the coupler is crimped to the plate that is attached to the axle. That  silver disc is just a good place to get good contact to the coupler body. The crimp between the coupler and the bottom plate is one place you can loose the ground contact.

Sounds like we're talking this area here.

So the unvarnished end of the wire Just sandwiched between the metal? If so, I imagine drilling the rivet out and trying to make a better connection is the fix?  Unless of course the coil is bad.

To test the coil, touch power from the transformer to the pickup shoe and to the loose wire. That should activate the coil and open the coupler.

Larry

@TrainLarry posted:

To test the coil, touch power from the transformer to the pickup shoe and to the loose wire. That should activate the coil and open the coupler.

Larry

Hi Larry.

What loose wire are you referring to?  The wire that my arrow is pointing to is attached from the coil to the solder lug....

My apologies, I thought the wire in the picture was loose and not connected to anything.

Connecting transformer power to the solder lug and to the truck frame should energize the coil. Does it?

Larry

Ok Larry, I feel stupid.....

I should just tried the transformer to begin with.....    They both work! 

I was too lazy to get the transformer and used the meter and it bit me!  LOL

I'm still stumped why the meter showed no continuity from the lug to the frame though. 

But the good thing is they both work. 

Thanks Larry and thers for the help!

TN