ZW rollers

Crush the old roller the take a pair of side cutters and cut the old pin between the roller bracket.

I crush the old carbon wheel with a pair of needle-nose pliers, then just use a Dremel cutoff wheel to slice the rivet in half.  They are very hard, and most cutters won't cut them easily.  The spacing between the ears is also pretty close for many cutters.

I have the same project coming up. How do you replace the new pin, or should I say how 's the new pin held in place?  Bob

The Pin and rollers come in a repair kit. I use a drill bit and drill the center out a bit until the flange is weak. Then I pull it through on the other side. To put the new pins in and roll the new flange I use a hole punch to work the flanges over.

What I do, not necessarily what the "experts" would recommend, is I just crush the end of the new pin so it won't come out.  You also want to make sure you insert the pins so that the heads are facing each other so they won't clash when the rollers pass each other (don't ask how I know this!).  I also clean the ears of the arm before I put the roller and pin back on, finally I solder the pin to the ears of the arm.  I get some static about this from the same "experts", but I've measured a significant voltage drop of .2-.3 volts under load ( 8 amps measured) that is eliminated by soldering the pin.  That's 2.4 watts being dissipated at the junction, that heats it up significantly!  I don't have any issue desoldering it when it's time to replace the pin, so I don't see any downside to my method.  There's plenty of heat already generated with the carbon roller spanning adjacent turns, no reason to add to the heat.

Important note, I don't take anything apart to do the repair, other than the top cover.  I just gently pull the arm out about 1/2" from the core and do the work on it there.  It makes the job go much faster, about 15 minutes for the four rollers.

gunrunnerjohn posted:

What I do, not necessarily what the "experts" would recommend, is I just crush the end of the new pin so it won't come out.  You also want to make sure you insert the pins so that the heads are facing each other so they won't clash when the rollers pass each other (don't ask how I know this!).  I also clean the ears of the arm before I put the roller and pin back on, finally I solder the pin to the ears of the arm.  I get some static about this from the same "experts", but I've measured a significant voltage drop of .2-.3 volts under load ( 8 amps measured) that is eliminated by soldering the pin.  That's 2.4 watts being dissipated at the junction, that heats it up significantly!  I don't have any issue desoldering it when it's time to replace the pin, so I don't see any downside to my method.  There's plenty of heat already generated with the carbon roller spanning adjacent turns, no reason to add to the heat.

Important note, I don't take anything apart to do the repair, other than the top cover.  I just gently pull the arm out about 1/2" from the core and do the work on it there.  It makes the job go much faster, about 15 minutes for the four rollers.

Thanks for the info !!!!!

Thanks for the advice and tips !!  I don't want to take it apart, I will do it in situ !!  I have the rollers and pins. A little bit more involved but will take my time.  Fun to learn new things.  My Standard gauge likes the ZW.

I use a twist-tie to hold the arm out away from the coil about 1/2" (don't get carried away, they're brittle!).  If you take the arms apart, it takes a lot longer to do the job.

I agree with John about soldering the pin in place.  Besides eliminating the resistance between the pin and the arm, you are also not putting any stress on the roller and potentially breaking it.  The first ZW I did was almost 40 years ago, and the rollers and pins are still in place.

Once the pin is out I clean the arm around it and us a drop of solder on the pin head to hold it in place. Works every time and easy to remove if a new roller is needed. No rivet squeeze or press is needed.

The squeeze of the other end takes seconds, and insures if the roller heats up enough to melt the solder, worse things don't happen with the pin coming lose.

What ever suits you. It has worked for me many years now.

I finally got the old rollers out-not the easiest thing to do and have the new ones in but quit for the night. Really tight working space, not too sure how I could squeeze the end. Want to put a solder on the pin though. The two arms on the one side are touching so have to deal with that. It would be a lot easier if the arms were out of the transformer but I don't want to even think about putting those back !!

You just squeeze it sideways with a pair of needle-nose pliers.  Other than when I've had to replace one, I've never taken the arms out of the ZW, no reason to IMO.