Oh, the tragedy!!!
I can no longer claim that all my American Models locomotives have been trouble free.
While running my New Haven AC HiRail U25B's over the Christmas Holidays, they made about six orbits of my loop and began squealing like a banshee. I removed each unit to see which one was squealing and it turned out to be both! Arrrgh...
I immediately dug out my scale U25B's and tested them, they ran fine.
I opened one up and discovered a split gear on one of the axles. Didn't bother checking the other trucks. Replace one, replace them all, I figured. I waited until after the holidays to order 8 new wheelsets to repair both locomotives. They arrived about a week later.
So, here we go...
Here's the replacements all in a row, the insulated sides face me so I wouldn't do something stupid...
The sideframes/gearbox cover are one piece nowadays, held on by two screws.
It's a snug fit, so a little care must be taken when pulling off the cover. This is where I found out I had one cracked gear on each truck assembly on both units and it wasn't on the traction tired set. Interestingly, the cracked gears were all on the outside wheelsets. Maybe something to do with the R20 curves I was running them on? Just a thought...
Once the wheels are out, be careful not to upset the bearing springs.
Here's one of the cracked gears. Three were cracked all the way through, the other was working its way from the axle to the gear face. The other 4 gears looked fine, but I replaced them all.
All in all, it took about 5-6 minutes per truck to replace the geared wheels. Most of that time was convincing the square bearings to return to their proper place. A little grease on the gears, a drop of oil on the bearings, button them up and I was good to go.
So happy together... I kept my Christmas loop up to test this repair and now the U-boats run like new.