A while back, I encountered a very worn out motor on one of my NW-2 switchers, the worst part of the wear being the bronze axle bearings and even the stainless magnetic axles. They were so worn that the gears would almost completely disengage and would occasionally bind. So I broke it all down figuring “What do I have to lose?” I took some measurements of the axles near the middle where there was no wear, and also measured the frame opening hole to see which ball bearings sets might fit. I purchased a few ball bearing sets (with flanges) that would be as close a match as possible – purchased right off the shelf based on my measurements, so I knew in advance the fit would not be perfect … but awful close! Sadly, this motor was not worthy of the expense of custom made bearings!!
I opened up the bearing holes in the aluminum frame a mm or two, and got a great fit for the new roller bearings – loose, but not very. My plan was to use JB Weld (metal version) to secure the outer portion of the bearings directly to the frame. That went well.
Then I slipped new (used) axles in place thru the inner portion of the bearings. Right away I felt some weirdness – the axles were ”sucked in” through the inner section of the new steel bearings - not too surprising considering the axles were magnets sliding through a steel bearing. Somewhere about half way in, the attraction changed to a slight repulsion – then as I pushed them all the way in, things just sort of stayed in place.
I did the other axle, then mounted both of the non-gear wheels and used Loctite to bond the axle to the inner portion of each bearing. The reason for the Loctite is that the axles are undersized to the inner bearing, just enough to allow the axles to spin, while the inner bearing remained stationary – I wanted the ball bearings to do their job instead of just mimicking Lionel’s bronze sleeve bearings. Insuring that no Loctite got squirted into the ball bearings, things went remarkably smooth here.
After things had set up for 24 hrs, I gave the wheels a quick twist. That’s the first time I felt what you can see in this link to a VIDEO of the action. For a portion of each revolution of the wheel, things are silky smooth – then I encounter resistance. Not the kind of resistance you feel when a wheel is dragging on the frame, but a “springy” resistance. In fact if you twist the wheel a bit more and then release it, the wheel bounces back! Clearly a magnetic effect I would think.
So here’s the question: can someone explain the dynamics of what I am seeing/feeling, and is there a simple fix where I could, for example, remove one wheel, then rotate one of the axles (say) 90 degrees, and everything cancels out? And then I have the silky smooth rolling effort of a real train? Or could this even be the work of some strange geometry when it came to the loose axles being glued in place to the inner bearing sleeve? After all, what could possibly go wrong when disassembling a soft aluminum frame, prying it apart, drilling new holes and then expecting everything to be nice and square upon reassembly?
I would appreciate hearing from anyone who has knowledge in the dynamics of this form of magnetism!