3 ms·

ArduinoVsEvil made a video about this, explaining how the demonstrations gifs are pretty meaningless: https://www.youtube.com/watch?v=uD7Lzv5fWhs https://www.y

ArduinoVsEvil made a video about this, explaining how the demonstrations gifs are pretty meaningless: https://www.youtube.com/watch?v=uD7Lzv5fWhs https://www.youtube.com/watch?v=uD7Lzv5fWhs In general, the concept doesn't make sense, or at least it's being inadequately explained. It is probably a hoax.

HCIdivision17 11y ago
I was thinking something similar. I immediately thought, "wait, doesn't a speed change imply a force on the bearing, and wouldn't that necessarily imply friction between the bearing and track?" Under load (and I've no idea how much), I just imagine this applying a subtle little ba-dump-ba-dump-ba-dump to the bearings as they spin around. Their innovation seems to suggest that this is such a small change that it has less of a bump and more of a very slight shape change effect. So there may actually be something there - I've certainly seen stranger topological results. But until I see one after a few thousand hours in a high speed motor, I'll be on the fence.
- jobu 11y ago
  > But until I see one after a few thousand hours in a high speed motor Add some load to that as well. It seems pretty unlikely any indentations will last very long under stress. I've replaced bearings on trailers and vehicles and they often have wear marks deeper than the indentations they showed in that video.
- ars 11y ago
  > doesn't a speed change imply a force on the bearing .... imply friction Not necessarily. A speed change could also be because the track is longer. That's how trains stay on the tracks, the wheels are slanted, and if they turn off the track the length of the wheel changes, which changes the speed (relative to the wheel on the other side) and steers it back onto the track. Feynman explains it: https://www.youtube.com/watch?v=y7h4OtFDnYE https://www.youtube.com/watch?v=y7h4OtFDnYE
  - function_seven 11y ago
    > and if they turn off the track the length of the wheel changes But is doesn't actually change. A different part of the wheel comes into contact with the rail, but that different part always had a higher linear speed. It just wasn't in contact with the rail until the turn. But with these bearings, it appears that the balls themselves actually do speed up or slow down to maintain separation from one another. In that case, there must be a force coming from somewhere to effect those changes.
snarfy 11y ago
They explain the balls spreading apart as they accelerate rolling down the bump. What about the balls compressing as they go back up the bump? Wouldn't the balls constantly collide and separate?
- HCIdivision17 11y ago
  To be charitable, I think the actual amount of the bump and spacing is very carefully calibrated to make sure that doesn't happen. Really, it's almost like replacing the cage with a subtle bumpy bit in the race. And that seems less-crazy. But without the grease, wouldn't it suffer the same as greaseless caged bearings? Albeit slower wear? Perhaps the wear is reduced enough that you'd be willing to replace them more often in exchange for the lower losses through friction. I dunno; I really think this just needs a (perhaps literal) ton of testing.
SwellJoe 11y ago
I'm always suspicious of claims of extraordinary gains from very old technology, and this is no different, but I don't understand the physics well enough to make a serious case for why. I figured someone on HN would debunk it, though I don't think that's entirely happened yet in this thread. Then again, the people making extraordinary claims are the ones with the responsibility to provide extraordinary evidence, which they clearly haven't done. But, Popular Mechanics is excited about it, so it must be awesome. Those guys are all about bearings. Anyway, this should be perfect for my perpetual motion machine. Less friction means it'll run for more forevers before it stops.

HCIdivision17 11y ago

I was thinking something similar. I immediately thought, "wait, doesn't a speed change imply a force on the bearing, and wouldn't that necessarily imply friction between the bearing and track?" Under load (and I've no idea how much), I just imagine this applying a subtle little ba-dump-ba-dump-ba-dump to the bearings as they spin around. Their innovation seems to suggest that this is such a small change that it has less of a bump and more of a very slight shape change effect. So there may actually be something there - I've certainly seen stranger topological results. But until I see one after a few thousand hours in a high speed motor, I'll be on the fence.

jobu 11y ago
> But until I see one after a few thousand hours in a high speed motor Add some load to that as well. It seems pretty unlikely any indentations will last very long under stress. I've replaced bearings on trailers and vehicles and they often have wear marks deeper than the indentations they showed in that video.
ars 11y ago
> doesn't a speed change imply a force on the bearing .... imply friction Not necessarily. A speed change could also be because the track is longer. That's how trains stay on the tracks, the wheels are slanted, and if they turn off the track the length of the wheel changes, which changes the speed (relative to the wheel on the other side) and steers it back onto the track. Feynman explains it: https://www.youtube.com/watch?v=y7h4OtFDnYE https://www.youtube.com/watch?v=y7h4OtFDnYE
- function_seven 11y ago
  > and if they turn off the track the length of the wheel changes But is doesn't actually change. A different part of the wheel comes into contact with the rail, but that different part always had a higher linear speed. It just wasn't in contact with the rail until the turn. But with these bearings, it appears that the balls themselves actually do speed up or slow down to maintain separation from one another. In that case, there must be a force coming from somewhere to effect those changes.

snarfy 11y ago

They explain the balls spreading apart as they accelerate rolling down the bump. What about the balls compressing as they go back up the bump? Wouldn't the balls constantly collide and separate?

HCIdivision17 11y ago
To be charitable, I think the actual amount of the bump and spacing is very carefully calibrated to make sure that doesn't happen. Really, it's almost like replacing the cage with a subtle bumpy bit in the race. And that seems less-crazy. But without the grease, wouldn't it suffer the same as greaseless caged bearings? Albeit slower wear? Perhaps the wear is reduced enough that you'd be willing to replace them more often in exchange for the lower losses through friction. I dunno; I really think this just needs a (perhaps literal) ton of testing.

SwellJoe 11y ago

I'm always suspicious of claims of extraordinary gains from very old technology, and this is no different, but I don't understand the physics well enough to make a serious case for why. I figured someone on HN would debunk it, though I don't think that's entirely happened yet in this thread. Then again, the people making extraordinary claims are the ones with the responsibility to provide extraordinary evidence, which they clearly haven't done. But, Popular Mechanics is excited about it, so it must be awesome. Those guys are all about bearings. Anyway, this should be perfect for my perpetual motion machine. Less friction means it'll run for more forevers before it stops.