Bearing Grease Leak

Technical Technical Discussion
1

Hi,

My team decided to use 13.75mm ID ThunderHex bearings this year to make assembly of mechanisms a little easier. We assembled our production shooter over the past few days, and they do indeed make it a lot easier. We ran them for the first time last night and everything was running fine. After running them on and off for about 10 minutes (maybe 50% on-time), we noticed that a small amount of a clear, yellow-ish fluid had come out of some of the bearings - presumably the internal grease on the bearing. We are running them quite quickly - about 9,500 RPMs. Everything seemed to still be running smoothly afterwards, but it was a bit surprising and concerning, as I’ve never observed this happening on other bearings in the past.

Some questions about this:

  • Is it typical for ThunderHex bearings to leak a bit of grease on their first usage?

  • Are we running them faster than they are spec’d for? I can’t find a maximum speed specification on any of the vendors that I know sell these (Vexpro, WCP, and ThriftyBot)

  • Is this a sign that these bearings are on their way to failing?

  • Is it likely that regular hex bearings will work better here?

Thanks!

2

Most of the bearings in FRC are shielded, rather than sealed. A bunch of centrifugal force, like while spinning at a bazillion RPM will cause them to shed any excess grease. I would not be concerned about that loss given the short operational life of a FRC robot.

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