[TheForge] OT - Grease/oil seals for a gear box

[Paul]

Bruce Freeman wrote:
> Well, I am surprised!  I always thought of packing seals for plumbing
> applications like valve stems, where the rotating rate is about once
> per day!  I've looked up a little and find some of them are good for
> "high speed" applications, but I don't have enough info yet to
> determine what RPM that means.
> 
> Does anyone know what considerations go into selecting design criteria
> and packing material for an application with speeds upwards of 2000
> RPM?  (I'm shooting for 10kRPM, but doubt I'll get there with this
> prototype, for reasons other than the packing seals.)

snip

What I gotta say is wow. 10000 rpm is a lot for a seal. I tend to think 
that the only type of seal that will withstand that speed is a ceramic seal
see:
http://www.pumpseals.net/Outboard_seals.htm
for a look see.
The ceramic seals operate well at high speeds but the majority of 
installations that I have seen them in are for pumping water... they are 
therefor cooled by the water.

If you can restructure the shaft and housing to accommodate a sealed 
high speed bearing such as those found in an automotive alternator you 
would be well served. The poor alternator operates at high rpm ( its 
usually 'geared' up at least 2:1 and some times 3:1, if the crank is 
turning 4000 rpm you can see what that does to the alternator shaft 
speed). Those bearings are pre lubricated and shielded.
As a testament to their toughness the six bearings in my three cars, 
100050 miles, 150000 mi and 132000 miles are all original. if you can 
adapt your shaft and housing sizes that's the way I'd go...
Good luck

-- 
Paul Sperbeck  WB9HCO

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