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

[Bruce Freeman]

I'm constructing a simple gearbox for a mechanism I'm playing with.
The gearbox itself is of no importance except as to provide power to
the mechanism, and the nature of the gearbox is such that I cannot
simply buy a commercial unit.

Perhaps naively, I simply mounted sealed ball bearings into
appropriate recesses in the housingn, counting on the small clearance
between bearings, shafts and housing to  seal against oil leakage.  No
go.  The oil leaks right out pretty quickly.  Grease works better, but
also leaks.  Loss of grease is not a problem - the potential for
contamination of the driven device is the problem.

Next I tried sealing between bearings and shafts or housing with a
medium-strength "lock-tight" product.  No go.  Oil leaks right out
when gearbox is run.

I could go to a product like RTV rubber, but I'd probably never be
able to change out the bearings again if I did that.  Still I may
consider it.

I'm looking for other ideas.  I'd prefer not to remanufacture the
housings, but  could do that if necessary.  For example, I'd have to
do something like that if I went to O-ring seals.  However, I'm not
convinced O-rings would do a better job, so am not ready to take that
particular step.

How is this done in commercial mechanisms?

Any suggestions would be appreciated.

-- 
Bruce
NJ

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