If your bearings are starting to go out after only 2 months, that is
only 1500 hours. And if I assume that many of those hours are not high
load (or no load), I'd say you have a design problem that won't be
solved with a better bearing. Moisture, dirt, axial loads, overloads,
bad mounting surface all come to mind.

I'd certainly be designing my hard to service equipment for 10,000 hours
MTBF with a goal of 20,000 hours. Keep in mind that many fractional
horse electic motor applications (ie furnace fans) have 50k to 100k hour
life expectancies.

tg wrote:
"Tom" wrote in message ...

tg wrote:

"Clive George" wrote in message ...


"tg" wrote in message ...

Define "best". Longest lasting?


yeah, longest lasting

LOL Don't we all. However as you don't disclose the environment or
the usage of this generator and as these bearings are common as
dirt with a price to match I don't see why you're so concerned.


the generator is a wind turbine. The bearings are to a small degree exposed to the elements, or at least the moisture and
constantly varying temperatures of the outdoors. The turbine is high up and getting access to it means erecting a scaffold tower.
All of this is a lot of work simply to replace bearings, thus I want a grade that is going to last. I expect that 'any brand name'
might not serve the purpose, the cheap type might start rumbling or squealing after a couple a months, thus I want to get it right
when I have to re-install the turbine high in the sky. It's no joke assembling a scaffolding tower and then building up the turbine
at the top of it. Ideally I'd like to service the turbine only once a year, or maybe even once every 18 months if possible, and
fitting top knotch bearings might get me that.