On Wed, 8 Oct 2003 10:26:10 +1000, "Deep Freud Moors"
wrote:

snip

Dirt is a bearing killer whether in grease or not. Contrary to what you just
said, grease provides an effective barrier against dirt when applied
correctly.

snip

DFM

I'm sorry Deep, but grease provides no barrier at all. In fact grease
plus dirt equals grinding compound. This mixture will result in the
rapid erosion of metallic surfaces ( in a dynamic situation).

Thirty years working in foundries forces me to agree with Jose.
Bearings will always fail if the seals are damaged.
Bearings designed to be used in particularly aggressive conditions
will often be double sealed.

Allan Jones