I have opened several motor bearing housings and seen signs of miserable distribution of new grease added during relub. The new grease doesn't make it anywhere near the bearing, unless a lot of grease is added. If too much grease is added for large bearings on 3600rpm machines, you will very soon have overheating problems.

I was just toying with the idea of a different approach. What if we remove the drain plug and hook up to the inlet fitting a supply of low-pressure room-temperature oil/air mixture to gently blow into/through the bearing? It seems like you would then have all surfaces well coated with oil film, plus some small amount of oil absorbing back into the grease, especially the grease right at the bearing which is the most critical. When you close up the bearing drain I think all that new oil trapped in there would keep everything "moist" with oil for quite awhile.

I'm picturing this might be done periodically instead of regreasing. It would only apply to problem machines - those large-bearing 3600rpm motors... I have a bunch. Air would have to be super clean and dry.

Could it work or is it off the wall? What would be the pitfalls?

This message has been edited. Last edited by: electricpete,

Hi Pete,

Are you talking about a particular type of grease or in general? If it is a particular type of grease you can consider to change to something less viscous having the same NLGI rating and also considering your operating conditions.

Otherwise you have other options like using an Ultra lube grease gun which will provide informations like when to stop greasing or whether the grease is already in the bearing or not! Then you can easily find whether your equipment is under greased or over greased!! Just a suggestion!!

Have a nice day!!

Mostly I was just throwing an idea around for disussion.

One thing I wasn't thinking clearly when I implied the air/mist could flow right in the inlet and right out the drain. Would either have to stick a poker up the drain to clear the passage or insert a tube into the inlet with enough room around it to allow for air to escape the same point. I wouldn't want to pressurize the cavity or make air escape from the seals.


The motors I am thinking about are the one's I mentioned in the thread "grease for high speed". Those are definitely causing me problems. I'd rather discuss switching grease in that thread.