To grease or not?

Messages
21
Location
Minnesota
We've been having a bit of an internal debate at work lately over the use of sealed/shielded vs open bearings. A bit of history: We have 2 compressors we rely on that are driven by electric motors. The electric motors in question are 30 HP a piece and run (24/7 3600 rpm) in a rotation of 5 days on, 5 days off. They were installed in 2003 and had the original bearings in place until 2 weeks ago. The bearings that came out were a greaseable bearing while the bearings that were installed were ordered as a sealed bearing. The tech that was installing the bearings pulled the shield off of the bearing to make it greasable since that was the way the originals were and he felt we would be better off with a greaseable bearing given the speed/load those motors run at. I guess my question is, is a sealed bearing designed to run at that speed and last 11 years? It is my feeling that the tech did the right thing in making the bearings greaseable and others feel that he may have been in the wrong since one (of 4) of the bearings failed over the weekend. But I may be way off base and completely wrong. Look forward to hearing a response on this. TIA!
 
Messages
5,117
Location
Columbus,Nebraska
I would have gone with the sealed bearings. Too easy to contaminate a bearing with a grease fitting by some smuck that was hired yesterday. Sealed bearings in furnace blowers run fifteen, twenty years and are still going when the furnace is replaced.
 
Messages
3,298
Location
West Michigan
I would have checked with the bearing mfg as to the expected service life. Also, make sure you either use compatible grease or thoroughly clean the bearing when you service it. A lot of mfgs are going with polyurea grease in sealed applications. What brand bearings did you use? If they are cheap generics you may get better life your way but I wouldnt mod a better brand like timken or skf.
 

Kestas

Staff member
Messages
13,977
Location
The Motor City
Shields are appropriate for greased bearings used indoors. Regreasing would depend on how much grease is purged from the bearing during use and the temperatures experienced by the grease.
 
Originally Posted By: HosteenJorje
I would have gone with the sealed bearings. Too easy to contaminate a bearing with a grease fitting by some smuck that was hired yesterday. Sealed bearings in furnace blowers run fifteen, twenty years and are still going when the furnace is replaced.
You cannot compare a furnace blower that runs an hour or two a day to a compressor that runs 24/7 50% of the time. I do agree though that greasable bearings can be contaminated, though with the life of the originals, that doesn't seem to be a problem.
 
Last edited:
Top