For What It's Worth
Mar 14, 2017
I've written in this blog and in the magazine about the possibility of over-greasing bearings. I won't beat a dead horse, but in brief, my understanding from lubrication engineers is that an over-filled bearing tends to run hotter than a bearing lubed according to recommendations in the owner's manual. Plus, I've always been concerned that over-greasing can pop off seals and expose bearings to contamination.
The other day I was working on a machine that had a little plastic cover over the end of an exposed shaft. I suppose the engineers have to put a cover on it to prevent some careless idiot from somehow getting tangled in the 1/2-inch of smooth shaft that was otherwise exposed. When I removed that plastic cover, it was packed full of grease, and the bearing's seal was embedded in that grease. The bearing block that supported the end of that shaft had a nice, shiny grease zerk in plain view, so the owner apparently greased it frequently, as opposed to 200-hour intervals recommended in the owner's manual.
The bearing was just fine--it was definitely well-lubricated. But it reinforced my experience that more grease is not always better. I'm not advocating UNDER-greasing machinery, but I've got one more reason not to OVER-grease.