Bearing starting to run hot

[corrosionman]

A 5 ton rotor at 500 rpm is supported on two big spherical roller brngs ( Skf 23072) It is not a pumped oil lubrication system but regularly greased with a carefully selected grease
One bearing has started to run much hotter than normal and it is thought to be failing. We took it off line and after cleaning out all the grease the bearing looks perfectly ok on the races and rollers.

My question is , does a rising temperature indicate a failing bearing and if so, how ; and can this temp rise be caused by other things??
All comments will be appreciated
Thanks CM

 

[unclesyd]

The first thing I would look at is the ammount of grease in the housing and if any had degraded. Either one of these can cause a bearing to run hotter.

 

[Skogsgurra]

Overgreasing is known to produce excessive heat. And when a bearing gets hot, it is very common to give it some more grease, which usually makes it run even hotter.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[dimjim]

I would interchange the bearings and see if the
same bearing overheats. If the second bearing
overheats, it is an application problem.

 

[Tmoose]

What drives this rotor? Is the hot bearing near a drive belt?
In addition to looking good, spherical bearings must have internal clearance, often set (reduced) by tightening a tapered adapter that locks the inner race to the shaft.
If the adapter was overtightened the internal clearance would be reduced or eliminated, and the bearing would start on a hot-hotter-toast sequence.

 

[BobM3]

Can you run the motor with no load and then with full load to see if the bearing temperature rise is about the same? If it gets hot with no load then it might be a mounting problem or a grease/speed problem.

 

[corrosionman]

Gents, your replies are appreciated. We stripped the bearing out and the outer race had a degraded area and also a brass labyrinth ring was broken and rubbing inside the cast steel bearing block - - possibly this caused the heat, although it did not look sufficiently worn to have generated lots of friction heat. I am inclined to go with Unclesyd and suspect too much grease Many thanks for your interest C M .