Bearing destruction due to lack of lubrication
Bearing destruction due to lack of lubrication
(OP)
Hi
I would like to know the typical destruction scenario of a bearing (ball, approx 2 in., no trust) having lack of lubrication (almost no lubrication at all). For example, inner ring is rotating (fit on the shaft), outer race is fit in the casing, no rotation. RPM = 3600
1- How much time it can roll without lubrication before catastrophic failure ?
2- What are temperatures it could reach on inner ring ?
3- Is outer race damaged or not ? (the one we are investigating is almost in perfect shape)
4- If you have typical visual references for this type of bearing failure, it would be good for comparison.
We are investigating bearing failure, we try to justify first hypothesis which is lack of lubrication.
Thanks
Ced
I would like to know the typical destruction scenario of a bearing (ball, approx 2 in., no trust) having lack of lubrication (almost no lubrication at all). For example, inner ring is rotating (fit on the shaft), outer race is fit in the casing, no rotation. RPM = 3600
1- How much time it can roll without lubrication before catastrophic failure ?
2- What are temperatures it could reach on inner ring ?
3- Is outer race damaged or not ? (the one we are investigating is almost in perfect shape)
4- If you have typical visual references for this type of bearing failure, it would be good for comparison.
We are investigating bearing failure, we try to justify first hypothesis which is lack of lubrication.
Thanks
Ced





RE: Bearing destruction due to lack of lubrication
- finally seized, or
- was undamaged, or
- was rebuildable, or
- was replaced with a new one by the mfgr.
Regardless of the variant, the story always has a happy ending, because outboards are built with ball, needle and roller bearings, all of which can survive operation with just a whisper of lube oil.
I suggest that you ask the manufacturer of your specific failed bearings for help. They have the resources, and some incentive to figure out what caused the failure, or at least what didn't.
Mike Halloran
Pembroke Pines, FL, USA
RE: Bearing destruction due to lack of lubrication
RE: Bearing destruction due to lack of lubrication
Johnny Pellin
RE: Bearing destruction due to lack of lubrication
This failure demonstrates why we don't like stamped steel cages. Our preferred thrust bearing is a pair of back-to-back single row bearings with machined bronze cages. Our preferred radial bearing is a deep groove, single row bearing with a riveted steel cage. The double row bearing is a bad idea since it cannot be made with anything but a stamped steel cage (unless it has a split inner race). We converted the pump to a single row bearing of the same size and modified the adapter to accommodate the narrower bearing. The modern version of the same model pump is built with the single row bearing, so we had good confidence that it could take the imposed load. We also redesigned the oil ring to make it more stable with a higher or lower oil level. We considered extending the flange on the end of the adapter to make it harder for the oil ring to jump out of the groove. But, in the end, we stayed with the same adapter.
I have seen this same sort of failure before. The damage has tended to be worse on the inner race. Even with a back-to-back pair of bearings, the inner race can become almost molten, rolling up over the lock-washer and nut.
Johnny Pellin
RE: Bearing destruction due to lack of lubrication
The tempering colour is a good indication of the temperature the bearing has reached. Search on the web, there should be some colour charts available.
RE: Bearing destruction due to lack of lubrication
RE: Bearing destruction due to lack of lubrication
Thanks a lot. Indeed, the inner race was melted and balls were indented on its surface. Outer race was good. So, your story fits with our case and confirm that lack of lube is a real mess at high speed and high load.
Have a nice day
RE: Bearing destruction due to lack of lubrication
It has been my experience with bearings that have the same or similar mode of failure as yours is to install the same bearing using all the tools available to you to get the very best installation possible. I would change the lubrication either grease or oil to the highest grade available, the ones I use are from LE. By doing this you can get a little time on the bearing where you can do a better analysis while it's running under load. I started this process when the best available analytical tool was a stethoscope and the hand.
I don't have the numbers but a least 80% of the bearings that were checked in this manner remained in service for their expected life.
RE: Bearing destruction due to lack of lubrication
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