Bearing failure, but a weird one

[dawz]

Dear engineers,

I have a failed bearing case but I was scratching my head on the cause of this. Bearing is a 62082RS Deep Groove ball bearing.

Design background: Bearing was used in a scissor lift for a rubber track carrier transporter. on each side, it has 2 bearings stacked together. I got the report that one of the bearings was toast. When it was brought back, the outer ring and bearing balls were missing. inspection on the inner ring looks mint to my naked eye, but when zoomed in with a camera, it seems like a pit on the inner ring but I need sharp eyes and opinion. My only thought was that this is due to misalignment, or the bearing was twisted out. The bearing race seems to have an inner dent at 12 o'clock, and stretched cage at 5 and 7 o'clock. the entire bearing race seemed "curved".

Appreciate your input.

-Dawson

 

[TugboatEng]

That inner ring is severely damaged. The missing outer race and damage to the inner indicates that the bearing was severely overloaded.

 

[dawz]

Okay, looks like a change for a bigger bearing. If severely overloaded, the bearing ball might be fratured too? I was thinking if deep groove design is not suitable for this application.

Will stacking another bearing add up to the static and dynamic load capacity?

 

[TugboatEng]

If you are experiencing significant axial loads you should consider a bearing with better axial load capacity. If you can stack two bearings then tapered roller bearings would likely be ideal.

 

[3DDave]

I would carefully examine the track the bearing was running on.

 

[dawz]

If you are experiencing significant axial loads you should consider a bearing with better axial load capacity. If you can stack two bearings then tapered roller bearings would likely be ideal.

Thank you for the suggestion. If bucket, if stacked (heaps, fruit) can reach to 2 tons, but in general it's a bout 1 ton plus. When bucket is jacked up high, it can be wobbly if bucket is not lowered down during traveling.

I would carefully examine the track the bearing was running on.

A possible obstruction.. like bearings that "climb" over it?

This is the specification for this bearing, seems strong, considering it has 2 stacked bearings on each side (left side - 2 bearings, right side - 2 bearings.)

 

[3DDave]

It does not appear to me there is any room allowed for the bearing to climb over anything. This would be in keeping with the need for resistance to any vertical movement at the base of a scissor lift link.

 

[dawz]

It does not appear to me there is any room allowed for the bearing to climb over anything. This would be in keeping with the need for resistance to any vertical movement at the base of a scissor lift link.

If a stacked bearing does not seat completely on the track, will it also cause one of the bearings to take all the load and suffer damage, even if it's just a slightly irregular track?

 

[dawz]

Will this be an acceptable design for the scissor lift? There is a 1mm gap for the plain bearing.

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As for reading bearing load capacity:

6208:
Static Load Capacity: 19kN
Dynamic Load Capacity: 32.5kN

GEH40ES:
Static Load Capacity: 640kN
Dynamic Load Capacity: 127kN

Is it alright to directly assume that the plain bearing has a "640kN / 19kN = 33.6 times" static load capacity compared to 6208?

And, i always hear people say "how many kg can this bearing handle?". How to actually know the radial load a particular bearing can handle? It's not just purely converting kN to kg from the static/dynamic load right?

For moderate sandy/muddy location, is 2RS (rubber seal) necessary?