Overrolling direction in bearing failure Analysis

[paramathma]

Hello all,

Could you please explain over rolling direction? In many bearing articles Example: in Tribological Aspects of Rolling Bearing Failures by Jürgen Gegner, over rolling direction is mentioned on the picture.
What is the difference between rolling and over rolling direction?
How do we find over rolling direction?
Thanks

 

[geesamand]

If I had read that caption, I would have assumed it meant rolling marks that passed over the damage.

Perhaps, as you suggest, there may be a difference.

 

[romke]

as i understand it from the caption "over rolling direction" means "the direction of the rolling element over the raceway". in other words: the rolling element moved from left to right over the raceway shown in the images.

i guess "over rolling direction" may be a more or less "literal" translation of the German word "Überrollrichtung"

 

[Skogsgurra]

Yes, that is correct. The ball (or roll) squeezes metal in the überrollrichtung. The pictures shown are produced by an electron microscope. To get a better overview of what happens, see the macro picture in frame 16 here:

http://www.gke.org/presentationer/files/GE Bearings and their electric environment w O and E.pdf

The überrollrichtung is obviously from below to top and there's quite a lot of debris moved from the crater.

Gunnar Englund

http://www.gke.org

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