Odd behavior of cap drawn full complement needle bearings

[israelkk]

We encountered an odd behavior of a shaft rotating on two full complement cap drawn needle bearings that in addition to pure rotation of the shaft, the shaft advances along it's axis in a "screw like" movement. The bearings were manufactured by a well known respected American bearing manufacturer. Looking at the bearings we noticed that the needles are not parallel to the bearing axis but are slightly slanted/inclined. We suspect that the needles are too long compared to the inner width of the bearing. We are planing to contact the bearing manufacturer, but in the mean time we will appreciate any comments including silmilar past experience.

 

[MikeHalloran]

I think that's normal behavior for needle bearings.
You might reduce it by using a shaft closer to the high limit diameter, but basically you need some other bearings to provide axial location.


Mike Halloran
Pembroke Pines, FL, USA

 

[israelkk]

There are other means to provide axial location in the system. From my 30 years of experience with needle bearings under very high loads for aerospace systems I have never encountered such behavior. But, in this case due to the very high loads on the bearings the axial movement effect is quite high. This is the first time we noticed slanted/inclined orientation of the needles in needle bearings and we are quite sure this is a bad batch of needle bearings.