If I understood your question correctly, you already have vibration spectra from a running machine and the machine is undergoing abnormal radial/axial stresses on the radial bearings (or at least you suspect). You are trying to find a sign in the vibration spectra that will tell you if the load is excessive in the radial or axial direction. Correct?

This is a generic question. I assume you'll receive only generic comments.

If the bearings are normal journal bearings, it's difficult to relate radial vibration data to axial load on the bearing. Radial loads on journal bearings can sometimes be detected by shaft average centerline plots.

If the bearings are rolling element bearings, they can take static loads (e.g. misalignment) or dynamic loads (e.g. unbalance) in both radial and axial directions. Generally speaking, the fundamental frequency and its first harmonics are related loads. If the spectra you have do not show high amplitudes at 1X, 2X, or 3X, then most likely there is no excessive load.

But I could be totally wrong as in many cases in the past.

Regards- Ali M. Al-Shurafa

Dear Mr.Ali,

first of all, I would like to express my gratitude toward your support.

few months ago, I experienced a situation when we had an electrical motor 550 kw with 425 RPM drives an alternative compressor, this motor has two rolling bearings in DE side (one's radial ball bearing and the second a roller bearing (skf NU)), in normal situation the radial ball bearing supports axially loading and the roller bearing support radially loading, in abnormal situation, I found a brief report the analyst tells that the radial bearing loaded under radial load instead of axial load, and the same for roller bearing, it loaded axial instead of radial, I confused How does he discover that the bearings loaded with inverse loading?

Thank you again

Regards