What is the general fault pattern in the velocity spectrum to an inner race?

The identification of an inner race fault in a rolling element bearing typically manifests as a peak in the velocity spectrum that is accompanied by sidebands based on the shaft speed. This occurs due to the repetitive impact of the rolling elements as they pass over the defect on the inner race.

Specifically, the fault creates periodic impulses that appear in the time domain signal, and when transformed into the frequency domain, these impulses result in a spectral peak at the fault's frequency, with sidebands on either side of this peak at intervals corresponding to the shaft rotation speed. This pattern is essential for diagnosing faults, as the presence of sidebands highlights the relationship between the rotational speed of the shaft and the fault frequency.

In contrast, a peak with no sidebands would typically indicate a singular, consistent fault, or that the fault is not dependent on rotational speed in the same way. A flat spectrum might suggest a healthy machine or random noise, lacking the clear indication of a specific fault pattern. Lastly, a peak with gear rate sidebands would be indicative of a gear fault rather than a bearing issue, as the frequency characteristics would align with gear interactions rather than those of rolling elements in bearings. Thus, the presence of peak with shaft rate sidebands is a clear and