Monitoring bearing lubrication by using vibration measurement equipment

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When do grease-lubricated roller bearings need to be relubricated?


1_Bearing lubricationwbWhile large roller bearings are increasingly being equipped with automatic continuous lubrication systems, this is not cost-effective in fans such as the one shown in Figure 1.


Figure 1: Fan

These units are lubricated by hand at specific intervals. But how long should these intervals be? Online Condition Monitoring Systems from PRÜFTECHNIK can provide the answer. When a roller bearing runs ‘dry’, a rough running sound arises that can easily be detected in the high frequency acceleration spectra, for example. At that point, it is high time to relubricate the bearing to lower vibration strain.


Figure 2: VIBNODE®

With advanced frequency-selective CMS like VIBNODE®, the broadband disturbance frequencies shown in Figure 3 can be selected as “characteristic lubrication values” and the associated amplitudes can be monitored as trend values.

3_Broadband disturbance frequencywb

Figure 3: Broadband disturbance frequency

Figure 4 shows that lubrication intervals can be determined easily: After lubrication, the amplitude of the acceleration decreased markedly. Of course, to use this analytical method, you must first identify the frequency band on which the lubrication condition has an impact.

5_After greasingwb

Figure 4: After Greasing

The PRÜFTECHNIK group, with subsidiaries and partners in more than 70 countries worldwide, is continuing to set new standards with path-breaking technical developments in the sectors of laser and vibration measurement technology to maximize and optimize machine and plant availability.

Florian Buder, Managing Director, PRÜFTECHNIK Canada

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Mrs. Anne-France Carter
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