8.1 Rolling element vibration measurements may require
special instrumentation because the defect frequencies may be above
the frequency response range of general purpose vibration instruments.
Various parameters have been developed such as shock pulse, spike
energy, curtosis factor, and acceleration crest factor. The measured
values are dependent on the instrumentation used and there are no
internationally accepted standards. The most useful technique for
fault finding is considered to be the envelope analysis described
in
Ch 3, 1 Vibration 1.9
. Otherwise,
the recommended procedure is to make regular, periodic measurements
and observe the trend of the levels.