PRÜFTECHNIK VIBTOOL - Bearing Diagnosis

VIBTOOL 02.2009
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Bearing diagnosis
VIBTOOL uses the Shock Pulse Method to evaluate bearing
condition. This method considers shock pulses which arise
during the metal to metal contact present in damaged
bearings. These shock pulses indicate distinct resulting
frequencies and amplitudes. Two values, carpet and maxi-
mum value, are used to evaluate the bearing condition. As
bearing damage progresses, the overall levels and the
difference between these values increases. VIBTOOL mea-
sures the carpet value (background noise) and the maxi-
mum value. These values generally allow early detection of
bearing damage as it progresses, especially when a com-
puter is used for trend observation.
Many bearings are inaccessible for direct measurement
with hand-held probes. This is a principle weakness of all
meters and data collectors which rely on hand-held mea-
surements. In such cases, the bearing has to be prepared
for VIBTOOL measurement by installing permanently
mounted transducers. External transducers, such as the
Industrial Accelerometer from PRÜFTECHNIK Condition
Monitoring, can be connected easily to VIBTOOL, thus
allowing access to difficult measurement locations.
For shock pulse measurements using the built-in VIBTOOL
probe, the measurement location should be prepared (pref-
erably with countersink bit VIB 8.610, see page 56 for
details) in order to achieve maximum measurement repeat-
ability.
The three-band scale of bearing condition ('good,'
'reduced' and 'poor') explained herein is used only as
an example to aid in learning. The actual boundaries
between 'good,' 'reduced' and 'poor' bearing condition
can vary significantly between individual bearings,
depending upon their design characteristics and ser-
vice conditions. Therefore, reliable diagnosis may be
made only in conjunction with a series of trend
observation measurements made on the bearing under
consideration over a period of time.
Attention!
Bearing diagnosis