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Technical data are subject to change without notice.
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SPM Instrument AB • Box 4 • S-645 21 Strängnäs • Sweden
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Confirming Bearing Damage
On receiving the typical bearing damage signal –
CODE D, high LR/HR reading with a large delta, ran-
dom peaks, strongest signal on the bearing housing –
you must confirm one of the following causes for the
reading:
• tapping of loose parts against the bearing
housing
• excessive bearing play in combination with
vibration
• particles in the lubricant
• bearing damage.
Interference can usually be detected by a careful in-
spection, including a vibration reading.
Lubrication Test
A lubrication test is the best means to reach a conclu-
sive verdict:
• Examine the grease or oil for contamination with
hard particles
• Grease or oil the bearing and repeat the
measurement. Measure immediately after
lubricating and again a few hours later.
Make sure that the grease or oil reaches the bearing.
Typically, you will get the following results:
A The shock pulse level remains constant. The
signal is caused by interference or cross talk
from another bearing.
B The shock pulse level drops immediately after
lubricating and remains low. Foreign particles in
the bearing were removed by the fresh lubricant.
C The shock pulse level drops immediately after
lubricating but rises again within a few hours.
The bearing is damaged.
Note that metal particles in the lubricant can origi-
nate from the bearing itself. Measure the bearing
again over the next few days and make sure that the
values stay low.
Fig. 39
Fig. 40
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