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The measuring range of the BearingChecker is large and
covers most bearing applications, but there are a few cases
where shock pulse monitoring should only be attempted with
installed measuring equipment, or not at all.
High-speed bearings: BearingChecker accepts max. 30,000
rpm, 2,000 mm shaft diameter, and a dBi of 40. The upper
part of the table contains examples of possible combinations
of shaft diameter and rpm giving a maximum dBi of 40. The
lower part of the table exemplifies combinations that give dBi
= 0. The instrument calculates the dBi up to 40. However, it
is possible to set the dBi to max. 60 manually. A reason for
setting dBi > 40 is when measuring on e.g. turbochargers,
high-speed gearboxes etc.
Low-speed bearings: The lowest acceptable dBi is –9 dB.
However, it is nearly impossible to get a meaningful reading
from bearings in the extremely low speed ranges. The practi-
cal limit are bearings with a dBi around 0 dB (see lower half
of the table).
A heavy load with a well defined direction and a low inter-
ference level make it easier to get readings from low speed
bearings. Successful shock pulse monitoring has been carried
out on bearings with dBi = –3 (54 rpm, shaft diameter 260
mm). Note that the dynamic measuring range decreases when
dBi values get below 0. For example, a bearing with dBi = –3
showed very heavy damages at dBn = 40.
Installed adapters required: The installation of adapters is
strongly recommended for all systematic shock pulse monitor-
ing. In some cases it is a requirement:
• on bearings with dBi below 5
• on heavily vibrating bearing housings
• on covered bearing housings.
Low speed: Do not use a handheld probe on low speed
bearings. As a rule, the measurement should cover at least
10 full revolutions of the shaft. A single damaged part in the
raceway will cause a strong pulse only when hit by a rolling
element while passing through the load zone. It can take
several revolutions before that event occurs or is repeated.
Adapters required!
Covered
housing
dBi < 5
Heavy vibration
Shaft, mm rpm dBi
25 30 000 40
50 20 000 40
100 13 000 40
180 10 000 40
300 6 000 40
500 5 000 40
1 000 3 400 40
1 999 2 200 40
1 999 24 0
1 000 35 0
650 45 0
500 52 0
300 72 0
180 100 0
100 140 0
50 210 0
Measuring range
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