KOHTECT BT-77
dB
n
<
20
Good condition
dB
n
=
20 - 40 Satisfactory condition
dB
n
>
40
Poor condition (i.e. bearing need replacement)
Table-3
3.3 Evaluation of Bearing Condition with BT-77
Technical condition of the bearing is mainly determined by the level and relation of two
measuring values dBm and dBc.
dB
m
- maximum value of normalized signal in decibel.
dB
c
- carpet value of normalized signal in decibel (background of the bearing).
However, under the work of the bearing the peak strikes have not only varying
magnitudes, but frequencies as well. Fig-3.2 shows the typical examples of the
evaluation of bearing condition and operating conditions (installation, roller bearing
fit, alignment, lubrication) based on the relation of shock magnitude value (reading
of scale dB
c
) and frequency value (number of shocks per minute):
Fig-3.2
dB
m
60
40
20
0
Time
dB
c
dB
n
dB
n
60
40
20
0
Time
dB
m
dB
c
dB
n
60
40
20
0
Time
dB
m
dB
c
dB
m
dB
c
60
40
20
0
Time
dB
n
dB
c
60
40
20
0
Time
dB
m
dB
dB
n
dB
m
dB
c
60
40
20
0
Time
dB
dB
n
16
Summary of Contents for BT-77
Page 1: ...BT 77 Bearing Tester with Non Contact Tacho Operating Instruction Manual...
Page 2: ......
Page 4: ...KOHTECT BT 77...
