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5.3 Bearing parameters and bearing vibration frequency
5.3.1 Bearing parameters
The bearing parameters which need to calculate the vibrational frequency of the bearing are rolling
element pitch circle d
p
(mm) of bearing, diameter D
w
(mm) of rolling element, number Z (pcs)
*
of rolling
elements, contact angle α (°) of bearing. The positions for the dimension of main bearing parameters are
as follows.
*It is the number of rolling elements for each row for the double row bearings.
Figure 5.2 Main bearing parameters
5.3.2 Calculating formulas of bearing vibration frequency
The calculating formulas of the bearing vibration frequency are shown below. n
i
is the rotational speed
(min
-1
) of inner ring.
Table 5.2 Calculating formulas of bearing vibration frequency Unit: Hz
Calculation item Sign
Calculating formula (inner ring rotation)
Rotational speed of inner ring
Rotational speed of outer ring
Rotational speed of retainer
Rotational speed of retainer in relation to inner ring
Rotational speed of retainer in relation to outer ring
Passing frequency of rolling element in relation
ring, BPFI (Vibration frequency due to inner ring flaw)
Passing frequency of rolling element in relation
ring, BPFO (Vibration frequency due to outer ring flaw)
Rotation frequency of rolling element, BSF/2
(Vibration frequency due to rolling element flaw)
*The frequency observed due to flaw on rolling element is twice the rotation frequency of rolling
element.
*The bearing vibration frequency for the bearing inner ring rotation can be calculated with the bearing
technological calculation tool in our homepage, excluding some bearings.
ball bearing
ball bearing
bearing
bearing
bearing
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