Page 35 - Y-bearing-units

Diagram 1 Fluctuating bearing load
Mean load within a duty interval In applications where the load varies over time,
both in magnitude and direction, bearing life 1
cannot be calculated without first calculating the
equivalent load related to the variable (or fluctu-
F
ating) load conditions. To do this, refer to the
F m
section Life calculation with variable operating
conditions in the SKF General Catalogue or
online in the SKF Interactive Engineering
F max
Catalogue at www.skf.com.
F min
Mean load within a duty interval
U
Within each loading interval, the operating
conditions can vary slightly from the nominal
value. Assuming that the operating conditions,
e.g. speed and load direction, are fairly constant
and the magnitude of the load constantly varies
Diagram 2 between a minimum value F min and a maximum
Rotating load value F max († diagram 1), the mean load can
be obtained from

F 1 F min + 2 F max
F m = –––––––––––
3

Rotating load
If, as illustrated in diagram 2, the load on the
bearing consists of a load F 1 which is constant
F 2
in magnitude and direction (e.g. the weight of
a rotor) and a rotating constant load F 2 (e.g.
an unbalanced load), the mean load can be
obtained from
F m = f m (F 1 + F 2 )
Diagram 3
Diagram #
Values for the factor f m can be obtained from
53.01 - Diagram caption heading
1 ,0 diagram 3.
f m
0 ,9 5
0 ,9 0
0 ,8 5
0 ,8 0
0 ,7 5
0 ,7 0
0 0 ,2 0 ,4 0 ,6 0 ,8 1 ,0
F 1
+
F 1 F 2

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