The loads affecting a Spherical Plain Bearing can vary. They can be:
<intermittent, constant or variable (illustration 1)
<static or dynamic


Illustration 1: Load Factors - check f_B 

Forces when under static load
Radial only (F_r) or radial and axial (F_a) forces arise and there is no movement
between the ball and the insert (illustration 2).


Illustration 2: Radial and axial Forces 

Forces when under dynamic load
Only radial or radial and axial forces arise, with the ball pivoting at angle a, oscillating
at angle b or rotating relative to the insert.


Illustration 3: Pivoting and oscillating angle 

In the case of a constant load F_r, F_a a dynamically equivalent bearing load F_ä can be
established in accordance with formula (2)

therefore:  F_ä ≤ F_{r, max}  according to formula (6); F_a ≤ F_{a, max} (6a)

The axial factor Y in table 2 is depending on the load ratio.

Table 2: Axial Factor Y

In the case of a variable load (illustration 4), formula (4) can be used to
calculate a mean dynamic bearing load F_m  from the individual load levels F_i  
and the appropriate time factor t_i.


Illustration 4: Variable load against time

Force F [kN]; time component t [%]; therefore the following must be valid:
F_i, _max ≤ F_r, _max according to (6)

In case of an additional axial load the equivalent bearing load is calculated according
to formula (4).

Axial Factor Y according to table 2; F_a ≤ F_{a, max} (6a)


Illustration 5: Oscillating angle b relative to crank rotation

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