SKF - Rolling Bearings

7 Tapered roller bearings
Calculating the radial load acting on
matched bearings
When matched tapered roller bearings,
arranged face-to-face or back-to-back, are
mounted together with a third bearing, the
bearing arrangement is statically indeterminate.
In these cases, the radial load F r acting on
the bearing pair must be calculated first.
Matched bearings arranged face-to-face
For matched bearings, where two bearings are
arranged face-to-face († fig. 8), it can be
assumed that the radial load acts at the geometric
centre of the matched bearings, as the
distance between the pressure centres of the
two bearings is short when compared with the
distance between the geometric centres of the
set and the other bearing. In this case, it can
be assumed that the bearing arrangement is
statically determined.
Matched bearings arranged back-to-back
The distance a between the pressure centres
of two matched bearings arranged back-toback
is significant when compared with the
distance L between the geometric centres of
the matched bearings and the other bearing
(† fig. 9). Therefore, it is necessary to calculate
the magnitude of the load acting on the
bearing pair and also the distance a 1 at which
the load acts. The magnitude of the radial load
can be obtained using
L 1
F r = ——– K r
L – a 1
where
F r = radial load acting on a bearing pair [kN]
K r = radial force acting on the shaft [kN]
L = distance between the geometric centres
of the two bearing positions [mm]
L 1 = distance between the centre of bearing
position ! and the point of action of the
force K r [mm]
a = distance between the bearing pressure
centres [mm]
a 1 = distance between the geometric centre of
the matched bearings, and the point of
action of the radial load F r [mm]
The distance a 1 can be determined using
diagram 2. The distance of the pressure
centres a and the calculation factor Y 2 are
listed in the product tables.
F r
Fig. 8
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