Small and medium size bearings are generally mechanically mounted. Traditionally
the bearing is mounted using a hammer and a length of old pipe. This practice can
cause forces to be transmitted through the rolling elements, causing damage to the
raceways. SKF fitting tools help prevent bearing damage by applying the forces to
the bearing ring with the interference fit.
Typical problems that can cause
premature failures are:
Damage caused during the fitting
procedure
Incorrect sized shafts and housings
i.e. too loose or too tight
Retaining lock nuts coming loose
in operation
Burred and damaged shaft and
housing seats and shoulders
Incorrectly mounted bearings
Interference fits: cylindrical shafts
Most bearings are fitted to their shaft or housing with one component having an
interference fit. For determining the correct fit, refer to the SKF General Catalogue,
the SKF Maintenance Handbook or consult an SKF application engineer.
Incorrect mounting
When bearings are mounted cold, care must be taken to ensure the drive-up forces
are applied to the ring with the interference fit. Damage and a resulting bearing
failure can occur if the mounting force is transmitted through the rolling elements
causing damage to the raceways.
Correct mounting
The correct way to minimise raceway damage is to use the specifically designed tools
from SKF, such as the TMFT 36 fitting tool kit. These tools allow drive-up forces
to be applied effectively and evenly to the component with the interference fit
avoiding raceway damage.
Interference fits: tapered shafts
Bearings mounted on tapered seatings achieve their interference fit by being driven
up the tapered shaft. Care should be taken to ensure the bearing is not driven up
too far, as all the internal clearance may be removed and damage to the bearing
is possible.
Spherical roller bearings
Method: Correct adjustment of spherical roller bearings is determined by measuring
the residual internal clearance in the bearing or by the amount of axial drive-up.
Details of the required reduction of clearance and axial drive-up can be obtained
from tables published in the SKF General Catalogue. For larger size bearings, it
is generally recommended to consider using a tapered seating to facilitate easy
mounting and dismounting.
Bearing
driven up the correct distance and the right clearance
is achieved
Bearing driven up too
far and all clearance removed; damage possible
Befor
Adjustment
After Adjustment
Self aligning ball bearings
Method: Adjustment of double row, self-aligning ball bearings is more difficult
to achieve than spherical roller bearings because the feeler gauge method cannot
be used. A very effective method to mount this type of bearing correctly is to use
the SKF TMHN 7 lock nut spanner set.
