Bearing fitting tools
Mounting bearings in a cold condition
Premature bearing failure can result from damage incurred when a bearing is incorrectly mounted
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
When bearings are mounted cold, care must be taken to make sure 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 (fig 1)
The correct way to minimise raceway damage is to use the specifically designed tools from SKF, such as the TMFT series fitting tool kits. These tools allow drive-up forces to be applied effectively and evenly to the component with the interference fit avoiding raceway damage (fig 2)
Interference fits: tapered shaftsBearings mounted on tapered seatings achieve their interference fit by being driven up the tapered shaft. Care should be taken to make sure 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.
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.
Incorrectly mounted: Bearing driven up too far and all clearance removed; damage possible (fig 3)
Correctly mounted: Bearing driven up the correct distance and the right clearance is achieved (fig 4)