Page 133 - The Tribology Handbook

A22 Rol I i ng bea ri ng i nsta I I at i o n

BEARING FITTING
1 Ensure cleanliness of all components and working areas in order to avoid contamination of the bearings and damage
to the highly finished tracks and rolling elements.
2 Check that the bearing seatings are to the design specification, and that the correct bearings and grades of clearance are
used.
3 Never impose axial load through the rolling elements when pressing a bearing on to its seating-apply pressure through
the race that is being fitted - see Figs. 22.8(a) and 22.8(b). The same principles apply when extracting a bearing from
its seatings.

Fig. 228la). Incorrect - load applied through outer Fig. 22.8fb). Correct - load applied through ring
ring when fitting inner ring being fitted

4 When shrink-fitting bearings on their seatings, never heat the bearings above 120°C and always ensure the bearing is
firmly against its abutment when it has cooled down.
5 Where bearing adjustment has to be carried out, ensure that the bearings are not excessively preloaded against each
other. Ideally, angular contact bearings should have just a small amount of preload in the operating conditions, so it is
sometimes necessary to start off with a degree of end float to allow for relative thermal expansion.
6 Ensure that the bearings are correctly lubricated. Too much lubricant causes churning, overheating and rapid oxidation
and loss of lubricant effectiveness. Too little lubricant in the bearing will cause premature failure due to dryness.

A22.9