These bearings are used where it is not practical to use plain bearings, and where a high degree of reliability and precision is required.
The advantages are:
· Low frictional losses
· Wide range of loads may be accepted
· Simple lubrication requirements
The most common type of bearing used on aircraft. The ball bearing has many variations in design allowing it to be used in a wide variety of situations/
They carry radial loads and moderate axial loads in both directions and where a high axial load may be experienced, the balls run in a deep groove in the races.Two types of ball bearings are in general use. The caged type and the crowded type.
Caged Ball Bearings
In general use, for engine applications and for equipment with rotational speeds in excess of 100 rpm. When used within engine/gearbox casings they are lubricated with engine oil supplied by jets or by splash. When used outside casings, they are lubricated by the application of grease which may be applied at specified intervals by grease gun, or may be of the pre-packed type where lubricating grease is packed and sealed into the bearing on assembly.
Crowded Ball Bearings
This bearing has filling slots in one or both races and has no cage or separators. The balls therefore touch each other during operation, hence the term ‘crowded’. They are suitable only where slow rotation or part rotation (oscillations) are found, and are usually of the sealed or pre-packed type.
Angular Contact Ball Bearings
Accept radial loads, and axial loads in one direction where a single bearing may be used. For axial loads in both directions an opposed pair of bearings is often used.