Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact ball bearings for their durability.

In standard solutions, reactions of the supports and bending moments in bearing shafts are calculated without taking into consideration the elasticity of the bearings themselves. They are treated as perfectly stiff supports of articulate character. Whereas, in reality, the majority of bearings do not fulfil conditions of being classified as joints, because the angular tilt of inner bearing ring in relation to the outer one causes inner elastic deformations in elements of bearings and the resulting reaction moments. These moments have an impact on reactions of bearings. The aim of the research is to determine how shaft loading influences the value of preload by using the criterion of the durability of the bearing and taking into consideration the elasticity of bearings.

Optimum values of preload can be achieved in well-tried constructions and then applied in similar structures. For new structures, it is recommended to calculate the preload force and to test the correctness of calculation by means of experiments. In practice it may be necessary to introduce corrections, because not all real work parameters can be precisely known. Credibility of calculations depends, first of all, on the consistence between the assumptions concerning temperature conditions during work and elastic deformations of cooperating elements -first of all of a holder -and the real work conditions. The aim of the study is to determine how preload influences the work of a system of angular ball bearings, in relation to durability of bearing, moment of friction and rigidity of the bearing.

ResumeAngular ball bearings are commonly used whenever there is a demand to increase stiffness of a bearing. The aforementioned increase of stiffness can be achieved by obtaining proper preload in bearings. In common belief, preload has a negative consequence: it increases the load of rolling elements, which must lead to lower durability of bearing compared to the situation before the preload use. The objective of the research was to analyse how a change of load plane, while applying the preload, affects durability of angular ball bearings. In calculations of durability of bearings, besides elasticity of a shaft, radial, axial and bending elasticities of bearings were taken into consideration, as well.