Influence of ball bearing contact angle on interface kinematics, load, and sliding power losses

• Effect of contact angle on load distribution, kinematics, and sliding losses is analysed. • Higher contact angles reduce load and pressure while increasing spinning motion. • Increasing contact angle leads to lower total sliding losses under axial load. • Kinematic hypotheses differ in how power losses split between inner and outer raceways. Ball bearings are widely used in rotating machinery to support combined radial and axial loads at high rotational speeds. The nominal contact angle is a key geometric parameter. Despite its recognised importance, the influence of the contact angle on contact-level kinematics and sliding power losses has not been systematically analysed. This work investigates the effect of the contact angle on load distribution, contact kinematics, and sliding power losses in lubricated ball bearings using a quasi-static formulation based on the minimum power loss principle explicitly accounting for frictional interactions. A reference angular-contact ball bearing is analysed while varying the nominal contact angle from deep-groove to thrust bearing configurations. The results show that increasing the contact angle significantly reduces contact load and Hertzian pressure, while enhancing the orbital, rotational, and spinning motion. Although higher contact angles promote increased local sliding, the dominant reduction in contact load leads to an overall decrease in total sliding power loss. Comparisons with classical kinematic hypotheses reveal substantial differences in the predicted distribution of power losses between the inner and outer raceways, highlighting the importance of friction-consistent kinematic modelling.