The actual radial clearance and runout of the bearing are different from design ones, because of the unavoidable raceway roundness and roller diameter errors of a cylindrical roller bearing. However, there is little knowledge about how the raceway roundness and roller diameter errors affect the radial clearance due to the lack of the analysis method. In this study, a mathematic model with algebraic equations is developed. The raceway curves are described by Fourier series. When the outer ring is turned a angle, iterative calculations are done until at least one roller contacts the raceways by judging whether the clearances between the rollers and inner raceway equal zero or not. Then the radial clearance and runout of the bearing can be determined when the outer ring is turned one revolution. The independent and synthetic effects of the raceway roundness and roller diameter errors on the radial clearance and runout of a cylindrical roller bearing are analyzed. Results show that the clearance and runout periodically vary with the increase of the flap number, which is also the harmonic number, of the rotating raceway. The ratio of the numbers of the raceway flaps and rollers determines the period. The clearance and runout of a cylindrical roller bearing are greatly affected by the rollers' diameter errors instead of their positions.

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Four finite element models of a slewing bearing with different supporting structures are established by the finite element software ANSYS. In these models, the ball–race contact is simplified by the spring element with the same contact stiffness. The nut and bolt head are simplified and coupled with the surface of other connected component. The preload is applied on the bolt by a few pretension elements. The ball–race contact forces, fatigue lives, and carrying capacities of the slewing bearing in the four models are calculated. The effects of supporting stiffness, bolt number, and bolt preload on the contact force and fatigue life of the slewing bearing are studied. Moreover, the effects of supporting stiffness, bolt number, bolt preload, ball–race contact truncation, and bolt–hole backlash on the carrying capacities of the slewing bearing are analyzed. Results show that the fatigue life and carrying capacity of the slewing bearing can be enhanced by appropriately decreasing the supporting stiffness. Optimal values of bolt preload and number for the fatigue life and carrying capacity of a specific slewing bearing are obtained.

Measuring and verification of contact force in a rolling element bearing is a big problem. In this study, a new measuring method for contact force in a large-scale ball bearing is developed. The idea is to measure the deformation under the ball–race contact by displacement sensor at first, and the displacement of the end face of load bearing ring is also measured to determine the contact angle of ball–race contact. Then, the corresponding theory is developed to calculate the contact angle of ball–race contact by the displacement of the end face of load bearing ring. At last, the ball–race contact force is determined by accurately calculating through finite element method (FEM). Results show that the relation between contact force and deformation of measuring surface which is under ball–race contact is linear. The position of ball greatly affects the contact angle of ball–race contact. The contact angle of the ball which is near the arm of force is larger than that of the ball which is far from the arm of force. On the contrary, the measuring deformation of ball–race contact that is near the arm of force is less than that of ball–race contact that is far from the arm of force. The method developed here is only suitable for large-scale rolling element bearing because of the size constraint of the sensor.

A method has been developed to study the radial stiffness of a cylindrical roller bearing with corrected roller generator. First, the finite-length contact question of roller-race contact was solved by cutting contact surface into slices and considering the influences among slices by a flexibility coefficient matrix, which was more accurate than the traditional method. Further, the more precise load-approach function of the contact of race and roller with corrected generator was determined. Then, the radial stiffness of a cylindrical roller bearing has been derived by coupling this load-approach function into a complete bearing mechanical model. Results show that the corrected roller generator has a great influence on the bearing radial stiffness. The maximum stiffness difference among the cases of straight and crowned generators is 28.7%. The bearing radial stiffness decreases rapidly with the rise of profile maximum deviation hmax. It is worthy noting that there is a sudden change of stiffness with the adding of load when the bearing is with clearance.