Abstract: Owing to the bearing space constraints and high load carrying capacity requirements, the traditional symmetric double-row four-point contact ball slewing bearing with negative clearance （α₀₁=α₀₂=45°）is improved, and a new asymmetric contact angle design（α₀₁=35°-60°，α₀₂=90°-α₀₁） with negative clearance is proposed. A calculation model of double-row four-point-contact bearing with asymmetric contact angle is established based on the Hertz contact theory and rolling bearing design method. The influences of asymmetric contact angle and negative clearance on bearing stiffness are analyzed. The results show that,with the increase in unidirectional loads F_a, F_r and M, the main stiffness decreases first and then increases nonlinearly, and a critical inflection point exists on bearing stiffness curve due to the negative clearance. In the initial stage, the initial preload stiffness of bearing is obviously improved, however, the effect of negative clearance on bearing stiffness is gradually weakened and eventually tend to be consistent with the increase in negative clearance. Under unidirectional loading condition, the integrated bearing stiffness is the best for the negative clearance being -0.03 mm and α₀₁=55° and α₀₂=35°. Under the combined loading condition, the bearing stiffness is optimum for the negative clearance being -0.03 mm and α₀₁=60°, α₀₂=30° or α₀₁=35°, α₀₂=55°. Asymmetric contact angle and negative clearance design have a significant effect to improve the overall stiffness of bearing. Key

Key words: mechanics, bearing, asymmertriccontactangle, negativeclearance, four-point-contact, stiffness