The Measurement and Analysis of Ball Motion in High Speed Deep Groove Ball Bearings

Abstract

This paper reports on a study of ball motion, including the measurement of ball rolling axis, in deep groove bearings operating at high speeds under thrust load conditions. The technique employed relies on viewing the test bearing, operating in the conventional fixed outer ring mode, through a rotating prism which eliminates optically the gross rotation of the separator. Videotape recordings of a selected ball, distinctively marked and illuminated stroboscopically, allows a complete analysis of ball bearing kinematics. Experimental results of separator speed, ball speed and rolling axis together with separator slip, ball slip and spin velocities at both the inner and outer raceway contacts are presented for a wide range of loads and shaft speeds up to 12,000 rev/min. These results are compared with the existing theory of Jones. Discrepancies between predicted and actual ball motion are due to the assumption made by Jones in neglecting bearing element slip. A further analysis of the experimental results including both gyroscopic torques and slip based on elastohydrodynamic traction values for the test lubricant explains actual ball motion more fully.