In this paper, authors have developed the measurement method of dynamic performance of ball bearings using a high-speed camera and an image-processing method. The dynamic performances of a ball bearing used in car auto-tensioner have been investigated for an example. The positions of ball centers have been measured by the reflected ring light on balls. The positions of cage and outer ring have been measured by the markers put upon them. The reaction between balls and a cage and the deformation of pocket prongs while the bearing rotated, have been observed. It was found that the bearing oscillation had significant effect on the ball lead and lag and the deformation of pocket prongs. It was also found that the ball lead and lag, and the deformation of pocket prongs varied significantly in the non-load zone. It can be considered that they have significant effect on the fatigue life of cage.

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This paper describes that the behavior of growth of cavitation formed in the journal bearing and the effect of cavity growth on the bearing performance. The journal bearing test apparatus in which the bearing was made of transparent acrylic plastic was used, and cavitation in lubrication film was observed by the fluorescent method in this study. Results show that the cavity is formed by the bubble occurred at the edge of bearing, and the angle of start and end position of cavity depends on applied weight. The cavity grows with time at a constant load of 45 N because the cavity coalesces with small cavities occurred at the edge of bearing, and the eccentricity ratio and the attitude angle are also changed during the time of growth. It is also shown by a numerical analysis that the cavity growth is related with the oil flow generated by the negative pressure at the outlet of the cavity.

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