Abstract: The raceway control assumption is used to determine the rolling element attitude angle in ball bearings. There are some problems in it. A clear understanding of the attitude angle cannot be obtained according to this theory. Analyzing the equilibrium of the rolling element, a new method of calculating the attitude angle is established. As contrasted with the raceway control assumption, the new method can be applicable to all kinds of speeds and is relative reasonable because it is based upon mechanical analysis. A calculation example is helpful to understanding the attitude angle well, which was difficulty to deal with.

Key words: Control assumption, Dynamics, Raceway, Rolling bearing, Rolling element