US Patent 7866889 Fluid dynamic bearing system

A fluid dynamic bearing system used particularly for a spindle motor having a shaft that is accommodated in a bearing bush and rotatably supported with respect to the bearing bush, a bearing gap filled with a bearing fluid being located between the shaft and the bearing bush. At least the outside circumference of a section of the shaft extending into the bearing bush is made of a plastic material. As an alternative, a film made of a plastic material whose thickness is less than the width of the bearing gap can be disposed in the bearing gap.