In this paper, modeling of the rotor motion in a jewel bearing is presented. Due to the presence of dry friction forces between the steel tip of the rotor and the cup sapphire surface, the rotor motion no longer consists only of pure rotation. The secondary motion based on the deviation from pure rotation, as well as the driving torque variations (sensitivity threshold) are determined and three basic cases are studied, i.e., the arbitrary position and initial driving torque at the time of motion initiation, the asymptotic position and driving torque which supports pure rotation, and the self-centering process, i.e., the transition from the rest state to pure rotation. The investigation is supported and validated by numerical simulation.Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4–7, 1992