A permanent magnet bearing supports part of thrust loads of a vertical shaft induction motor, or the thrust loads of other types of rotation machinery regardless of shaft rotational axis orientation, in parallel with a lubricated mechanical bearing. The permanent magnet has a stationary magnet portion coupled to a bearing bracket and a rotating portion adapted for coupling to a rotor shaft. The permanent magnet bearing exerts a directional magnetic force that generates a preload support force on the rotor shaft that is selectively varied by varying air gap between the stationary and rotating magnet portions. Air gap between the magnet portions is varied with an air gap adjustment mechanism. The gap adjustment mechanism may be coupled to a control system that in some embodiments causes the permanent magnet bearing to vary the air gap based on external load applied on the motor.