Abstract
Guide with clearance is often used to constrain the excessive deflection due to vibration or sudden disturbance in the rotary machinery. But the impacting and rubbing can cause serious problems in the machineries. Back up bearing is recently used for reducing the friction as the inner ring can rotate. This paper deals with the rotor-backup bearing system and demonstrates the impact model. The dynamic characteristics, such as forward rub, backward rub and impacting, have been investigated theoretically, experimentally and by simulation. The friction force, exerted during the rubbing between the backup bearing and the rotor, shows very important factor to change the motion from impacting and forward rub to backward rub.
