Abstract: Serial safety bearing assembly includes two concentric bearing sets and an actuatable device for selectively switching to engage either the inner or the outer of the two concentric bearing sets upon failure of one set or to alternate to first one set and then the other set thus to prolong the working life of the two concentric bearings.

Abstract: Bearing assemblies use serial bearings in order to extend the operational speeds for the bearings. Speed distribution planetary gears are mounted upon an intermediate ring disposed between two other rings. Each of the rings has bearing surfaces which are separated from adjacent bearing surfaces by ball-bearings or other bearings. The planetary gears mesh with gear teeth upon the first and second rings so as to cause rotation of the intermediate ring at a speed intermediate the relative speed between the two other rings. The speed distribution planetary gears may be used in a serial thrust bearing assembly serial radial bearing assembly, or a serial radial thrust bearing assembly.