US Patent 9045941 Hybrid bearings for downhole motors

A bearing assembly for use in a down-hole drilling apparatus includes a bearing housing configured for connection to a drill string and a mandrel disposed at least partially within the bearing housing. The mandrel is configured to rotate about a longitudinal axis extending therethrough. A hybrid thrust bearing package is provided and disposed radially between the bearing housing and the mandrel. The hybrid thrust bearing package includes a plurality of ball bearings movable through at least one race, an annular stator supported by the bearing housing and an annular rotor ring supported on and rotatable with the mandrel. The annular stator and rotor rings define first and second flat PDC bearing surfaces engaged with one another at a bearing interface oriented generally orthogonally with respect to the longitudinal axis.