Patent ID: 7318674

Claim:
A fluid dynamic bearing arrangement comprising a sleeve defining a bore and further defining a thrust surface extending transversely to the bore, a shaft supported in the bore, the shaft and bore together defining a fluid dynamic journal bearing which supports rotation of the shaft and the sleeve relative to one another, a thrust plate extending transversely from the shaft and having a first axial thrust surface and an ungrooved second axial surface, the first thrust surface and a sleeve thrust surface defining together a first fluid dynamic thrust bearing, an asymmetric journal bearing defined between the shaft and the sleeve and operable to establish an asymmetric pressure directed toward the first fluid dynamic thrust bearing, and an ungrooved counterplate mounted to the sleeve and defining together with the ungrooved second axial surface of the thrust plate a gap which is in fluid communication with the first fluid dynamic thrust bearing and the fluid dynamic journal bearing, wherein the asymmetric pressure defined by the asymmetric journal bearing is further operable to act against a portion of the ungrooved second axial surface disposed radially inward of the radius of the shaft to support distancing of the ungrooved second axial surface from the counterplate.