Patent ID: 7147377

Claim:
A fluid dynamic bearing comprising a shaft and having a thrust plate supported on an end thereof, a sleeve defining a bore surrounding the shaft, a gap between the shaft and the sleeve having fluid therein to support the shaft and the sleeve for relative rotation, the sleeve further defining a first recess at an end of the shaft bore, a thrust plate mounted on an end of a shaft and rotating relative to the sleeve in the recess, a counterplate supported adjacent the thrust plate defining a gap between the counterplate and one surface of a thrust plate, and the thrust plate further defining a gap between a second surface thereof and a surface of the sleeve recess, fluid in the thrust plate gaps supporting the shaft and thrust plate for relative rotation, a second recess in the sleeve radially spaced from the thrust plate recess, and a hollow crush ring in the second recess crushed in place by the counterplate, wherein the crush ring exerts little elastic force against the counterplate, and the crush ring is selected from a group consisting of: o-ring, block ring, and x-ring; further wherein the crush ring is configured to fill the gap between the surface of the sleeve and the surface of the counterplate to prevent loss of fluid through any space between the sleeve and the counterplate.