An earth boring bit has rotating cones with two lubricant passages to increase bearing capacity and cause lubricant circulation. A lubricant reservoir in the body supplies lubricant to passages between the cone and bearing pin. A pressure compensator equalizes lubricant pressure to the exterior of the bit. A first passage leads from the reservoir to the upper side of the bearing pin. A second passage leads from the reservoir to the bearing pin at a point from 185 degrees to 225 degrees as seen from an inner end of the bearing pin. This point is located in a diverging region 51d of an annular clearance surrounding the bearing pin.

 
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> Hydrodynamic bearing, method of manufacturing the same, method of manufacturing shaft member for hydrodynamic bearing, spindle motor, and recording disk driving apparatus

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