Patent ID: 11142958

Abstract:
An earth boring bit with sealed cutter bearings has a dual function pressure compensator for a lubricant reservoir. The earth boring bit has a bit body and downwardly extending legs which include bearing shafts that extend inward and downward for mounting rotary cutters, and seals are provided between the bearing shafts and the cutters. Lubricant flow passages extend from an interior cavity of the bit body, through the legs and the bearing shafts, and into the spaces located between the bearing shafts and the cutters. The pressure compensator extends between the cavity and the flow passages and has a movable piston. The compensator may be operated in a sealed lubricant system mode when the piston is locked in place or an air flow bypass mode by removing a locking member from securing the piston in place prior to securing the earth boring bit to a drill string.