Borrkrona med kapslat lager med dubbettätad utformning

摘要

A sealed-bearing drill bit for use in an earthen annulus is provided having a dual seal arrangement. The drill bit includes at least one leg having a journal segment, and a roller cone mounted upon the journal segment and forming at least one bearing cavity therebetween. An annular primary seal is disposed between the leg and roller cone and between the bearing cavity and the earthen annulus. An annular secondary seal is disposed between the annular primary seal and the earthen annulus and is capable of substantially preventing the ingress of debris from the earthen annulus to the annular primary seal.