A lubrication system for an earth boring drill bit having a pressure compensator for minimizing the pressure differential between the drill bit lubricant and the well bore fluid is improved in a manner to prevent sharp edges in the lubricant reservoir wall from damaging the flexible diaphragm and for...http://www.google.fr/patents/US4942930?utm_source=gb-gplus-shareBrevet US4942930 - Lubrication system for an earth boring drill bit and methods for filling and retrofit installing thereof
Lubrication system for an earth boring drill bit and methods for filling and ...
