Importance

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Abstract

A sealed bearing assembly used in earth drilling is described having a first tubular member and a second tubular member telescopically received in the first tubular member. The second tubular member has an interior passage through which drilling fluids pass under pressure from surface pumps. A clearance space is provided between the first tubular member and the second tubular member defining a lubricant filled sealed chamber. The sealed chamber has a bit end sealed by a bit end seal which faces a drill bit and a pump end sealed by a pump end seal which faces surface pumps. A fixed mechanical seal is disposed in the sealed chamber intermediate the pump end seal and the drill bit end seal. The mechanical seal divides the sealed chamber into a pump end portion and a drill bit end portion. The pump end seal is responsive to pressure exerted by drilling fluids pumped along the interior passage by surface pumps. The drill bit end seal is responsive to pressure exerted by drilling fluids flowing externally to the first tubular member and the second tubular member. The mechanical seal seals a pressure differential between the pump end portion and the drill bit end portion of the sealed chamber.

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First Claim