Patent ID: 7086487

Claim:
An earth boring bit adapted to be loaded with weight from a drill string during operation, comprising: a body having at least one bit leg with a bearing pin depending therefrom; a cone that is rotatably mounted on the bearing pin; a seal in engagement with the bearing pin and the cone, the seal having an interior side exposed to lubricant within the cone and an exterior side adapted to be exposed to drilling fluid for sealing the lubricant from the drilling fluid; and the cone having an annular surface on an exterior side of the seal separated from an annular surface of the bearing pin by a clearance into which drilling fluid is adapted to flow, the annular surface of the bearing pin being concentric with an axis of the bearing pin, the annular surface of the cone having at least one portion spaced closer to the annular surface of the bearing pin than at least one other portion when the bit is unloaded and when loaded, so that rotation of the cone when the bit is in operation causes a reduction at each point around the clearance as said at least one portion rotates around the bearing pin.