Abstract: A roller-cone drill bit in which a large groove is machined into the backface of each cone, near the crack where the cone meets the arm assembly. By making the outer lip of this crack more exposed to the open volume of turbulent flow, turbulence near the crack is increased, deposit of sediments near the crack is reduced, and infiltration of sediments through the crack is also reduced. Drill bit lifetime has been shown to be greatly extended by this change.

Abstract: A roller-cone drill bit in which a large groove is machined into the backface of each cone, near the crack where the cone meets the arm assembly. By making the outer lip of this crack more exposed to the open volume of turbulent flow, turbulence near the crack is increased, deposit of sediments near the crack is reduced, and infiltration of sediments through the crack is also reduced.

Abstract: A rock bit seal in which the shape of the retainer lip (which restrains the seal from axial motion in response to pressure differentials) is optimized, with respect to the as-deformed shape of the seal in place, to achieve a preload stress which is everywhere nonzero. Preferably the ratio of maximum to minimum stress in the as-installed condition is kept to a small ratio, e.g. less than 2:1.

Abstract: A rotary drill bit includes a bit body that includes a plurality of upright legs that terminate in an exterior bearing surface. At least one roller cutter is affixed to a corresponding exterior bearing surface of one of the plurality of legs. The roller cutter has an exterior cutting surface and a base edge and defines an interior bearing surface that is complementary to a corresponding exterior bearing surface. At least one duct is defined by the lower surface of the lateral wall and is adjacent to at least one exterior bearing surface. A plug is disposed in the duct at a distance from the base edge one of the roller cutters so that if either the interior bearing surface or the exterior bearing surface wears beyond a threshold, the plug will cause a remotely-sensible indication of excessive bearing wear to be asserted.

Abstract: A rock bit seal in which the shape of the retainer lip (which restrains the seal from axial motion in response to pressure differentials) is optimized, with respect to the as-deformed shape of the seal in place, to achieve a preload stress which is everywhere nonzero. Preferably the ratio of maximum to minimum stress in the as-installed condition is kept to a small ratio, e.g. less than 2:1.

Abstract: A roller-cone drill bit in which a large groove is machined into the backface of each cone, near the crack where the cone meets the arm assembly. By making the outer lip of this crack more exposed to the open volume of turbulent flow, turbulence near the crack is increased, deposit of sediments near the crack is reduced, and infiltration of sediments through the crack is also reduced. Drill bit lifetime has been shown to be greatly extended by this change.

Abstract: A rotary drill bit includes a bit body that includes a plurality of upright legs that terminate in an exterior bearing surface. At least one roller cutter is affixed to a corresponding exterior bearing surface of one of the plurality of legs. The roller cutter has an exterior cutting surface and a base edge and defines an interior bearing surface that is complementary to a corresponding exterior bearing surface. At least one duct is defined by the lower surface of the lateral wall and is adjacent to at least one exterior bearing surface. A plug is disposed in the duct at a distance from the base edge one of the roller cutters so that if either the interior bearing surface or the exterior bearing surface wears beyond a threshold, the plug will cause a remotely-sensible indication of excessive bearing wear to be asserted.

Abstract: The rotary drilling jar includes inner and outer mandrels releaseably locked against relative longitudinal movement. The inner mandrel is connected to the drilling string and the outer mandrel is connected to the drill bit or other well tools suspended below the jar in the well bore. A detent mechanism releaseably connects the inner and outer mandrels and includes a stack of Belleville springs that is configured to determined the amount of force required to move the detent mechanism to unlock the mandrels to permit relative longitudinal movement. In one aspect, the jar also includes an upwardly facing shoulder on the inner mandrel and outwardly facing shoulder on the outer mandrel that are in engagement when the jar is being lowered into, suspended in, and pulled from the well bore to prevent the imposition of string weight on the detent mechanism.

Abstract: The body of the bit includes an axis of rotation, an upper end connectable with the drill string for rotating the bit and three downwardly projecting arms. Each of the arms includes an inwardly and downwardly inclined shaft defining an axis of cutter rotation with all of the axes intersecting at substantially a common point. First, second and third conical cutter members are journaled on a respective one of said shafts. Each cutter member includes a nose and a base with the base being oriented generally toward the wall of the well bore. A plurality of outwardly projecting, circumferentially-spaced inserts are located in annular rows in each cutter member for engaging the bottom of the well bore.

Abstract: A rotatable cutter is mounted upon the bearing pin of a rotary rock bit. The cutter contacts and disintegrates earth formations during the drilling of an earth borehole thereby imposing a thrust load on the cutter. The thrust load consists of an out thrust load component substantially parallel to the axis of cutter rotation and a radial thrust load component substantially perpendicular to the axis of the cutter rotation. Substantially the entire out thrust load component is transmitted from the cutter through a ball bearing raceway on the interior surface of the cutter to the ball bearings and from the ball bearings to a ball bearing raceway on the bearing pin. The ball bearing raceways on the cutter and the bearing pin extend a substantial distance on either side of the axial axes of the ball bearings.