Abstract: A shock absorbing apparatus for use in a drill string for earth boring operations has a pressurized lubrication system. The shock absorber has a tubular body and a mandrel reciprocally mounted in the body for rotation with it. The mandrel and body telescope with respect to each other, with an annular pressurized chamber being located between them for absorbing load and shock. Lubricant cavities contain lubricant for lubricating the seals of the pressurized chamber. The lubricant in the lubricant cavities is maintained at a pressure greater than ambient but less than that in the pressurized chamber. This is accomplished by utilizing a differential piston that operates in response to the pressure differential between the chamber and the lubricant in the lubricant cavity.

Abstract: A shock absorbing apparatus for earth boring drilling is disclosed herein. The shock absorber is of the type having telescoping members with a sealed chamber containing pressurized fluid between the members for supporting load and absorbing shock. The members have axial passages for the passage of high pressure air to the bottom of a borehole to remove cuttings. A tube is connected to one of the members and inserted in telescoping relationship into the axial passage of the other member to transmit the circulating air. The seals of the tube are protected from the heat of the circulating air by a liner disposed concentrically in the tube. The liner is cylindrical and of lesser diameter than the inner diameter of the tube to create an annular air space for thermal insulation.

Abstract: Apparatus is disclosed for use in a drill string during rotary well drilling, especially of shallow holes such as blast holes, to absorb the shock loads imposed upon the drill bit and drill. A floating solid piston in an outer tubular body separates a gas chamber from a liquid chamber and equalizes the pressure between the two. A mandrel with large diameter bearing surfaces is carried reciprocally within the body, and has annular lubricating cavities separated from the liquid chamber. Lubricating passages include one in which a pressurized gas in a cavity supplies lubricant under pressure to the various bearing and sealing surfaces. Cylindrical pins inserted between the mandrel and the outer tubular body transmit torque between the body and mandrel.