A hybrid bit includes fixed blades and wheel support structures. The wheel support structure includes a wheel inserted into a slot between a leading support and a trailing support. One or more shims fill a gap between a flange and the leading supports. An elongated seal between the wheel and the supports is provided to seal the wheel support.

An earth boring bit with sealed cutter bearings has a dual function pressure compensator for a lubricant reservoir. The earth boring bit has a bit body and downwardly extending legs which include bearing shafts that extend inward and downward for mounting rotary cutters, and seals are provided between the bearing shafts and the cutters. Lubricant flow passages extend from an interior cavity of the bit body, through the legs and the bearing shafts, and into the spaces located between the bearing shafts and the cutters. The pressure compensator extends between the cavity and the flow passages and has a movable piston. The compensator may be operated in a sealed lubricant system mode when the piston is locked in place or an air flow bypass mode by removing a locking member from securing the piston in place prior to securing the earth boring bit to a drill string.

An earth boring bit with sealed cutter bearings has a dual function pressure compensator for a lubricant reservoir. The earth boring bit has a bit body and downwardly extending legs which include bearing shafts that extend inward and downward for mounting rotary cutters, and seals are provided between the bearing shafts and the cutters. Lubricant flow passages extend from an interior cavity of the bit body, through the legs and the bearing shafts, and into the spaces located between the bearing shafts and the cutters. The pressure compensator extends between the cavity and the flow passages and has a movable piston. The compensator may be operated in a sealed lubricant system mode when the piston is locked in place or an air flow bypass mode by removing a locking member from securing the piston in place prior to securing the earth boring bit to a drill string.

1. Cutting roller.

2. A cutting roller having an axle (2), on which a cutting ring (4) is rotatably guided by means of a bearing device (10, 12), which is sealed against the environment by means of a sealing device (28, 30), is characterized in that by a compensating device (40) any differential pressure between the bearing device (10, 12) and the environment is compensable.

1. Cutting roller.

2. A cutting roller having an axle (2), on which a cutting ring (4) is rotatably guided by means of a bearing device (10, 12), which is sealed against the environment by means of a sealing device (28, 30), is characterized in that by a compensating device (40) any differential pressure between the bearing device (10, 12) and the environment is compensable.

An earth-boring rotary tool includes a body comprising a pin, a roller cone mounted on the pin, and a seal assembly disposed between the pin and the roller cone. The seal assembly includes a seal ring to form a seal between the seal ring and the roller cone. The seal assembly includes a first polymer ring, while compressed, applies a first force on the seal ring that biases the seal ring towards the roller cone. The seal assembly includes a second polymer ring proximate the first polymer ring. The second polymer ring, while compressed, applies a second force on the seal ring to further bias the seal ring towards the roller cone. The second force is greater than the first force.

An earth-boring rotary tool includes a body comprising a pin, a roller cone mounted on the pin, and a seal assembly disposed between the pin and the roller cone. The seal assembly includes a seal ring to form a seal between the seal ring and the roller cone. The seal assembly includes a first polymer ring, while compressed, applies a first force on the seal ring that biases the seal ring towards the roller cone. The seal assembly includes a second polymer ring proximate the first polymer ring. The second polymer ring, while compressed, applies a second force on the seal ring to further bias the seal ring towards the roller cone. The second force is greater than the first force.

A pressure compensating lubrication system for sealed bearing earth boring bits having a lubricant reservoir fitted with a piston. A spring member is disposed between one end of the reservoir and the piston. The spring member applies pressure through the piston to the lubricant in the reservoir and bearing and absorbs pressure fluctuations in the lubricant generated while drilling.

A pressure compensating lubrication system for sealed bearing earth boring bits having a lubricant reservoir fitted with a piston. A spring member is disposed between one end of the reservoir and the piston. The spring member applies pressure through the piston to the lubricant in the reservoir and bearing and absorbs pressure fluctuations in the lubricant generated while drilling.

A piston for use in a rotary steerable system includes a body formed from a first material. A sealing surface extends around the circumferential wall of the body. The sealing surface is formed from a plurality of layers of a second material. The second material is harder than the first material. The piston can be within a downhole piston assembly that also includes a housing, and the piston being longitudinally movable in a bore in the housing. A method for producing a piston includes preparing a piston formed from a first material, with the piston including a first end. A sealing surface is applied to the piston using laser cladding, with the sealing surface including a second material harder than the first material. The sealing surface is finished to a sealing surface diameter.