A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.

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.

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

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

Earth-boring rotary drill bits include heel portions exhibiting reduced aggressiveness. Earth-boring rotary drill bits may comprise a bit body and a plurality of roller cones coupled to the bit body. Each roller cone comprises a plurality of rows of cutting elements, and a continuous disk heel located further from an axis of rotation of the roller cone than the at least one row of cutting elements, the continuous disk heel exhibiting a reduced amount of aggressiveness compared to the at least one row of cutting elements.

Earth-boring rotary drill bits include heel portions exhibiting reduced aggressiveness. Earth-boring rotary drill bits may comprise a bit body and a plurality of roller cones coupled to the bit body. Each roller cone comprises a plurality of rows of cutting elements, and a continuous disk heel located further from an axis of rotation of the roller cone than the at least one row of cutting elements, the continuous disk heel exhibiting a reduced amount of aggressiveness compared to the at least one row of cutting elements.

A cutting apparatus includes a support structure and first and second cutting assemblies. Each cutting assembly includes a rotatable cutting head and a mounting assembly for movably attaching the cutting head to the support structure. The cutting head is movable about a first pivot axis of the mounting assembly in a sideways direction relative to the support structure, and about a second pivot axis in an upwards-downwards direction. Each cutting head includes a plurality of cutting units, which each have a rotatable shaft and a cutter mounted thereon. The cutter includes a disc body and a plurality of buttons mounted in a radially peripheral portion of the disc body. At least some of the buttons have a central longitudinal axis that subtends an angle to a reference axis, which extends perpendicularly outwards from an axis of the shaft, the angle being to 20 and to 34.

A disc cutter for a cutting unit used in an undercutting operation and a method of producing the same. The disc cutter including an annular disc body made of a metal alloy or metal matrix composite having a first side, a second side arranged substantially opposite to the first side and a radially peripheral part. At least one metal alloy, metal matrix composite or cemented carbide cutting part is mounted in and substantially encircling the radially peripheral part of the disc body which protrudes outwardly therefrom to engage with the rock during the mining operation. The at least one cutting part is made from a material having a higher wear resistance than the material used for the disc body, wherein the disc body and the cutting part are joined by diffusion bonds.

A disc cutter for a cutting unit used in an undercutting operation and a method of producing the same. The disc cutter including an annular disc body made of a metal alloy or metal matrix composite having a first side, a second side arranged substantially opposite to the first side and a radially peripheral part. At least one metal alloy, metal matrix composite or cemented carbide cutting part is mounted in and substantially encircling the radially peripheral part of the disc body which protrudes outwardly therefrom to engage with the rock during the mining operation. The at least one cutting part is made from a material having a higher wear resistance than the material used for the disc body, wherein the disc body and the cutting part are joined by diffusion bonds.