Abstract: A rotary roller bit comprising at least one rotatably carried roller cutter (12) and provided with sealing means (21) for preventing impurities from entering into the bearing system (14, 15, 16,) of the roller cutter. For purposes of preventing axial and wobbling movements of the roller cutter (12) relative to the bit head from creating high contact pressure at the contact surface between the sealing means (21) and the surface against which same seals the sealing means (21) is provided with an elastically yieldable tongue (25) which extends radially relative to the rotational axis of the roller cutter (12).

Abstract: A rotary drill bit assembly comprising a trunnion and at least one rotary cutter mounted on the trunnion. The trunnion is supported by bearings including at least one radial bearing and at least one axial roller bearing. The axial bearing is comprised of conical rollers and one of the races for this bearing is disposed perpendicular to the axis of rotation of the rotary cutter and the complementary bearing race is conical. A guide rim is associated with one of the bearing races which guides the conical rollers in a radially outward direction.