Abstract: A roller bit comprises a plurality of legs each of which has a longitudinally extending pin. A cutting cone is rotatably mounted on each of the pins and a prefabricated sealing insert is fixedly connected at a longitudinally inner end of each of the pins. A sealing element is positioned between the cone and a sealing surface of the insert. The insert is formed of a material having a hardness greater than a core hardness of the pin.

Abstract: The present invention relates to an improved rotary drill bit having a bit body with at least one bearing pin attached thereto for rotatably carrying a roller cutter over a bearing system. The bearing system includes at least a forward bearing and a rear bearing with at least one inflow passage provided in the bit body for supplying fluid through the passage to the rear bearing during operation of the bit for flushing and for cooling of the rear bearing. The passage terminates in the bearing system ahead of a forward end of the rear bearing between an intermediate sealing arrangement and an annular outlet gap provided between the bit body and the roller cutter. The bearing pin includes a flange for axially fixing a forward end of the rear roller bearings with the inflow passage preferably terminating on the periphery of the flange. The sealing arrangement preferably engages a forward radial surface of the flange on the bearing pin.

Abstract: A device for lubricating rotary drill bits of the type comprising a roller cutter (14) which is rotatably carried by means of a bearing system (15, 16, 17, 18). Fluid is supplied to the bearing system for cooling and/or cleaning thereof through a passage (31, 32, 33; 51, 61), and a lubricant is delivered to said passage from a body (31; 39) of porous material, which is soaked in lubricating means. For purposes of controlling the supply of lubricating means the porous member forms a fraction of the inner wall of said passage.