Abstract: The invention relates to a tool for breaking or excavating of hard material, such as asphalt. The tool comprises a cutting insert (11) secured to a tool body (10). For purposes maintaining the required cutting force low while ensuring that the risk is low that the cutting insert (11) will get loose the cutting insert (11) is provided with a concave portion (17.sup.1) between the tip portion (12) of the cutting insert and a rear shoulder (13) thereon.

Abstract: The invention relates to a tool for breaking or excavating hard material, such as asphalt. The tool comprises a cutting insert (11) secured to a tool body (10). For purposes of maintaining the required cutting force low while ensuring that the risk is low that the cutting insert (11) will get loose the cutting insert (11) is provided with a concave portion (17.sup.1) between the tip portion (12) of the cutting insert and a rear shoulder (13) thereon.

Abstract: A cutter (10) intended for use on a planing blade on a road planing machine is provided with a plurality of tools (14) rotatably mounted in the cutter. The tools (14) are mounted side by side and are adapted to carry out the working of the road surface (17).

Abstract: A support for a cutting tool for cutting hard material comprises a machine-oriented member and a tool-oriented member. A projecting portion on the machine-oriented member is adapted to be received in a recess in the tool-oriented member. The two members are adapted to be secured to each other by wedge action between cooperating wedge surfaces on the projecting portion and in the recess.

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 thereof through a cooling passage (31, 32, 33; 51, 61), and a lubricant is delivered to the cooling passage from a lubricant reservoir (36; 46) through a lubricating passage (40; 54). For purposes of controlling the supply of lubricant the outlet of the lubricating passage into the cooling passage is arranged axially behind the inlet of the lubricating passage in the lubricant reservoir.

Abstract: A rotary drill bit comprising at least one rotatably carried roller cutter (17) and provided with passages (26,27,28) for supplying cooling fluid to the bearing system (11-15) of the roller cutter. For purposes of preventing the heat generated at an annular surface (31) transmitting axial forces from causing rapid bearing wear a recess (32) is provided in the annular surface (31). The recess (32) communicates with the passages (26,27,28) and extends entirely around the bearing shaft (16) for allowing circulation of cooling fluid therearound.

Abstract: A check valve for a rock drill comprises a valve plate carrying a cylindrical strainer. An insert is carried by the valve plate and is movable between valve-open and valve-closed positions. A spring biases the insert to a valve-closed position. The insert unit includes a lid which engages and covers the top of the strainer in a valve-open position, and a bottom plate which covers the valve plate in a valve-closed position to prevent cuttings from fouling the valve mechanism.

Abstract: A rotary roller bit for drilling earth and rock formations, having a main body and three legs extending outwardly therefrom. Each of the legs carries a conical roller cutter with internal bearings and there is a seal around the periphery of the top of the roller cutter. The periphery of the roller cutter is spaced from the adjacent portion of the leg so as to provide a jet slot for the discharge of air. Adjacent the slot and radially inwardly is an air chamber which is formed between an annular surface of the leg and a seal ring. The air chamber is substantially greater in its dimension axially of the roller cutter and air is supplied to it under sufficient pressure to cause a jet of air to flow from the jet slot at a sufficient rate to prevent the entry of rock particles and dirt into the roller cutter.