Rotating cutting tool for formation of soil cores - by pull operation - has central shaft for holding cutter and enclosing concentric shell

The cutter is used especially in soils which exert markedly strong suction effect on the soil column to be excavated and in soils which are relatively loose or porous. The cutter has means for compacting the cut soil in order to reduce the suction effect and for facilitating the removal of the material. The boring tool has a central spindle whose both ends, are threaded. This cutter unit can be connected to an excavating machine. A hollow tapering sheet is held by radial ribs on the shaft. The f ront end of the cutter is narrower than the rear end. The front end of the radial ribs has a number of cutting teeth. Cutting teeth are also arranged around the air open edge of the shell at the narrower end. The core is cut by the circumferential teeth and the core formed is cut up by the teeth at the end of the radial rib. The suction effect in the borehole is reduced by the cutting edge at the wider rear end of the shell.