another cutting wheel the opposite rotation is indicated by arrow 9 a trench is made in that the cutting frame 1 is vertically lowered accompanied by the continuous rotation of cutting wheels 5 to 8 the advance being produced by the weight of the cutting wheels 5 to 8 and the cutting frame 1 the loosened soil is transported inwards by the cutting wheels 5 to 8 to a suction means 11 where it is sucked off with a supporting liquid by means of a hose line 12 fig2 makes it clear that the cutting wheels are equipped over the circumference of their hubs 13 with rolling tools 14 and brushes 15 the tools 14 in each case comprise cutting rolls 16 which are mounted in rotary manner in fork like mounting supports 17 the rotation axis or spindle of the cutting roll 16 is substantially parallel to the rotation axes or spindles 18 of cutting wheels 5 to 8 during sinking as a result of the rotation of cutting wheels 5 to 8 tools 14 temporarily engage with the bottom of the bore hole in the vicinity of the semicircle located in the advance direction as a result of the applied load g as well as the torque m acting on the cutting wheels 5 to 8 the soil is loosened the crushed material is conveyed inwards by brushes 15 to the suction means 11 in place of brushes 15 it would also.