Machine for making underground excavations

A machine for making underground excavations by compacting soil, comprising:

• an eccentric shaft having journals eccentric relative to one another;
• a conical member provided in front of the eccentric shaft on the side of the face of the excavation being made;
• tapered rolls mounted in a sequence, looking away from the face of the excavation being made behind said conical member, on said journals of said eccentric shaft, said rolls defining, in combination with said conical member, a conically expanding body, the tapered rolls being mounted for free rotation about said eccentric shaft;
• a drive for rotating said eccentric shaft and for longitudinally moving said machine within the excavation;
• a through longitudinal diffuser passage in said conical member;
• a through longitudinal diffuser passage in said eccentric shaft, the cross-sectional area of said passage of the eccentric shaft enlarging in the direction away from the face of the excavation being made, and the smallest cross-sectional area of said passage of the conical member being smaller than the smallest cross-sectional area of said passage of the eccentric shaft so that said inside cross-sectional area of said passage of the conical member, during operation of the machine, is substantially within said inside cross-sectional area of the eccentric shaft, and both passages defining in combination a through passage for the transfer of soil partially removed during operation of the machine.