unit fig2 shows the exemplary embodiment according to fig1 in a sectional view along line ii ii looking in the tunneling direction it can be seen from fig2 that owing to the arrangement of the transverse conveyor belt 24 crosswise to the tunneling direction or removal direction a clearance is created under the main screw conveyor cladding tube 20 fig3 is a descriptive side view of the arrangement according to fig1 engaged in slurry tunneling in which on the one hand the working chamber slide valve 6 the overflow line slide valve 9 and the annular gap slide valve 12 are open in order to maintain the slurry feed necessary for slurry tunneling and the corresponding pressure conditions in the working chamber 4 and the buffer chamber 8 on the other hand in slurry tunneling the main screw conveyor outlet sealing slide valves 23 are closed and the transitional opening throughpass slide valve 27 is open and consequently the transitional opening throughpass 28 located between the main screw conveyor cladding tube 20 and the downstream screw conveyor cladding tube 29 is now open and material containing excavated material destined for removal and conveyed by the main screw conveyor 19 can be conveyed into the downstream screw conveyor cladding tube 29 and by means of the downstream screw conveyor 31 rotating in a conveying direction can be carried on through the.