requirement of the coal plough during the downhill run approximately equals the power requirement during the uphill run the actual position of the preliminary cut e is determined among other things by the actual seam profile and the type of plough used it can also be seen from fig1 that the auxiliary cutters operate during the uphill run with a depth of cut sz b which is considerably smaller than the depth of cut sz t during the downhill run and which is approximately equal to the depth of cut s t of the main cutters fig2 shows a cutting profile which is similar to that of fig1 in that the depths of the cuts s t s b sz b and sz t are the same as for fig1 the essential difference as compared with the cutting profile of fig1 is that the preliminary cut e is here produced adjacent to the floor of the working the cutting profile shown in fig3 is similar to that of fig2 in that the preliminary cut e is again produced in the floor region of the working here however the depths of the cuts s t s b sz b and sz t are different thus the depth of the cut sz t is about twice the depth of the cut s t moreover the depth of cut sz t of the auxiliary cutters on the downhill run equals the depth of cut sz b of these cutters on the uphill run fig4 shows a cutting profile which is similar to that of fig3 in that the depth of the cuts s t s.