angled at an acute angle to the floor 5 on which a plough 7 is supported on its two front side ends by means of a sliding runner 8 each of which only one sliding runner 8 is shown in fig1 above the rail 6 the plough guide has a lower chain channel 9 and an upper chain channel 10 through which the runs of an endless plough chain 11 extend to drive the plough 7 along the plough guide 4 a bearing journal 12 is formed on the plough body of the plough 7 for a pivotable mounting of a cutting bar not illustrated on which tools are disposed to dislodge for example coal the plough guide 4 has an upwardly directed guide rail 13 at its apex an upper guide pawl 14 engages over the guide rail 13 at both face side ends of the plough 7 like a hook between the guide pawl 14 and the guide rail 13 a u shaped guide piece 15 is provided that can be detached from the guide pawl and replaced because it is exposed to increased wear and is therefore a wearing item here the guide piece 15 sits in a similarly u shaped holding fixture of the guide pawl 14 that is open to the bottom crane eyelets 16 are disposed on an upper side of the plough 7 with which the plough 7 can be lifted with suitable.