mounting 11 also comprises a bearing support 15 and a depending skirt 17 two pivotting ram connection lugs 19 are provided on the depending skirt 17 a bearing 21 is carried in the bearing support 15 and a cutting boom 23 is fixed onto the free ends of the bearing 21 a pivotting ram 25 is connected to each side of the cutting boom 23 and each ram 25 is connected to its respective lug 19 on the depending skirt 17 the rams 25 operate to pivot the cutting boom 23 in a vertical plane about the bearing 21 a conventional cylindrical cutting head 27 is rotatably mounted on the cutting boom 23 with its axis horizontal the cutting boom 23 contains conventional motors 29 and the assembly is provided with conventional gear boxes 30 and chain drive equipment 31 for causing the cutting head 27 to rotate in use the boom arrangement is removably secured to the chassis 1 by means of bolts 33 passing through the clearance holes 14 and screwed into the threaded holes 3 in the chassis the only other connections which need to be made are electrical connections for the motors 29 and hydraulic connections for the pivotting rams 25 the machine comprising the boom arrangment removably mounted on the chassis 1 can be used in exactly the same fashion as is a conventional continuous miner if an area of hard material is encountered the machine can be converted to.