Abstract: A machine is disclosed which is for use in mining or tunnelling work and employs a beam or arm supporting cutting means and connected through a support structure to a turntable carried by a movable chassis. The turntable is adjustably rotatable about a vertical axis and one or more piston and cylinder units are provided to raise or lower the arm in relation to the support structure. This structure is itself adjustably pivotable in relation to the turntable about a further axis which is generally aligned with the horizontal forward position of the arm i.e. in the direction of advancement of the mining or tunnelling work. In addition part of the structure connected to the arm is also displaceable along this further axis so that the cutting means located at the free end of the arm can be adjusted in respect of a variety of directions. The cutting means is itself composed of cutter rollers driven to rotate about an axis extending laterally of the arm.