Abstract: A drilling boom has an articulated arm 12 which carries a drill feed beam 28 on its outer end. Apart from the articulation 36, 38 provided by the joint at the outer end of the arm, the feed beam can rotate about two mutually perpendicular axes at the end of the arm. One of these axes is defined by the so-called rollover unit 44 and the other axis 92 is at right angles to the length of a drill rod on the feed beam and allows at least 180 degrees of rotation so that parallel holes can be drilled in all parts of the roof, floor and side walls of a heading.