Abstract: An automatic control of the operation of a machine used for excavating drifts, tunnels, stopes, caverns or the like of a predetermined profile having a rotatable head (10) and cutting arms (14, 16) mounted on the head for rotation therewith, extending in the direction of excavation with at least one cutting arm (14, 16) being radially pivotable. The angular position (.phi.) of the head (10) is continuously measured and the output signals from these measurements are processed by the computer (44) which controls the angular positions of the head and of the arms according to a predetermined profile code or program stored in the computer memory for cutting the predetermined profile. Additional sensors (54,56) may be provided to control other parameters such as RPM of the rotating head, the force exerted on the arms, the positioning of the machine and the like.

Abstract: To excavate drifts, tunnels, stopes, caverns or the like, tools operating in an undercutting manner are mounted on radially pivotable tool arms, which are located on a rotary working head. With at least one tool (54) on a tool arm (51), a central region (Z) of the rock face is cut radially from the outside inwards by pivoting of the tool arm (32), an outer region (A) surrounding the central region (Z) of the rock face is cut radially from the inside outwards by pivoting of the tool arm (32). Pivot drives (30) for at least some tool arms (31, 32, 33) can be controlled in such a manner that cross-sections with contours deviating from a full circular shape can be cut. Muck removing devices (27, 28) are used for collecting and transporting away the muck produced by the cutting operation.

Abstract: A loose rock detector comprises an impact tool for hitting the rock face, sensors for detecting acoustic, rock motion and/or impact force signals generated by movement of the impact tool against the face of the rock, a data processor responsive to the sensors for correlating the above signals in the time and/or frequency domain against predetermined relationships to detect loose rocks and to assess mass and degree of looseness of the rock, and a display unit for displaying the results of the correlation.