Abstract: A hydraulic drill boom arrangement for drifting and tunnelling comprises a boom proper (10) that is universally pivotably carried by a support plate (13) and carries a feed beam (40) for a rock drill (41) at its outer end. Two hydraulic cylinders (16, 17) are coupled between the support plate and the boom and located on each side of the boom so that both cylinders are loaded by the weight of the boom, which makes the boom very stable in all positions.

Abstract: In a drill boom arrangement, a feed beam for a rock drill is turnable by means of a hydraulic turning device (34) about an axis (45) that is normally parallel with the axis of drilling during drifting. When not actuated, the turning device (34) is at least partially relieved of torque by means of a friction coupling (52) which is coupled in parallel with the turning device and is normally engaged. The coupling is automatically released when the turning device is actuated. A slip-coupling (67) is coupled in parallel with the first coupling (52) and in series with the turning device in order to avoid overloading of the turning device which is hydraulically self-braking.

Abstract: A drill boom arrangement comprises a boom proper (10) that is universally pivotably mounted on a support plate (13). The boom is swingable by means of two hydraulic cylinders (16, 17) that are coupled between the support plate and the boom to form a tripod with the boom. The hydraulic cylinders are located on each side of a vertical plane through the boom. A boom head (24) is universally pivotably mounted on the outer end of the boom (10) and it carries a feed beam (40) for a rock drill (41). The boom head is swingable by means of two hydraulic cylinders (27, 28) that are coupled between the boom and the boom head to form another tripod with the boom. These two tripods have similar geometry but the hydraulic cylinders of one tripod is located under the boom and the hydraulic cylinders of the other tripod is located above the boom.

Abstract: In a drill boom pivotally supporting a rock drilling apparatus, hydraulic parallel motion means is provided which includes a hydraulic pilot cylinder for sensing the setting of the elevation angle of the drill boom. During elevating of the drill boom the hydraulic pilot cylinder is furthermore used as an additional elevating cylinder.