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: 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: A support and positioner for a rock drill has an extendable and retractable feed boom pivoting about a pivotal support arranged laterally below the axis of the feed boom, so that when the boom is swung downwardly to maintain a desired line of advance of the drill, the boom rocks forwardly so as to increase axial drilling thrust and the extent of forward movement of the drill, and reduce the bending stresses imposed on the drill steel.