Abstract: A rock bolt in the form of a steel tube (11) is placed in a borehole in rock and is then expanded against the rock by means of an expandable body (15) inside it. The expandable body (15) comprises a rubber hose which is temporarily pressurized to a pressure that is usually 50-100 MPa so that the bolt anchors in the borehole. The expandable body (15) is part of a mounting tool and it is withdrawn immediately when depressurized.

Abstract: A rock bolt comprises an inflatable tube (11) which has a deep longitudinal depression (12). A wire coil (20) is mounted on the tube before the bolt is inserted in the borehole. When pressurized by high pressure water the tube (11) expands and clamps the coil (20) between itself and the borehole and the tube (11) is thereby permanently anchored in the borehole. The depression (12) develops during the expansion but the coil (20) prevents full expansion of the tube (11).

Abstract: A rock drill boom structure comprises a support means, an elongated boom swingably carried by the support means and a feed beam on which a rock drill is mountable so as to be power displaceable therealong, the feed beam being carried by one end of the boom. The support means includes an elongated hollow guide means of substantially less longitudinal length than the boom and in which the boom is slidably received to project through both ends of the guide means, the boom being arrestable in the guide means, a rotatable member on which the guide means is pivotably mounted for pivotable movement about an axis transverse to the axis of rotation of the rotatable member, first power means for pivoting the guide means and second power means for rotating the rotatable member. The rotatable member 19 is preferably disc-shaped and has an aperture therein through which the power lines of the rock drill are drawn.