Abstract: A mine roof support has a base and a roof shield pivoted to the base and carrying at its upper end a pivoted cap which is urged upwardly against the mine roof by a hydraulic pit prop reacting between the cap and the base. The lower end of the roof shield is connected to the base by two links each having a pivot cooperating with a pivot on the roof shield, and a pivot cooperating with a pivot on the base. In addition, the base and/or the lower end of the roof shield has an auxiliary for each link and each link has an auxiliary pivot which can be connected with one of the auxiliary pivots of the base or lower end.

Abstract: A mine prop provided with an overpressure valve of large flow-through section which opens when excessive forces suddenly act on the prop to discharge pressure fluid from the interior of the prop. The overpressure valve comprises a hollow cylindrical housing forming at one end a valve seat communicating with the fluid-filled inner space of the prop and a valve member axially guided in the housing for movement between a closed position engaging the valve seat and an open position. The fluid-filled space of the prop communicates with channels leading to the outside of the prop. The valve member is normally maintained in the closed position by a gas pillow under high pretension confined in a pressure space delimited peripherally by the wall of the valve housing and at opposite ends respectively by the valve member and a plug fluid tightly mounted in and closing the other end of the housing.

Abstract: A valve arrangement for operating a walking mine roof support so as to automatically move the props of the mine roof support first to a collapsed position and advancing the mine roof support and only thereafter moving the props to their extended position and in which control of the valve arrangement is carried out with the pressure fluid which acts on the members of the walking mine roof support.

Abstract: A method for mechanically advancing clean cut underground mining galleries of various profiles, in which during a primary phase of the operation a pilot excavation of circular cross-section smaller than the final desired cross-section of the mining gallery is carried out and in which during a secondary phase of the operation, overlapping in time with the primary phase, the pilot excavation is widened to the desired finished cross-section of the mining gallery; and a machine for carrying out the method.

Abstract: A door-like closure for passageways in high-risk high-security installations includes a multilayer protective plate which has a rather high resistance to mechanical, thermal and chemical damaging influences, but which can be rather easily damaged by the action of explosives. To reinforce the protective plate, a reinforcing grid is juxtaposed therewith at the major surface thereof which faces the interior of the installation so that, when an attempt is made to destroy the protective plate by explosives, the reinforcing grid not only will increase the resistance of the protective plate to damage but also will permit the explosive shockwave and the possible debris of the protective plate propelled thereby to penetrate through the apertures of the grid without causing any considerable damage to the grid. The apertures of the grid have such dimensions that an intruder will not be able to reach through the aperture into the interior of the installation to, for instance, manipulate the lock of the closure.

Abstract: A walking mine support unit has a pair of adjacent supporting frames each having a multi-partite sole plate and a multi-partite roof shield. The sole plate and roof shield of each frame are connected only at their respective leading and trailing ends, by hydraulic rams which permit the roof shields to be raised and lowered relative to the sole plates, and by four-bar linkages which permit length-wise displacement of the roof shields parallel and relative to the sole plates. A multi-section overshield is located above each of the roof shields and connected thereto by adjustable supports. An arrangement is provided for advancing the unit in stepwise manner.

Abstract: A walking mine roof support has a roof engaging cap element, two supporting units each including a floor engaging plate member and a prop extending between a respective one of the plate members and the roof supporting cap element so as to support the latter, which floor engaging plate members are displaceable in a first direction toward a mine face and are spaced from one another in a second direction transverse to the first direction, and displacing elements for displacing the floor engaging plate members in the first direction and including two guiding elements spaced from one another in the second direction and two hydraulic cylinder-piston units operative independently of one another. Each of the hydraulic cylinder-piston units connects one of the guiding elements with a respective one of the floor engaging plate members so as to displace the latter relative to but independently of one another in the first direction.

Abstract: A mine roof support for an underground mine gallery comprises a sole plate adapted to rest on the floor of the mine gallery. The sole plate is connected by links to the region of the lower end of a rear shield, and the upper end of the latter is connected by pivot means to a roof shield, between opposite ends of the latter, in such a manner that a portion of the roof shield between the front end thereof and the pivoted means is considerably longer than the portion of the roof shield between the pivot means and the rear end of the roof shield. At least one extensible and collapsible prop extends between the sole plate and the portion of the roof shield which is located forwardly of the pivot means and at least one additional prop extends between the sole plate and the rear shield, so that the roof shield may be pressed against the roof of the mine gallery and be shifted relative to the mine face.

Abstract: In a longwall mining operation the roof of the breast extending laterally from a heading or gangway is supported by at least two pairs of pit props. Each pair is substantially identical, having an elongated upper part and an elongated lower part displaceable away from each other by hydraulic rams. In addition a shield is provided extending vertically between the upper and lower parts of each prop at the upstream end of the prop turned toward the stowage area. In addition the props furthest from the mine are substantially longer than the props closest to the mine and are provided at their ends turned toward the stowage area with side shields forming a closed chamber so as carefully to segregate the gob from the breast. The upper parts of the props are formed of several articulated sections so as to allow these upper parts to conform to the shape of the roof.

Abstract: In longwall mining wherein a mine roof is normally supported by a succession of arches each in turn supported at one mine wall on a respective leg, a plurality of vertically expensible holders are pressed up against a plurality of respective adjacent arches with a common first beam, and legs of the thus-supported arches are removed so that the mine wall can be worked at this location. For advancing along the longwall all of the holders except the holder at one end of the row of holders are pressed upwardly against the respective arches with a second beam. The leg of the arch of the end holder is replaced and then the first beam is dropped down away from the row of holders. The end holder is then displaced to the opposite end of the row and the first beam is advanced toward this other end and the end holder is positioned under the arch immediately adjacent the other end.

Abstract: A mine roof support for underground excavations includes a support adapted to engage the floor of the underground excavation, and a movable roof shield which engages the roof of the underground excavation. A movable rear shield is mounted on the support and is pivotally connected with the roof shield for relative movement thereto about a pivot axis. A pit prop arrangement is provided intermediate the shields and the support for moving the shields relative to each other about the pivot axis between a plurality of inclined positions in which the rear shield is inclined at different angles of inclination relative to the roof shield. A pair of abutment members are respectively provided on the shields for limiting relative movement of the latter beyond a predetermined one of the inclined positions in which the shields are inclined at a predetermined angle of inclination relative to each other.

Abstract: A method for advancing and supporting an underground mine gallery in which a groove following the outline of the cross-section of the mine gallery is formed in the mine face and simultaneously thereto a plurality of bore holes are drilled in the part of the mine face located inwardly of the groove, in which a support frame is then placed into the groove and braced against the surrounding rock, whereafter explosives placed in the bore holes are exploded to remove the part inwardly of the groove from the mine face, while the loose material formed during the preceding steps is transported away from the mine face; and a machine for carrying out the method which is advanced after the above-mentioned steps are performed, whereafter the above-mentioned steps are repeated to thus advance the underground mine gallery while properly supporting the same during such advance.

Abstract: A mine roof support for an underground mine gallery includes a sole plate resting on the floor of the mine gallery, a roof shield pressed against the roof of the mine gallery by a plurality of hydraulically operated props, and means for maintaining the position of the props relative to the sole plate and the roof shield.

Abstract: An underground excavating system includes a conveyor device which is operative for conveying material away from a mine face, and an excavation roof support device which is operative for supporting the roof of the excavation. A hydraulic cylinder-piston unit is operatively connected to both of the devices and is operative for advancing one of the devices towards the mine face while the other of the devices remains stationary, and vice versa. A guiding arrangement is connected intermediate the control unit and the conveyor device and is operative for guiding the advancing device during its advance towards the mine face. The guiding arrangement includes a pair of elongated support members which are spaced apart of each other and which have one end region located closer to the mine face and another end region located further from the mine face. The guide arrangement further includes a pair of guide sleeve members one at each of the aforementioned end regions.