Abstract: A device for transferring the debris cut by a cutting machine during mining operations onto a drift conveyer comprises a pair of bridge conveyers connected to each other. The first bridge conveyer has its receiving end pivotally connected to the cutting machine with its discharge end being supported by a dirigible chassis. The second bridge conveyer is supported on the chassis of the first conveyer and pivotable about its horizontal and vertical axis. The support chassis is capable of being swivelled around a vertical axis relative to the first bridge conveyer.

Abstract: A hydraulic mine prop includes an inner piston-like prop guided within an outer cylinder-like prop, and a roof fall valve. The interior space of said inner prop communicates freely with the working chamber of the prop, and the roof fall valve is arranged outwardly on the prop and rigidly secured thereon, the valve being connected to the working chamber by an orifice provided in the prop and leading to the working chamber. The cross-sectional area of the roof fall valve in its open position.

Abstract: The invention refers to a device with which provisional consolidating frames adapted to be brought to a smaller size can be transported to the drift face and can be put in place. According to the invention this device is arranged on the cutting machine itself so that the narrow space remaining between the contour of the cutting machine and the cross section of the drift is sufficient for transporting in forward direction and putting in place the provisional consolidating frames without the necessity to retract the face advancement machine from the drift face. Thus, face advancement machines can be used which occupy the major part of the inside width of the drift, noting that the face advancing machine is maintained in its working position. The invention further describes a doorjamb frame for the provisional drift consolidation and which is particularly suitable for the device proposed.

Abstract: A cutting machine includes an endless conveyor and a loading ramp having movable loading arms which continuously shift the cut material in an upward direction of the loading ramp to conveyor. The rear deflector wheel of the conveyor is driven by a squirrel-cage motor, and the drive of the loading arms is, via the conveyor derived from the front deflector wheel. A slipper clutch is interpositioned within the drive between the motor and the loading arms, and the slide torque of the slipper clutch as reduced to the motor shaft, exceeds the breakdown torque of the squirrel-cage motor.

Abstract: Apparatus for removing dust particles from an air stream includes a tubular housing having an inlet end and an outlet end; a plurality of Venturi tubes having open inflow ends and open outflow ends supported side-by-side within the housing, with their axes parallel to the housing axis so that their inflow ends receive air flowing into the inlet end of said housing; a nozzle for spraying water into the air entering each of the Venturi tubes whereby dust particles in the air are collected in the water and whereby sludge-containing water and air are discharged through the outflow ends of said Venturi tubes; a tank which surrounds said tubular housing, the tank having an outer wall surrounding and spaced from the tubular housing and partition means in the space between said outer wall and the tubular housing dividing the space into first and second compartments; a sludge separator in communication with the outflow ends of the Venturi tubes; conduit means connected to the sludge separator for supplying sludge-cont

Abstract: In a method and apparatus for cutting minerals utilizing a cutting tool provided with cutting teeth, the tool rotates about an axis approximately parallel to the winning face and is moved at a feeding rate essentially in axial direction. Several grooves spaced from each other are carved in sequence, and in dependence on the mineral properties the feeding rate is increased with respect to the rotatory velocity when a brittle mineral is to be cut, while the feeding rate is diminished with a tough mineral.

Abstract: A pressure relief valve for hydraulic mine supporting elements, particularly mine props, has a valve member loaded in its closing direction by a spring, a piston is connected to the valve member end sealingly sliding within a cylinder of the valve housing and arranged to be acted upon in closing direction by the pressure prevailing within the space before the seat of the valve member. The valve member has a neck portion of reduced diameter between the valve seat and the piston and the annular cross section, being acted upon in closing direction, between the neck portion and the circumference of the piston is smaller than the annular cross section, being acted upon in opening direction, between the neck portion and the valve seat.

Abstract: Device for consecutively supporting a drift by means of caps and posts or props in dependence on face advancement, said device being designed for lifting and for pressing the caps to be positioned against the mine roof, characterized in that a breast frame is provided for being suspended to the positioned caps in a manner to be shiftable in direction of face advancement, lifting beams forming a support for the caps to be positioned being supported on said breast frame for being lifted in upward direction and a crane being guided on the breast frame for being shifted in direction of face advancement.

Abstract: A drift advancing machine or the like having a cutting head with replaceable bits. Each bit is disposed in a sleeve-shaped bit holder fixed to the cutting head. Arranged at an oblique angle to the axis of each bit is a pivotal locking bolt having a first pivotal position wherein it engages a recessed portion of the bit and prevents removal of the bit, and a second pivotal position wherein it is out of engagement with the recessed portion of the bit and allows removal of the bit. The front end of the locking bolt is shaped particularly for engagement with the bit recessed portion.

Abstract: The invention relates to a shield structure particularly adapted for longwall mining providing a protected area that effectively insures operator safety even if total collapse of the mine roof should occur. The prop supporting the load-bearing cap of the shield is inclined rearwardly with respect to the mine face, and a pair of tension links that are pivotally connected to each other and are acted upon by a hydraulic cylinder in a direction transverse to the tension links, provide a structure which will ensure a widened (though shorter) protected area in which an operator may reside even upon complete roof collapse. The widening of the area helps insure that any fallen material from the roof will not harm an operator in the protected area.

Abstract: Crawler track means are mounted on and adapted to carry the frame of the machine and have a tread having a rear end. A loader is mounted on and protrudes forwardly beyond the forward end of said frame and has a scooping lip which has the configuration of an arrowhead and is formed with forward edges defining a plane. The loader is forwardly and downwardly inclined toward the scooping lip and is adapted to be raised and lowered relative to the frame and crawler track means and adapted to assume a lowermost position. When the loader is in said lowermost position, said plane defined by said forward edges of said scooping lip is tangent to said crawler track means behind the center of the length of said crawler track means and spaced from said tread before the center of the length of said crawler track means.

Abstract: A tool body defines an axis of rotation for the tool and has a periphery surrounding said axis. A plurality of cutter bits are carried by said body and protrude substantially radially from said periphery and have free ends. Said cutter bits are arranged in a plurality of groups which are spaced in the direction of said axis. The free ends of the cutter bits of each of said groups define a circle. The circles defined by the free ends of the cutter bits of said groups increase in diameter in one direction along said axis.