Abstract: A mining machine for performing a continuous mining operation in hard rock. The operating portions of the machine are mounted on substantial deck sections hingedly connected to each other to promote maneuverability of the machine in confined spaces. A mining implement capable of breaking ore from the solid is mounted on a rotatable, extensible boom and broken ore is collected by power operated means also provided on the machine. The machine may be adapted for remote operation through a remote hydraulic and/or electric control and may be provided with optional wheels or alternatively may be self propelled.

Abstract: The system for digging subterranean galeries comprises a cutting tool articulated on a frame and mounted so as to be movable along the height of the mine face. This frame is provided with ground support means and with propulsion means for following the progress of the cutting, the articulation point of the cutting tool being situated in the upper half of the system in operating position. The articulation point of the cutting tool may be situated on a member movable with respect to the frame and movable in a direction substantially parallel to the direction of advance. The shaft bearing the cutting tool may be mounted on two bearings, one of which is movable vertically to give the tool an oblique path in a pre-determined direction.

Abstract: A portable pneumatic cleaning device for removing particulate material from crevices and channels particularly between component parts of railroad switch mechanisms, is provided which has a heavy duty nozzle including a central port and a pair of outwardly divergent side ports having axes which are coplanar with the axis of the central port for discharging a pressurized stream of air in a generally fan-shaped pattern along a surface to be cleaned when the device is connected to a pressurized air source. The device has an elongated body portion and end portions formed at an angle therewith and parallel to one another, and includes a switch for controlling the flow of air therethrough, a runner to maintain the nozzle at a spaced distance from a surface to be cleaned, and a handle to facilitate manual use of the device.

Abstract: Apparatus is disclosed for regulating the capacity of a tunnelling machine. The tunnelling machine is of the type having a rotatable cutting head mounted at one end of an arm. The other end of the arm is pivotally mounted on a carrier about a pivot pin whose axis extends transversely to the axis of the arm. A hydraulic rotary drive is provided for rotating the arm about the axis of the tunnel being formed. The regulation apparatus includes a regulator for regulating the rotary drive of the arm in dependence upon the capacity of the cutting head drive. An angle/current transducer is provided for measuring the angle between the axes of the arm and the tunnel. The regulation apparatus is such that the capacity of the cutting head drive decreases as said angle decreases, the reduction in capacity being effected by a reduction in the force applied by the cutting head to the working face.

Abstract: The reciprocably supported member is accompanied by means whereby its stroke can be relocated so that it can be used to drive its support if desired, even while it is simultaneously driving a tool or the like connected therewith. Also, the member may have its own onboard drive means; as well as onboard means for removing any debris that the tool generates. The drive means may comprise a combustion engine and the debris removal means may use the combustion gases of the engine as a flush medium for the same. Ordinarily, the flush medium is discharged adjacent the outer periphery of the working face of the tool and removes the debris through apertures adjacent the outer peripheral edge of the same. Other features are also described.

Abstract: There is disclosed a hard rock trench cutting machine comprising a main body assembly and a cutting wheel assembly. A cylinder is transversely mounted on the main body assembly and carries a pair of pistons which extend axially from each end of the cylinder. Pads are provided on each piston to bear against the sidewalls of a trench. Each piston has an end face within the cylinder which, together with an inner sidewall of the cylinder, comprises a pressure chamber adapted to force the pads against the trench. The main body and its cylinder are free to move laterally relative to the pistons when the cylinder is pressurized. Extensible arms are provided between the pistons and the main body assembly for forcing the main body assembly and its cutting wheel forwardly to progressively cut a trench. A steering assembly is provided to shift the main body assembly laterally relative to the pistons and about the central axis of the cutting wheel.

Abstract: A slideway arrangement comprises a slideway component and a slide component guidably slidable with respect to the slideway component under the action of a hydraulic ram. At least one of the components comprises at least one wedge arrangement and a hydraulic ram for urging the wedge arrangement to releasably wedge one of the components to the other of the components.

Abstract: The cutting machine body comprises a non-rotary housing mounted on a slideway and a boom carrying rotary housing rotatably supported by annular support means arranged adjacent to a radially outer margin of the body, drive means being provided on the non-rotary housing for rotating the boom carrying rotary housing.

Abstract: Bottom plates for walking mechanisms for the movement of heavy loads, which bottom plates are connected by means of connection pieces. The bottom plates are elastically connected with connection pieces, the latter being formed as open profiles.

Abstract: A method of mining a mineral deposit from a remote point, particularly useful in mining pitching or horizontal seams, comprises boring, casing and preparing a log of a probe hole; the casing will later be used as a guide for the mining head. All personnel are remotely located from the mining face and the mining head follows the probe hole and is rotated by means of a novel drive stem powered from a portal based plant. Thrust is imparted to the rotating mining head in a non-cyclical manner by the intermittently supported drive stem. The mineral being mined is automatically removed from the face and discharged at the portal. Steel or reinforced concrete support collars follow the mining head and support the drive stem until the bore is mined out whereupon the collars, the drive stem and the guide are removed for reuse.

Abstract: An apparatus for cutting a flat elongated channel, chamber or passage in subterranean strata, e.g. a crosscut between two mine galleries or shafts, which comprises upper and lower shoes or shields which can be spread apart by a fluid-cylinder system and to which a frame is connected by further fluid cylinders, this frame carrying an excavating worm whose flights are formed with picks for removing the face of the channel to be advanced. A conveyor extends past the frame or through the latter to carry rearwardly the detritus excavated by the worm.

Abstract: An apparatus for the sinking of a shaft in which a machine platform can be anchored against the wall of the incipient shaft and carries an orbiting tool for cutting away the floor of the shaft, thereby dumping the detritus into a pilot-bore hole continuously drilled by a pilot-bore unit. The latter has a head for advancing the pilot bore and is provided with a worm conveyor running centrally through the shaft to transfer the detritus to a bucket on a loading platform disposed above the main platforms and connected thereto for feed cylinders. The platforms have cylinder arrangements whereby they can be independently anchored to the vertical wall of the shaft.

Abstract: A mining installation includes a mine roof support the base of which has a forward part on which is located an elevated track on which a mining machine can be supported for reciprocal movement. A conveyor is disposed beneath the cantilever track for the receipt of mined mineral, but does not bear any of the weight of the machine. The support element has utility supply conduits for use at any location along a mineral face. The installation can be used in thick seams working on the retreat principle and for seams of the order of 8 m can be provided with a rear section also having an elevated support track for supporting a machine capable of taking a substantial roof cut in the wake of the forward section.

Abstract: A contour miner has walker means carrying an external deck outside the formation being mined having power supply and control means for movement along the periphery of a coal seam with a reciprocating carriage having a rotary cutter for removing the coal from a work face extending inwardly below the overburden perpendicular to the seam periphery; a conveyor extends adjacent the work face and conveys the removed coal out beyond the external deck; an internal roof support-walker assembly is positioned inwardly of the formation and has hydraulic cylinder actuated movable roof supports and ground pads and hydraulic cylinders for walking forward toward the work face with dragline means moving prefabricated roof supports behind the support-walker assembly as it is moved toward the work face.

Abstract: An improved advancing mechanism for a dual auger continuous miner of the type adapted to be advanced by a pair of anchoring jack assemblies, a pair of cables extending from the anchoring jack assemblies to a pair of winch mechanisms on the sides of the frame. The mechanism includes a mounting arm mounted on each side of the frame for movement about a vertical axis, a telescoping structure extending longitudinally between each mounting arm and the associated anchoring jack assembly and hydraulic piston and cylinder units for effecting the pivotal movement of each arm and the telescoping movement of each telescoping structure.

Abstract: A track-mounted vehicle having legs which can be retracted or extended, so that the vehicle can be raised to permit advancement of the track and then lowered, the vehicle either being raisable off the track to permit advancement, or having captivating means by which the track is raised, together with the vehicle, the track and the vehicle having rack-and-pinion or rack-and-chain drive means so that, in the raised position, the track can be advanced by said drive means and, in the lowered position, the vehicle is movable along the track by said drive means.

Abstract: A device for mining thick coal strata comprising a plough pressed in the ion of the floor by a ram, whereas in the vicinity of the roof the plough is pressed by a unit fixed to a canopy of the lining. The unit is provided with guides on which the plough is supported through a slide. A lever of a distributor is deflected by the plough and causes the unit to extend by an amount equal to the web of the plough.

Abstract: A full face miner including a simplified conveying arrangement and designed for easy maneuverability into and out of mine sites. A plow operatively mounted to and longitudinally movable with each of a pair of rotatable cutting heads of the miner provide for the conveyance of cut coal to a middle conveying portion for ultimate transport away from the mine site. The mounting mechanism for the cutting heads is designed so that at least the end portions thereof are movable from a position generally parallel to the mine face to a position generally perpendicular to the mine face and extending in front of and in line with the central conveying means, for ease of withdrawal from the mining area. A motive power source, such as a powered crawler or powered wheels, is provided which is movable into operative engagement with the ground to transport the miner to and from the mining site when in a collapsed position.

Abstract: A tunnelling machine has a swing unit (31) that is swingable about a horizontal axis (I). The swing unit has a head (50) that rotates about an axis (II) that is transverse to said horizontal axis and passes the horizontal at a distance below the horizontal axis. The head is equipped with a plurality of disc-cutters (53-58, 63) that are arranged to have their cutting edges on an imaginary sphere with a radius of about the same length as the swing radius. Upon simultaneous upward swinging of the swing unit and rotation of the head, the cutters cut both when on the leading side of the head and when on the trailing side. No cutting occurs during the return swing stroke. When the swing unit has been returned, the machine is advanced a step which is somewhat larger than the distance between the two axes, and another upward cutting stroke can be effected.

Abstract: A tunnel-excavating machine in which a chassis carrying a cutting drum is displaceable toward the face of a subterranean structure in which a tunnel is to be formed, the chassis being provided independently from a roof-support unit which is connected to the chassis only by at least one fluid-pressure cylinder arrangement. The cylinder arrangement is connected to the unit and/or the chassis by vibration damping means so that the cylinder arrangement can advance the chassis relative to the roof support unit or vice versa and vibration transmission from the chassis to the roof support unit is damped.

Abstract: A continuous mining machine comprising a central longitudinally extending conveyor assembly, a pair of cutting and conveying mechanisms mounted on the forward end of the central conveyor assembly for movement between a normal operating position wherein the cutting and conveying mechanisms are in alignment and extend laterally outwardly with respect to the forward receiving end of the conveyor assembly and a transporting position wherein the cutting and conveying mechanisms are in parallel relation alongside the central portion of the conveyor assembly, the cutting and conveying mechanisms having vertically movable endless track assemblies operable to move the continuous mining machine when the cutting and conveying mechanisms are in the transporting position, and a pair of mine floor-to-roof anchoring canopy units for (1) advancing the continuous mining machine so that the cutting and conveying mechanisms are moved inwardly of the working face, (2) facilitating the installation of mine roof bolts at positions

Abstract: A knife shield comprises a plurality of elongate knives which are arranged side-by-side upon a common support frame, the knives defining a generally cylindrical shield. Each knife is supported on the frame for movement in its longitudinal direction. At least one pair of diametrically opposed knives are coupled together, in the manner of a trackrod, for conjoint movement with respect to the longitudinal axis of the shield. During this movement the knives of the coupled pair concerned remain substantially parallel. The movement of the knives is used for controlling the direction of advance of the shield.

Abstract: The mining machine consists of a main frame having a front portion and a rearwardly extending portion, and cutter heads disposed for movement across the front portion for dislodging mineral. A conveyor system is provided which extends across of the front of the main frame and along the rearwardly extending portion thereof for carrying dislodge mineral from the mine face. Forward roof support jacks, which are attached to the main frame for unitary movement therewith, provide temporary roof support as the entry is being formed. Rear roof support jacks, disposed behind the forward roof support jacks, also provide temporary roof support. Sumping cylinders, which are disposed generally parallel to the mine floor, connect the rear roof support jacks to the main frame and are used for moving the mining machine. The sumping cylinders are connected to the main frame with a universal joint connection to permit free movement of each sumping cylinder around its point of connection to the main frame.

Abstract: A diametrically compact tunneling machine for boring tunnels is disclosed. The machine includes a tubular support frame having a hollow piston mounted therein which is movable from a retracted position in the support frame to an extended position. A drive shaft is rotatably mounted in the hollow piston and carries a cutter head at one end. The hollow piston is restrained against rotational movement relative to the support frame and the drive shaft is constrained against longitudinal movement relative to the hollow piston. A plurality of radially extendible feet project from the support frame to the tunnel wall to grip the tunnel wall during a tunneling operation wherein the hollow piston is driven forwardly so that the cutter head works on the tunnel face.

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: Tunnel excavating apparatus comprises a hollow cylindrical shield adapted to be axially forced through subterranean material and having a circular cutting edge at a leading end portion. An inclined baffle and guide member has a central opening spaced upwardly from a lower edge of the baffle and guide member and an auger-like member extends across the shield adjacent the opening. Sections of the auger-like member extending on horizontally opposite sides of the baffle opening have oppositely directed flutes and subterranean material dislodged by the cutting edge and deposited atop and about the auger is urged inwardly toward the opening in the baffle and guide member for deposition on a conveyor having a receiving end beneath the opening. The conveyor extends rearwardly and upwardly and deposits the material in a receptacle. Horizontal and vertical breasting plates also serve to cut and dislodge material and support the shield.

Abstract: Machine for the digging of passages, galeries or tunnels in underground work, of the type in which the stoping device consists of a single stoping drum or mill of which the axis of rotation is practically perpendicular to the plane of the working-face, and whereby this rotary mill is attached to an arm which pivots around a shaft which is also practically perpendicular to the working-face, characterized by the fact that the latter bears in a second arm, which in its turn is attached on a shaft which is practically perpendicular to the working-face and bears in the machine frame, whereby the length of the two arms and the angles of rotation of the arms are chosen in such a manner that the mill can cover the entire surface of the working-face to be stoped, without having to move the machine laterally.

Abstract: Shield tunneling machine and method which may minimize the variation in water- and earth-pressure at the tunneling face so as to hold the ground firm and to ensure the safe tunneling.

Abstract: A duct section or other load to be moved axially along a bore hole has two reciprocating drivers mounted on it and two sets of gripping elements. Each driver reacts axially between the load and a set of gripping elements to move the gripping elements relative to the load through a defined stroke in each axial direction. An endless cable with axially extending straight stretches has one stretch connected to each driver to constrain the drivers always to move in opposite axial directions and to begin and end their strokes simultaneously. The gripping elements are so formed that when engaged with the surface of a bore hole, increasing axial force on the load in one direction increases the radially outward force under which they bite into the surface.

Abstract: A tunnel-excavating machine comprises an excavating head, preferably a full-cut head, adapted to excavate the full-cross-section of the tunnel to be formed, which is slideably mounted for movement relative to a pair of support frames. Means is provided to relatively displace the support frames axially and the support frames are surrounded by a blade shield made up of a multiplicity of individual blade segments, each of which can be individually advanced by hydraulic means connected to the support frames. The individual blade members, which span both frames, can be urged against the wall of the tunnel by respective fluid pressure means in each of the frames.

Abstract: The excavating machine has a cutter carrying boom carried by a boom support member which can be swung about an axis extending in the direction of the roadway. The machine includes a cutter unit and a stay unit each of which is releasably anchorable in the roadway and each of which can be advanced relative to the other unit.

Abstract: The mining machine has a body portion mounted on a pair of endless propelling tracks which advance the mining machine forwardly in the mine. Pairs of forwardly extending arm members are pivotally connected to the body portion and support at their end portions a skid plate which is positioned transversely across the body portion and arranged to rest on and slide over the mine floor. A first conveyor is supported by the skid plate and receives and directs dislodged material from the mine floor to a second conveyor connected to the end portion of the first conveyor. The second conveyor discharges the dislodged material to the rear of the body portion. A support frame is positioned on the skid plate and horizontally supports a pair of transverse guide rails at the front end of the body portion. A carriage is slidably mounted for transverse movement on the guide rails and includes a rotatable supporting shaft.

Abstract: A coal mining method at a long-walled pit face of a coal mine comprises combining self-advancing supports with a conveyor which is arranged along the long-walled pit face and on which a shearer is mounted, and arranging the effective shearing depth of shearing drums of the shearer to be at least half as long as the stroke of a shifter for shifting both of the self-advancing supports and the conveyor toward the pit face, whereby each of the self-advancing supports is progressively shifted toward the pit face every time that the whole area of the pit face is sheared at least twice by the shearer.

Abstract: A tabular mineral deposit is mined by drilling overlapping holes in the plane of the deposit, the first hole being drilled in any convenient manner and each subsequent hole being drilled by a box hole type machine with a coring bit. The core breaks up and passes out of the core barrel into the orbit of vanes that transfer the broken rock into the hole being lapped. The broken rock is then removed along the hole being overlapped as by means of a drag line scraper.

Abstract: A tunnel drive shield is provided with a plurality of bracing units spaced around its periphery. The bracing units are expansible against the surrounding tunnel wall to control the direction of shield advance. A bracing unit is provided in each of the four shield quadrants defined by the vertical and horizontal center planes of the shield. Each of the bracing units is expansible in a non-radial direction.

Abstract: A bore hole to be deepened far into air-impermeable bedrock has an air-tight lining and an air lock in its upper portion, and it is pressurized below the air lock. A duct comprising endwise connected but disconnectable duct sections extends through the bore hole, its top end open to the atmosphere. A drilling mechanism having a telescoping connection with the bottom of the duct comprises a bit driven by a pneumatic motor that has an exhaust air outlet opening into the duct and a pressure air inlet in the bore hole outside the duct. At intervals along the duct remotely controllable supporting and moving devices are fixed to duct sections, each device having a pneumatic actuator with an inlet opening to the bore hole and an outlet opening to the duct. The devices have gripping elements that frictionally engage the bore hole surface to confine the duct against motion or to move it up or down for raising or lowering the drilling mechanism.

Abstract: This mining system utilizes a row of roof support units in conjunction with a row of conveyor sections and a continuous mining machine which rides on the conveyor sections. Each roof support includes a primary support shield supported on a base by means of jacks and a secondary support shield telescopically mounted to the primary support shield and having a wall engagement portion at the outer end to provide bearing support for the secondary support shield by the wall rather than merely by cantilever support. Each support unit is connected to an associated conveyor unit by a ram for moving said units relative to each other. The mining machine includes a kerf cutting member for creating a continuous ledge at the junction of the longwall and roof for supporting the secondary support shield wall engagement portion.

Abstract: A variable wall mining machine to release coal from a longwall mine face includes an articulated auger assembly made up of a plurality of side-cutting auger sections joined together by universal couplings in an end-to-end relation and coupled to a drive at one end of the assembly. A scavenger plow, supported on the mine floor, consists of sections connected together for articulated movement toward and away from the longwall mine face. Two support arms are journaled by bearings to each auger section and the other ends of the arms are pivotally supported by one of the scavenger power sections. Hydraulic actuators, supported by mine roof supports, move two adjacent scavenger plow sections together with two auger sections as a pair into sumping cuts with the longwall mine face. Other hydraulic actuators supported by the scavenger plow control the elevation of the pivotal arms and, hence, the auger assembly coupled thereto for shear cutting the mine face.

Abstract: A vehicle for use in mine workings for enlarging a tunnel or for forming a heading and comprising a wheeled chassis having a rock breaker and a bucket loader mounted thereon further includes a conveyor means extending generally longitudinally of the chassis to receive rock and spoil collected by the bucket loader at the forward end of the chassis and to discharge such rock and spoil at the rearward end of such chassis. Rams are provided laterally of the chassis for supporting the same relative to opposed surfaces of the workings.

Abstract: The roof of an underground mine working which is newly exposed by a mining machine passing along a face of the working is supported by applying a flexible mat to the roof and underpinning the mat by self-advancing roof supports. A supply of mat is stored in a region which is already supported by the roof supports, is fed from the store in a first direction, and turned through a right-angle to extend along the newly exposed face. The device which turns the mat and applies it to the roof may have its vertical position controlled in accordance with the vertical position of a cutting cylinder of the mining machine.

Abstract: An excavating mining and conveying apparatus is formed of trough segments or sections with screw sections mounted on the trough sections carrying out the mining and conveying functions. Actuating means are provided to bring the screws successively into inclined contact with the face or seam of coal at an angle of from 5.degree. to 50.degree.. A drive is provided to transmit a torque to drive the conveying and transporting screws.

Abstract: A method and apparatus for applying lateral thrust for moving a member, especially for applying lateral thrust to an earth penetrating device. A tubular mandrel of fixed length has four generally toroidal force cells disposed thereon, two laterally expandable force cells having a substantially constant radial dimension, the sum of the lateral dimensions of the lateral force cells always being the same, and two radially expandable force cells having a substantially constant lateral dimension. By alternately expanding and contracting the cells the mandrel is moved laterally. The radial cells engage the walls of a borehole during earth penetration to anchor themselves thereto when expanded. Any type of earth penetrating device may be placed in front of the lateral thrust applying unit, such as a drill bit or a compacting device.

Abstract: Apparatus for anchoring a mining installation to the floor of a mining excavation includes an anchor beam and at least one anchoring element which is anchored in a borehole in the floor of the mining excavation. Each anchoring element is provided with a respective tensioning device for prestressing that anchoring element. Each tensioning device comprises a freely pivotable support member on which is arrayed an adjustable anchoring element connection element.

Abstract: A hole reamer according to the invention includes a main body or support with roller cutters rigidly connected to a drill stem, and an additional support with roller cutters arranged co-axially with the main body or support. A additional support device can move along the axis of the main body and is provided with a means to effect this longitudinal movement. The main body and additional support device are adapted to drill holes of one diameter with consequent reaming thereof.

Abstract: An apparatus for protecting coal mine workers from flying coal, rocks, coal dust, scattering coal and the like, which are produced as a drum shearer works in a longwall coal face. The apparatus is provided with isolated walls or chambers between iron props installed in the self-advancing supports provided in the longwall coal face by use of fastening members. The isolated wall or chamber is connected with its adjacent wall or chamber by a flexible connecting member.

Abstract: Tunnel driving apparatus has a shield with a plurality of cutter planks arranged side-by-side around the tunnel axis. The planks are supported and guided by two frames connected via a rigid bracing structure. One of the frames is provided with adjustable means capable of expanding or contacting the frame radially of the tunnel axis. The planks are advanced in known manner individually or in groups and the adjustable frame can be used to make the axes of the planks converge rearwardly of the tunnel driving direction when desired. Such control permits steering of the apparatus by making the reactive forces on the advancing planks cant the shield within a tapered gap between the planks and the tunnel wall. In addition the tendency of the frames to become jammed in the planks when being shifted up can be precluded.

Abstract: The specification describes a mining machine, in particular slot drilling machine for mining of minerals, especially ores of non-ferrous metals from narrow layers of reefs in hard rock, comprising at least one drilling head pivotable about a vertical pivoting axis for arcuate drilling of a slot cavity and a carrier comprising a front part and a rear part joined by thrust cylinders and hydraulic props supportable against the upper and lower slot cavity walls, characterized in the drilling head having at least one oscillation disc segment armed with at least two or preferrably more drilling tools and provided with at least one operation cylinder engaging eccentrically to the disc segment and this oscillation disc segment being supported oscillatingly in horizontal position about the vertical pivoting axis in the front part of the carrier.

Abstract: Mining apparatus for longwall mining comprising a mineral winning machine which traverses a mineral face, a row of self-advanceable roof supports parallel to the face, and a conveyor also parallel to the face for removing cut mineral, the supports having platforms which support the conveyor, the hydraulic props of the supports being positioned between the mineral face and the conveyor. The winning machine thereby can cut substantially across its whole depth, the props being adjacent the face to be cut. Ramps are provided on the supports and the conveyor to scoop out mineral onto the platforms and then on the conveyor, during advance of the supports and the conveyor.

Abstract: Apparatus for constructing an underground tunnel employs a drive shield composed of elongate drifting cutters disposed side-by-side in a circular configuration around a support frame. Hydraulic rams serve to advance the cutters and to shift up the frame when all the cutters have been advanced. The cutters have rear end portions which engage on a follow-up ring behind the drive shield.A platform is supported by the frame within the shield and carries some form of working appliance for detaching and removing the debris material. The platform also carries a rotatable concrete spraying device which serves to seal and secure the tunnel wall exposed when the follow-up ring is shifted up to the shield.

Abstract: A miner especially adapted for high-production mining of low-coal seams (24-36 inches thick) while providing maximum miner safety and complying with applicable federal safety regulations. One or more cutting heads rotatable about the vertical axes are provided along with electric motors for rotating the heads. The heads are mounted for reciprocal longitudinal movement along the cutting face, and hydraulic cylinders, or the like, are provided for reciprocating the heads so that they move toward each other during shearing. A paddle-type conveyor continuously (even during sumping) conveys the cut coal away from the coal face, substantially perpendicular thereto through the formed tunnel. Hydraulic rams associated with roof-supporting and anchoring means are provided for sumping the cutting heads. A curtain assembly or the like contains the dust generated during cutting to a confined area adjacent the cutting face, and an exhaust fan or fans continuously draws the dust away from the confined area.