Abstract: A drive unit for a mining machine such as a mining plow or conveyor drives a sprocket wheel of the chain thereof by an electric motor through a drive train having a turbocoupling and a transmission driven by the motor. A free-shifting clutch is provided in the case of overload to disconnect the load from the motor, the clutch reengaging upon standstill of the two clutch halves. Alternatively the turbine output of the fluid coupling is branched and is applied through one friction clutch directly to the input shaft of the transmission or through a second friction clutch to a parallel shaft connected by gearing to the transmission input shaft.

Abstract: A mining machine for excavating coal along a coal front of a seam in which a chain displaces excavating tools along an excavating stretch at a leading side across the coal face and a conveying stretch is provided rearwardly thereof, the stretch terminating in direction reversal stations with wheels at opposite ends of the stretches. A linear drive for at least one of the wheels can extend in a gallery alongside the mined cut. According to the invention, the excavating conveyer bottom is at an angular of 70.degree. to 130.degree. to the bottom of the conveying trough and the shafts of the wheels are inclined to the vertical forwardly and upwardly to include angles of 10.degree. to 45.degree..

Abstract: A mining machine especially for seam mining as in the mining of coal has a sensor for incipient sag of the plow pass of the continuously driven endless chain and a computer to which the sensor is connected and which controls the conveyor drive at the upstream end of the plow pass and the downstream end of a conveyor pass to reduce the speed of this drive until the plow pass is retensioned and any sag is accumulated at the conveyor pass. This arrangement eliminates problems with dislocation of the mining plow or of the conveyor flights as they are guided by guide devices onto the plow trough at the upstream end of the plow pass.

Abstract: A long-wall mining machine has an operating chain entraining conveyor flights or mining tools and displaceable in a trough which can be provided with rows of sensors of an inductive proximity type responding to the chain and the tools and generating measurement pulse trains which are compared with setpoint pulse trains to signal functional parameters of chain operation. The sag of the chain is determined by a row of sensors and in response to the sag a chain-tension unit can be controlled.

Abstract: In a longwall mining operation wherein a takeoff shaft provided with a takeoff conveyor and an access shaft extend crosswise from a longitudinally extending face, a material recovering and conveying system has a chain itself having a longitudinally extending rear stretch extending along the face from a turnaround in the access shaft to a turnaround in the takeoff shaft and a longitudinally extending front stretch extending along the face between the rear stretch and the face. An undriven idler wheel is provided in the takeoff-shaft turnaround over which the chain is engaged between its stretches and a conveyor trough extends between the turnarounds and has a floor formed in the takeoff shaft with a throughgoing outlet hole above the takeoff conveyor. Conveyor/cutting elements on the chain move in the front stretch along the face and in the rear stretch along the trough.

Abstract: A long-wall mining apparatus has a conveyor trough extending longitudinally from a turnaround adjacent a longitudinal face from which material is to be cut, a pair of longitudinally extending and generally parallel rear guide rails extending along and flanking the conveyor, a pair of longitudinally extending and generally parallel front guide rails extending along the face between the conveyor trough and the face, and a longitudinally fixed anchor bollard in the turnaround provided with upper and lower guide rails each connecting a respective one of the front guide rails to a respective one of the rear guide rails. A drive wheel in the bollard rotates about an upright axis and has an outer periphery exposed between the bollard guide rails. A chain having front and rear stretches respectively running along the guide rails is engaged in the turnaround with the periphery of the drive wheel.

Abstract: The advance of a mining front in longwall mining is effected by a process in which sensors measure the displacement of displacement cylinders coupling the linked prop elements to the linked conveyor elements with their respective cutters. A computer generates a baseline represented by the actual prop line as a starting point and the conveyor elements and cutters are then advanced all along the mining front via the displacement cylinders. The sensors input the respective displacements into the computer so that an actual conveyor line is determined in the computer and serves as the baseline for after-drawing of the prop elements via the cylinders. The new prop line calculated by the computer then forms the baseline for further advance and the advance can be controlled to ultimately align the conveyor elements along the conveyor line corresponding to a setpoint line defined by the computer and parallel to the original baseline.

Abstract: The pressure measuring device has a housing in which a pressure chamber is located in a pin extending freely in the interior of the housing from a base. The pressure chamber wall is deformable elastically under an applied pressure. In the free end portion of the pin a magnetoresistive sensor is mounted which is moved with the chamber wall in a displacement occurring because of pressure changes in the chamber and thus is displaced relative to a permanent magnet. The magnet is mounted slightly transversely in the end portion of a compensating sleeve which surrounds the pin with wall contact. The change of the magnetic field at the sensor on displacement causes a proportional resistance change of the sensor so that an electrical signal proportional to the pressure change is generated which is a measure of the pressure. An amplifier for the signal from the magnetoresistive sensor can be mounted inside the housing adjacent the permanent magnet or the magnetoresistive sensor.

Abstract: An apparatus for the contactless measurement of geometrical dimensions includes a light source emitting a light beam, a first deflector deflecting the light beam at an angle toward an object to be measured, a receiver receiving the light beam and a second deflector for deflecting the light beam reflected by the object toward the receiver. The second deflector rotates about an axis extending perpendicularly to the light beam reflected by the object. The axis of the light beam emitted by the light source extends parallel to the axis of rotation of the second deflector. The light beam conducted to the receiver extends coaxially to the axis or rotation of the second deflector. This apparatus requires no calibration, but only an adjustment. For measuring a distance it is sufficient if only the second deflector rotates. If both deflectors rotate, the second deflector must rotate at a substantially higher rate of rotation than the first deflector. The first deflector is vertically adjustable and lockable.

Abstract: A shut-off valve has a sealing cone which in a closed position of the valve abuts against a conical sealing seat and is formed as a part of a cylindrical throttling piston, a sealing surface of the sealing seat cooperates at its one end with a cylindrical receiving opening for the throttling piston, and the outer diameter of the throttling piston is selected with respect to the inner diameter of the receiving opening so that a throttling gap is formed between the receiving opening and the the throttling piston.

Abstract: A cutting tool has a cutting edge for cutting into a surface of material to be mined so that fissures develop in the region of the bottom of the cut. The cutting tool is provided with apertures adjacent said cutting edge. High pressure fluid medium jets are directed through the apertures in the cutting tool adjacent the cutting edge thereof and against the bottom of the cut so that such jets can enter into the fissures.

Abstract: An arrangement for discharging liquid medium under a high pressure from a feed pipe having a tubular end portion, includes a jet support with a jet. The jet support is installed inside the tubular end portion of the feed pipe. The jet support has an inlet, an outlet and passages which connect the inlet to the outlet and are so formed and shaped as to increase the pressure of the liquid medium as the same exits the arrangement through the outlet. The jet support is screwed into the tubular end portion of the feed pipe and sealingly connected thereto.

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.