Abstract: A positioning cylinder assembly for subterranean mining applications has a rotary potentiometer connected through a friction wheel transmission with the spindle of the cylinder which is rotated when the piston is axially displaced therein. The friction wheel assembly comprises a pinion wheel connected to the spindle and a hollow wheel connected to the rotary potentiometer, that not only matches the pitch of the spindle to the rotary spring of the potentiometer but also functions as a slip clutch for zero setting of the potentionmeter and the piston.

Abstract: A mining apparatus of the type in which a mining machine excavates a mining face, especially a coal face in a subterranean mining application, and has a plurality of emitters of electromagnetic waves of different character diverging toward receivers on the individual walking props. The walking props are provided with a control unit which, in response to leading and trailing zones of the respective magnetic beams and/or an overlap region of the two beams, causes the advance of the walking prop as the mining machine travels past it to follow the excavation of the mining face.

Abstract: The noise spectrum in a mining chamber is captured by at least one microphone and is digitized and filtered to separate an operation-typical pattern from an operation atypical pattern. The operation atypical pattern is compared with reference patterns to establish the malfunction or vocal command or emergency and the apparatus is automatically operated in response thereto.

Abstract: The pressure sensor has a mechanical pressure receiving member and a mechanical-electrical transducer connected to it. The transducer comprises a permanent magnet attached with a moving portion of the pressure receiving member which cooperates with a locally fixed Hall-effect sensor mounted on the housing. To linearize the characteristic response curve of the transducer the inner surface of the housing wall is shaped like a funnel in a region between the permenent magnet and the Hall-effect sensor and in the vicinity of the permanent magnet. Because of this geometry the field strength lines are bunched increasingly on increasing separation of the permanent magnet from the Hall-effect sensor so that the field strength at the Hall-effect sensor increases and/or decreases approximately linearly with displacement path of the magnet.

Abstract: A mining system comprises a laterally deflectable segmented conveyor extending longitudinally along a longitudinal face from which material is to be cut, a mining machine displaceable longitudinally along the conveyor and engageable with the face to cut material therefrom and deposit in the conveyor, and a longitudinal succession of support frames each having a respective actuator connected to a respective segment of the conveyor and each also having a respective a respective retractile roof-engaging flap. The process of this invention comprises bracing the frames and conveyor in a safety zone immediately adjacent the mining machine against the roof with their flaps retracted. The machine is advanced in the safety zone while cutting the face in the safety zone, and the flaps of the frames in a zone immediately downstream of the safety zone are sequentially retracted and the flaps of the frames in a zone upstream of the safety zone are sequentially advanced.

Abstract: A method in underground coal mining for separating the upper coal of the seam from the roof during the advancement of the upper sliding cap of a support frame, wherein the front edge of the cap is forced in a plane of the cap between the upper coal to be separated and the rock from which the coal is to be separated. During the advancement of the sliding cap, the sliding cap is alternatingly moved backwardly and forwardly, so that the from edge of the sliding cap separates the upper coal during its forward movement. Alternatively or additionally, when the front edge of the sliding cap contacts the upper coal, alternatingly higher and lower pressure can be admitted to the sliding cap in order to obtain a shaking effect. In this combined method, the sliding cap is advanced, the shaking procedure is carried out as the front edge contacts the upper coal, and the sliding cap is subsequently moved backwardly. The cycle is then repeated several times.

Abstract: A method of controlling a plurality of hydraulically-actuated arrangements in underground excavations, comprises the steps of providing an electrical power supply, connecting a plurality of control devices with said power supply and interconnecting the control devices with one another, arranging a plurality of current-suppliable consumers to be connected with the control devices, comparing in each of the control devices a coded information about a number of consumers which have been current supplied from the power supply with a maximum possible number of consumers which can be supplied from the power supply, determining from the comparison the number of the consumers which still can be current-supplied and obtaining by the control device a release for current supplying such consumers, adding consumers which are released by the control device and current supplied with the consumers which have been indicated in the control device as current-supplied, and further transferring the result of the addition in coded