Abstract: A multipole connector in the form of a sealed lead-through for fitting through a wall of a casing of a control device used for underground working, comprising a contact-holder secured via securing parts in sealing-tight manner in an opening in the wall and having a number of contact chambers extending through the contact holder parallel to one another in the direction of the longitudinal axis of the connector, each contact chamber containing contact elements which have connecting pieces which project outwards from one side of the contact holder for the purpose of making connections, characterized in that the connecting pieces of the contact elements comprise parallel soldering taps.

Abstract: A method of electro-hydraulic control of the cutting and self-advancing mine-roof support units in an automated longwall is carried out in dependence on the measured lengths to which the rams pushing the support are extended, with extraction by the cutter occurring in long cuts extending over almost the entire length of the longwall. After each extraction cut, the conveyor is advanced by an amount equal to the depth to which the cutter has cut, and the process of advancing each group is triggered in dependence on the length to which the pushing rams have been extended. The self-advancing roof-support units inserted in the longwall are divided into groups which, depending on the respective state of operation, are moved forward individually and successively, in each case by a preset extension length of the pushing rams.

Abstract: A 3-port, 2-position, directional control valve has two cylindrical closure elements for the alternate connection of a control line to a return flow line and a high pressure line. The switching force exerted on a thrust member is transmitted via pressure pins, and a manifold member with a centrally-positioned axial bore connected to the control line is arranged between the closure elements. Sealing elements on the closure elements seal the exit openings of the bore in the manifold member alternately. One of the pressure pins extends through the manifold member eccentrically while extending parallel to the axial bore and is always under pressure, like the high-pressure-side closure element, so that the closure element on the low pressure side is always held open in the zero position of the valve while the closure element on the high pressure side is acted on by the pressure medium in the direction of closure.

Abstract: A self-advancing mine roof support has a beam-like abutment adapted to be disposed generally adjacent and parallel to a work face. Three roof support elements are spaced apart along the abutment and are pivoted to the abutment. The abutment may be angled relative to the direction of advance by arranging the three support elements in staggered formation. A beam of the central support element is pivoted to the abutment. The two outer roof support elements are connected to the abutment by a linkage, e.g., guide arms, which allows the abutment to pivot about the beam of the central element without changing the distance between the three elements as measured at right angles to the direction of advance.

Abstract: The invention is concerned with apparatus for maintaining a set "between-centers" distance between the elements of self-advancing mine-roof supporting means for long-wall mining, the support means having at least two elements connected via connecting means so that they can pivot to a limited extent with respect to an abutment which, in use, extends substantially parallel to the long-wall face, the connecting means of at least one element being constructed as a drive means, in which the portions of the abutment connected to the respective connecting means are interconnected so that their length can be varied, and a guide lever is pivoted to the connecting means of at least one element and to an abutment portion connected to an adjacent element so that the two places at which the lever is pivoted and the place at which the connecting means of the first-mentioned element are connected to the abutment lie at the corners of a triangle.

Abstract: A multiple valve control device is suspended by means of a chain or other flexible supporting means such as a cable from a rod or bar carried on a walking mine-roof support frame, the chain or other flexible supporting means being movable with and/or along the rod or bar and being adjustably hooked or otherwise releasably fastened in any one of a line of recesses in a balance beam secured to the control device.

Abstract: A mine roof-supporting arrangement comprising a series of assemblies each comprising a cross beam, three shield-type roof-supporting units, and a pair of rams, a center one of said three units being directly secured to the cross beam, and the other two (i.e. outer) units being secured to the cross beam via respective ones of said rams so that each outer unit may be aligned with or trail behind its corresponding center unit depending upon the position of its respective ram, wherein each assembly is arranged (in the normal roof-supporting position of the assemblies) with that one of its outer units which is adjacent a next trailing assembly being so disposed as to trail behind its corresponding center unit and the other outer unit whereby to protect from waste the adjacent outer unit of said next trailing assembly.