Abstract: A shaking control unit for a hydraulic cylinder, wherein a first predetermined pressure is admitted to the piston space of the cylinder through a first hydraulic line. A three/two-way valve connects in its zero position a second hydraulic line to a return tank, the second hydraulic line being connected to the first hydraulic line through a check valve. A first control line leads from the first hydraulic line to a first control area of the three/two-way valve. A second control line leads from the second hydraulic line to a second control area of the three/two-way valve. The three/two-way valve is constructed in such a way that, when the pressure in the first hydraulic line reaches a second predetermined pressure which is greater than the first predetermined pressure, the three/two-way valve switches and connects the first hydraulic line to the second hydraulic line. If the piston of the hydraulic cylinder meets an obstacle, the pressure in the first hydraulic line rises above a certain limit value.

Abstract: A shaking control unit for a hydraulic cylinder, wherein a first predetermined pressure is admitted to the piston space of the cylinder through a first hydraulic line. A three/two-way valve connects in its zero position a second hydraulic line to a return tank, the second hydraulic line being connected to the first hydraulic line through a check valve. A first control line leads from the first hydraulic line to a first control area of the three/two-way valve. A second control line leads from the second hydraulic line to a second control area of the three/two-way valve. The three/two-way valve is constructed in such a way that, when the pressure in the first hydraulic line reaches a second predetermined pressure which is greater than the first predetermined pressure, the three/two-way valve switches and connects the first hydraulic line to the second hydraulic line. If the piston of the hydraulic cylinder meets an obstacle, the pressure in the first hydraulic line rises above a certain limit value.

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: 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 apparatus for removing stratified outcropped minerals and for transporting these minerals parallel to the mining face or breast comprises a digging portion and a conveyor portion as well as a chain conveyor guided positively in them with digging tools and carrier members. The digging portion and the conveyor portion are assembled together from a plurality of pan-like members. Each pan of the conveyor portion comprises a conveying trough made from two guide pieces which are mirror images of each other attached to a base plate and from two identical bent plates. The guide pieces engage in members in the bent plates and are clamped with them by clamping plates on the top side of the bent plates. The digging portion has a guide piece indentical with the guide piece of the conveyor portion. A basin-like plate of the digging portion is pivotably mounted by a welded substantially circular cross section strip on the breast wall side of the conveyor portion.

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: An adustable cap unit for a mine support frame including a main cap, an adjustable cap connected to the main cap with a hinge-type connection, an adjusting cylinder mechanism extending within the widths of the main cap and the adjustable cap, and a guide for guiding a portion of the adjusting cylinder mechanism in a restrictive manner. The adjusting cylinder mechanism is provided either in the main cap or in the adjustable cap and an end portion of the adjusting cylinder mechanism is hinged to a bearing member provided at the bottom edges of the main cap or the adjustable cap adjacent the hinge-type connection. The adjustable cap unit can be used in extremely small seam thicknesses of as little as approximately 500 mm, while the contact pressure available at the front end of the adjustable cap is sufficient.

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

Abstract: In a hydraulically operated unit, particularly a prop for a support in an underground excavation, a thin-walled tubular jacket is pressed on an inner element which is movable in an outer tubular element so that the tubular jacket has an inner diameter which is determined with a substantial undersizing relative to the outer diameter of the inner element, and the tubular jacket is clamped on the inner element with exceeding of the flow limit of the inner element and only in a plastic expansion condition which exceeds with a reliable distance and elastic deformation region of the tubular jacket and with a sufficient residual springing part.

Abstract: A method of and an arrangement for loosening, loading and transporting of stratified minerals includes a single continuously rotating and forceably guided pulling organ, a plurality of loosening elements integrated in the pulling organ in its working run extending in a longitudinal direction of a longwall, and a plurality of transporting elements also integrated in the same single pulling organ at its transporting run located behind the working run at a back filling side, wherein the loosening elements perform loosening and loading functions, whereas the transporting elements perform the transporting functions in an opposite longitudinal direction of the longwall.

Abstract: An arrangement for supplying consumers, particularly mobile consumers, with pressure fluids such as pressure air or pressure liquid, particularly in underground excavations, has a composite rail track for guiding a pressure fluid, a plurality of nipples arranged at a predetermined distance from one another in the longitudinal direction of the rail track, and at least one fluid withdrawing unit which cooperates with the nipples to open the latter and has a length selected with respect to the distance between two neighboring nipples so that one nipple is always located in the effective region of the withdrawing unit to be opened by the latter.

Abstract: A hydraulic control arrangement for providing synchronism of a return cylinder between a face conveyor and a support, has a pushing cylinder which displaces the support transverse to a face, a control valve, a control cylinder influencing loading of the pushing cylinder via the control valve, and a control column provided between the return cylinder and the control cylinder and composed of a working fluid.