Abstract: The control device is adapted to be inserted between the control valves of a pilot device and the pressure-medium consumers (hydraulic prop and hydraulic working cylinder) in an hydraulic self-advancing mine-roof support and is connected to a pressure-medium line and to a return line. The control device comprises a valve block with continuous longitudinal bores for connection to a multiple tubing line leading to the pilot device, the valve block having bores for receiving piloted 3/2-way valves and bores for connection to the directly-controlled working cylinders of the mine-roof support.

Abstract: In a method of mining coal seams using a ploughing cutter, a longwall conveyor extending along the coal face is moved forwards by the extension of self-advancing cylinders, the advance being controlled in dependence on a piston stroke of a respective self-advancing cylinder and being made in individual defined partial strokes using travel-measuring signals generated at each partial stroke. The distance covered by the partial strokes corresponds to the preset depth of cutting and is increased by an amount sufficient to compensate an average mechanical clearance at the pivot points of the self-advancing cylinders. In addition, a defined face line is fixed with respect to a center of rotation on the side of a main or auxiliary drive of the cutter so as to form a straight line through the center of rotation, the straight line being pivoted through an angle <90.degree. so that a circular segment is mined.

Abstract: A hydropneumatic suspension system for motor vehicles. The system contains at least one piston cylinder unit (202) including a cylinder (212) and a piston (214) cooperating with a spring storage system (204, 206) containing a compressible medium, where a hydraulic pressure (p.sub.3, p.sub.4) of the piston cylinder unit (202) acts against a pneumatic pressure (p.sub.1, p.sub.2) of the spring storage system. The pneumatic pressures are smaller than the respective hydraulic pressures. In a preferred embodiment, the piston (214) of the piston cylinder unit divides two pressure spaces (228, 230) whose volumes are varied in opposite directions, where the two pressure spaces are hydraulically separated from each other and are each connected to a separate spring storage system (204, 206).

Abstract: A device for closing an injection mould and comprising a first, stationary mould-part holder, a second mould-part holder movably guided relative to the first holder, and at least one pressure medium-actuated closing cylinder arrangement connected to the mould-part holders, wherein the closing-cylinder arrangement is pivotably connected at least to the movably guided second mould-part carrier.

Abstract: A control system for longwall face support frames as used in mines, the system comprising pushing rams which are adapted to be actuated at two different pressures (for example, a low pressure of about 70 to 120 bar for non-defined cutting and a high pressure of 120 to 350 bar for defined cutting) with each pushing ram being individually actuatable by a respective non-return valve arrangement, the pushing rams being connected by a common pressure line to an hydraulic pressure unit.

Abstract: The invention pertains to a damping valve(1), especially for hydraulic media in damping systems, such as shock or vibration damping systems and the like, with at least one throttling channel (38) equipped with a valve element for damping adjustment. The valve element at least partially covers the outlet mouth (40) of the throttling channel (38) and is designed as a leaf-spring element (42) clamped at one end, while the damping adjustment is accomplished by varying the length (1) of the free end of the leaf of the leaf-spring element (42).

Abstract: An intrinsically safe power supply unit, more particularly for face supports in mining, comprising an ac transformer connected to a rectifier and power resistors for limiting the current and connected to the dc voltage output, wherein the ac voltage transformer is a resonance transformer which stabilizes the secondary voltage, and the dc voltage occurring behind the power resistors is kept constant by three voltage limiters connected in parallel.

Abstract: A control means for hydraulic self-advancing support units for underground working, comprising at least one electrohydraulic control device comprising an electric circuit for energizing electromagnets which actuate hydraulic valves, a command keyboard connected to the energizing circuit, a display connected to the energizing circuit and two multipole connectors for connecting the control device to respective adjacent devices, the multipole connectors being connected to one another and to the energizing circuit by electric lines inside the control device, characterized in that the energizing circuit is substantially made up of a CPU control sub-assembly, a keyboard and display sub-assembly, and a magnet control sub-assembly, these sub-assemblies being interconnected by a common bus line, the line connection between the plug-in connectors comprises at least one flexible printed circuit board connected by at least one ribbon cross-connection to one of the three sub-assemblies, and the magnet control sub-assembly

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 pressure-control valve is connected to a working cylinder of an hydraulic, walking, mine roof support on one side of the piston in the cylinder. In its function as a pressure-limiting valve, it regulates the pressure in the working cylinder in dependence upon a predetermined pressure in a control conduit which is connected to the pressure chamber of a prop of the mine roof support. Through it a spring-loaded control piston of the pressure-control valve is hydraulically loaded so as to act on a spring-loaded valve closure member in the pressure-control valve. The control piston holds the valve-closure member in the closure position if the pressure in the control conduit exceeds the predetermined pressure. If the pressure in the control conduit drops off, the valve-closure member then regulates the pressure in the working cylinder to a comparatively low value.

Abstract: A change-over valve for hydraulic walking mine-roof supports comprises a valve housing containing a sealed-off operating piston in which a valve member supported on a helical spring is displaceably arranged, the piston being responsive to the supply of small quantities of hydraulic fluid through an end connection in the housing and having a sealing cone adapted to close a connection of large throughflow cross-section at the opposite end of the housing which also has a side connection for the supply of pressurized fluid to a working cylinder of a mine-roof support, the large throughflow cross-section at the connection thereby guaranteeing brisk pushing-in of a piston rod of a piston in the cylinder.

Abstract: A mobile mine-roof support comprises a powered track-laying carriage having a carrier shaft extending longitudinally of the carriage between its tracks, the end portions of the carrier shaft being arranged to support mountings of bracket form for props supporting a roof beam which is stabilized by a lemniscate guide linkage the floorward links of which ar articulated to an attachment part or extension of one of the prop mountings, with stabilization of the laterally-pivotable props being effected by an orienting cylinder supported on the chassis.

Abstract: Valves regulating the supply of hydraulic fluid to hydraulic cylinders of an hydraulic walking mine-roof support are controlled by apparatus comprising an axially-movable switching shaft provided with cams which is rotatable into successive switching stations where it is immobilized by spring-loaded stop pins to that the cams bear on tappets to actuate the respective valves, there being a switching spring acting on the shaft to return the shaft to its initial position of rest after it has been axially displaced and rotated out of that position of rest.

Abstract: A video terminal has a housing composed of a basic housing encompassing a back portion of a picture tube and a frame encompassing a picture area of the tube. The basic housing is uniformly designed for a plurality of picture tubes of different sizes and variously designed frames are adapted to the basic housing in accordance with a respective picture tube. The frames are preferably secured to support mounts fixed to the frame which are disposed in said basic housing. Given an axially symmetrical design of said support mounts, the frame with said picture tube is optionally insertable either horizontally or vertically. The frame can be formed of one or more parts. The parts of the frame and/or of the frames and the basic housing can be connected to one another by snap-in closures.

Abstract: A pressure-limiting valve comprises a cylindrical actuator piston guided displaceably in a bore and held under the pressure of a spring in the closure position of the valve. Longitudinally-directed throughflow passages are formed in the actuator piston on the pressure-loaded end and are arranged concentrically with respect to the central axis and open into an annular groove extending around and in the circumferential surface of the actuator piston. This groove is sealed off by a gasket mounted in the bore wall. When the set pressure predetermined by the closure spring is exceeded, the actuator piston travels with the gasket over the annular groove so that the pressure medium can flow away through the outlet opening.

Abstract: An hydraulically-controlled non-return valve for the hydraulic cylinders of a walking mine-roof support is provided with a cylindrical valve-closing member which is spring-loaded in the closing direction and is guided in a valve case in a valve housing, the valve-closing member being sealed off therein by means of a seal. A space on one face of the valve-closing member is connected to a circulating duct by way of a stepped bore in the valve case, which bore contains a spring-loaded throttle member having through-flow bores of which one has a throttle-like reduced cross-section. During setting of the hydraulic cylinder pressurized fluid flows past the opened valve-closing member through inclined bores and, by way of the circulating duct, to the stroke space of the hydraulic cylinder. During retraction of the hydraulic cylinder, a control piston in the non-return valve is loaded at the same time as an annular space in the hydraulic cylinder.

Abstract: A pressure-limiting valve for hydraulic fluids comprises a stepped switching piston which is loaded by a closing spring to oppose high fluid pressure obtaining in an inflow duct of the valve. Radial transverse bores branch from an axially-extending bore in the switching piston. When the setting pressure established by the closing spring is exceeded, the transverse bores in the piston move past an O-ring seal as the piston compresses the spring, and pressure fluid thus flows from the axially-extending bore into a discharge duct of the valve. The stepped switching piston is guided in a pressure chamber by a portion of its cross-section which is greater than that in the zone of the O-ring seal. Adjacent the inflow duct, the axially-extending bore in the piston has a reduced flow cross-section. Further radial bores lead from the axially-extending bore in the piston in the region of the stepped portion of the latter.

Abstract: A rotating drum-shaped cylinder block with pistons longitudinally displaceable in the cylinder bores is mounted in the housing of a reciprocating-piston pump of inclined-disc construction. The cylinder block is fitted on the free end of a rotating driving shaft which, in a median zone along its length, is mounted on two roller bearings in a bearing box which is completely sealed off from the machine housing. The pistons are supported in piston shoes on a stationary inclined disc the inclined position of which can be adjusted in the machine housing. For the purpose of sealing off the machine housing from the bearing box, there are slide-ring sealing means composed of a rotating ring secured to the driving shaft and of a stationary ring in the machine housing.

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 control device for the sequential control of an advancing mine-roof support comprising pressure-controlled directional control valves alternately connectable to a high pressure line and to a return line in order to convert a pressure pulse into a switching step at the main control unit of the advancing mine-roof support and for transmitting an answering pressure pulse signalling the completion of the workstage for continuing the sequence.