Abstract: A check valve arrangement for a hydraulic consumer which permits connecting the hydraulic consumer selectively to a medium pressure line or a high pressure line. The valve arrangement comprises a medium pressure switching valve 10, a high pressure switching valve 14, and a check valve 6 downstream of these valves. The check valve 6 is constructed as a combined sliding and seat valve and comprises control surfaces 28, 29, 38 for the medium pressure P1, the high pressure P2, and the pressure applied to a consumer line 5, i.e., the pressure applied to the hydraulic consumer. The control surfaces are dimensioned such that a connection of the hydraulic consumer to the high pressure line can occur only when a predetermined limit pressure is reached in the hydraulic consumer.

Abstract: A hydraulic pressure sensor for measuring the pressure in a hydraulic pressure chamber 1. A reservoir housing 9 is connected to the pressure chamber, and the interior of the housing is divided by a slideable partition 13 which defines a reservoir chamber 8 which is connected to the pressure chamber and a sensor chamber 7 which is connected to a sensor element 5. The partition 13 is constructed as a piston and extends for sliding movement along the walls of the reservoir housing while exerting a frictional force. A spring 11 supports the partition relative to the reservoir housing against the pressure in the reservoir chamber 8. The partition 13 may be constructed as a differential piston, and consist of two or more piston sections 13.1, 13.2, 13.3, which extend independently of one another in a sliding and sealing manner, and mutually support one another by an intermediate spring 14.

Abstract: For an explosion-proof connection of two electric line ends (25, 26), the contact elements (27, 28) are accommodated in two tubes (1, 2), which can be joined in an explosion-proof manner. Each of the plug-in contact parts is axially secured in its tube by a radial projection (41) in the direction toward the end facing the other tube. At its line end, each of the tubes is closed by an end cap (42), which sealingly surrounds with a narrow outlet (44) the electric lines, including an insulation (43). The tube, in which the plug-in contact part with the contact pins is axially secured, extends beyond the tip of the contact pins, and has there an enlarged diameter, with which it surrounds the other tube (inner tube 1,3) with a narrow cylindrical gap (sealing gap 20).

Abstract: A machine control system for a machine or plant controls a plurality of functions within an operating cycle. The start signals and stop signals for releasing and ending respectively the function can be preselected with respect to their mutual relative time slot by means of a data processor (computer) with a display screen. To this end, the functions of the machine or plant are listed in parallel lines on the display screen. Each of the functions can be represented in a graphic quantifying the duration of the function by inputting display screen signals with the limits, which correspond to the times of connection (start limit) and disconnection (stop limit) of the respective function. After starting up the operating cycle, the display screen signals are scanned by a switching signal, which advances in time in the direction from the start limit to the stop limit.

Abstract: A longwall control system controls a longwall support and facilitates the remote inspection of the longwall support. The longwall support comprises a plurality of hydraulically operated supports. The longwall control system comprises a plurality of shield control devices respectively associated with the supports for rearranging the supports in the sense of robbing, advancing, and setting. The longwall control system further comprises detection devices for detecting inspection values associated with the operating parameters of the shield control devices. The longwall control system also comprises a hand-operated device. The hand-operated devices comprises signaling devices, such as a readout or display. Long-distance transmission devices transmit the detected inspection values from the detection devices to the hand-operated device, and the signaling devices provide signals representative of the transmitted inspection values.

Abstract: In a control system for the longwall support with a plurality of hydraulically actuated supports (mining shields), which are each automatically rearranged in the sense of robbing, advancing, and setting as a function of the position of the mining machine (coal cutter or plow), the position of the mining machine is automatically signaled to the mining shield control system. To this end, the mining machine is equipped with a position signaler. A microprocessor (31), which receives the signals of the position signaler, converts the signals into position signals and/or signals of the direction of movement. A radio set (32) transmits the position signals and/or signals of the direction of movement to radio receivers (33), which are distributed over the mining section and connected to the mining shield control system (34) for converting the position signals and/or signals of the direction of movement into signals for rearranging the mining shields (longwall support devices 1-18).

Abstract: A hydraulic seat and holding valve for hydraulically controlling and holding a hydraulic load in a leakproof manner comprises a seat pairing, whose valve cone, which is part of the piston, is capable of adapting itself to the conical valve seat. To this end, the valve piston is supported for pivoting relative to the valve seat. The cone angles of the valve cone and the valve seat are different.

Abstract: A mining control system for adjusting the advance of the working tools of a mining machine with respect to working depth and/or working height connects to a detection device that is for recognizing the rock being mined and is carried along by the mining machine. A central command station connects by radio to the detection device of the mining machine. The mining control system comprises a plurality of radio receivers arranged in spaced relationship along the longwall, as well as a comparator, which is used for comparing the intensity of the radio signals received by the individual radio receivers and for retransmitting only the strongest of the radio signals to the central command station for generating the command signals for controlling the advance of the mining tools. It is also possible to transmit the radio signals received by each radio receiver to adjacent radio receivers. A separate comparator is associated to and controls each radio receiver.

Abstract: The hydraulic multiway valve comprises a control piston (main piston 3), which is displaceable against the force of a spring (main spring 18) by the plunger of a magnet (12) from its first position (closing position) to its second position (opening position). In the closing position, a pressure chamber (7) with a pump connection (P) is closed toward a consumer chamber (8), and the consumer chamber with a consumer (A) is opened toward a return flow chamber (20) and a reservoir connection (R). In the opening position, the consumer chamber (8) is closed toward the return flow chamber (20). To this end, the consumer chamber (8) and the return flow chamber (20) are arranged at the opposite ends of the main piston (3), namely the consumer chamber (8) on the side facing the magnet, and the return flow chamber (20) on the side facing away therefrom. A central channel (21) extends through the main piston. The central channel interconnects the consumer chamber (8) and the return flow chamber (20).