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: 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: 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).

Abstract: A cutting machine for mining minerals from a seam thereof, the machine executing reciprocal movements parallel to the face of the seam and being provided with switches for generating signals indicative of the direction of movement of the machine for controlling the removal of protective bumpers on support structures located forwardly of the machine and for moving support structures against the face of the seam and relocating bumpers rearwardly of the machine.

Abstract: An electro-hydraulic control system for a mineral mining installation has a plurality of control units (4) sub-divided into operational groups (I, II, III) with associated roof supports. Each group has its own power source (5) and power at an intrinsically safe level is provided to each of the groups independently of and in isolation from the other groups. The control units (4) are interconnected via a system data bus (13,14) in the form of conductors of multi-core cables which also carry the electrical power. A further data bus (20) independent of the system bus (13,14) is coupled to some of the units of the groups.

Abstract: An electro-hydraulic control system has a valve unit allocated to a roof support (support shield, support trestle or the like) and equipped with electromagnetic valves. The unit is controlled by a control unit via a cable which includes two current supply leads serving as a common current supply for all the electromagnetic valves and at least one data bus through which an actuator connected with the valve unit is actuated from a microprocessor of the control unit. The actuator itself consists preferably of a shift register through which all the electromagnetic valves can be actuated.

Abstract: A cable assembly for use in electro-hydraulic control systems of mineral mining installations is composed of a cable with a plurality of electrical wires encased in a multi-layered armoured sheath and connectors at the ends of the cable. The cable is bonded to sealing bodies which fit in the connectors. The connectors are one-piece components each with a sleeve for coupling to the cable and a plug which fits into a socket of a complementary connector. The sealing bodies locate in the sleeves of the connectors and the wires pass through the sealing bodies to join with contacts supported by carriers in the plugs of the connectors. A screw-threaded ring clamps the cable to the sleeve of each connector.

Abstract: The operation of an electromagnetic valve is monitored by connecting the coil of the valve to a d.c. source for a period of time sufficient to permit the current in the coil to reach its maximum steady state value then disconnecting the coil to permit the current to fall and re-connecting the coil to the source again and measuring the current which is established in the coil.

Abstract: A pressure-relief hydraulic valve device for mining equipment is composed of a hollow sleeve mounting a guide with a through bore slidably receiving the stem of a valve member. The stem is provided with a blind axial bore leading to a set of radial bores and a seal in the bore of the guide co-operates with the radial bores to form a valve. A spring accommodated in the sleeve acts through a shaped pressure member to urge the valve member to a position with the valve closed. Pressure fluid in equipment to be protected acts on the valve member and excess pressure displaces the valve member against the spring force to open the valve and permit the escape of fluid via an outflow chamber and outlets in the sleeve. The pressure member has a piston like flange guided within the sleeve against which the spring bears and the underside of the flange of the pressure member is shaped to provide a concave guide face in the outflow chamber.

Abstract: As is known mineral, e.g. coal, is won from a mineral face with the aid of a winning machine guided for movement along a conveyor composed of individual pans joined end-to-end. The conveyor is advanced towards the face behind the machine by shifting rams linked to the pans. In accordance with the invention, the rams are connected to and disconnected from a supply of pressure fluid in a controlled manner to form a group composed of a predetermined number of rams which are simultaneously charged with pressure fluid and this group progresses along the working behind the machine step-by-step in a sliding fashion within and over larger bank-push groups of rams.

Abstract: The invention relates to a method for the simultaneous actuation of a plurality of hydraulic consumers by means of intrinsically-safe electro-hydraulic valves. The consumers are connected by hydraulic directional control valves to a pressure line and/or a return line. These hydraulic directional control valves can be connected in a predetermined manner, via pre-control valves to a control line. The pre-control valves are pressureless, and possess electro-magnets with a current consumption of less than 50 milliamps. By connection of a series-connected electro-hydraulic directional control valve means, the pre-control valves are connected to the control line, and at the same time are hydraulically locked.

Abstract: A gearing unit has an input shaft coupled via a gear train and a clutch to an output shaft which can propel a drive chain for a mineral winning machine or plough.The clutch is released by hydraulic pressure and a load sensor operates a valve device to release the clutch should an excessive load occur. The response of the hydraulic system is optimised by using a special fast-switching valve device and by maintaining a certain pressure in a release chamber of the clutch by circulating pressure fluid through the valve device when the clutch connects the drive to the output shaft. This pressure is lower than that necessary to release the clutch and the valve device rapidly switches to increase the pressure should an overload occur.

Abstract: A hydraulic control device is incorporated in a hydraulic control system for a mine roof support assembly. The hydraulic control system includes a plurality of hydraulic control valves which are controlled by the hydraulic control device. The hydraulic control device is constituted by a longitudinal slide valve having a slide member longitudinally reciprocable in a slide valve housing. A rotary drive is provided for moving the slide member within the slide valve housing. The slide member is provided with two axial bores each of which opens into a respective pair of axially-spaced radial bores which terminate at the peripheral surface of the slide member. A first radial bore of each axial bore opens into a respective annular groove formed in the slide valve housing. The second radial bore of each axial bore is connected to a respective group of control ports provided on the slide valve housing.