Abstract: An electro-hydraulic control system for an underground mineral mining installation employs individual control assemblies and devices on a series of support units which are interconnected to one another and to a central control station via lines conveying electrical control signals. Manually-operable selector switches on the units enable groups of the support units to be operated in sequence at will by operating the switches of adjacent units outside the group.

Abstract: A mine roof support unit has a floor sill, a roof cap supported above the floor sill by a pair of inclined hydraulic props, and control apparatus for controlling load-bearing capacity of the props. The inclination of the props relative to the vertical increases as the props are retracted. The control apparatus comprises a pressure-relief valve for limiting the pressure of the hydraulic fluid supplied to the hydraulic props. The pressure-relief valve has a closure member which is biased towards its closed position by a spring. The spring is backed by an abutment member which constitutes a setting device for adjusting the biasing force of the spring, thereby controlling the operating pressure of the pressure-relief valve, and hence the load-bearing capacity of the props.

Abstract: A roof support unit for a longwall mineral mining installation has a roof shield supported above a floor sill. A first hydraulic ram is provided for advancing the roof support unit. The roof shield is provided with a forward extension which is advanceable by means of a second hydraulic advance ram. A hydraulic control arrangement, which includes the two hydraulic advance rams is provided for controlling the advance of the roof shield extension in dependence upon the working stroke of the first hydraulic advance ram. The control arrangement is such that the amount of hydraulic fluid supplied to one of the pressure chambers of the second hydraulic advance ram is dependent upon the amount of hydraulic fluid expelled from one of the pressure chambers of the first hydraulic advance ram during the working stroke of the first hydraulic advance ram.

Abstract: A longwall mineral mining installation has a conveyor and a plurality of roof support units positioned side-by-side on the goaf side of the conveyor. Each roof support unit has a roof shield having an advanceable shield extension. Each unit has a first hydraulic ram for extending its shield extension, and a second hydraulic ram for advancing the conveyor. The extension of each first ram is controlled in dependence upon the retraction of one of the second rams (either the second ram of the same unit or that of an adjacent unit). This control is effected by controlling the supply of pressurized hydraulic fluid to the first rams. In one embodiment this is carried out by a control valve which has a spring-loaded plunger which engages with a series of equispaced cams on the movable cylinder of the associated second ram. In another embodiment, the piston rods of the rams are provided with series of equispaced magnets.

Abstract: A mine roof support has hydraulic props mounted between a floor sill and a roof bar which can be raised and lowered by extension and retraction of the props. A goaf shield is pivotably connected to the rear of the roof bar and is linked via levers to the floor sill. A hydraulic piston and cylinder unit is connected between the roof bar and the goaf shield. Apparatus serves to prevent damage to the support components, and especially to the unit which could be extended beyond its full stroke when the props are retracted to bring the goaf shield and the roof bar more or less into alignment. The protective apparatus is composed of a compact valve device operated by a member, such as a cam, to block the props from hydraulic pressure when the goaf shield and the roof bar assume a pre-determined angular disposition. Both the valve device and its operating member are disposed in a protected position within chambers formed inside the roof bar and the goaf shield adjacent the pivot connection therebetween.

Abstract: A hydraulic control system for a mine roof support unit has a control valve assembly for controlling the hydraulic appliances of the unit, and an actuator for actuating the control valve assembly. The actuator has a valve block provided with a plurality of pairs of spool valves. The spool valves of each pair are detachably fixed in a pair of generally parallel bores formed in the valve block. Each pair of spool valves is provided with a respective rocker arm for actuating purposes. Each of the rocker arms is mounted on a respective cover plate, which covers the mouths of the corresponding pair of bores, and which is detachably secured to the valve block.

Abstract: A hydraulic control system serves to control the operation of hydraulic rams used to position and displace an annular member which delimits a concrete reception space disposed at the rear of a tunnel-driving apparatus. The system acts to compensate for irregular loading on the annular member to ensure the latter is drawn up behind a forward drive shield without twisting or tilting. The rams are divided into groups each connectible to its own pump unit and the system connects the chambers of the rams which reduce in volume as the member is drawn up to the pump units in a manner such that the latter act as brake motors to restrain the member against the concrete pressure differential on its rear side.

Abstract: A hydraulic control system, particularly for controlling the operation of roof support props of a mine working, employs control devices operated manually to feed pressure fluid to the working chambers of the props to effect extension or retraction thereof. A two-state valve device is operated when the props are extended to ensure that the correct setting pressure is established. This valve device has a control piston which is actuated to cause the device to establish independent connection between the main fluid pressure line and the associated working chambers of the props charged with fluid by the initial operation of the control devices. The connection established by the valve device is maintained even if the control devices break connection between the chambers and the pressure line. When the correct setting pressure is reached, a further control piston of the valve device is actuated to break the connection established by the valve device ready for the next operative cycle.

Abstract: A hydraulic coupling device for connection to a multi-line hose including a plurality of hydraulic conduits bunched together comprises a casing, a plurality of plug pins housed within the casing, and a holder for holding the plug pins. The plug pins are each connectible to a respective conduit of the multi-line hose. Each of the plug pins has a circumferential groove, and the thickness of the holder is greater than the width of the circumferential grooves in the plug pins. The plug pins are held in radial slots in the holder, the radial slots being so shaped as to retain the plug pins against axial movement with respect to the holder.

Abstract: A control unit/hydraulic control mechanism for controlling the hydraulic working appliances of a mine roof support unit has a control unit mounted on one side of a distributor plate, and a valve block mounted on the other side of the distributor plate. The distributor plate and the valve block constitute the hydraulic control mechanism, the valve block being constituted by a stack of pilot-operated hydraulic control valves. The control unit has a protective casing defining first and second chambers. The first chamber accomodates a plurality of electromagnetic valves. The second chamber constitutes a lead-through chamber for leading electric cables to the electromagnetic valves. The second chamber is provided with a respective socket for each of the electric cables.

Abstract: A hydraulic control system is provided for a mine roof support assembly constituted by a plurality of roof support units positioned side-by-side. The control system comprises a respective control valve assembly having a plurality of similar control valves each of which controls a respective hydraulic appliance associated with the corresponding roof support unit. Each control valve can be actuated optionally by an actuator mounted on either one of the two adjacent roof support units, or by either one of two actuating devices mounted one on each of said two adjacent roof support units. Each control valve includes two servo valves having a pair of first and second axially aligned servo-pistons which are separate and independently operable with respect to each other.

Abstract: A longwall mineral mining installation has a longwall conveyor and a plurality of roof support units positioned side-by-side at the goaf side of the conveyor. The hydraulic appliances of the roof support units, such as their hydraulic props, hydraulic advance rams and hydraulic control valves, are supplied with pressurized hydraulic fluid from hydraulic supply lines which run along the goaf side of the conveyor. A plurality of flat, plate-like intermediate members are provided at the goaf side of the conveyor. These intermediate members are formed with internal ducts for feeding the hydraulic fluid from the supply lines to the hydraulic appliances of the roof support units.

Abstract: A hydraulic coupling device hydraulically couples a multi-line hose to a connector having a plurality of sockets. The coupling device comprises a screw cap, a plurality of plug pins, housed within the screw cap, and an annular holding disc for holding the plug pins. The plug pins are each connectible to a respective line of the hose. Each plug pin is engageable within a respective socket of the connector. One of the plug pins is of a larger diameter than the other plug pins, and constitutes an alignment pin for accurately aligning all the plug pins with the corresponding sockets of the connector.

Abstract: A pressure-relief valve device, especially for use with hydraulic props, has a main hollow housing containing a guide piece with a through bore in which a cylindrical shank of a valve or piston member is received. The shank is slidable within the guide piece bore and is held, by a spring force applied to a head thereof, in a closed position. The shank has a blind axial bore leading through five, or preferably six radial borings to outlets at is periphery. An O-ring held in a groove in the wall of the guide piece bore engages on the peripheral surface of the shank. An elastic deformable thrust disc is located in the groove and contacts a wall of the groove adjacent the head of the valve member as well as the O-ring. The thrust disc serves to prevent creep of the O-ring during use whereby excess fluid pressure acts to displace the valve member against the restoring force of the spring to move the outlets of the shank of the valve member passed the O-ring to allow pressure-relief.

Abstract: A unitary hydraulic control device, especially for use with mining apparatus, has a main housing carrying replaceable individual valves arranged in bores. The valves are operated by tappets which engage on cams provided on one of three relatively rotatable coaxial parts forming a multi-part cam shaft. The rotatable parts have hand levers external to the housing permitting the parts to be partly-rotated in either direction, together or separately, to operate selected groups of valves. Each rotatable part has its own "dead man's" handle safety or restoring system which automatically return the rotatable part to a neutral position upon release of its hand lever and after part-rotation in either direction. Each such system is composed of a pair of spring-loaded plungers guided in casings fitted in the housing and engaging on diametrically-opposed cam surfaces of an additional cam on the associated rotatable cam shaft part.

Abstract: A longwall mineral mining installation has a conveyor and a plurality of roof support units positioned side-by-side on the goaf side of the conveyor. Each roof support unit has a roof shield having an advanceable shield extension. Each unit has a first hydraulic ram for extending its shield extension, and a second hydraulic ram for advancing the conveyor. The extension of each first ram is controlled in dependence upon the retraction of one of the second rams (either the second ram of the same unit or that of an adjacent unit). This control is effected by controlling the supply of pressurized hydraulic fluid to the first rams. In one embodiment this is carried out by a control valve which has a spring-loaded plunger which engages with a series of equispaced cams on the movable cylinder of the associated second ram. In another embodiment, the piston rods of the rams are provided with series of equispaced magnets.

Abstract: Hydraulic control means are provided for controlling an auxiliary shield positioned at one side of the roof shield of a mine roof support unit. The auxiliary shield is moved laterally of its roof shield by means of three hydraulic rams and the roof shield is supported by hydraulic props. The hydraulic control means comprises a control valve device and two pilot check valves. One pilot check valve is positioned in a line leading from the control valve device to two hydraulic rams which act in tandem. The other pilot check valve is positioned in a line leading from the control valve device to the other hydraulic ram. The pilot check valves are actuated in dependence upon the pressurization of the hydraulic props whereby the hydraulic rams are depressurised when the props are pressurized and vice versa.

Abstract: A hydraulic coupling device for a multi-line hose comprises a screw cap which houses a plurality of plug pins. The hose has a plurality of hydraulic lines bunched together within a flexible sheath. The hose is connected to the coupling device by means of a sleeve, and the lines are connected to the plug pins. Each of the plug pins has a collar. The collars are held against an apertured holding disc by abutment faces formed respectively on a retainer disc and the sleeve. The plug pins are mounted so as to have a predetermined amount of axial and radial play.

Abstract: A valve device for pressure-relief of, e.g., hydraulic props of mine equipment, has a main hollow housing into which a guide is in screw threaded engagement for adjustment purposes. The guide has a through bore which slidably receives the cylindrical stem of a valve member. The valve member has a domed head with a stop face held against an inner end face of the guide by means of a compression spring located in the housing and bearing on a thrust bushing guided and located on the head of the valve member. The stem of the valve member has a blind axial bore leading to frusto-conical outlets at its periphery via radial borings. The axial bore in the stem receives pressure fluid to be controlled via the guide bore. A sealing ring held in a groove in the guide bore engages on the periphery of the stem of the valve member.

Abstract: In a mine installation which employs a winning machine moved back and forth along a guide in a working and coupled via shifting rams to roof supports, the invention provides a hydraulic fluid supply conduit system for supplying the pressure fluid for operating the shifting rams and the props of the roof supports. The system employs a first conduit containing fluid at a pressure of 300 to 400 bars for setting the props of the roof supports, a second conduit containing fluid at a pressure of 100 to 200 bars for use as a robbing aid during retraction of the props, a third conduit containing fluid at a pressure of 100 to 200 bars for operating the shifting rams and a common fluid return conduit. The conduits are laid along the working and the first and the second or third conduits are fed by separate pumps in a heading or gallery while the third or second conduit is connected via a pressure-reducing valve to the pump feeding the first conduit.