Abstract: A coupling device is provided for connection to a plurality of hydraulic conduits which are bunched together to form a multi-core duct. The coupling device has a casing which houses a plurality of plug pins, the plug pins each being connectible to a respective one of the conduits. A holder is provided for holding the plug pins, the holder being rotatably mounted in the casing. A connector, which is formed in two detachably interconnected parts, is also provided for connection to the coupling device.

Abstract: A hydraulic control system is provided for a roof support unit of an underground mining installation. The roof support unit is provided with a roof cap supported by hydraulic props. The control system comprises a valve for controlling the supply of pressurized hydraulic fluid to the props, and an actuator for closing the valve when the props have been retracted by a predetermined amount.

Abstract: Mining apparatus comprises a longwall conveyor and tensioning means for tensioning the conveyor in its longitudinal direction. The tensioning means is constituted by a plurality of hydraulic tensioning rams, each of which is mounted, in use, by means of pivot joints at each end thereof directly between the conveyor and a respective roof support unit of a roof support assembly. Each tensioning ram extends at an acute angle to the longitudinal axis of the conveyor. The tensioning rams are positioned in two groups, one in each end zone of the conveyor.

Abstract: A multi-core duct is constituted by a plurality of resilient conduits bunched together within a protective sleeve. Each of the conduits is formed from a high-strength synthetic plastics material and the protective sleeve is made of a flame-resistant synthetic plastics material.

Abstract: A system for controlling the thrust applied to a mineral winning machine, which is movable along a guide at a longwall face in a mine working, includes control means which regulates the thrust applied to the guide by hydraulic rams in dependence upon the loading of the winning machine drive. The control means may include one pressure regulator for each ram, one pressure regulator for each of a plurality of groups of rams, or one pressure regulator for all the rams.

Abstract: A pressure-relief valve device has a housing with bores for admitting and discharging pressure fluid. The fluid admitted to the housing passes via a hollow member or sleeve to a valve inlet. The sleeve has at its upper end a chamfered seating surface for engaging with a sealing surface of a valve member and these surfaces form the valve. The valve member has a head with the sealing surface at its periphery and a stem which is guided within the sleeve. The stem is axially and circumferentially grooved to allow pressure fluid to pass through the housing to flush dirt away from the valve inlet even while the valve is closed. Opposed spring forces bias the surfaces of the valve together and a stop member limits the movement of the sleeve. The spring or springs acting on the valve member engage on a support member and this support member engages via a punctiform contact with a thrust piece.

Abstract: A mineral mining installation has a conveyor along which a winning machine such as a plough, is guided for movement back and forth along a mineral face. A series of water-spray nozzles are distributed along the working and is divided in the operational sense into different groups. Each of these groups is controlled by a valve which allows water to pass through non-return valves to one or two adjacent groups of nozzles. The control valves are in turn operated by further valves disposed remote from the actual working zone and these further valves are operated by local means separate and remote from the machine and providing signals and an indication, dependent on the distance moved by the machine and hence its position as it progresses along the face.

Abstract: Chain-tension control apparatus for use with mine installations utilizes a hydraulic multi-piston engine motor driving a reduction gearing which can be selectively coupled to a drive system for a chain or chains used in the installation. The motive fluid for the motor is derived from the main pressure fluid source supplying fluid to other components of the installation and is preferably a 2-5% oil in water emulsion supplied via a pressure-reducing device. Pipe means in the form of a siphon conveys waste fluid as an overflow back to a storage tank independently of the main flow and return lines to the motor and the pipe means provides a fluid trap to maintain a certain quantity of fluid in the motor at all times.

Abstract: A hydraulic control system for use with double-acting shifting rams in a mine working.The system has a pump for supplying pressure fluid and main and return feed lines or conduits connected to the pump and laid along the working. An adjustable pressure-regulating device or devices serves to provide fluid at variable pressure in a further feed line or conduit.Each ram has its working chambers connected to a control device which is in turn connected to the main and further feed lines or conduits and to the return line or conduit. The devices can each be set to various positions to operate the rams in order to extend one of the rams its associated device is set to connect the working chamber used for extension (having the larger piston working surface area) to the further feed line or conduit, and to connect the other working chamber used for retraction (having the smaller piston working surface area) to the to the main feed line or conduit.