Abstract: A tunnel is constructed by progressively cutting away a predetermined depth of rock from a face using rotary diamond saws. Slots are cut into the face (12) at an acute angle to the face such that first slots intersect second slots to detach blocks from the face. In one embodiment, the cutter (29) is mounted on a slide which can traverse an elongate guide 26. The guide is carried on an arm (24) which can swivel about its own longitudinal axis. A series of angularly spaced slots are cut into the face through 360.degree. with alternate slots being cut at opposite acute angles to the face so that they intersect. A cylindrical tunnel is produced.

Abstract: Apparatus for excavating a tunnel of generally quadrilateral cross-section, the apparatus comprising a cutting head having the head being mounted for rotation about a first axis and a second axis to change the angle of inclination of the cutter. The cutter may be retracted on its support and may be moved transversely of the excavation on a slide, horizontally. It may be moved vertically by mounting the head on an arm pivotally mounted or in another embodiment by mounting the head on a vertically movable carrier carried on a slide. This can be used for excavating by making a set of cuts at various angles; first and second slots are generally parallel at the face but the first slots are inclined to the second, and to the face, so that they intersect. A third set of slots may intersect the first and second sets (for example, vertically) to separate the material from the face in convenient-sized blocks.

Abstract: There is provided a continuous mining system comprising at least one chassis, boom arrangement for supporting a continuous miner cutting head, roadheader turntable assembly and, optionally, drilling machine. The latter three items are adapted so that each of them can be removably mounted on any one of the at least one chassis. This enables a continuous mining operation to be carried out without the need to remove the whole of the mining machine if hard rock is encountered.

Abstract: The invention relates to strainers or filters, particularly such oil strainers of the type which have removable filter elements held, against spring bias in a casing.As shown in FIG. 1 the strainer comprises a casing 10 with inlet apertures 11 and outlet apertures 12. Spring biased shutters 17 and 21 are held in their open positions (as illustrated) by the filter element 13 when the closure cap 24 is screwed down.On removal of the filter element 13 the springs 18 and 22 cause shutters 17 and 21 respectively to close the inlet and outlet apertures automatically.

Abstract: A mining machine adapted to be driven forwardly towards a working face comprises one or more cutting booms projecting forwardly from the machine, a cutting tool mounted on the forward end of the or each boom, and a drive mechanism for rotating the cutting tool relative to the boom, the said mechanism including a multi-speed gearbox whereby the cutting tool may be selectively driven at two or more different cutting speeds.

Abstract: A mining machine suitable for cutting roadways in coalmines comprises a cutting head, a conveyor for moving mined material rearwardly of the machine and a discharge conveyor for unloading the mined material to one side of the machine. As the machine advances the discharge conveyor can be used selectively to unload coal onto a stage loader and other material into packholes, thereby saving labor. The discharge conveyor may be pivotable about horizontal and/or vertical axes, longitudinally extendable or movable relative to the machine or cutting head to obtain maximum control over the area in which it discharges material.

Abstract: The invention relates to gathering arms for a mining machine to operate in conjunction with a forwardly extending apron to sweep mined material across the apron where it can be transferred by a conveyor to the rear of the machine. Although a single gathering arm is envisaged, preferably two are provided which are hydraulically operated by means of two pairs of piston and cylinder devices arranged to extend and retract the arms and sweep them between inboard and outboard positions after the style of extendable windscreen wiper blades, the arms being extended during a work sweep and retracted during a return sweep. The invention also extends to a hydraulic circuit for operating the arms largely automatically in synchronism and to a mining machine fitted with such arms.