Abstract: An element, adapted to be inter-engaged with a plurality of similar elements to form a rack for a mining machine haulage system, has each element comprising at one end, a looped end portion including inner and outer arcuate bearing surfaces, the inner bearing surface defining one end of an upwardly open aperture. A downwardly projecting tooth is spaced from the inner bearing surface and adapted to fill partly the aperture of the next adjacent inter-engaged element, while a correspondingly arcuate bearing surface is also provided on the tooth for abutment against the inner arcuate bearing surface of the adjacent element. Also, a transversely extending bridge is provided at the other end of the element, which bridge has transversely extending, and upwardly converging, planar faces for engagement, in use, by a tooth of a driven haulage system of an associated mining machine, dependent upon the direction of haulage.

Abstract: Operating head assembly, e.g. cutter head of a coal or other mining machine having provision for feeding a supply of water or other fluid to the head during operation has provision for phasing the fluid delivery to limit it to the zone about the head in which the cutting action is taking place dependent on the direction of movement of the head. Delivery jets of the head are fed through individual valve units (22) each having an independently operable hydraulic or other actuator (28), the power input thereto being controlled by apertured timing faces (36, 38) on co-acting parts of the head (11) and body (10), power feed through the timing faces being controlled e.g. in correspondence to the position of change-over valve (44, 46) operating in response to controls which direct movement of the head. In an alternative construction the valve units are actuated mechanically by a camming formation which can be indexed depending on the direction of movement.

Abstract: A gas detector (1) to detect a predetermined gas of interest within an air sample, the detector (1) comprising a sampling tube (12), an infra-red radiation source (13) located at one end of the tube (12), an infrared sensing means (17) located at the other end of the tube, an optical filter (16) appropriate to the gas of interest located in the infra-red radiation beam, either adjacent the infra-red source (13), or adjacent the infra-red sensing means (17), an air sample inlet located at or towards one end of the tube (12) and an air sample outlet located at or towards the other end of the tube (12), with the detector (1) capable of emitting an electrical signal or a changed electrical signal in accordance with whether the gas of interest is or is not detected, a pure, reference gas source (26-30) and valve means (31, 32) to control admission of the reference gas to the sampling tube (12) at prescribed intervals of time.

Abstract: A scraper chain conveyor with conveyor pans defining a bend round which flight bars are guided in the general plane of the conveyor is provided at the outside of the bend with an auxiliary conveying unit comprising two spaced apart sprockets rotatable about upstanding axes, a line joining the axes being parallel to a tangent to the bend at least when the auxiliary conveying unit is in use, at least one endless auxiliary chain trained round the sprockets, and means for driving the auxiliary chain in a direction such that its chain run adjacent the scraper chain conveyor moves in the direction of feed of the scraper chain conveyor.

Abstract: The invention relates to a conduit length to be joined in use to adjacent ends of similar conduit lengths to form an electrical power supply conduit when housing one or more electrical conductors, for the supply of electrical energy to electrical machines, e.g. a mining machine adjacent the conduit, the conduit length being generally of "U" section and internally lined with a seal of flexible material having a corresponding "U" shaped cross section, upper ends of the "U" arms of the conduit each carrying rigid locating means each housing an elongate displaceable sealing means, the two sealing means abutting one another so as to normally close an elongate aperture of the conduit length.