Abstract: An optical element is fitted to a high intensity light emitting diode used in a variable message sign. The optical element has surfaces which redirect any stray light from the light emitting diode to form useful light. The faces of the optical element are angled to shape the light beam emitted therefrom. The light beam is shaped by the faces to produce a beam having increased intensity in a predetermined direction. The optical element enhances the visibility of the sign and allows a reduction in the number of light emitting diodes used in the sign.

Abstract: A boring machine having a cutter head rotatably mounted on a hydrostatic bearing. High pressure water is supplied to passageways between confronting bearing surfaces which react axial and radial loads and which are capable of relative rotational movement. The flow of pressurized water discharges from the passageways to prevent contamination of the bearing by the ingress of material removed by the cutter head in operation.

Abstract: An electrical machine has a rotor shaft which carries a plurality of rotor discs for rotation therewith. Each rotor disc has two pairs of rotor rims secured thereto. Each rotor rim consists of a single row of alternate magnets and pole pieces and is opposed by a series of stator cores which straddle the rotor rim. The stator cores are `c` shaped so that they receive flux from two adjacent magnets and close around two opposite rotor poles on either side of the rotor rim. The stator cores, formed by winding electrical steel around a former, reduce the losses caused by eddy currents generated when flux impinges on the side faces of the stator core.

Abstract: A rotor disc for use in an electrical machine has circumferential rotor rims mounted thereon. The rotor rim comprises a row of alternate magnets and pole pieces. The magnets are tapered at their radially inner and outer extents and engage with correspondingly tapered surfaces on adjacent pole pieces to prevent relative physical movement therebetween.Each side of the radially inner and outer extents of the magnets may be tapered by a different amount to ensure correct orientation of the magnet polarity.

Abstract: A fossil fuel air burner nozzle is provided with a wall (22) at its inlet, in which are apertures (34) which narrow in a direction radially outward of the nozzle. Each aperture is axially aligned with a respective bluff member (18) at the outlet so as to deliver thereto a fuel air mix flow at a velocity which is graded in said radial direction so as to ensure flame retention on the bluff members (18).

Abstract: A burner (10) for the combustion of fuel comprises a passage (32) through which in operation a mixed flow of fuel and air passes for primary combustion at it's outlet. Two further annular passages (34, 36), concentric with and radially outward of the passage (32), are provided through which supplementary flows of air pass to support the primary combustion. The outlets of the two annular passages (34, 36) diverge to discharge the supplementary flows of air at an angle to the mixed flow of fuel and air. Members (62) are provided in the annular passage which obstruct the discharge of the supplementary flow of air. Furnace gases circulate in the region downstream of the obstruction members (62). Circulation of the furnace gases delays the mixing of the fuel and air mixture with the supplementary air flows to reduce the nitrogen oxides produced.

Abstract: A rotating assembly (10) comprises an inner (12) and an outer ring (14) having a hydrostatic bearing therebetween. The bearing incorporates fluid passageways (30 and 32) between confronting surfaces (22, 24, 26 and 28) of the rings (12 and 14). When rotation is required the surfaces (22, 24, 26 and 28) are separated by the supply of a pressurised flow of fluid to both of the passageways (30 and 32). The bearing can be locked to prevent rotation by removal of the fluid in one of the passageways (32) whilst maintaining the flow of pressurised fluid in the other passageway (30) so as to hold confronting surfaces (26 and 28) in contact with one another. Frictional forces between the confronting surfaces (26 and 28) prevents rotation of the ring (14) and the flow of pressurised fluid prevents the confronting surfaces (26 and 28) separating under the application of a moment.

Abstract: The assessment of clearance conditions in an operating turbine structure has provide difficult to achieve. The invention provides apparatus which enables the clearance between seal fins on rotating blades and adjacent fixed structure, to be observed during rotation, and comprises refracting prisms (30, 32) on the fixed structure arranged so as to straddle sealing fin (14) on the blades. The stage of blades on their associated disc are moved towards the fixed structure and light which is refracted through the prisms is obscured by the fins. In one embodiment, the ratio of obscured to unobscured light is utilised to generate electrical signals, which are then manipulated so as to indicate the magnitude of the clearance.

Abstract: A bearing assembly comprises a piston mounted within and capable of reciprocating movement with respect of a fixed bearing shell. The bearing shell is provided with openings for the supply of a bearing medium, such as compressed air, into a clearance between the piston and the bearing shell. The bearing shell is resilient so that as the diameter of the piston increases due to thermal expansion, the diameter of the bearing shell changes to automatically maintain the clearance therebetween.

Abstract: A solid particulate fuel/air burner has opposing fluted members within a rectangular conduit which in operation forms a nozzle. Splitter plates with the fluted members define passages through which a particulate solid fuel and air flow to a combustion chamber. The passages so defined provide and control separate streams of the mix such that flame retention at the exit of the conduit is achieved and reduced NOx is produced and the gathering of ash in the conduit avoided by the obviation of recirculation of the products of combustion into the conduit.

Abstract: An apparatus and method are provided for reducing NO.sub.x production during combustion in an tangential burner. Air nozzles are arranged tangentially to a fuel/air nozzle and are tilted relative to the fuel air nozzle. Upon operation, spaces are formed between the air flow and the fuel flow which entrain laterally combustion gases thereby delaying mixing of the air and fuel flows. By this delay, NO.sub.x production is reduced.