Abstract: A pyrometer has a lock nut that engages a threaded sighting tube. The lock nut has a flange with a circle of thirteen apertures. A second similar flange is mounted on the body of the pyrometer which is restrained from rotation by splines which engage splines in the sighting tube. The second flange has a circle of only twelve apertures which is concentric with the circle of apertures on the first flange. The two flanges are locked together and the pyrometer is thereby locked in the sighting tube by means of a split pin pushed through aligned apertures. The different number of apertures in the flanges gives a number of locking positions that exceeds the number of apertures.

Abstract: A seal for a linear displacement optical transducer has a tubular flexible bellows which is joined at one end to a movable carriage supporting an optically encoded track and which is movable along a cylinder supporting an optical read head. The bellows extends within the cylinder and has its other end sealed to an open end of the cylinder. A compensation chamber is sealed to the outside of the cylinder to enclose a major part of the length of the bellows and forms a sliding seal with a push-rod extending from a carriage. The bellows encloses a first volume of the dry inert gas within the cylinder to one side of the bellows and a second, similar volume of gas on the other side of the bellows and in the compensation chamber. Displacement of the carriage causes only a small change in pressure across the bellows which is accommodated by flexure.

Abstract: A speed and torque sensor has a permanent magnet and a pole piece about which are wound together a torque coil and two speed coils and identical with the torque coil. The coils and permanent magnet assembly are contained in an outer housing together with resistors and connected in series with the respective speed coils. The resistance of the resistors and is approximately fifty times that of the speed coil and so that shorting of the output of a speed coil beyond the resistor does not substantially increase current drawn by the coil. A temperature sensor in the housing enables compensation for changes in temperature on modulus of elasticity of the member subject to torque.

Abstract: In a pyrometer system, a pyrometer provides output signals to a processor indicative of the temperature of rotating blades in a gas-turbine engine. The processor includes a synchronization unit and a gate controlled by the synchronization unit. After monitoring the output of the pyrometer to identify which parts of the output signal arise from radiation from the blades and which arise from the combustion chamber, the synchronization unit is set in synchronism with the blade signals and the gate is controlled to pass signals from the blade and to interrupt signals arising from the combustion chamber. The output of the processor is thereby indicative of blade temperature and is insensitive to combustion chamber radiation.

Abstract: A radiation pyrometer has an inner tube with a lens mounted in a rear portion which is stepped to a forward portion of reduced diameter that is open at its forward end. An outer tube extends coaxially around the inner tube and is separated from it by an annular gas passage. The outer tube has an aperture at its forward end that is smaller that the external diameter of the forward end of the inner tube and larger than the internal diameter. The outer tube has gas inlets into the passage which are located rearwardly of the forward end of the inner tube, the area of the gas inlets being greater than the gap between the forward end of the inner tube and the outer tube. Gas flows through the inlets, along the passage, across the forward end of the inner tube and out the aperture, thereby setting up a substantially constant pressure in the rear portion of the inner tube and reducing the entry of contaminants.

Abstract: A radiation pyrometer for a gas-turbine engine has a sapphire lens that focusses radiation from the turbine blades onto the end of a fibre-optic cable. The front, exposed surface of the lens has a vapor deposited layer comprising a mixture of platinum and aluminum oxide which acts as a catalyst to promote oxidation of soot to a gaseous form and thereby reduce contamination of the lens.

Abstract: An oil-level detector is mounted on the outside face of a glass window in the wall of an oil tank. The detector has two fibre-optic cables which extend within a cavity between the detector and the window. The ends of the cables are mounted one above the other, one cable transmitting a beam of light at an angle .alpha. of 60.degree. to the window, through an oil in the cavity which has a refractive index substantially equal to that of the window glass. The angle .alpha. is greater than the critical angle of glass with air, and less than the critical angle of glass with the oil in the tank. When the window is covered by oil in the tank the light is refracted into the tank. When the oil level falls below the window, the light is reflected to the other cable which is connected to a control unit. The control unit gives a warning a predetermined time after the level has fallen.