Patent GB-801325-A (GB)
Title: Contact or runway light
Inventor: CLARK PHILIP BRYAN
IPC: B64F1/20
Filed: 1956-04-06
Abstract: 801,325. Air-port runway marker lights: supporting lamps. McGRAW ELECTRIC CO. April 6, 1956, No. 10601/56. Classes 75(3) and 75(4) In a marker light for an airport runway including a filament light source, means for controlling the current through the filament and a lens having a focusing portion for projecting a light signal in a predetermined direction relative to the geometrical axis of the lens, in order to restore along the centre line of the runway a path, for a pilot, of equal brightness destroyed by variations in atmospheric conditions produced e.g. by fog and necessitating an increased intensity of the light source, the light source and the lens are arranged for relative movement transversely of said geometrical axis for projecting the light signal in a predetermined direction with respect to the runway at a predetermined light intensity of the source under the control of means responsive to variation in filament current. Preferably the light source is movable tranversely of the said geometrical axis under the control directly of the filament current as by a bi-metallic actuator heated by the filament current, Figs. 1-3, or a current proportional thereto flowing either through the ohmic resistance of the actuator or through a heating coil, Fig. 6 (not shown), or by the heat energy radiated by the source, Fig. 5 (not shown), or by an actuator such as a bellows-chamber filled with a thermally expansible fluid heated by the filament current, Fig. 7 (not shown), or a current proportional thereto or by an electromagnetic actuator such as a rotary solenoid or a D'Arsonval moving coil ammeter type of instrument. Figs. 8 and 9 (not shown). As shown in Figs. 1 and 3, a cast housing 1 supported by a vertical support 2 projecting from a base 3 carries the lens structure 5 comprising a bull's eye portion surrounded by inner and outer reflecting prisms 6, 7 and is provided with a door 8, Fig. 3, pivoted at one side on trunnions 9 and secured at the opposite side by a latching clamp 10. The housing is positioned on a slip-fitter 11 to permit levelling the projector with reference to the runway and/or remaining projectors of a selected series as by the screws 12, 13 operating with relation to the fulcrum 14. The lamp 25 is mounted in a U-shaped cradle 26, Fig. 1, pivotally supported from trunnions 22, 23 of a frame having a base 20 supported by nut and stud assemblies 24 for adjusting the mechanism vertically relative to the lens 5. A helically wound bimetal strip actuator 35 with the highexpansion metal on the outside has one end secured to a pivot pin 36 projecting from the limb 27 of the cradle 26 and extending through an opening in trunnion 22. The other end of the actuator 35 is fastened to the free inner end of a spirallyformed bimetallic compensator 37, with the high-expansion metal on the inside of the spiral which compensates for variations in ambient temperatures by reindexing the stable end of the actuator 35. The other end of the compensator 37 is secured to an insulating member 38 projecting from the base 20. The actuator 35 is connected electrically in series with the lamp filament to give a functional relationship between movement of the lamp with respect to the lens and the current supplied to the lamp. Upper reflectors 42, 43 having a generally concave cross-section direct light upwardly from the lamp to the lens 5 and a lower reflector 44 collects light rays which would otherwise fall on the control mechanism and reflects that light towards the lenses on either side of the lamp. A reflector 45 reflects light away from the door 8.