ELIMINATION OF GLARE

Shannon News, 5 August 1927, Page 4

ELIMINATION OF GLARE

The following interesting article X>n the elimination of glare from automobile headlamps by proper focussing has been supplied by General Motors, Melbourne. Automobile head-lights are so easily adjusted that the motorist is rendering an injustice, not only to himself, but to fellow drivers, by not obtaining the full illuminating qualities and preventing glare. It is impossible for a driver to get maximum road illumination from glaring head-lights, because part of the light rays are projected into the air at a comparatively high distance from the ground where they are naturally of no value to the driver and a source of annoyance to the passing motorist. Once the theory of the reflector is understood, it is a simple matter to adjust the bulbs in the reflectors for correct focus. If all lights were correctly focussed and tilted slightly downward there would be no necessity for dimming lights, as the light rays would all strike the road, and any that reach the eyes of another motorist would be too weak to cause annoyance. The method of correctly focussing a head-light can be easily explained. First be certain that the device for moving the bulb backward and forward in the reflector is free from rust and properly lubricated. Usually this adjustment is made by means of a screw, the head of which is accessible from the rear of the head-light. Make certain that the bulbs used are capable of adjustment in the lamp to which they are fitted, by using the lamp recommended by the car manufacturer. If it is necessary to purchase a bulb in an emergency, the position of the filament with relation to the prongs on the side of the base is as important as the voltage and candle power.

To focus, place the car on level ground about 25 feet from a light coloured blank wall, and remove the head-light lenses unless they are plain glass. Disconnect or cover up one lamp and test each separately. Screw the bulb forward as far as it will go. and a black spot will appear in a ring of light on the wall. Then screw the bulb back slowly until"" the black spot just disappears. Next screw the bulb still further back and the black spot reappears in a ring of light. Finally screw the bulb forward again until the spot just disappears and the lamp is correctly focussed. Results other than these indicate that the bulb i.° unsuitable. If the filament is shaped like a letter "V" the lamp socke< should be set with the "V" in a horizontal plane. The purpose of the "V" is to make the beam of light cover more road surface. The top of the light beam on the wall should be no higher than the top of the lamp on the car.

The latest cars have an adjustable bracket for raising or lowering th' light beam, but on older models it is sometimes necessary to slightly bend the head-lamp brackets to get th' beam down where it belorjfrs, which ti about four feet high at a distance of 25 feet. After both lamps Tiav been adjusted the lens may be replaced and the driver can rest assured that his lights will not glare.