Headlamp Aiming (Except North America): General
Directive 76/756 EEC and ECE-Regulation 48 cover checking and aiming of headlamps on vehicle. Correct aiming of headlamps of vehicles should enable optimal road illumination by the low beam-, with minimal glare to oncoming traffic. For this purpose the inclination of the light beam in relation to the road surface and the angle of the beam to the vertical longitudinal plane running through the vehicle centre must comply with the requirements laid down in the ECE regulation and EEC directive.
Glaring of the low beam is considered eliminated if the intensity of the illumination at a distance of 25 m (82 ft) from each individual headlamp on the plane perpendicular to the road and at the height of the headlamp as well as above, is not greater than 1 lux. This requirement is generally satisfied if the headlamp aiming is carried out according to these aiming guidelines.
For the nondazzling high beam (Intelilux) special attention must be turned to the correct lateral alignment of the headlamps (low beam).
If a non-railed adjustment device will be used, the lateral orientation of the adjustment device has to be checked separately in front of each single headlamp.
The measurement of adjustment for the basic headlamp aiming is displayed in % on the headlamp housing.
Example: Label for a headlamp inclination of 1.0% for the low beam on the headlamp.
Reference 1.0 percent corresponds to the adjustment dimension of the headlamp with reference to the inclination of the light beam. The inclination at a distance of 10 m (33 ft) from vehicle headlamp is therefore 10 cm (4 in). The inclination of the low beam headlamp is indicated by its light/dark boundary (cut-off line).
Depending on the specific inner design of the headlamps, the movement of the lightbeam on the measurement screen is not exactly vertical or horizontal during the aiming on the aiming screws. This is caused by the technical solution of the suspension of the reflectors in the headlamp housing. After aiming of one axis the aiming of the other axis should be rechecked. For instance the vertical aiming could be changed a bit after the aiming of the horizontal axis. Therefore the vertical axis must be checked and if necessary aimed again after the aiming of the horizontal axis.
If a headlamp shows a significant deviation from the correct aiming for both horizontal and vertical direction the aiming operation must be performed step by step for the two directions. This means that in such a case the aiming of horizontal and vertical direction must be done alternately in small steps. Not more than one turn of an aiming screw shall be performed at once. After one turn change to the other aiming screw. Repeat this procedure until the headlamp is correctly aimed.