 Lighting - Adjustment 2
The better the measuring devices for the workshop become, the more they actually obscure the basic principles of the measuring process. Of course, you don't need a laser device if you are able to place the light
adjustment device at a right angle 30 to 70 cm in front of the vehicle. A camera is also not necessary if you are checking whether certain shadow boundary lines match the specified ones.
And you certainly don't need internet access to upload the customer data and results to a cloud. Yes, you could actually do without the light adjustment device altogether. And that's exactly what we want to do in this chapter -
workshop people please do not listen - in order to explain once more the basics of light adjustment in more detail.
Take a (imaginary) completely flat road, wide enough for the vehicle in question, and also comfortable for trucks and construction machinery. It doesn't have to be horizontal, but it does have to be long enough, because
exactly 10 m in front of the headlights we build a wall perpendicular to the road. It is enough if it is as high as the headlights.
We then draw a line parallel to the road. The height of this line and its distance from the road are very important to us. If the information on the headlight is '1%', for example, then the line would have to be drawn exactly 65
cm - 6.5 cm = 58.5 cm high if the light exits from the road is, say, 65 cm high.
So the percentage indicates the proportion by which the upper light-emitting edge falls. At a height of 130 cm and 2 percent, that would be 130 cm - 26 cm = 104 cm. As you can see, these are very high-mounted headlights,
such as those found on construction machines. The higher percentage is because there are legal restrictions on dipped beam.
What is important here is not only the boundary within which the light falls on the ground or the road, often assumed to be around 50 m. No, it also depends, for example, on the strength of the lighting above the height of
the headlights at half of this distance. But this only applies up to certain maximum heights of their arrangement. If they are installed higher, the rules are stricter. Blinding oncoming traffic should be avoided at all costs.
For each headlight, the light cone may extend up to 150 m from the center to the passenger side. This is called 'asymmetrical dipped beam' and an angle of no more than 15° must be maintained from this point. You can
recreate this wonderfully by drawing on the linnen cloth at a distance of 10 m from the center of each spotlight another line 15° diagonally upwards.
Actually, the idea is that the two angles put put themselves on top of each other at a greater distance and act as if they were coming from a single spotlight. The 15° are not that important and can be undercut. However, the
point at which they leave the horizontal line is. A possible horizontal shift becomes visible here.
The illuminated area may only reach these lines from below. The lines apply to all systems, including the newest ones. The adjustment screws used to be clearly visible from the front, but today they are sometimes
scattered all over the headlight. You have discovered one when you can clearly see in which direction the light-dark boundary is moving when you turn it.
In theory, you could also change the adjustment by using washers on the fixings of the headlight. This means, on the other hand, that you have to have the adjustment checked in this area every time you dismantle it. When
changing a lamp, it is also essential that you restore its exact positioning using the appropriate recesses.
If the extension of the light cone on the passenger side is caused by the lens, as in classic cars, this can be covered with a kind of triangle when changing from a left-hand drive to a right-hand drive country, for example, so
that only symmetrical low beam remains and the high beam is not obstructed too much.
If the asymmetry is caused by a specially shaped reflector, then a folding aperture and a lens are usually also present. The light rays that are too high are then filtered out by the aperture in the respective position. This
makes the transition between the two countries described above much easier.
Further developments such as matrix technology can only be inadequately checked with the existing lighting measuring devices. However, this is the high beam area anyway. During the main inspection, the data will
probably be looked at and seen to see whether an error has been laid down, e.g. that a sub-area is not switched off even though a vehicle appears in it.
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