Use of a Headlight
|The wall screen is a very good method of aiming
headlights. However, it is extremely time consuming to use and
requires a long, flat, work bay. It is not practical for the
majority of repair shop applications. This webpage describes
the proper use of a headlight aiming screen and explains why
the screen is impractical for most people.
One of the first considerations a shop must make when determining
whether an aiming screen is suitable for their operation is
the amount of space required for the screen. The SAE recommends
that the screen be at least 10' wide and tall enough for all
headlights (about 5'). In addition, the shop must have approximately
45' of flat floor space with wall space at the end for the aiming
screen. This is distance is based on the need for the screen
to be located 25' from the headlights. Allowing 20' for the
length of the vehicle and 25' for the screen (25'+20'=45').
In the vast majority of shops, this space requirement alone
is enough reason to avoid using a screen.
The floor must be completely flat on the full 45' length of
the aiming bay. Any deviation from this will result in the vertical
aim being too high or too low.
|3) Aligning vehicle
to the screen
The vehicle must be aligned at exactly 90 degrees to the aiming
screen. Any deviation from this will result in left-right variation
in headlight aim. This alignment is difficult because in addition
to being 90 degrees from the screen, the vehicle must also be
exactly 25' from it. Most shops accomplish this by painting
a line on the floor that is measured to be 90 degrees from the
screen. They try to drive the car on the line so that both tires
are exactly centered on the line (this process is much more
difficult than it sounds, try it).
|4) Placing the
aiming lines on the screen at the center of the headlights
This is the most difficult problem when using an aiming screen.
A vertical line and a horizontal line must be aligned exactly
with the center of each headlight. Aligning the horizontal line
is easy, simply use a ruler to measure the distance from the
floor to the center of the headlight and place the horizontal
line on the screen at the same distance from the floor.
The vertical lines are much more difficult. They must me aligned
with the left-right center of the each headlight. This is very
difficult to do because the screen is 25' from the lamp and
(unlike the floor for the horizontal line) there is no reference
point to measure from.
One of the common methods of making this measurement is to draw
a line on the floor exactly perpendicular to the aiming screen
and extending it to the location of the vehicle. Using a plumb-bob,
mark the floor at the center of the headlight. Then measure
the distance from the line on the floor to the mark of the plumb-bob.
At the wall screen, transfer this measurement to the screen
and place the vertical aiming line at this location. You must
repeat the process for both headlight.
When all three lines are positioned as explained, the screen
is ready to aim the headlights. The difficulty with all of these
measurements is that they must be taken at the car and then
transferred to the aiming screen which is 25' away. In addition,
it is considered good practice to repeat the measurements to
confirm their accuracy after the screen is set-up. This entire
process is very difficult and time consuming to do.
|5) Aiming the
This is where the aiming screen works extremely well. You simply
view the beam pattern on the wall and aim the pattern using
the lines on the screen as reference points.
|The advantage of a wall screen is it's low cost.
However, they are difficult to use and the floor and space requirements
make them impractical for most shops.
The Sniper provides all of the advantages of the aiming screen
with none of the disadvantages. It is a visual system that is
fast and easy to use with none of the space restrictions of
the wall screen.