JDNSW,
You have done the hard work and found the relevant ADR.
ADR 13 relevant bits to the current question.
snip .....
6.2.6.1. Vertical orientation
6.2.6.1.1. The initial downward inclination of the cut-off of the dipped-beam to be set
in the unladen vehicle state with one person in the drivers's seat shall be
specified within an accuracy of 0.1% by the manufacturer and indicated in a
clearly legible and indelible manner on each vehicle close to either headlamp
or the manufacturer's plate by the symbol shown in annex 7.
The value of this indicated downward inclination shall be defined in
accordance with paragraph 6.2.6.1.2.
6.2.6.1.2. Depending on the mounting height in metres (h) of the lower edge of the
apparent surface in the direction of the reference axis of the dipped-beam
headlamp, measured on the unladen vehicles, the vertical inclination of the
cut-off of the dipped beam shall, under all the static conditions of Annex 5,
remain between the following limits and the initial aiming shall have the
following values. For category N3G (off-road) vehicles where the
headlamps exceed a height of 1,200mm, the limits for the vertical inclination
of the cut-off shall be between:
-1.5% and -3.5%. The initial aim shall be set between : -2% and -2.5%:
h < 0.8
limits:between -0.5% and -2.5%
initial aiming:between -1.0% and -1.5%
0.8<h<1.0
limits:between -0.5% and -2.5%
initial aiming:between -1.0% and -1.5%
or, at the discretion of the manufacturer,
limits:between -1.0% and -3.0%
initial aiming:between -1.5% and -2.0%
The application for the vehicle type approval shall, in this case, contain
information as to which of the two alternatives is to be used.
h > 1.0
limits:between -1.0% and -3.0%
initial aiming:between -1.5% and -2.0%
The above limits and the initial aiming values are summarized in the
diagram below:
percentage vs height diagram not pasted if interested follow this link and go to pg 32
6.2.6.2. Headlamp levelling device
6.2.6.2.1. In the case where a headlamp levelling device is necessary to satisfy the
requirements of paragraphs 6.2.6.1.1. and 6.2.6.1.2., the device shall be
automatic.
6.2.6.2.2. However, devices which are adjusted manually, either continuously
or non- continuously, shall be permitted, provided they have a stop positon
at which the lamps can be returned to the initial inclination defined in
paragraph 6.2.6.1.1. by means of the usual adjusting screws or similar
means.
These manually adjustable devices must be operable from the driver's seat.
Continually adjustable devices must have reference makes indicating
the loading conditions that require adjustment of the dipped-beam.
The number of positions on devices which are not continuously adjustable
must be such as to ensure compliance with the range of values prescribed in
paragraph 6.2.6.1.2. in all the loading conditions defined in Annex 5.
For these devices also, the loading conditions of Annex 5 that require
adjustment of the dipped-beam shall be clearly marked near the control of
the device (see Annex 8).
6.2.6.2.3. In the event of a failure of devices described in paragraphs 6.2.6.2.1. and
6.2.6.2.2., the dipped-beam shall not assume a position in which the dip is
less than it was at the time when the failure of the device occurred.
6.2.9. Other requirements
The requirements of paragraph 5.5.2. shall not apply to dipped-beam
headlamps. Dipped-beam headlamps shall not swivel according to the angle
of lock of steering.
Dipped-beam headlamps with gas-discharge light sources
shall only be permitted in conjunction with the installation of headlamp
cleaning device(s) according to Regulation No. 45.4/ In addition, with
respect to vertical inclination, the provision of paragraph 6.2.6.2.2. shall not
be applied when these headlamps are installed.