Bosch HTD 6 Series - Measurement Value Explanations; Pitch Angle Definition; Low Beam Measurement; High Beam Measurement

1 692 104 610 2015-01-14| Robert Bosch GmbH
24 | HTD 6xx | Explanatory notes on measured valuesen
4. Explanatory notes on
measured values
The following Sections explain the most important
measurement quantities required for headlamp
adjustment.
4.1 Pitch angle
The definition of the pitch angle is illustrated in the
following.
Fig. 10: Definition of pitch angle
R "H": Height of centre of headlamp measured from
theground
R "h": Height of image projected by headlamp at
adistance of 10 m, measured from the ground
R "e": Pitch angle, calculated with the following
formula: e = [(H-h) / 1000] x 100
4.2 Low beam
The following illustration shows the most important low
beam measurement quantities.
hh‘
v
v‘
HV
α
β
A
B
C
D
Fig. 11: Low beam measurement quantities
R "A": Cut-off, made up of two portions:
$ Horizontal section,
$ Rising straight line, also referred to as "shoulder";
the cut-off must be within the stipulated
tolerance range.
R "B": Break point with asymmetrical light;
centre point with symmetrical light.
R "C": Deviation of break point from the vertical
(alsoreferred to as pitch angle). The value is always
shown as an absolute value. Possible units:
%, cm / 10 m, degrees
R "D": Deviation of break point from the horizontal.
Thevalue is always shown as an absolute value.
Possible units:
%, cm / 10 m, degrees
R "α": Angle between the "shoulder" and the horizontal
section of the cut-off (also referred to as yaw angle
with asymmetrical low beam).
R "b": Angle between the left portion of the cut-off
andthe horizontal (also referred to as roll angle,
usually 0°).
4.3 High beam
The following illustration shows the most important
high beam measurement quantities.
hh‘
v
v‘
HV
E
F
G
H
I
Fig. 12: High beam measurement quantities
R "E": Zero point of beamsetter (centre of headlamp).
This point is the basis for the measured values.
Deviations are measured from this point.
R "F": Tolerance band. The high beam hot spot should
be within this range.
R "G": Hot spot.
R "H": Horizontal distance of hot spot from centre
point. Possible units:
%, cm / 10 m, degrees
R "I": Vertical distance of hot spot from centre point.
Possible units:
%, cm / 10 m, degrees
4.4 Fog lamp
The fog lamp is measured in a similar manner to the low
beam, the difference being that the cut-off does not
have a break point but takes the form of a continuous
horizontal line.