Bosch Professional GLL Series Original Instructions Manual page 9

The automatic levelling function automatically compensates
irregularities within the self-levelling range of ±3°. The pen-
dulum lock button (21) flashes during levelling. The levelling
is finished as soon as the pendulum lock indicator goes out.
If automatic levelling is not possible, e.g. because the sur-
face on which the measuring tool stands deviates by more
than 3° from the horizontal plane, the pendulum lock
indicator (21) flashes continuously.
If this is the case, set up the measuring tool in a level position
and wait for the self-levelling to take place. Once the level-
ling is finished, the pendulum lock indicator (21) goes out.
It is not possible to work with automatic levelling outside the
self-levelling range of ±3°, as the levelling accuracy of the
laser beams cannot be guaranteed and it cannot be guaran-
teed that the laser beams are perpendicular.
In case of ground vibrations or position changes during oper-
ation, the measuring tool is automatically levelled again.
Upon re-levelling, check the position of the horizontal or ver-
tical laser line with regard to the reference points to avoid er-
rors by moving the measuring tool.
Working with the pendulum lock
To work with the pendulum lock, press the pendulum lock
button (2). When working with the pendulum lock, the pen-
dulum lock indicator (21) is continuously lit.
For work with the pendulum lock, the automatic levelling is
switched off. You can hold the measuring tool freely in your
hand or place it on a sloping surface. This means that the
laser lines are no longer levelled and no longer necessarily
run perpendicular to one another.
Accuracy Check of the Measuring Tool
Influences on Accuracy
The largest influence is exerted by the ambient temperature.
In particular, temperature differences that occur from the
ground upwards can refract the laser beam.
Since the temperature stratification is greatest at ground
level, you should always mount the measuring tool on a tri-
pod for measuring distances of 20 m or more. In addition,
position the measuring tool in the centre of the work surface,
wherever this is possible.
In addition to external influences, device-specific influences
(e.g. falls or heavy impacts) can also lead to deviations. For
this reason, check the levelling accuracy each time before
beginning work.
First check the height accuracy and levelling accuracy of the
horizontal laser line, then the levelling accuracy of the ver-
tical laser line.
Should the measuring tool exceed the maximum deviation
during one of the tests, please have it repaired by a Bosch
after-sales service.
Checking the height accuracy of the horizontal lines
For this check, you will need a free measuring distance of
5 m on firm ground between two walls (designated A and B).
– Mount the measuring tool close to wall A on a tripod (24),
or place it on a firm, flat surface. Switch on the measuring
Bosch Power Tools
tool in the mode with automatic levelling. Switch on hori-
zontal mode and vertical mode with a laser line forwards.
A
5 m
– Aim the laser at the closer wall A and allow the measuring
tool to level in. Mark the middle of the point at which the
laser lines cross on the wall (point I).
A
180°
– Turn the measuring tool 180°, allow it to level in and mark
the point where the laser lines cross on the opposite wall
B (point Ⅱ).
– Position the measuring tool – without rotating it – close to
wall B, switch it on and allow it to level in.
A
– Align the height of the measuring tool (using the tripod or
by placing objects underneath as required) so that the
point where the laser lines cross exactly hits the previ-
ously marked point Ⅱ on wall B.
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B
B
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1 609 92A 58T | (07.08.2020)