Bosch GLL 2-20 Professional, Original Instructions Manual

10

 | English

mode is displayed by the corresponding "Laser operating
mode" indicator 

(11)

 lighting up.

You can choose between the following operating modes:

Indicator

Operating mode

Cross-line operation

 (see figures 

A

, 

B

and 

E

): The measuring tool generates a ho-

rizontal laser plane (360° surrounding
laser line) and a vertical laser line.

Horizontal operation

 (see figure 

C

): The

measuring tool generates a horizontal laser
plane.

Vertical operation

 (see figure 

D

): The

measuring tool generates a vertical laser
line.

All operating modes can be selected with both automatic lev-
elling or the pendulum lock.

Automatic Levelling

Working with automatic levelling (see figures F–G)

To work with automatic levelling, the pendulum lock
indicator 

(12)

 must not light up. If necessary, switch the

automatic levelling on again by pressing the pendulum lock
button 

Lock

(8)

 so that the pendulum lock indicator goes

out.
Position the measuring tool on a level, firm surface or attach
it to the universal holder 

(13)

 or the tripod 

(23)

.

The automatic levelling function automatically compensates
irregularities within the self-levelling range of ±

4

°. The level-

ling is finished as soon as the laser lines stop moving.
If automatic levelling is not possible, e.g. because the sur-
face on which the measuring tool stands deviates by more
than 4° from the horizontal plane, the levelling warning 

(10)

lights up red and the laser is switched off automatically.
If this is the case, set up the measuring tool in a level position
and wait for the self-levelling to take place. As soon as the
measuring tool is within the self-levelling range of ±4° again,
the levelling warning 

(10)

 goes out and the laser is switched

on.
It is not possible to work with automatic levelling outside the
self-levelling range of ±

4

°, 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 a pendulum lock (see figure E)

To work with the pendulum lock, press the pendulum lock
button 

Lock

(8)

. The pendulum lock indicator 

(12)

 lights up

red when the pendulum lock is switched on.
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 mount the measuring tool on a tripod and
position it 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.
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 Horizontal Levelling Accuracy

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, or

place it on a firm, level surface. Switch on the measuring
tool. Select cross-line mode with automatic levelling.

A

B

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

B

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.

1 609 92A 4HK | (08.10.2020)

Bosch Power Tools