Automatic Levelling - Bosch GLL 2-50 Professional Notice Originale

OBJ_BUCH-817-007.book Page 14 Monday, July 4, 2016 6:35 PM
14 | English
Operation Modes (see figures A–D)
The measuring tool has three operating modes between
which you can switch at any time:
– Horizontal operation "–": Produces a horizontal laser line,
– Vertical operation "l": Produces a vertical laser line,
– Cross-line operation "+": Produces a horizontal and verti-
cal laser line.
After switching on, the measuring tool is in cross-line operat-
ing mode. To change the operating mode, press the operating
mode button 4.
All three operating modes can be selected either with or with-
out automatic levelling.
Pulse Function
When working with the laser receiver 21, the pulse function
must be activated, – independent of the selected operating
mode.
In pulse function, the laser lines flash at very high frequency
and thus become detectable by the laser receiver 21.
To switch on the pulse function, press button 3. When the
pulse function is switched on, the pulse-function indicator 2
lights up green.
When the pulse function is switched on, the visibility of the la-
ser lines is reduced for the human eye. Therefore, shut off the
pulse function by pushing button 3 again when working with-
out laser receiver. When the pulse function is switched off,
the pulse-function indicator 2 is deactivated.

Automatic Levelling

Working with Automatic Levelling (see figure C)
Position the measuring tool on a level and firm support or at-
tach it to a commercially available photographic tripod.
When working with automatic levelling, push the On/Off
switch 7 to the " on" position.
After switching on, the levelling function automatically com-
pensates irregularities within the self-levelling range of ±4°.
The measuring tool is levelled in as soon as the laser lines no
longer flash.
If the automatic levelling function is not possible, e.g. be-
cause the surface on which the measuring tool stands devi-
ates by more than 4° from the horizontal plane, the laser
beams flash. In this case, bring the measuring tool to the level
position and wait for the self-levelling to take place.
In case of ground vibrations or position changes during oper-
ation, the measuring tool is automatically levelled in again.
To avoid errors, check the position of the horizontal and ver-
tical laser line with regard to the reference points upon re-
levelling.
Working without Automatic Levelling (see figure D)
For work without automatic levelling, push the On/Off switch
7 to the " on" position. When the automatic levelling is
switched off, the laser lines flash continuously.
When the automatic levelling is switched off, the measuring
tool can be held by hand or placed on an inclined surface. In
cross-line operation, the two laser lines do not necessarily run
at a right angle to each other.
1 609 92A 27R | (4.7.16)
Levelling Accuracy
Influences on Accuracy
The ambient temperature has the greatest influence. Espe-
cially temperature differences occurring from the ground
upward can divert the laser beam.
Because the largest difference in temperature layers is close
to the ground, the measuring tool should always be mounted
on a tripod when measuring distances exceeding 20 m. If pos-
sible, also set up the measuring tool in the centre of the work
area.
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 both the height as well as the 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 Line
For this check, a free measuring distance of 5 m on a firm sur-
face between two walls A and B is required.
– Mount the measuring tool onto a tripod or place it on a firm
and level surface close to wall A. Switch on the measuring
tool. Select cross-line operation with automatic levelling.
A
5 m
– Direct the laser against the close wall A and allow the meas-
uring tool to level in. Mark the centre of the point where the
laser lines cross each other on the wall (point I).
A
180˚
– Turn the measuring tool by 180°, allow it to level in and
mark the cross point of the laser lines on the opposite wall
B (point II).
B
B
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