CST/BERGER LMPL20 Manual Original página 36

– Now subtract the distance D (clearance from laser
beam centre to bottom of the canal pipe) from the
total height A.
– Now place the levelling rod in such a manner in the
manhole cone or riser that it shows the calculated
height A – D and position the measuring tool at
the correct height with reference to the levelling
rod.
Please note that the levelling rod can also be placed
on the measuring tool. In this case, a correction of the
height A – D of 70,5 mm is necessary.
Adjusting the Grade
Proceed as described in section "Grade Adjustment",
page 31.
Adjusting the Correct Lateral Alignment of the
Laser Beam (Procedure 1) (see figure D1)
– Place an alignment tool/theodolite above the cen-
tre line of the canal using a plumb bob.
– Align the telescope of the theodolite in such a
manner that the vertical crosshair points directly at
the centre A of the next manhole cone or riser.
– Incline the telescope in the direction where the
measuring tool is set up. Position the laser beam
such that the plumb point (LED 5) lies in the axis of
the telescope. If required, use a plumb bob.
– Raise the telescope so far upward that the cross-
hair is aligned in front of the laser in the direction
of the open ditch where the laser beam impinges
on.
– Take the remote control (button 19.1 or 19.2) and
turn the laser beam so far left or right until the laser
beam is in line with the vertical axis of the theodo-
lite.
The laser beam is now aligned exactly to the axis of
the canal.
Adjusting the Correct Lateral Alignment of the
Laser Beam (Procedure 2) (see figure D2)
– Fasten the manhole mount (optional accessory) to
the manhole cone or riser and position an optical
instrument/theodolite directly above the centre
line of the canal.
– Using the plumb bob of the theodolite, plumb
downward and position the measuring tool with
the plumb point (LED 5) directly below the plumb
bob.
– Align the theodolite with the vertical axis on the
centre A of the next manhole cone or riser.
– After locking the horizontal circle, tilt the telescope
so far downward that you can see the laser beam
in the ditch.
– Take the remote control (button 19.1 or 19.2) and
turn the laser beam so far left or right until the laser
beam is in line with the vertical axis of the theodo-
lite.
36 | English
When the laser beam can be seen in the centre of the
crosshair, the measuring tool is aligned exactly to the
axis of the canal.
Adjusting the Correct Lateral Alignment of the
Laser Beam (Procedure 3)
– Position the measuring tool in the centre of the
canal bed or above the marked centre line at the
bottom of the manhole cone or riser such that the
plumb point (LED 5) lies on the centre lines.
– Fasten the loose end of the plumb bob rope in the
plumb-point notch.
– Tension the plumb bob rope to the upper edge of
the manhole cone or riser and place the rope over
your thumb in such a manner that the end with the
plumb bob hangs down on the other side of your
thumb.
– Use the plumb bob rope as a target aide and move
your thumb right and left until both sides of the
plumb bob rope are vertically aligned and are in
the axis to the next manhole cone or riser centre.
– Take the remote control (button 19.1 or 19.2) and
turn the laser beam so far left or right until the laser
beam is in line with the two vertical plumb bob
ropes.
The laser beam is now aligned exactly to the axis of
the canal.
Determining Excavator Depth and Canal Depth
(see figure E)
In order to precisely adjust the measuring tool to the
ditch depth, the difference between the ditch and the
centre of the measuring tool (basic height X) must be
calculated.
The procedure is shown in the following example cal-
culation.
Given data:
– Canal diameter 300 mm
– Canal-wall thickness 25 mm
– Thickness of the backing material 150 mm
Example calculation for the basic height:
– Canal radius: 300/2 = 150 mm
– Basic height =
canal radius + canal-wall thickness + thickness of
the backing material:
150 mm + 25 mm + 150 mm = 325 mm
– To check the basic height with the laser beam,
mark a reference point on a levelling rod at
325 mm height and bring this point to the height of
the laser beam.
– Afterwards, you can determine the ditch depth by
checking with the levelling rod.
2 610 A13 727 • 13.10.10