David White AL8-26, Owner'S Manual

Page: 9 / 12

-9-
After aligning and focusing the measuring
tool, read the heights at both levelling
rods. Calculate the difference d between
the height
a
1
of levelling rod A and the
height b
1
of levelling rod B .
Example:
a
1
= 1.937m
b
1
= 1.689m
a
1
– b
1
= 1.937m– 1.689m = 0.248m=d
B A
100’
(30 m)
a
1
b
d
1
B A
3’
(1 m)
a
2
b
2
d
350
340
0
10
50
40
30
a
2
– d = b
2
a
1
– b
1
= d
Set up the measuring tool approx. 6 ft (2
m) away from levelling rod A . After aligning
and focussing the measuring tool, read
the height a
2
at levelling rod A .
Subtract the previously calculated value
d from the measured height a
2
in order to
receive the set value for the height b
2
at
levelling rod B .
Measure height b
2
at levelling rod B .
When the measured value deviates by
more than 3 mm (AL8-26) or 2 mm (AL8-
32) from the calculated set value, the
crosshair must be readjusted.
Example:
a
2
= 1.724m
d =0.248m
a
2
– d = 1.724 m – 0.248 m = 1.476m
AL8-26: When measuring, height b
2
must
be 1.476 m ±3 mm.
AL8-32: When measuring, height
b
2
must
be 1.476 m ±2 mm.
Readjusting the Crosshair
B A
100’
(30 m)
a
1
b
d
1
B A
3’
(1 m)
a
2
b
2
d
350
340
0
10
50
40
30
a
2
– d = b
2
a
1
– b
1
= d
Unscrew the eyepiece cover 5 . Using
the adjusting pin 18 , turn adjusting
screw 5 clockwise or anticlockwise,
until the calculated set value for height
b
2
is reached when measuring on
levelling rod B .
Screw on eyepiece cover 5 again.