5 Checking and adjusting
Checking and adjustment of the circular level
Checking
1. Operate the three levelling screws to center the circular level. Turn the instrument 180°.
No adjustment is necessary if the bubble lines in the center circle. If not, take the following
measures for adjusting.
Adjusting
1. Use the hexagonal wrench to turn the three circular level adjusting screws to center the
bubble by a half that it is out-of-level.
2. Turn the three levelling screws to bring the bubble to the center. Check the instrument
again by turning 180°, and adjustment is satisfactory if the bubble remains at the center. If
not, repeat the adjusting procedure.
Collimation of the instrument
Checking
1. Place levelling rods A and B about 30 to 40 meters away from each other, and set up the
instrument with a tripod almost in the middle between the rods.
2. Use the levelling screws to center the circular level.
3. Sight the rods for A and B reading (a
4. Move the instrument to a position 2 to 3 meters away from point A.
5. Center the bubble again.
6. Sight the rods for reading again (a
7. No adjustment should be necessary if the difference between two pairs of readings is
equal: b
-a
=b
-a
. If not, make the following adjustment.
1
1
2
2
Adjusting
Calculate b
'=a
+ (b
-a
2
2
1
reticule adjusting screw for collimating b'.
Follow "Checking" again, and confirm that the adjustment is satisfactory.
, b
).
1
1
, b
).
2
2
) and apply to the rod farther away. Use adjusting pin to turn the
1
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