SHANGHAI ESURVEY GNSS CO., LTD.
98
7.2 Tubular Level
To do checking and correction for the tubular level, do the following:
1. Place the instrument on a stable device (such as a tripod or instrument calibration
table), and fix it.
2. Do basic levelling-up.
3. Make the tubular level parallel to a line connecting two of the three foot screws on
the base, and adjust the two foot screws to set the bubble of the tubular level at the
center.
See 3.3 Do Levelling-up for details.
4. Rotate the instrument 180°, and observe if the bubble is at the center of the tubular
level:
o If it is, no correction is required.
o If not, proceed to step 5 ~ 6.
5. When the bubble gets stable, make fine adjustment of the screws by using a
calibration pin, driving the bubble to move half distance toward the center of the
tubular level.
6. Repeat step 3 ~ 5 until the bubble can remain at the center of the tubular level
when the tubular level rotates to any position after accurate levelling-up.
7.3 Circular Level
To do checking and correction for the circular level, do the following:
1. Place and fix the instrument onto a stable device.
2. Use the tubular for accurate levelling-up of the instrument.
See 3.3.2.1 Do Accurate Levelling-up with the Tubular Level for details.
3. Observe if the circular level bubble is centered.
o If it is, no correction is required.
o If not, proceed to step 4.
4. Adjust the three correction screws by using an Allen wrench to make the bubble at
the center of the circular level: