AccuLine 40-6926 Instrukcja obsługi - Strona 7

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AccuLine 40-6926 Instrukcja obsługi
1316H-English
7/10/08
9:45 AM
Page 7
5.3 Line-of-Sight
The line-of-sight needs to be horizontal within 3mm of level to be accurate.
Set up and level the instrument on a tripod midway between two
leveling rods set approximately 100 ft. to 160 ft. (30m to 50m) apart.
Sight rods A and B; the height readings are a1 and b1 (Fig. 7). The
value "H" is equal to (a1 - b1). Move the instrument to within 6 ft. (2m)
of rod A and re-level. Again sight rods A and B; these height readings
are a2 and b2 (Fig. 8).
Fig. 7
Fig. 8
If a1 - b1 = a2 - b2 = H, the line-of sight is horizontal. If not, the level
should be adjusted as follows.
Because the instrument is set halfway between A and B, any error in the
line-of-sight causes both readings to be erroneous by the same amount.
Error e cancels out, so the value a1 - b1 = H is correct. Therefore,
a2 - H = b3, the adjusting value.
Fig. 9
To adjust, unscrew the eyepiece cover.
Turn the adjusting screw with the
adjusting pin (Fig. 9) until the horizontal
cross hair gives the reading b3 on rod B.
Repeat the above procedure until
{(a1 - b1) - (a2 - b2)}
3mm.
©2008 Johnson Level & Tool
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