Figure 2-20. Vertical collimation error, adjustment.

TM 5-6675-306-14

STEP 1.

REFER TO FIGURE 2-19 AND CORRECT

HORIZONTAL COLLIMATION IF NECESSARY.

STEP 2.

SIGHT A WELL DEFINED OBJECT WITH THE'

HORIZONTAL CROSSLINE.

COINCIDE THE

COLLIMATION LEVEL BUBBLE BY TURNING THE

COLLIMATION; SLOW--MOTION SCREW. MAKE

THE COINCIDENCE OF THE GRADUATION LINES

AND RECORD THE SCALE READINGS.

STEP 3.

REVERSE THE TELESCOPE POSITION, SIGHT

THE OBJECT.

COINCIDE THE COLLIMATION

LEVEL BUBBLE. MAKE THE COINCIDENCE OF

THE GRADUATION LINES AND RECORD THE

SCALE READINGS.

STEP 4.

THE TOTAL OF THE -10 READINGS, REDUCED BY

360 DEGREES IS TWICE THE COLLIMATION

ERROR.. COMPUTE THE ZENITH DISTANCE AND

SET THE MICROMETER SCALP, AT THE

CORRECT READING.

STEP S.

MAKE THE COINCIDENCE OF THE GRADUATION

LINES.

STEP 6.

COINCIDE THE COLLIMATION LEVEL BUBBLE BY

LOOSENING ONE ADJUSTING SCREW AND

TIGHTENING THE OTHER ADJUSTING SCREW BY

AN EQUAL DEGREE.

Figure 2-20. Vertical collimation error, adjustment.

2-31

Index