MIL-DTL-48556B
4.8.2 Correction counter excursion range. Mount the quadrant on a cross level
fixture in the orientation specified in 4.8. Manually rotate the correction counter knob until
the full excursion has traveled the minimum and maximum limits specified as read on the
"+" and "-" dials of the correction counter.
4.8.3 Elevation accuracy. Mount the quadrant on a cross level fixture in the
orientation specified in 4.8. Use the elevation knob to set the elevation counter to indicate
200 mils depression ("9800" as read on the elevation counter) with backlash removed and
the correction counter indicating 00 mils. Elevate the cross level fixture until the elevation
level vial bubble of the quadrant under testing is centered within the thickness of a
graduation line. Do not overtravel the center position. Measure and record the angular
elevation setting of the cross level fixture. Repeat the above procedure with the elevation
counter set to indicate 0000 mils, 200 mils, 400 mils, 600 mils, 800 mils, 1000 mils, 1200
mils, and 1400 mils elevation. The recorded readings shall indicate the elevation counter
settings within the values specified.
4.8.4 Backlash. Mount the quadrant on a cross level fixture in the orientation
specified in 4.8. Ensure the elevation reading is "0000 mils" and that the backlash has been
removed by turning the knob clockwise to reach the desired elevation setting; if turning the
knob counter clockwise, overtravel the desired setting by at least a half turn of the knob
and come back to it clockwise. Adjust the cross level fixture elevation to center the
quadrant level vial bubble within the width of a level vial graduation line. Measure and
observe the elevation setting of the cross level fixture. Rotate the elevation knob a
minimum of one turn clockwise, and then reset the elevation counter to "0000 mils" by
turning the knob counter clockwise without overtravel of the "0000 mils" setting. Adjust
the cross level fixture elevation to center the quadrant level vial bubble within the width of
a level vial graduation line. Measure and record the elevation setting of the cross level
fixture. Repeat the above procedure with the elevation counter set to indicate 0000 mils,
200 mils, 400 mils, 600 mils, 800 mils, 1000 mils, 1200 mils, and 1400 mils elevation.
The backlash is the difference between the two recorded cross level elevations at each of
the quadrant elevation counter readings, and shall meet the requirements specified.
4.8.5 Cross level vial bubble. Observe the position of the cross level vial bubble of
the quadrant at the elevations checked in 4.8.3. The position of the cross level vial bubble
of the quadrant shall conform to the requirements specified when observed at these
elevations. This test may be done concurrently with 4.8.3.
4.8.6 Correction counter setting effect on elevation counter. Mount the quadrant on
a cross level fixture in the orientation specified in 4.8. Use the elevation knob to set the
elevation counter to indicate 200 mils depression ("9800" as read on the elevation counter)
with backlash removed and the correction counter indicating 00 mils. Elevate the cross
level fixture until the elevation level vial bubble of the quadrant under testing is centered
within the thickness of a graduation line. Rotate the correction counter knob to indicate
"+50" on the correction counter. Observe and record the elevation counter reading. The
elevation counter reading shall decrease by 50 mils within the limits specified. Rotate the
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