MIL-DTL-48554B
4.8.3 Level travel (azimuth). This test shall be accomplished with the test
procedure of 4.8.1. During the azimuth reading for each 800 mil increment, the position of
the horizontal reticle line of the telescope shall be observed with respect to the zero
elevation line on the target. The telescope reticle shall track the zero elevation line on the
target within the tolerance specified in 3.9.3 for two revolutions of the head.
4.8.4 Lift (azimuth). Position the telescope as specified in 4.4. The azimuth knob
shall be rotated, first in one direction and then in the opposite direction. Lift is indicated if
the line of sight is vertically displaced from the original zero elevation setting upon
direction change of the azimuth knob, and it shall not be greater than the tolerance
specified in 3.9.4 at any azimuth setting.
4.8.5 Five mil click lead mechanism (azimuth). Set the lead actuator knob to
"Direct" and rotate the azimuth knob through one full revolution of the azimuth knob.
During rotation, a tactile examination shall be made to feel the detent action required in 5
mil increments. An audible examination shall be simultaneously performed to listen for a
distinct click resulting from positive detent seating. At no fewer than five readings
throughout the range of operation, the displacement from one increment setting to the next
shall represent a 5 mil angular change within the tolerance specified in 3.9.5. All the above
examinations shall be performed at standard ambient temperature (+60 °F to +90 °F) and
the extreme operating temperatures of 3.3.2 to determine compliance with 3.9.5.
4.9 Backlash.
4.9.1 Azimuth mechanism backlash. The azimuth knob shall first be rotated in one
direction to bring the vertical line of the telescope reticle in coincidence with the azimuth
zero point on the target. Record the reading of the azimuth counter and deflection or
bearing counter. Continue the rotation of the azimuth knob in the same direction, one
complete turn, and then reverse the direction of the knob while sighting through the
telescope and reposition the vertical reticle line of the telescope in coincidence with the
azimuth zero point on the target, without overtravel. Take readings from the azimuth
counter and the deflection or bearing counter then compare them with the original set of
readings; this difference is the amount of backlash in the azimuth mechanism. The
backlash shall not be greater than the tolerances specified in 3.10.1 when checked at 3200
and zero mils.
4.9.2 Elevation mechanism backlash. The test for backlash in the elevation
mechanism may be accomplished concurrently with the tests indicated in 4.7.1 and 4.7.2.
Position the telescope as specified in 4.4. The horizontal reticle line of the telescope shall
be brought into coincidence with the horizontal target line, at zero elevation without
overtravel, when the elevation knob is rotated in a clockwise direction. Scribe a continuous
vertical reference line on the head and elevation knob. Rotate the elevation knob clockwise
to +300 mils, then reverse direction of the knob and align the reference line on the knob
with the reference line on the head without overtravel. Observe, through the telescope, the
position of the telescope reticle on the target. The telescope reticle shall be within the
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