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Cross level travel and backlash. |
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|  MIL-M-70742 (AR)
dew point of at least -25F. Accuracy of the test equipment
used on this test shall be equal to or exceed the accuracies
depicted on Drawing F8565556.
4.6.1.7 Purging. The counter box area of the mount shall be
flushed with dry nitrogen gas to conform to the requirements of
3.5.7. A dew point tester (standard shop type test equipment)
shall be used to measure the nitrogen dew point for conformance
with 3.5.7. Purging to be performed at standard ambient
temperature and prior to performing temperature test. Pressure of
nitrogen remaining within the counter box area to be between .25
and .5 psi.
4.6.1.8 Rain. The mount shall be subjected to the rain test
outlined in Procedure I of MIL-F-13926. After completion of the
rain test, a visual examination shall be made to determine leakage.
4.6.2 Performance testinq.
4.6.2.1 Orientation. Using test equipment as described in
4.5.3.4, the mount shall be set up and checked for conformance
with 3.6.1.
4.6.2.2 Elevation travel. With the mount and fixture
Positioned as outlined in 4.6.2.1, rotate the mount's elevation
knob to reflect maximum elevation. Note the reading on the
elevation counter. Set this reading into Inspection Aid (Gunner's
Quadrant) A8658940. Position the inspection aid on the quadrant
seat assembly and by means of the fixture elevation handwheel,
relevel the inspection aid. Observe the elevation level bubble of
the mount with respect to the quadrant level vial. Both must
indicate level within the limits outlined in 3.6.2.1. Repeat this
procedure in the opposite direction. Any non-compatibility in
level vial bubble position shall be measured by means of the
quadrant.
4.6.2.3 Correction counter. Rotate the correction counter
knob to indicate that the maximum correction range is within the
limits of 3.4.2.2.
4.6.2.4 Cross level travel and backlash. With the mount
positioned on the fixture as outlined in 4.6.2.1 and with the
auxiliary telescope's sighting device assembled to the mount,
rotate the cant mechanism to full extent of travel. Place the
inspection aid over the appropriate set of pads of the sighting
device and read the cant angle. This reading must be equal to or
exceed the minimum requirement outlined in 3.6.2.3. Repeat this
procedure at the opposite extreme setting. Return the cross
leveling mechanism somewhere between zero and maximum angle and
scribe a line on the casting and cross leveling knob and obtain a
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