4.6.14 Excursion range (elevation mechanism).- With the line of
sight established in accordance with 18.104.22.168, elevation and depression of
the prism in the rotating head by means of the elevation knob shall cause
the line of sight to displace the amount specified in 22.214.171.124 for elevation
and depression, This test can be accomplished by using a target collimator
(or a wall target) that has an established level line of sight and the
excursion limits required.
4.6.15 Plumb travel.- This test can be performed concurrently with
4.6.14. The telescope shall be in a level position with the vertical
reticle line brought into coincidence with the vertical target line by
rotating the azimuth knob. The horizontal reticle line of the telescope
shall be in coincidence with the horizontal target line by rotating the
elevation knob. Rotate the elevation knob to elevate the line of sight
of the telescope 300 mils. Reserve the rotation of the knob to depress
the line of sight to 300 mils depression. Reverse the rotation again,
returning the line of sight to zero elevation. The vertical reticle line
of the telescope must track the target line within the tolerance specified
4.6.16 Backlash (elevation) .- The test for backlash in the elevation
mechanism shall be accomplished concurrently with the tests indicated in
4.6.14 and 4.6.15. 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. The zero line on the knob and the index line on the rotating
head shall be set in alignment with each other, Rotate the elevation knob
clockwise to 300 mils, then reverse direction of the knob and align the
zero line on the knob with the index 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 tolerance specified
in 3,8.1.3 of the zero level line on the target. This test shall also
be conducted in the counterclockwise direction.
4.6.17 800 Mils steps.- Position the test equipment to zero azimuth.
Set the telescope azimuth and reset counters to 3200 (zero) and the gunner's
aid counters to zero. The vertical line on the reticle of the telescope
shall be coincident with the vertical line on the target, and the horizontal
line of the reticle shall be coincident with the zero elevation line.
Azimuth readings shall be made at 800 mil increments through two full
revolutions in each direction. The error in the readings taken shall not
exceed the tolerance specified in 126.96.36.199 including backlash.
188.8.131.52 Level travel.- This test shall be accomplished with the test
procedure of 4.6.17. 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 184.108.40.206 for at least one full revolution in