220.127.116.11 Plumb travel .- With the instrument positioned as outlined
in 18.104.22.168, plumb travel test is performed by sighting through the
collimating telescope toward a plumb line while simultaneously rotating
the pitch knob through full excursion. The line of sight shall not
deviate from the plumb line by more than the thickness of the collimator's
vertical reticle line to assure conformance with 3.5.8.
22.214.171.124 Crosslevel travel (cant).- With the fixture positioned as
outlined in 126.96.36.199, remove "V" block and collimator from mount. Rotate
cant knob to full clockwise position and position inspection aid seated
on a parallel over one of the mount's top surface used in seating mating
panoramic telescope. Angular reading over both surfaces shall be
identical to each other and shall be equal to or exceed the limits
specified in 3.5.3.
188.8.131.52 Backlash (cant) .- This test may be accomplished in conjunction
with the preceding test. Prior to the test, scribe an index line on the
crosslevel knob and a mating index line on the casting in line with the
previous index line. Rotate the knob one turn and reposition both indices
in coincidence. Using an appropriate size parallel, support the inspection
aid on one of the seating surfaces at the top of the mount and level the
level vial. Record this reading and continue to rotate cant knob one half
turn beyond point of coincidence and return to point of coincidence. Do
not override this point of coincidence. Replace the parallel and inspec-
tion aid over the same seating surface and observe level vial bubble.
Reset the level bubble level if necessary, and observe the angular reading.
This reading and the previous reading to be identical within the limits
outlined in 3.5.5. Repeat this check at zero cant and two places each
side of zero cant at zero elevation only.
4.6.2,10 Rigidity.- With the mount positioned as outlined in 184.108.40.206,
sight through collimator telescope and observe where the optical axis
falls upon the target with respect to the intersecting point of target
lines C and D, Figure II. Record this position. Apply the load
tangentially to the mount in the direction of the target. Remove the
load and observe where the line of sight falls with respect to the inter-
secting point of target lines C and D. Apply load in the opposite
direction. Movement, if any, shall be added, total movement not to
exceed the limits specified in 3.5.9. Perform this procedure using
elevation angles listed in Table 11 with zero cant and zero pitch settings
set into the fixture and mount.
220.127.116.11 Azimuth correction.- Prior to performing this test, a
sighting device capable of measuring azimuth correction readings and
having an accuracy equal to or exceed those depicted on Drawing
F10555619 is required.
18.104.22.168.1 The sighting device depicted on Drawing F10555619 is to
be calibrated by setting the reticle's center vertical line parallel to
a plumb line. Parallelism is obtained by rotating Collimator F5549108
between set screws of the sighting device.