MIL-DTL-48557B
4.7.8 Cant adjustment range. Position the mount as specified in 4.7 and mount
sighting device, 10549200, to the telescope mounting surface. Rotate the cant adjustment
to the limit of its excursion in one direction. When at the limit of excursion, place the
inspection aid, 8658940, on the surface of the sighting device and measure the cant angle at
the limit. Repeat in the opposite direction. Cant elevations at the limit shall meet the
requirements of 3.7.8.
4.7.9 Cant adjustment backlash. Position the mount as specified in 4.7 and install
leveling adapter, 10558253-11 on the quadrant mounting surface. Assure that both of the
mount s level vial bubbles are centered. Turn cant knob at least one complete turn counter
clockwise and then center the cant level bubble using only a clockwise motion of the cant
knob without overtravel. Place inspection aid, 8658940, on the leveling adapter, measure
the cant read by the inspection aid and record. Scribe an index line on the mount casting
nearest to the cant knob. Place an index pointer on the cant knob directly opposite the
scribed index line. The index pointer may be held in place mechanically or by the use of
commercial putty. Turn cant knob at least one half turn clockwise and then return it to the
position previously established by the indices in a counter clockwise motion without
overtravel. Place inspection aid on the leveling adapter, measure the cant read by the
inspection aid and compare with initial reading. The difference between these readings is
the backlash and it shall be within the limits specified in 3.7.9.
4.7.10 Mount rigidity. Position the mount as specified in 4.7 and install sighting
device, 10549200, to the telescope mounting surface. Position the wall target shown in
Figure 3 or equivalent, 40 feet from the objective end of the sighting device and align the
plumbed vertical line of the wall target with the reticle of the sighting device. Apply a 20
pound load to the left side of the telescope support, perpendicular to the keyways and 1-2
inches down from the telescope mounting surface. Gradually release the load. Observe
and record the displacement of the vertical line as seen through the sighting device. Apply
a 20 pound load to the right side of the telescope support, perpendicular to the keyways and
1-2 inches down from the telescope mounting surface. Gradually release the load.
Observe and record the displacement of the vertical line as seen through the sighting
device. Repeat the above procedure at elevations of 800 mils, 1100 mils, and 1333 mils.
The total lateral movement of the lines of sight from the vertical line of the target board
shall be within the limits specified in 3.7.10 at the corresponding elevations.
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