OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

397
for maximumelevation, then to that required for maximum
depression. Note movement of indicator dial, indicating
eccentricity. Adjust as indicated in l(b) until movement
of indicator dial is brought, not necessarily to zero, but
to a minimum. Lock operating shafts feeding into the
subject mechanism.
(c) Vertical alignment of sight station assembly (item l(c)).
Mount a gunner's quadrant on a metal base which is fitted
on its under side with two V-block bearings, and on the
top side with an alignment slot into which the quadrant
can be placed and secured. Scrape V-block bearings so
that when the unit is placed on a truly round bar of uniform
diameter, with the quadrant index set at zero, the
level bubble is at the center of its run. MoUnt a small
cross-level bubble on the V-block bearing base for correctly
positioning the gunner's quadrant in the vertical
plane. Set quadrant scale index to the angle corresponding
to the slope or ·til t of the gun trunnion axis, and
place the quadrant assembly on the extended portion of
the rod which was mounted previously in the telescope
bearings in accordance with item 2(b). Bring bubble to
center of its run by carrying out instructions in l(c).
(d) Alternate methods of alignment for items 2(b) and 2( c).
This method requires the use of a collimator, similar to
that shown on drawing 164343, which should be carefully
centered (optically) after being assembled in a pair of
ball bearings of the same type and accuracy as those used
to mount the telescope in the telescope holder. Set teles-"
cope holder trunnions to as nearly a vertical position as
possible. Place collimator unit in the telescope bearings.
Set up a transit in front of and looking into the collimator
obj ecti v e , Level the transi t. Bring vertical wire in
transi t to vertical crossline in telescope. Elevate or
depress line of sight of the transit telescope so that the
vertical circle reads the same as the measured tilt of the
gun trunnion axis. Sight thru transi t and align sight station
assembly vertically in accordance with item l( c), so
that the collimator crosslines are .m coincidence with
those in the transi t. Rotate telescope bracket to give maximum
eievation and depression. The crossline intersection
in the telescope should remain on that of the transit, or
within reasonable limits. Corrections, if deemed necessary,
may be made.
(e) Commonali@ment of sights. - Check common alignment of
sights when set for maximumdeflection. Set center line of
each sight on its properly bore sighted and not too near target,
with elevation zero. Set lines of sight of the telescopes
10 0 to right. Train turret 10 0 to left. Each line