Abrams SC-1, Техническое руководство

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DESCRIPTION
pass.
A
spare level
is provided
with
each
instrument
in
case
of
breakage.
c.
Protractor
Plate.
—
The protractor
plate
(item 3)
is
a
round
steel
plate fastened to the gimbal mounting and marked
off
in
one degree
intervals
numbered every
ten degrees,
and
so
arranged
to be
read
in
a
counter-clockwise direction.
A
line
on
the
180
degree to
0
degree
diameter
of
the
protractor
plate
must
be
parallel
to the center-line
of
the vehicle,
with
the
arrowhead pointing
in
the
direction
of
travel. The
protractor is
used
in
setting the azimuth of
a
pre-determined course, or
for
determining in whiqh direction the vehicle is traveling.
d.
Date
Bar.
(1) The date bar (item 4)
is
a
flat
steel
bar mounted at
its
center
on the
pivot bolt.
The
solar plate can
be moved
along
the
date bar. The date bar has
a
center line terminating
in
an
arrowhead
by
which the azimuth is
set on
the protractor.
In
operation, the arrow points true north
if
all
settings on the
instrument have
been
correctly
made.
(2)
There are
a
series
of
date lines engraved on the date bar,
which represent the
10th, 20th, and
last day of
each
month.
These date lines indicate
the
proper position
for
the outside
edges
of
the
solar
plate.
Adjustment of
the
edge
of
the solar
plate in
between
the lines
can be made
for
intermediate
dates.
This
setting compensates
for
the changing angle
of
the sun's
rays ip the earth, as the altitude of
the sun changes
from
day
to day.
FIOUBE
2
—
The Date Bar.
(3)
Along
the outer edges
of the date bar, there are
a
series
of numbers.
These numbers represent the equation of time or
the
amount of time
in
minutes
to be
added or subtracted
from
the
mean
solar time (the time at
that instant
on
the time
3