compass clamp screw (1).
(3) Secure the compass circle in place by
releasing the compass caging knob (para 2-8).
( 4 ) Remove compass needle screw (2, fig. 3-9)
f r o m sleeve (3) in the bottom of compass base (1)
b y turning it in a counterclockwise direction.
(5) Remove the
two machine screws that
secure the eyepiece
to the compass housing.
Remove the eyepiece.
b . Cleaning, Inspection, and Repair. C l e a n a l l
exterior parts of the compass with a cloth moistened
with an approved cleaning solvent. Clean the
e y e p i e c e lens with a camel hair brush (5, fig. 2-7)
and lens tissue. Inspect the compass housing,
holder, clamp screw, caging knob, and eyepiece
housing for bends, breaks, and worn or badly
damaged threads. Replace a badly worn compass
needle screw. Report all other defects to direct
support maintenance.
c . Installation.
(1) Install the eyepiece in reverse order of
removal.
(2) Install compass needle screw (2, fig. 3-9) in
1.
Compass
base
sleeve (3) located in the bottom of the compass base
2.
Compass
needle
screw
( 1 ) . Secure the screw by turning it in a clockwise
3.
Sleeve
direction.
F i g u r e 3-9. C o m p a s s
needle
screw,
removal
points.
( 3 ) Release the compass circle by tightening
3-32. Compass Assembly
the compass caging knob (para 2-8).
a.
Removal.
(4) Release the compass housing from the
( 1 ) Remove two machine screws (4, fig. 3-2)
l o c k e d position with the clamp screw (1, fig. 2-1).
which secure compass holder (2, fig. 1-3) to the
(5) Aline the compass assembly and the
a l i d a d e , and remove compass assembly (2, fig. 2-1)
compass holder on the alidade and secure with the
from alidade.
two machine screws (4, fig. 3-2).
(2) Lock the compass housing in place with the
Section
XIII.
CIRCULAR
AND
PLATE
LEVELS
3-33. General
3 - 3 4 . Circular and Plate Levels
The circular level, located on the tribrach, is used to
Clean the circular level (8, fig. 1-1) and plate level
(6, fig. 2-3) with a cloth moistened with an ap-
bring the theodolite into rough level during in-
proved cleaning solvent. Inspect the vials for
stallation. The plate level, located in the lower
c r a c k s , etchings, and an old (jump) bubble. Inspect
center of the alidade, is used for more accurate
the vial cover for cracks, splits, scratches, and wear.
l e v e l i n g during installation.
R e p o r t all defects to direct support maintenance.
Section
XIV.
ALlDADE
AND
OPTICAL
PLUMB
ASSEMBLY
assembly, with a soft cloth moistened in an ap-
General
proved cleaning solvent. Dry and polish with a
The alidade is the upper part of the theodolite,
clean, soft, dry cloth. Be sure not to get any of the
i n c l u d i n g the telescope and microscope assemblies,
solvent on the lens assembly. Brush any dust or
and the vertical circle assembly. The optical plumb
loose dirt from the alidade with a camel hair brush
assembly is mounted through the lower part of the
( 5 , fig. 2-7). Inspect the alidade for bends, dents,
alidade, a n d e x t e n d s d o w n w a r d t h r o u g h t h e
c r a c k s , and missing or damaged hardware. Report
h o r i z o n t a l circle and inner base housing assembly.
a l l defects to direct support maintenance.
Alidade
Carefully
clean
the
alidade,
except
the
lens
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