Install guide
ARMY TM 5-6675-308-34
MARINE CORPS TM 08837A-34/2
CHAPTER 5
MATERIEL USED IN CONJUNCTION WITH MAJOR ITEM
5-1. General. The Position and Azimuth Determining
System Test AN/USM-427 is used to test the PADS
computer, CDU, and IMU. Its operation is described in
TM 5-6675-238-14. Marine Corp users shall refer to TM
08839A-14/1
a. The Power Supply Test Set AN/USM-428 is
used to test the PADS power supply and computer
power supply. Its operation is described in TM 5-6675-
309-14. Marine Corp users shall refer to TM 08840A-
14/1.
b. A Wild theodolite T-2 and target set are re-
quired for IMU alignment. Their operation is described
below.
5-2. Theodolite T-2
a. The theodolite T-2, roil-graduated, is used to
measure angles for PADs alignment. The theodolite,
ving only one spindle, is a direction-type instrument.
t has interior scales which are read by a built-in optical
system. The scales, graduated in roils, are readable
directly to 0.002 mil and by estimation to the nearest
0.001 roil. The scales may be illuminated by sunlight or
by a built-in wiring system using artificial light. All
components of the instrument which can be seriously
damaged by dust or moisture are enclosed.
b. The theodolite is used with a canvas accessory
case containing diagonal eyepieces for the telescope and
reading microscope, a sun filter, a jeweler’s screwdriver,
two adjusting pins, a camel’s-hair brush, a plastic instru-
.
ment head cover, two lamp fittings for artificial illumi-
nation a battery case containing lighting devices and
spare bulbs, and a universal tripod with a plumb bob,
plug-in sleeve, and tripod key in a leather pouch at-
tached to the tripod. The accessories of some models of
the theodolite are stored in the base of the carrying
case.
c. Nomenclature of the Theodolite T-2. (See figure
5-1, sheets 1 and
2.)
(1) Ttibach. The tribrach is that part of the
theodolite which contains the three leveling screws and
e circular level. The leveling screws are enclosed and
dustproof. On models manufactured subsequent to
1956, the tribrach is detachable. On these models, the
tribrach is secured to the theodolite by three tapered
locking wedges controlled by the tribrach clamp lever.
An optical plumb system is located in the tribrach for
accurately centering the theodolite over a station.
(2) Horizontal circle housing. The horizontal cir-
cle housing contains the horizontal circle, the vertical
axis assembly, prisms for illuminating and reading the
horizontal circle, contacts and connections for electric
illumination, and three spike feet for securing the
theodolite to the tribrach. The following items are
located on the horizontal circle housing:
(a) Circle-setting knob and cover. The circle-
setting knob, which is located on the side of the hori-
zontal circle housing, is used to rotate the horizontal
circle to any desired position. The cover of the circle-
setting knob is provided to prevent the operator from
disturbing the orientation of the horizontal circle by an
accidental touch. The cover should be closed at all
times except when the horizontal circle is being ori-
ented.
(b) Horizontal circle illumination mirror. A
hinged, tilting mirror to illuminate the horizontal circle
is located on the lower portion of the horizontal circle
housing. The intensity of the light on the horizontal
circle can be adjusted by rotating and tilting the mirror
until the circle is properly lighted. For artificial illumi-
nation, this mirror is removed and replaced by a plug-in
lamp.
(c)
Instrument support lugs.
Three rectangular-
shaped instmment support lugs uniformly spaced
around the base of the horizontal circle housing. These
lugs are used to secure the theodolite to the base of the
carrying case. The plug-in socket, which received the
battery box cable for artificial illumination, is located
immediately above one of the lugs.
(3) Alidade. The alidade is the upper (rotating)
part of the theodolite. It includes the telescope and
microscope assemblies and the two standards that sup-
port them, the vertical circle housing, and the horizon-
tal clamp assembly. Located on the alidade are the
following
(a) U-standard assembly. The U-standard as-
sembly forms the’ support for all the components mak-
ing up the upper part of the instrument and includes
the horizontal circle axle and flange, the circle selector
knob and prism, and the horizontal axis prism.
(b) Levels. The theodolite has a plate level and,
a vertical circle level (split bubble) in addition to the
circular level on the tribrach. The plate level is located
at the bottom of the opening between the standards and
is graduated to aid the operator in the precise leveling
5-1