Chapter 1 INTRODUCTION - TM-5-6675-250-340009

TM 5-6675-250-34

CHAPTER

INTRODUCTION

GENERAL

Section I.

1-1. Scope

Form 2028-2 are attached in the back of the manual

for your use. Please mail your recommended changes

This manual is for your use in maintaining the

directly to Commander, U. S. Army Troop Support

Surveying Instrument: Azimuth, Gyro, Lightweight

Command, ATTN: DRSTS-MPP, 4300 Goodfellow

(SIAGL) Model AG-8 Type 1 and Model AG-8A

Blvd., St. Louis, MO 63120. A reply will be fur-

Type 2. Subsequent sections include description,

nished directly to you.

testing, troubleshooting, repair, and procedures

necessary to maintain the equipment in a serviceable

1-4. Equipment Serviceability Criteria (ESC)

condition. Information in this manual is to be used in

This equipment is not covered by an ESC.

conjunction with, information in the Operator and

1-5. Destruction of Army Material to Prevent

Organizational Maintenance Manual, TM 5-6675-

Enemy Use

250-12.

Using an axe, pick, mattox, sledge or another heavy

1-2. Maintenance Forms and Records

implement, damage all vital elements such as the

Maintenance forms, records, and reports that you

theodolite, electronic control unit, gyroscopic

are required to use are DA Form 314, 2400, 2401,

reference unit and battery.

2404 and 2406 (see TM 38-750).

1-6. Administrative Storage

1-3. Reporting of Errors

Administrative storage procedures which are to be

You can help to improve this manual by calling

used by maintenance personnel are described in TM

attention to errors and by recommending im-

740-90-1.

provements. Your letter, DA Form 2028 (Recom-

1-7. Calibration

mended Changes to Publications), and DA Form

Periodic calibration of this equipment is not

2028-2 (Recommended Changes to Equipment

required.

Technical Manuals), may be used. Copies of DA

Section II.

DESCRIPTION AND DATA

1-8. Description

and preorienting the instrument is mounted on top of

the GRU. An adjustable tripod assembly is provided

a. General. The SIAGL is man portable north-

for supporting the unit.

seeking gyroscope capable of determining true north

(1) Internal components of the unit are con-

with extreme accuracy without the assistance of

tained in a cylindrical housing and are discussed in

celestial or landmark sightings. The SIAGL consists

detail in the theory of operation (para. 1-9). Controls

of a gyroscopic reference unit (GRU) with an integral

on the housing are limited to a caging knob; an

theodolite and tripod assembly, an electronic control

uncaged indicator light is located adjacent to the

unit (ECU), a transit case which houses the GRU

knob .

and auxiliary equipment. The complete SIAG1 is

(2) The theodolite contains a magnetic compass

contained in a transport case. The maintenance

for preorientation of the unit to approximately true

paragraphs o f this manual contain detailed

north, a telescope for sighting and focusing, and a

descriptions of its components.

b. Gyroscopic Reference Unit (GRU). The GRU

microscope for reading a 0.02-mil graduated scale.

(fig. 1-1) contains the pendulous gyro, gyro motor,

The theodolite is secured to the GRU housing by

suspension system, follow-up mechanism, and

three screws and is electrically connected through a

components necessary to accomplish the azimuth

cable.

determination operation. A theodolite for reading

1-1