TM-9-2350-311-20-2
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS
DECEMBER 1993
TM-9-2350-311-20-2 - Page 54 of 828
TM 9–2350–311–20–2
1–23
Cross-level adjustment
±
334 mils
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Incremental reading (counters)
1 mil
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
M42 Tank Periscope:
Height
10–1/4 in. (5.51 cm)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weight
8 lb (3.363 kg)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Length
5–1/2 in. (13.97 cm)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Width
5 in. (12.7 cm)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–17 EQUIPMENT CONFIGURATION
Not applicable.
Section III.
PRINCIPLES OF OPERATION
The purpose of Section III is to familiarize the mechanic with the basic operating capabilities of the howitzer cab. The systems
covered in this section are the armament, fire control, elevating and traversing systems, NBC system, and related components.
This section will provide information needed to understand instructions on how to service, test, and maintain the cab sys-
tems. The functions of each system are presented separately. However, information is also given on how the different cab
systems work together so that the mechanic can understand equipment operation. Separate explanations are given for
cab systems which require both electrical and hydraulic power to operate. Functional diagrams are included to show how
the components of each cab system work together.
1–18 EQUIPMENT OPERATION AND DESCRIPTION
1–18.1
Mount and Howitzer Assembly
A 155 mm cannon assembly is the primary armament for the M109 series howitzer. M185 cannon assembly is used on
M109A2/M109A3/M109A4 howitzers. M284 cannon assembly is used on M109A5 howitzers (para 1–15).
THRUST
COLLAR
MUZZLE
BRAKE
CANNON
TUBE
BORE
EVACUATOR
DUST
SHIELD
UPPER GUN
ROTOR
MOUNT
ASSEMBLY
LOWER
GUN
SHIELD
RECUPERATOR
BEARING
BALLS
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