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 50 of 828
TM 9–2350–311–20–2
Change 2
1–19
Functional group and part
Number of Variations
How assemblies/parts differ
06
Electrical contact segment
2
Segment ring for vehicle with 3 con-
tact arm assemblies has more attach-
ing hardware than segment ring on
vehicles having 5 contact arm assem-
blies. Also, vehicles with 3 contact arm
assemblies have a segment ring
cover. Vehicles with 5 contact arm as-
semblies have no segment ring cover.
09
Traversing mechanism
2
M109A4/M019A5 howitzers have
modified traversing mechanisms. The
electric clutch has been replaced by a
hydraulic clutch, the brush assembly
has been eliminated, and a clutch
valve replaces it. A different hand-
wheel is also used.
10
Commander’s cupola
2
On earlier design vehicles, the cupola
can be opened from both the inside
and outside. On later design vehicles,
the cupola can be opened only from
the inside. Some earlier design vehi-
cles allow rotation of the cupola by
loosening a ring lock. On later design
vehicles, the cupola can be rotated
by pulling out a latch and by placing
the latch into one of ten notches to fix
the cupola into position.
11
Commander’s seat handle latch
2
Some early design vehicles have a
short handle on the commander’s
seat assembly, and some vehicles
have a long handle.
12
Gunner’s escape hatch
2
On later design vehicles, the escape
hatch is opened by pushing a knob
and turning a handle.
17
NBC system
2
NBC system is provided only on
M109A4 /M109A5 howitzers.
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