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 192 of 828
TM 9–2350–311–20–2
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TROUBLESHOOTING — CONTINUED
g.
CAB POWER SYSTEM
The cab power system consists of the slip ring, contact arm assemblies, and gunner’s selector switch box assembly. The
internal gunner’s selector switch box assembly components that relate to the cab power system are the CAB POWER
switch and the CAB POWER indicator light.
Power is transferred from the hull to the cab through the slip ring and contact arm assemblies. This power is then distributed
by wire 100 directly to various cab systems such as cab lighting and NBC. These systems will operate with the CAB
POWER switch in the OFF position. Other systems receive power through the CAB POWER switch. These systems in-
clude elevating,
cab traversing, and cab hydraulics.
CONTACT ARM
ASSEMBLIES
GUNNER’S
SELECTOR
SWITCH BOX
ASSEMBLY
POWER
RELAY BOX
ASSEMBLY
GUNNER’S SELECTOR
SWITCH BOX ASSEMBLY
POWER
RELAY BOX
ASSEMBLY
POWER
PACK
ASSEMBLY
PRESSURE
SWITCH
CAB
POWER
SWITCH
CIRCUIT BREAKER
100
148
645
104
100
100
645
104
645
TO INTERCOM
SYSTEM
TO CONTACT
ARM ASSEMBLIES
645
645
625A
625A
645
PNABC
EFGH
IJK
LM
NO
D
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