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 157 of 828
TM 9–2350–311–20–2
3–46
3–3
TROUBLESHOOTING CHART — CONTINUED
d.
ELEVATING SYSTEM
The elevating system consists of a gunner’s selector switch box assembly, assistant gunner’s control assembly, gunner’s
control assembly, selector valve assembly, manual elevating hand pump, equilibration manifold assembly, primary accu-
mulator, secondary accumulator, locking relief and valve, and the equilibrated elevating cylinder.
The gunner’s selector switch box assembly is used to electrically switch between power and manual elevation through the
selector valve assembly. The selector valve assembly allows for the powered elevation control from either of gunner’s
control assemblies. The gunner’s control assembly, hydraulically operates the equilibrated elevating cylinder through the
locking relief and valve.
The equilibrated elevating cylinder can also be operated manually using the manual elevating hand pump at the equilibra-
tion manifold assembly. Hydraulic pressure is supplied by the primary and secondary accumulators and through the equili-
bration lines.
SECONDARY
ACCUMULATOR
PRIMARY
ACCUMULATOR
EQUILIBRATION
MANIFOLD
ASSEMBLY
MANUAL
ELEVATING
HAND PUMP
SELECTOR
VALVE
ASSEMBLY
LOCKING RELIEF
AND VALVE
EQUILIBRATED
ELEVATING
CYLINDER
ASSISTANT
GUNNER’S
CONTROL
ASSEMBLY
(RIGHT)
GUNNER’S CONTROL
ASSEMBLY (LEFT)
GUNNER’S
SELECTOR
SWITCH BOX
ASSEMBLY
POWER
PACK ASSEMBLY
MAIN
ACCUMULATOR
POWER
RELAY
BOX
ASSEMBLY
SLIP RING
ELECTRICAL
CONTACT
HOLDER
OPERATING PRESSURE
900 PSI (6206 kPa)
ELEVATING
SYSTEM POWER,
900 PSI
(6206 kPa)
DRAIN RESERVOIR
PRESSURE, 0 PSI
(0 kPa)
PUMP PRESSURE,
925 TO 1225 PSI
(6378–8446 kPa)
ELECTRICAL
CONTROL
CIRCUIT
EQUILIBRATION
LINES
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