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 189 of 828
TM 9–2350–311–20–2
3–78
3–3
TROUBLESHOOTING — CONTINUED
f.
RAMMER HYDRAULIC SYSTEM
The rammer hydraulic system consists of the rammer, actuating valve, tray assembly, rammer cylinder, main release han-
dle, cylinder handle assembly, cylinder latch, and the blocking valve.
The rammer is used for loading and ramming the projectile into the tube. Hydraulic power from the power pack supplies the
pressure to the rammer cylinder which rams the projectile into position. Normal hydraulic pressure is between 925 to 1225
psi (6378 to 8446 kPa). The rammer actuating valve controls the inflow of hydraulic fluid for the ramming operation and
outflow of hydraulic fluid for the retraction of the rammer after use. The tray assembly holds the projectile in position for
ramming while the cylinder latch locks the rammer cylinder into position on the tray assembly. The rammer cylinder con-
tains a piston which rams the projectile into the chamber. The main release handle releases the locking mechanism so that
the rammer may be moved into RAM position, and also back into STOW position. The cylinder handle assembly provides a
hand hold for rotating the rammer cylinder into ramming position. The blocking valve prevents accidental ramming of ram-
mer in stowed position.
ACTUATING VALVE
BLOCKING VALVE
RAMMER
ASSEMBLY
MAIN
ACCUMULATOR
POWER
PACK
ASSEMBLY
POWER
RELAY
BOX
ASSEMBLY
SLIP RING ELECTRICAL
CONTACT HOLDER
OPERATING
PRESSURE
900 PSI
(6206 kPa)
DRAIN
RESERVOIR
PRESSURE
0 PSI (0 kPa)
PUMP PRES-
SURE
925–1225 PSI
(6378–8446 kPa)
GUNNER’S
SELECTOR
SWITCH BOX
ASSEMBLY
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