points to the howitzers in the field locations.
The M992 features
ammunition handling equipment (AHE), which includes a hydraulically-
operated conveyor, stacker, and projectile rack assemblies which have a
stowage capacity of ninety 155mm projectiles. The M992 has an auxiliary
power unit (APU) that supplies enough power to run the vehicle's
electrical system and a supported vehicle via the use of slave cables and
The APU also powers the primary hydraulic pump which
supplies hydraulic fluid to all hydraulic circuits.
2.
The Primary/backup Hydraulic System.
o The Primary System. The APU drives the primary hydraulic pump
for hydraulic system operations (Fig. 1). The primary hydraulic
pump is capable of delivering 4.5 gallons per minute (gpm) of
flow at a system pressure of 1550 pounds per square inch (psi).
Hydraulic fluid is pumped from the hydraulic reservoir to the
hydraulic control panel.
The hydraulic control panel contains three electro-mechanically
activated directional control valves used to route hydraulic
fluid to the system to be operated (Fig. 2F).
The upper
directional control valve controls the action of the upper rear
door, extending or retracting the actuator to open or close the
upper rear door (Fig. 2F). The center directional control valve
controls the stacker tray's up and down movement (Fig. 2F). The
lower directional control valve controls the forward and reverse
action of the conveyor motor (Fig. 2F).
The hydraulic control panel also incorporates a pressure gage
which indicates primary or backup system pressure.
Locate the
conveyor control switch on the hydraulic control panel.
This
switch actuates the solenoids attached to the conveyor
directional control valve. Locate the rear door switches at the
upper and lower left side of the rear door opening. They actuate
the solenoids attached to the upper rear door directional control
valve.
o The Backup System.
Use a hand hydraulic pump to activate the
hydraulic backup system (Fig. 3F).
Use the selector valve,
located next to the hand pump, to select the mode of operation.
Push the selector valve in to for primary pump operation. Pull
the selector valve out for backup pump operation (Fig. 3F).
When you select the backup pump, put the selector valve out and
pump the handle on the manual pump until the pressure gage
indicates 125 psi minimum to 150 psi
4
OD1703
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