TM 5-2350-378-23&P
FIELD MAINTENANCE
THEORY OF OPERATION
SCOPE
This section contains information relative to the principles of operation for the hydraulic system and the Hydraulic
Diagnostic Center (HDC). The general functional description of the hydraulic system and HDC is contained in this
section. Field maintenance personnel should be familiar with the principles of operation of these systems before
working on or troubleshooting the hydraulic system. A more thorough understanding of the hydraulic system and
electrical system/HDC integration may be obtained by referring to the interconnecting wiring diagram (FP-17) and
the HDC hydraulic schematic (FP-6).
Components:
HYDRAULIC DIAGNOSTIC CENTER
This component analyzes and diagnoses problems within the M9 ACE vehicle's hydraulic system. Connected to
valves and transducers on manifolds and at components by wiring harness W4, it sends messages to the LED screen
concerning problems it encounters within the hydraulic system. The HDC is stowed in the operator's compartment.
LCD SCREEN
This screen is used to input commands to the unit itself and displays alerts and diagnoses as they become available.
SOLENOID VALVES
The HDC uses twenty electronically-controlled solenoids, as well as three manual valves.
TRANSDUCERS
Thirteen transducers are installed into the hydraulic lines at critical points and remain there. Connected to the HDC
system, they aid in diagnosing any problems the M9 ACE may be having with the hydraulic system.
WIRING HARNESSES
Four wiring harnesses connect the components of the HDS system to the vehicle's hydraulic system. When not in
use, harness W4 is stowed in the operator's compartment.
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