TM-5-2350-378-24-P
HYDRAULIC DIAGNOSTIC CENTER (HDC) SUPPORTING ARMORED COMBAT EARTHMOVER (ACE), M9
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST
TM-5-2350-378-24-P - Page 84 of 790
TM 5--2350--378--24&P
0005 00--25
USING THE HYDRAULIC DIAGNOSTIC CENTER (HDC) SYSTEM TO TROUBLESHOOT
THE M9 HYDRAULIC SYSTEM -- Continued
0005 00
NOTE
S
The probability of a stuck solenoid valve is low and would occur after a hydraulic
maintenance test is performed where a solenoid valve was energized (to change
status) as part of a specific test.
S
Numbers in parenthesis (possible consequences) correspond to vehicle hydraulic
line numbers as shown on M9 ACE HDC hydraulic system schematic (FP--1 through
FP--6).
Table 5. POSSIBLE SYMPTOMS OF FAILED HDC SYSTEM COMPONENTS
HDC SYSTEM
POSSIBLE CONSEQUENCES
Solenoid Valve V1--Shutoff valve -- ejector
control valve extend
S
Can’t extend ejector cylinder or can’t retract ejector
cylinder.
S
Can’t dump load or can’t retract ejector to fill load.
S
Can’t fold or unfold apron.
Solenoid Valve V2--Shutoff valve -- No. 1
actuator right front
SPRUNG MODE:
S
No hydraulic fluid return (11) from right front wheel valve.
S
Wheel valve stays in unsprung position.
S
No hydraulic fluid supply (9) to right front actuators 1 & 2.
S
Front right of vehicle will not be raised.
S
Right front of vehicle will drag or bottom out.
S
No suspension shock absorbing capability on right front
side.
UNSPRUNG MODE:
S
No hydraulic fluid supply (11) to right front wheel valve.
S
Wheel valve stays in sprung position.
S
No hydraulic fluid return (3) connection from actuators 1 & 2
to DCV.
S
Undesired hydraulic fluid supply (9) to front right actuators 1
&2.
S
Right front of vehicle is raised to sprung position.
S
Undesired suspension dampening on right front side.
UNSPRUNG--LOWER:
S
No hydraulic fluid supply (17) to front right actuator 1.
S
No hydraulic fluid return (3) from right front actuators 1 & 2.
S
Front right of vehicle will not be lowered.
UNSPRUNG--RAISE:
S
No hydraulic fluid supply (3) to right front actuators 1 & 2.
S
No hydraulic fluid return (17) from right front actuators 1 &
2.
S
Front right of vehicle cannot be raised but is already in
sprung/raised position.
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