TM 5-2350-378-23&P
0025
Table 4. Possible Symptoms Of Failed HDC System Components - Continued.
HDC SYSTEM
POSSIBLE CONSEQUENCES
Solenoid Valve V17 - Shutoff valve - Apron retract
No hydraulic fluid supply going to (raise) or from
(lower) apron cylinders.
Apron cannot be raised or lowered.
Cannot unload or cannot retain load in bowl.
Solenoid Valve V18 - Shutoff valve - No. 4 actuator, left
STUCK OPEN
suspension port 9 to port 2 (normally closed)
SPRUNG MODE:
Compensating pressure continuously supplied
to left rear actuators 3 & 4.
UNSPRUNG MODE:
Compensating pressure at 2850 psi (19650.06
kPa) continuously supplied to left rear actuators
3 & 4 and right rear actuators 3 & 4. If this is
normal pressure in unsprung mode, there is no
impact.
Solenoid Valve V19 - Shutoff valve - Suspension relief
STUCK OPEN
valve port 17R (normally closed)
SPRUNG MODE:
Compensating pump pressure is directed to
reservoir return.
No hydraulic fluid supply (9) to wheel valves.
No hydraulic fluid supply (9) to actuators.
Vehicle will not be raised.
Track may be thrown if vehicle is backed.
No suspension shock absorbing capability.
UNSPRUNG MODE:
Main accumulator/compensating pump
pressure is directed to right front intermediate
control valve.
Main accumulator pressure is directed to right
front actuator lower side.
No vehicle change in height since raise side
pressure is trapped.
UNSPRUNG MODE-LOWER:
No impact.
UNSPRUNG MODE-RAISE:
Hydraulic fluid supply is directed to return.
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03/15/2011Rel(1.8)root(maintwp)wpno(M10001)
