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 61 of 790
TM 5--2350--378--24&P
0005 00--2
USING THE HYDRAULIC DIAGNOSTIC CENTER (HDC) SYSTEM TO TROUBLESHOOT
THE M9 HYDRAULIC SYSTEM -- Continued
0005 00
The hydraulic pressure transducers can also fail in two ways; failure to measure any hydraulic pressure (complete
failure) or failure to accurately measure the hydraulic pressure (producing erroneous measurement indications)
and provide an analog voltage back to the HDC Control Box that is outside of the range of acceptable voltages
(outside the 0.5 -- 9.5 V DC range). If “measured” the DC voltage returned to the HDC Control Box from the
pressure transducer is within the acceptable range of 0.5 to 9.5 V DC, regardless of how inaccurate the
measurement may be, the inaccuracy/malfunction cannot be detected by the HDC Control Box as part of the
System BIT.
The HDC System Functional Check--Out addresses many of the HDC System components and fault isolates most
problems/malfunctions associated with those components. For those HDC System solenoid valves and pressure
transducers specified, and those not specifically addressed in the Functional Check--Out, refer to Table 5 to aid in
determining if an HDC System solenoid valve or hydraulic pressure transducer may have failed or malfunctioned,
based on possible consequences and symptoms of a malfunctioning or failed HDC system component.
USE OF THE HDC SYSTEM
The HDC is only used when a problem has been detected (or suspected) in the M9 ACE hydraulic system and
formal troubleshooting of the system is necessary. Before the HDC System is actually used to aid in
troubleshooting the vehicle hydraulic system, the M9 ACE HDC System Functional Check--Out should be
performed to establish the operational readiness of the HDC System. The HDC system is only used when the
vehicle is not moving, the vehicle is in “neutral” and the parking brake is fully engaged.
M9 ACE HDC SYSTEM FUNCTIONAL CHECK--OUT
Purpose:
The purpose of the Functional Check--Out is to ensure that the vehicle and the HDC System are functioning
properly.
Assumptions:
1.
Vehicle relief valve settings have previously been adjusted using a GS--5 pressure gauge, with a tolerance of
+/-- 100 psi (689.4757 kPa).
2.
The accuracy of the HDC system is +/-- 100 psi (689.4757 kPa).
3.
Pressure values within +/-- 200 psi (1378.951 kPa) are considered within specification.
4.
Other vehicle operational characteristics meet the specifications.
Procedure:
The individual tests should be conducted in accordance with this procedure. The HDC System is considered fully
operational when it has passed all of the tests.
WARNING
Before performing any troubleshooting in bowl, move the ejector forward and
disconnect the ejector cylinder from the hydraulic system by pulling the handle down
on ball valve V23, located in the rear of the bowl area, just below the main directional
control valve (DCV) bank. Failure to comply may result in severe injury or death to
personnel.
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