TM 9-2350-256-34-2
Table 2-3. Troubleshooting--Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
HOIST WINCH CIRCUIT (AUXILIARY HYDRAULIC SYSTEM) - Continued
CAUTION
When performing auxiliary hydraulic pump pressure test, do not restrict oil flow beyond operating pressure.
Remove auxiliary power unit from vehicle, and replace broken auxiliary hydraulic pump drive mechanism parts, or
faulty auxiliary hydraulic pump. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
Step 5.
Test for faulty or improperly adjusted relief valve within system selector valve. Install pressure gage in system
selector valve gage port. With auxiliary power unit operating, and auxiliary power unit (APU) emergency winch
control valve lever placed in CLOSED position, place system selector valve lever in AUX position, and adjust relief valve.
a. Adjust relief pressure to 1450-1550 psi. For location of valve gage port, and adjusting screw, refer to view D, figure 3-20.
b. Replace system selector valve if pressure cannot be adjusted to 1450-1550 psi. Refer to TM 9-2350-256-34-1, Medium Recovery
Vehicle, M88A1.
NOTE
Perform following tests using main hydraulic system (step 6 only).
Step 6.
Test spade combination control valve, and spade cylinders. Refer to malfunction 21, steps 13, 14 and 15
in Spade
Circuit (Main Hydraulic System).
HOIST BOOM CIRCUIT (AUXILIARY HYDRAULIC SYSTEM)
32. BOOM WILL NOT OPERATE
Step 1.
Inspect all hydraulic hoses and connections for visible indications of oil leaks.
Repair leaks or replace hydraulic hose. Refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
Step 2.
Inspect system selector valve lever for improper position.
Place system selector valve in AUX position.
Step 3.
Inspect auxiliary power unit (APU) emergency winch control valve lever for improper position.
Place auxiliary power unit (APU) emergency winch control valve lever in CLOSED POSITION.
WARNING
Test components must be capable of withstanding a working pressure of 1450-1550 psi (step 4 only).
Step 4.
Test for broken drive mechanism or faulty auxiliary hydraulic pump. Disconnect auxiliary hydraulic pump.; discharge
hose no. 12. Install suitable gate valve, in conjunction with pressure gage, to outlet of auxiliary hydraulic pump.
When restricting oil flow, operating pressure should be 1450-1550 psi.
CAUTION
When performing auxiliary hydraulic pump pressure test, do not restrict oil flow beyond operating pressure.
Remove auxiliary power unit from vehicle, and replace broken auxiliary hydraulic pump drive mechanism parts, or
faulty auxiliary hydraulic pump. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
Step 5.
Test for faulty or improperly adjusted relief valve within system selector valve. Install pressure gage in system
selector valve gage port. With auxiliary power unit operating, and auxiliary power unit operating, and auxiliary
power unit (APU) emergency winch control valve lever placed in CLOSED position, place system selector valve
lever in AUX position, and adjust relief valve.
a. Adjust relief pressure 1450-1550 psi. For location of valve gage port, and adjusting screw, refer to view D, figure 3-20.
b. Replace system selector valve if pressure cannot be adjusted to 1450-1550 psi. Refer to TM 9-2350-256-34-1, Medium Recovery
Vehicle, M88A1.
NOTE
Perform following tests using main hydraulic system (step 6 only).
Step 6.
Test boom combination control valve and flow regulators. Inspect for mechanical failure of boom or hydraulic
cylinder attaching pins. Refer to malfunction 24, steps 13, 14, and 15 in Hoisting Boom Circuit (Main Hydraulic System).
Change 2
2-20
