TM 9-2350-256-34-2
Table 2-3. Troubleshooting-Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
HOISTING BOOM CIRCUIT (MAIN HYDRAULIC SYSTEM) - Continued
28. BOOM LIVE OPERATION DOES NOT FUNCTION
Step 1.
Inspect boom limit valve actuating shafts for binding.
Move boom limit valve actuating arm by hand and lubricate shafts. Refer to TM 9-2350-256-10, Medium Recovery
Vehicle, M88A1, for lubrication points.
MAIN WINCH CIRCUIT (AUXILLARY HYDRAULIC SYSTEM)
29. MAIN WINCH WILL NOT OPERATE
Step 1.
Inspect all hydraulic hoses and connections for visible indication 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 lever 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 OPEN position.
WARNING
Test components must be capable of withstanding a working pressure of
1450-1550 psi (step 4 only).
Step 1.
Test for broken drive mechanism or faulty auxiliary hydraulic pump. Disconnect auxiliary hydraulic pump discharge
hose no. 12. Install suitable gage 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 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.
Step 6.
Inspect for faulty check valve in hoses. nos. 4B and 6B. Refer to TM 9-2350-256-20. Medium Recovery Vehicle,
M88A1, for hose identification.
Replace check valve. Refer to TM 9-2350-256-34-1. Medium Recovery Vehicle, M88A1.
NOTE
Perform following tests using main hydraulic system (step 7 only).
Step 7.
Test main winch combination control valve. and control valve. Refer to malfunction 1, steps 10 and 11, in Main Winch
Circuit (Main Hydraulic System).
HOIST WINCH CIRCUIT (AUXILIARY HYDRAULIC SYSTEM)
30. HOIST WINCH WILL NOT OPERATE
Step 1.
Inspect all hydraulic hoses and connections for visible indication 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 lever in AUX position
2-18
Change 7
