TM 9-2350-256-34-2
Table 2-3. Troubleshooting--Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
HOIST WINCH CIRCUIT (MAIN HYDRAULIC SYSTEM)-Continued
CAUTION
Make sure that the load valve is in full open position before performing test. When performing main hydraulic pump pressure test, do not
restrict oil flow beyond operating pressure.
With main engine operating at 1800 rpm, operating pressure should be 1950-2050 psi when restricting flow using load valve.
After testing, remove hose no. 4B from pump port no. 1. Remove pilot-operated relief and unloading valve assembly from pump port no.
44. Install hose no. 4B on pump port no. 4-1.
With main engine operating at 1800 rpm, operating pressure should be 1950-2050 psi when restricting flow using load valve.
a. Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1. Medium Recovery Vehicle.
M88A1.
b. Replace main hydraulic pump. Refer to paragraph 3-16.
Step 8.
Test for improperly adjusted pilot operated relief and unloading valve. Install test gage in valve gage port. With engine operating at 1800
rpm, and spade in stowed position, place spade combination control valve lever in RAISE position and adjust relief valve.
Adjust relief pressure to 1950-2050 psi. For location of valve gage port, and adjusting screw, refer to views B and C, fig. 3-22.
Step 9.
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 10.
Test combination control valve. Install pressure gage in valve gage port. Remove hose no. 23A from valve, and plug outlet of valve. If no
pressure is indicated on gage when operating hydraulic system, it indicates a faulty combination control valve. Refer to view A, fig. 3-24.
for location of test gage port. Replace and adjust combination valve. Refer to paragraph 3-19 and 3-21.1.
Step 11.
Test control valve. Install pressure gage in combination control valve port no. 21. If no pressure is established on gage when actuating
control valve, but if pressure is established when removing hose no. 23A from control valve and plugging outlet, it indicates a faulty hoist
winch control valve.
Replace hoist winch control valve. Refer to view P, fig. 3-20, and refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
Step 12.
Test for hydraulic motor failure. Remove hose no. 48 from rear of hydraulic motor. A large volume of oil discharged fro
m port when hoist
winch control valve is engaged indicates a faulty motor.
Replace hydraulic motor. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
Step 13.
Inspect system selector valve lever for improper position.
Place system selector valve lever in MAIN position.
Step 14.
Mechanical failure of hoist winch gear train.
a. Remove hoist winch assembly. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
b. Replace hoist winch. Refer to paragraph 3-19.
Change 5
2-10
