TM 9-2350-256-34-2
Table 2-3. Troubleshooting-Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
SPADE CIRCUIT (MAIN HYDRAULIC SYSTEM)
21. SPADE WILL NOT OPERATE
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Step 8.
Attempt operation of main winch, hoist winch and boom
If main winch, hoist winch and boom operate, proceed to step 13. If main winch, hoist winch and boom do not
operate, proceed with step 2.
Inspect mechanical transmission drive shaft.
If not rotating, repair or replace. Refer to TM 9-2350-256-34-1, Medium Recovery Vehicle, M88A1.
Inspect mechanical transmission for broken or restricted hose.
Replace mechanical transmission hose. Refer to TM 9-2350-256-20, Medium Recovery Vehicle, M88A1.
Inspect mechanical transmission output shaft If not rotating, proceed with mechanical transmission clutch
pressure check. Install pressure gage in mechanical transmission clutch pressure line. For location, refer to
TM 9-2350-256-20. Medium Recovery Vehicle, M88A1. With engine operating at 1800 rpm. and power control
valve lever in OS position. normal operating pressure is 150 ± 10 psi.
a.
Remove mechanical transmission and main hydraulic pump assembly. Refer to TM 9-2350-256-34-1. Medium
Recovery Vehicle. M88A1.
b
Replace mechanical transmission. Refer to paragraph 3-16
Test for defective power control valve or restricted hose. Remove hose No. 66 from mechanical transmission. With
mechanical transmission drive shaft rotating. and power control valve lever placed in ON position. oil should flow
from hose.
a.
Replace defective power control valve. Refer to TM 9-2350-256-34-1. Medium Recovery Vehicle. M88A1.
b.
Replace restricted or damaged hose. Refer to TM 9-2350-256-20, Medium Recovery Vehicle. M88A1.
Inspect main hydraulic pump for broken or damaged shaft coupling
a.
Remove mechanical transmission and main hydraulic pump assembly Refer to TM 9-2350-256-34-1, Medium
Recovery Vehicle, M88A1.
b.
Repair or replace shaft coupling. Refer to paragraph 3-16
WARNING
Test components must be capable of withstanding a working pressure of 1950-2050 psi (step 7 only).
NOTE
After performing main hydraulic pump test. return all plumbing to original configuration.
Test main hydraulic pump. Remove check valve and tee between hose no. 4A and 4B. Install main hydraulic
pump pressure tester kit (Item 14, Table 2-1) between hose no. 4A and hose no. 4B. Install test pressure gage in
tee.
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. 44.
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.
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 LO views B and
C. figure 3-22.
Change 5
2-15
