TM 9-4940-568-34
2-70
Table 2-7. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
12. HOIST DOES RAISE OR LOWER OR RAISES SLOWLY (Continued).
Test 1.
Remove five function control cover. Refer to paragraph 3-31. Disconnect the line that
comes from the hoist raise fitting on the hoist control valve. Install a flow meter in line
between control valve and line. Open pressure control valve fully by turning control knob
counter clockwise to DECREASE. Start FRS. Have assistant operate HOIST control lever
to attempt to raise hoist. Slowly close pressure control valve by turning knob clockwise to
INCREASE. Create 2,550-2,750 psi (17,582-18,961 kPa) working pressure. Check for 12
gpm (45 lpm) flow.
If pressure and flow is within specifications, replace hoist assembly. Refer to
paragraph 3-26.
If pressure and flow is not within specifications, ensure hydraulic pump is working
properly. Refer to paragraph 4-3. If fault is not corrected, adjust relief valve. Refer
to paragraph 3-41. If adjustment will not bring into specifications, replace HOIST
control valve/shuttle valve circuit. Refer to paragraph 3-35.
HOIST
CONTROL
LEVER
RELIEF VALVE
RAISE
BOOM
