TM 9-4940-568-34
2-46
Table 2-7. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
5. MAST DOES NOT RAISE OR LOWER (Continued).
Test 1.
Check that tension links are not damaged or seized up.
If damage is not found, and tension links are not seized up, go to Test 2.
If damage is found, or tension links are seized up, replace tension link cylinders.
Refer to paragraph 3-20.
NOTE
If mast does not lower, go to Test 3.
Test 2.
Remove five function control cover. Refer to paragraph 3-31. Disconnect the line that
comes from the extend fitting to the mast 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 MAST control lever to
attempt to raise mast. Slowly close pressure control valve by turning knob clockwise to
INCREASE. Create 3,000 - 3,200 psi (20,684 to 22,063 kPa) working pressure.
If pressure is within specifications, repair or replace erection cylinder. Refer to
paragraphs 3-19 or 6-10.
If pressure is not within specifications, repair MAST control valve/shuttle valve
circuit. Refer to paragraph 3-35. If fault is not corrected, repair or replace erection
cylinder. Refer to paragraphs 3-19 or 6-10.
ERECTION
CYLINDER
TENSION
LINK CYLINDERS
EXTEND
MAST
CONTROL
LEVER
