TM 9-4940-568-34
2-62
Table 2-7. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
9. BOOM DOES NOT TELESCOPE OUT OR IN (Continued).
Test 1.
Remove five function control cover. Refer to paragraph 3-31. Disconnect the line that
comes from the telescopic cylinder extend fitting on the telescopic 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
TELESCOPE control lever to attempt to extend boom. 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 boom telescopic cylinder.
Refer to paragraph 3-15 or 6-11.
If pressure is not within specifications, repair telescope control valve/shuttle valve
circuit. Refer to paragraph 3-35. If fault is not corrected, repair or replace boom
telescopic cylinder. Refer to paragraph 3-15 or 6-11.
TELESCOPE
CONTROL
LEVER
EXTEND
