TM 9-4940-568-20
2-168
Table 2-21. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
8. BOOM DOES NOT TELESCOPE OUT WITH REMOTE CONTROL.
NOTE
Before performing crane troubleshooting procedures, make sure the FRS electrical
supply system is functioning properly. Insure that Overload Shutdown System (OSS)
is functioning properly and lockouts are not engaged.
Unless advised otherwise, the FRS 24V MASTER switch and the crane MAIN
POWER switch must be in the ON position for all voltage checks.
Test 1.
Are the boom up and down, and hoist up functions also not working using remote
control?
If none of the above listed functions operate, go to Test 2.
If boom up/down and hoist-up function properly, go to Test 3.
Test 2.
Are the boom up and down, and hoist up functions also not working?
If none of the above listed functions operate, faulty overload shutdown system,
Notify Supervisor.
If boom up/down and hoist-up function properly, faulty lockout solenoid valve,
Notify Supervisor.
Test 3.
Loosen screw and remove connector from telescope OUT solenoid. Place MAIN
POWER and EMERGENCY STOP switches in ON position. Hold remote control
unit telescope controller in OUT position and check for 24 volts between solenoid
connector, terminal 1, and known good ground.
If 24 volts are not present, go to Test 4.
If 24 volts are present, turn MAIN POWER switch OFF and go to Test 10.
Test 4.
Disconnect the remote control cable from the remote control unit and remote control
hook-up connector on crane sub-frame. Check the cable for continuity between the
two cable ends, terminal C.
If no continuity is found on terminal C, replace the remote control cable.
If continuity is found, go to Test 5.
