TM 9-2320-279-34-1
TroubleshootingMalfunctions(Cont)
2-7. TROUBLESHOOTING INSTRUCTIONS (CONT).
Table 2-3. Troubleshooting (Cont)
Malfunction
Test or lnspection
Corrective Action
MATERIAL HANDLING CRANE (M977, M985, M984E1) (CONT)
20.
SWING OPERATION SLOW OR ERRATlC IN BOTH DIRECTIONS (CONT).
Step 6. Check for contaminated swing directional control valve.
Remove, clean, inspect, and install directional control valve (para 17-28 for M977
and M985) (para 17-28.4 for M984E1).
Step 7. Check for defective drive motor. Remove motor (para 17-7 for M977 and M985) (para 17-7.1
for M984E1), but do not remove swing drive valve body, swing drive valve hoses and tubes,
or swing drive motor hydraulic hoses and tubes. Operate crane (TM 9-2320-279-10). Operate
SWING control CW or CCW.
If motor binds or there are grinding or rumbling noises, dissemble, clean,
inspect, assemble, and install swing drive motor (para 17-7 for M977 and M985)
(para 17-7.1 for M984E1).
Step 8. Check for defective swing drive brake.
Remove, disassemble, clean, inspect, assemble, and install swing drive brake
(para 17-8 for M977 and M985) (para 17-8.1 for M984E1).
Step 9. Check for defective swing drive.
Remove swing drive (para 17-9 for M977 and M985) (para 17-9.1 for M964E1).
Turn swing drive pinion gear If there is binding, disassemble, clean, inspect,
assemble, and install swing drive (para 17-9 for M977 and M985) (para 17-9.1 for
M984E1).
2-118
