TM 9-2320-279-34-1
Troubloshooting Malfunctions (Cont)
Table 2-3. Troubleshooting (Cont)
Malfunction
Test of lnspection
Corrective Action
MATERIAL HANDLING CRANE (M977, M985, M984E1) (CONT)
21.
SWING OPERATION ERRATIC OR SLOW IN ONE DIRECTION ONLY (CONT),
Step 5. Check for defective swing drive brake.
F&move, disassemble, clean, inspect, assemble, and install swing drive brake
(para 17-8 for M977 and M985) (para 17-8.1 for M984E1).
Step 6. Check for defective swing drive motor. Remove swing drive motor (para 17-7 for M977 and
M985) (para 17-7.1 for M984E1). 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, disassemble, clean,
inspect, assemble, and install swing drive motor (para 17-7 for M977 and M985)
(para 17-7.1 for M984E1).
Step 7. Check if swing operation is erratic or slow in one direction only.
Replace swing drive valves (para 17-6 for M977 and M985) (para 17-6.1 for
M984E1).
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