TM 9-2320-279-34-1
Troubleshooting Malfunctions (Cont)
Table 2-3. Troubleshooting (Cont)
Malfunction
Test or Inspection
Corrective Action
MATERIAL HANDLING CRANE (M977, M985, M984E1) (CONT)
20. SWING OPERATION SLOW OR ERRATIC IN BOTH DIRECTIONS (CONT).
Step 4.
Check for contaminated or damaged swing drive valves.
Set up hydraulic pressure tester.
Operate crane (TM 9-2320-279-10). Operate SWING control in both directions. Hydraulic
pressure should be within the range shown when operated from turntable stop to turntable
stop.
M977
1600 psi (11 032 kPa) -
1800 psi (12 411 kPa)
M985
1800 psi (12 411 kPa)
-
2000 psi (13 790 kPa)
M984E1
1400 psi (9 653 kPa)
- 1600 psi (11032 kPa)
If pressure is outside of the range shown while at full swing, replace CW or CCW
swing drive valve (para 17-6 for M977 and M985) (para 17-6.1 for M984E1).
Step 5.
Check for defective turntable. Operate crane (TM 9-2320-279-10). Operate SWING control
Watch for any binding and listen for grinding or rumbling noise of turntable when
swinging. Check for damage to swing drive gear or turntable bearing gear.
If binding or noisy, remove, clean, inspect, and install turntable and bearing
(para 17-5 for M977 and M985) (para 17-5.1 for M984E1). If swing drive is damaged
replace (para 17-9 for M977 and M985) (para 17-9.1 for M984E1).
Change 2
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