SANY Crawler Hydraulic Excavator SY365H-9, SY365BH-9. Shop Manual (2014) - page 29
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Troubleshooting
SY365(B)H-9 Crawler Hydraulic Excavator
H-21 Upper structure overrunning remarkably
Failure information (1)
●
Upper structure overruns remarkably when it stops swinging in
both directions.
Related information
●
Set working mode to S and fuel control dial at position 10 to carry
out troubleshooting.
Possible causes and standard values
Cause
Standard values and troubleshooting references
1
Improper adjust-
ment or malfunc-
tion of swing motor
(relief valve)
●
Stop the engine before troubleshooting. Perform troubleshooting
while the engine is running at high idle.
Swing control lever
Swing relief pressure
Swing relief
25.5~28.5 MPa
{260~291 kg/cm
2
}
If oil pressure does not become normal after adjustment, swing motor
relief valve may have malfunction or internal defect. Check the relief
valve directly.
2
Failure of swing
motor
●
Stop the engine before troubleshooting. Perform troubleshooting
while the engine is running at high idle.
Control lever
Leakage from swing motor
Swing relief
≤
10 ml/min
Failure information (2)
●
Swing acceleration is only poor on one side, or swing speed is
low.
Related information
●
Set the working mode at gear (10) of power mode (S) to perform
troubleshooting.
Possible causes and standard values
Cause
Standard values and troubleshooting references
1
Malfunction of pilot
valve
●
Stop the engine before troubleshooting. Perform troubleshooting
while the engine is running at high idle.
Swing control lever
Pilot valve output pressure
NEUTRAL
0 {0}
Left swing
Right swing
≥
3.5MPa {
≥
36 kg/cm
2
}
2
Malfunction of swing
control valve (spool)
Spool of swing control valve may have malfunction. Check it directly.
3
Defective seal of
swing motor (make-
up valve)
Seal of makeup valve in swing motor may be defective. Check it di-
rectly.
●
Swap the left and right makeup valves and observe the result to
determine whether the seal fails.