SANY Crawler Hydraulic Excavator SY195C9, SY205C9, SY215C9, SY225C9. Service Manual - page 31
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Troubleshooting
H-22 Large shock is produced when upper structure stops swinging
Trouble
●
Large shock is produced when upper structure stops swinging.
Related information
●
Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.
Possible causes and standard value in normal
state
Cause
Standard value in normal state/Remarks on troubleshooting
1
Malfunction of swing
pilot valve
●
Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.
Swing control lever
Pilot valve output pressure
"NEUTRAL"
0 {0}
Left swing
Right swing
≥
3.5MPa {
≥
36 kg/cm²}
2
Malfunction of swing
reverse prevention
valve
Reverse prevention valve of swing motor may have malfunction.
Check it directly.
●
Replace the valve with a new on in order to determine whether the
valve fails.
3
Malfunction of swing
relief valve
Swing relief valve may be worn or sluggish.
H-23 High noise is produced when upper structure stops swinging
Trouble
●
High noise is produced when upper structure stops swinging.
Related information
●
Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.
Possible causes and standard value in normal
state
Cause
Standard value in normal state/Remarks on troubleshooting
1
Malfunction of back
pressure valve
Back pressure valve may have malfunction. Check it directly.
2
Malfunction of swing
motor (relief valve)
Relief valve of swing motor may have malfunction. Check it directly.
3
Malfunction of swing
motor (makeup valve)
Seal of makeup valve in swing motor may have malfunction. Check it
directly.
●
Swap the left and right makeup valves and observe the result in
order to determine whether the seal fails.
4
Failure of swing mecha-
nism
The swing mechanism is suspected of an internal failure. Check the
inside of the machinery itself.
●
Internal defect of swing mechanism can be determined with ab-
normal noise, overheat, and metal powder or debris contained in
the oil drained.