Komatsu Galeo PC800-8 Shop Manual page 819

40 Troubleshooting
Failure
• Machine deviates in one direction
phenomenon
Relative • Check that the travel speed is normal. (If it is abnormal, carry out the related troubleshooting.)
information • Carry out all the troubleshooting in working mode P.
Malfunction of travel PPC
1
valve
Malfunction of travel
2
control valve (spool)
Possible causes
and standard
value in normal
Defective seal of center
state
3
swivel joint
Low set pressure of travel
4
motor safety valve
Fig. 1 Defective seals in center swivel joint and travel deviation directions
PC800, 850-8
Cause Standard value in normalcy and references for troubleshooting
aPrepare with the engine stopped, then carry out troubleshooting with
the engine at high idle.
FORWARD, REVERSE
Since the spool of the travel control valve may have a malfunction,
check it directly.
aPrepare with the engine stopped, then carry out troubleshooting with
the engine at high idle.
If seal is defective, the machine deviates as shown in Fig. 1.
aPrepare with the engine stopped, then carry out troubleshooting with
the engine at high idle.
(2) Machine deviates in different directions, depending
on its travel direction
Travel lever
Full stroke
Travel lever
Relieved on one side
Travel lever
Relieved on one side
SEN00794-02
PPC valve output pressure
+0.8
2.9 MPa
–0.2
+8
{30 kg/cm }
2
–2
Leakage from swivel joint
Max. 100 cc/min
Travel relief pressure
+1.0
34.8 MPa
–2.0
+10
2
{355 kg/cm }
–20
25