Komatsu Galeo PC800-8 User Manual

14 PC800, 850-8
SEN00794-02 40 Troubleshooting
H-5 Boom speed or power is low
Failure
phenomenon
• Boom speed or power is low
(1) The boom speed or power is low in the normal
mode.
Relative
information
• The normal mode is the state that the heavy lift switch, swing priority switch, and machine push-up
switch are turned OFF.
• Check that the other work equipment, travel, and swing are normal. (If any of them is abnormal, carry
out troubleshooting related to it.)
• Check that the machine does not deviate. (If it deviates, carry out troubleshooting related to deviation.)
• When carrying out the following troubleshooting, set the working mode in the P-mode.
• Before carrying out troubleshooting, check that electric circuit related to boom control is normal.
Possible causes
and standard
value in normal
state
Cause Standard value in normalcy and references for troubleshooting
1
Malfunction of right PPC
valve (Boom circuit)
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Right work equipment control lever PPC valve output pressure
Boom RAISE/LOWER stroke end
2.9 MPa
{30 kg/cm
2
}
2
Malfunction of swing
priority solenoid valve
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Swing priority switch and
right work equipment control lever
Solenoid valve outlet pressure
Swing priority switch OFF +
Lever in neutral
0 MPa {0 kg/cm
2
}
Swing priority switch ON +
Boom RAISE operation
2.9 MPa
{30 kg/cm
2
}
3
Malfunction of boom
control valve (spool)
The spool of the boom control valve (Lo, Hi) may malfunction. Check it
directly.
4
Malfunction of boom
control valve
(Safety-suction valve)
The safety-suction valve of the boom control valve (Lo) may malfunc-
tion. Check it directly. (When checking the safety-suction valve by
exchanging it with a valve of another work equipment circuit, stop the
hose of the machine push-up solenoid securely. After finishing check, be
sure to return the safety-suction valve since its set pressure and struc-
ture are different from others.)
5
Boom control valve
(control valve unit)
defective
The control valve unit of the boom control valve (Lo, Hi) may be defec-
tive. Check it directly.
6
Boom cylinder seal defec-
tive
aKeep the engine stopped for the preparations, and run it at high idle
during troubleshooting.
Right work equipment control lever Leakage from cylinder
Boom RAISE relief Max. 20 cc/min
+0.8
–0.2
+8
–2
+0.8
–0.2
+8
–2

Komatsu Galeo PC800-8 Specifications

General

Brand	Komatsu
Model	Galeo PC800-8
Category	Excavators
Language	English