Speed Or Power Of All Work Equipment, Swing, And Travel Are Low - Komatsu Galeo PC138US-8 Shop Manual

SEN02468-01
H-1 Speed or power of all work equipment, swing, and travel are low
Trouble

• Speed or power of all work equipment, swing, and travel are low.

Related
• Conduct the troubleshooting in working mode P.
information
1 Malfunction of unload valve
Defective adjustment or
2
operation of main relief valve
Malfunction of self-pressure
3
reducing valve
Possible causes
and standard
value in normal
state
Defective adjustment or
4
operation of PC valve
Defective adjustment or
5
operation of LS valve
6 Malfunction of servo piston
7 Piston pump defective
6
Cause Standard value in normal state/Remarks on troubleshooting
a
a
Arm relieved in IN direction
If the oil pressure cannot be set normally by adjustment, the main
relief valve may be malfunction or may have an internal defect.
Check the main relief valve directly.
a
a
Pump discharge
PC valve output
If the oil pressure cannot be set normally by adjustment, the PC
valve may be malfunction or may have an internal defect. Check
the PC valve directly.
Pump discharge
LS valve output
If the oil pressure cannot be set normally by adjustment, the LS
valve may be malfunction or may have an internal defect. Check
the LS valve directly.
The servo piston may have malfunction. Check it directly.
If there is none of the causes listed above, the piston pump may
have problems of lowering of performance, malfunction, internal
defect, etc.
Keep the engine stopped for the preparations, and keep it
running at high idle during the troubleshooting.
Control levers
All levers in NEUTRAL
Keep the engine stopped for the preparations, and keep it
running at high idle during the troubleshooting.
Control lever
Keep the engine stopped for the preparations, and keep it
running at high idle during the troubleshooting.
Control levers
All levers in NEUTRAL
Keep the engine stopped for the preparations, and keep it
running at high idle during the troubleshooting.
Measured oil Measurement
pressure conditions
Swing lock: ON
pressure
Arm: Relieved in IN
direction
pressure
Measured oil
All levers in
pressure
NEUTRAL
pressure
Almost same
pressure
pressure
40 Troubleshooting
Unload pressure
2.8 ± 1.0 MPa
{28 ± 10 kg/cm }
2
Main relief pressure
+2.0
34.8 MPa
–1.0
+20
{355 kg/cm }
2
–10
Control circuit basic pressure
3.2 ± 0.5 MPa
{33 ± 5 kg/cm }
2
Oil pressure ratio
1
Approx. 0.6
(Approx. 3/5)
Oil pressure ratio
Bucket curled
(Lever at stroke end)
1
Approx. 0.6
(Approx. 3/5)
PC138US, USLC-8
1