Engine Speed Lowers Remarkably Or Engine Stalls - Komatsu Galeo PC800-8 Shop Manual

SEN00794-02
H-2 Engine speed lowers remarkably or engine stalls
Failure

• Engine speed lowers remarkably or engine stalls

phenomenon
Related • Set the working mode in P-mode when troubleshooting is carried out.
information • If a failure code relating to the pump control is displayed, carry out the troubleshooting for it first.
Defective pump EPC
1
current output
Possible causes
and standard
value in normal
state
Defective actuation of
2
pump EPC solenoid valve
Malfunction of pump VC
3
valve
4 Defective engine itself
Table 1 Judgment table
Operation mode
EPC valve output pressure
(Pce1 (Pce2))
(VC valve control pressure)
MPa {kg/cm 2 }
Servo piston position
Judgment value of VC valve
output pressure (Pce1 (Pce2))
(Servo piston large-diameter
pressure)
*1. Since the swash plate is at the intermediate point, the pressure is about "0.5 – 0.6 times" (approx. 1/2 of) the relief pressure (discharge
pressure).
10
Cause Standard value in normalcy and references for troubleshooting
aPrepare with engine stopped, then run engine at high idle speed and
carry out troubleshooting.
When traveled with idle turns
(the lever to the stroke end)
aPrepare with engine stopped, then run engine at high idle speed and
carry out troubleshooting. (Make sure that failure cause 1 is normal
before troubleshooting.)
When traveled with idle turns
(the lever to the stroke end)
Refer to table 1
If causes 1 – 3 are not the cause of the trouble, the engine itself may
have failed. Troubleshoot the engine (in the S-mode).
All levers in neutral
Max. 0.78
{Max. 8}
Contact with stopper on min.
swash plate angle side
Approx. 1/2 of basic pressure C
1/2 Pch1 (Pch2) to
Pch1 (Pch2)
Control lever
All levers in neutral
Control lever
All levers in neutral
Boom circuit relieved in raising
operation (With heavy lift OFF)
1.03 – 1.43
{10.5 – 14.5}
Intermediate between min. and
max. swash plate angles
Approx. 1/2 of basic pressure
(C 1/2 x Pch1 (Pch2)) *1
40 Troubleshooting
EPC current of the pump
265 ± 50 mA
575.5 ± 50 mA
EPC solenoid valve output
pressure
Max. 0.78 MPa {Max. 8 kg/cm
Min. 1.23 MPa
{Min 12.5 kg/cm 2 }
Track running with no load
(Lever at stroke end)
Min. 1.23
{Min. 12.5}
Contact with stopper on max.
swash plate angle side
Approx. 1/2 of basic pressure
to drain pressure C
1/2 Pch1 (Pch2) to Pd
PC800, 850-8
2 }