Komatsu PC88MR-10 Shop Manual page 984

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)
No. Cause
Malfunction of travel
control valve (pressure
compensation valve)
8
(right travel FORWARD
side)
Malfunction of travel
control valve (pressure
compensation valve)
9
(right travel REVERSE
side)
Malfunction of travel
control valve (pressure
compensation valve)
10
(left travel FORWARD
side)
Malfunction of travel
control valve (pressure
compensation valve)
11
(left travel REVERSE
side)
Malfunction of travel
control valve (suction
12
valve)
13 Defective travel motor
14 Defective final drive
40-496
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
Right travel FORWARD hydraulic
pressure
a If only one of right, left, forward, and reverse is abnormal, pressure
compensation valve may malfunction.
Interchange pressure
REVERSE sides, and check whether failure symptom changes.
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
Right travel REVERSE hydraulic
pressure
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
Left travel FORWARD hydraulic
pressure
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
pressure
If relief pressure of only 1 port is low after adjusting relief valve, suction valve
may malfunction.
Check suction valve (check valve) for defects and fatigue of spring.
The travel motor may have a defect in it. Check it.
(It may be checked whether or not the direction of travel deviation changes by
swapping right and left travel motor and final drive assemblies.)
a Check for unusual noise, unusual heat, and metallic powders in drained oil
to make judgment.
relief
compensation valves
relief
relief
Left travel REVESE hydraulic
relief
26.5 ± 1.5 MPa
{270 ± 15 kg/cm 2 }
on FORWARD and
26.5 ± 1.5 MPa
{270 ± 15 kg/cm 2 }
26.5 ± 1.5 MPa
{270 ± 15 kg/cm 2 }
26.5 ± 1.5 MPa
{270 ± 15 kg/cm 2 }
PC88MR-10