Komatsu PC88MR-10 Shop Manual page 980

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)
No. Cause
Malfunction of travel
control valve (pressure
compensation valve)
9
(R.H. travel FORWARD
side)
Malfunction of travel
control valve (pressure
compensation valve)
10
(R.H. travel REVERSE
side)
Malfunction of travel
control valve (pressure
compensation valve) (L.
11
H. travel FORWARD
side)
Malfunction of travel
control valve (pressure
compensation valve) (L.
12
H. travel REVERSE
side)
40-492
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
R.H. travel FORWARD hydraulic
pressure
a If only 1 place of right, left, forward, and reverse is abnormal, pressure
compensation valve may malfunction.
Interchange pressure
REVERSE sides, and check whether failure symptom changes.
a If relief pressures of R.H. travel FORWARD and L.H. travel REVERSE are
the same and low, main relief valve of rear pump may malfunction. Check
arm relief pressure additionally.
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
R.H travel REVERSE hydraulic
pressure
If measured values in checks on causes (10) and (11) are the same and low,
main relief valve of rear pump may malfunction. Check arm relief pressure
additionally.
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
L.H. travel FORWARD hydraulic
pressure
If relief pressures of L.H. travel FORWARD and L.H. travel REVERSE are
same and low, main relief valve of front pump may malfunction. Check bucket
relief pressure additionally.
a Be ready with engine stopped, then perform troubleshooting with engine at
high idle.
Travel relief
pressure
If measured values in checks on causes (12) and (13) are same and low,
main relief valve of front pump may malfunction. Check bucket relief pressure
additionally.
relief
compensation valves
relief
relief
L.H. travel REVESE hydraulic
relief
3.48 (+2.0/-1.5) MPa
{355 (+20/-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