Bucket Moves Slowly Or Lacks Power; Work Equipment Does Not Move In Its Single Operation - Komatsu ecot3 PC300LC-8 Shop Manual

40 Troubleshooting
H-9 Bucket moves slowly or lacks power
Trouble • Speed or power of bucket is low.
Related infor-
• Set the working mode in P-mode before start.
mation
Malfunction of right PPC
1
valve (bucket circuit)
Malfunction of bucket control
2
valve (spool)
Possible causes
Malfunction of bucket control
and standard
3 valve (pressure compensa-
value in normal
tion valve)
state
Malfunction or defective seal
4 of bucket control valve
(safety-suction valve)
Malfunction of LS shuttle
5
valve (service)
6 Defective bucket cylinder
H-10 Work equipment does not move in its single operation
• Boom does not move singly.
Trouble • Arm does not move singly.
• Bucket does not move singly.
Related infor-
• Set the working mode in P-mode before start.
mation
Possible causes
and standard 1 Malfunction of PPC valve
value in normal
state
Malfunction of control valve
2
(spool)
PC300, 350-8
Cause Standard value in normal state/Remarks on troubleshooting
a
Spool of bucket control valve may have malfunction. Check it
directly.
Pressure compensation valve of bucket control valve may have mal-
function. Check it directly.
Safety-suction valve of bucket control valve may have malfunction
or defective seal. Check it directly.
LS shuttle valve of service control valve may have malfunction.
Check it directly.
a
Cause Standard value in normal state/Remarks on troubleshooting
a
Spool of control valve may have malfunction. Check it directly.
Prepare with engine stopped, then run engine at high idle and
carry out troubleshooting.
Bucket lever
Neutral
CURL or DUMP
Prepare with engine stopped, then run engine at high idle and
carry out troubleshooting.
Bucket lever
CURL relief
Prepare with engine stopped, then run engine at high idle and
carry out troubleshooting.
Work equipment lever
Neutral
Operated
SEN02633-03
PPC valve output pressure
2
0 MPa {0 kg/cm }
Min. 2.7 MPa
2
{Min. 28 kg/cm }
Leakage from cylinder
20 cc/min
PPC valve output pressure
2
0 MPa {0 kg/cm }
Min. 2.7 MPa
2
{Min. 28 kg/cm }
1
1
15