H-11 Work Equipment Does Not Move In Single Operation - Komatsu PC88MR-10 Shop Manual

40 Troubleshooting
Troubleshooting of hydraulic and mechanical system (H-
mode)

H-11 Work equipment does not move in single operation

(1) Boom does not move in single operation.
(2) Arm does not move in single operation.
Failure
(3) Bucket does not move in single operation.
Related
Perform all troubleshooting with working mode set in power (P) mode.
information
No. Cause
1 Malfunction of PPC valve
Malfunction of boom
2
control valve (spool)
Malfunction of arm control
3
valve (spool)
Malfunction of bucket
4
control valve (spool)
(Reference) While work equipment is moved in single operation, if pump pressure remains at approximately 4
MPa {approximately 40 kg/cm
is drained to tank through unload valve.)
40-482
Procedure, measuring location, criteria, and remarks
a Be ready with engine stopped, then perform troubleshooting with engine
at high idle.
Work equipment
PPC valve output
pressure
Work equipment
a Release remaining pressure from hydraulic tank and piping, and then
perform troubleshooting with engine stopped.
Check for stuck or seized boom spool in control valve body.
(Spool must move smoothly and must not be caught.)
Remove boom spool from valve body and check it for defects and dirt.
Take care not to let foreign matter enter valve when re-installing spool.
a Release remaining pressure from hydraulic tank and piping, and then
perform troubleshooting with engine stopped.
Check for stuck or seized arm spool in control valve body.
(Spool must move smoothly and must not be caught.)
Remove arm spool from valve body and check it for defects and dirt.
Take care not to let foreign matter enter valve when re-installing spool.
a Release remaining pressure from hydraulic tank and piping, and then
perform troubleshooting with engine stopped.
Check for stuck or seized bucket spool in control valve body.
(Spool must move smoothly and must not be caught.)
Remove bucket spool from valve body and check it for defects and dirt.
Take care not to let foreign matter enter valve when re-installing spool.
}, control valve spool probably stays at NEUTRAL position. (All oil from pump
2
NEUTRAL
control lever
Operation
control lever
(PC88MR-FTC-400-A-Z0-A)
0 MPa {0 kg/cm 2 }
2.65 MPa {27 kg/
cm 2 } Min
PC88MR-10