TROUBLESHOOTING H-21
20-538
PC58UU-3
1
H-21 Travel speed or power is low (Work equipment, swing, and
blade operations are normal)
★
If there is any other trouble in the work equipment, see H-1.
1
Cause Remedy
• 26.0
+1.0
-0.5
MPa
265
+10
-5
kg/cm²
• Run engine at full throttle.
Is relief pressure normal?
NO
YES
2
Is pressure at PP oil pressure
pickup port at top of control valve
equal to port pressure?
NO
YES
3
Does merging valve spool move
smoothly and is drilled hole free of
clogging?
NO
Defective operation of
merging valve
Repair or
replace
YES
Defective operation of
logic valve
Repair or
replace
4
• When pump pressure is
below 12.7 MPa {130 kg/
cm²} while traveling on flat
concrete with engine at full
throttle
Is pump pressure normal during
travel?
NO
Large resistance of
travel motor and under-
carriage
Repair or
replace
YES
Large leakage from
travel motor or swivel
joint
Repair or
replace
5
• Above 2.45 MPa {25 kg/cm²}
• Run engine at full throttle.
Is PPC pressure normal (at PPC
pressure inlet of control valve)?
NO
Defective centralized
safety valve
Replace
YES
Defective suction valve
6
Does spool move smoothly?
NO
Defective operation of
spool
Repair or
replace
YES
7
Does pressure compensation valve
move smoothly?
NO
Defective pressure com-
pensation valve
Repair or
replace
YES
8
Does unload valve move
smoothly?
NO
Defective unload valve
Repair or
replace
YES
Large leakage from
travel motor or swivel
joint
Repair or
replace
9
When PPC circuit check valve is
replaced, is travel speed normal?
NO
Defective PPC valve
Repair or
replace
YES
Defective PPC circuit
check valve
Replace
To Next Page
Loading...
Need help?
General
