Hyundai HX145LCR Manual page 374

2) 2) BOOM, ARM OR BUCKET SPEED IS LOW BOOM, ARM OR BUCKET SPEED IS LOW
YES
Is speed low only
in composite
operation?
Are LH/RH travel
speeds within
NO
standard levels?
Is MCV pilot
ⓐ
pressure within
standard level?
See Note 3, 4
Is pilot pressure
ⓑ
within standard
level?
See Note 1
AIs engine
ⓒ
revolution within
standard level?
Is not orifice in
ⓓ
main control
valve clogged?
YES
Is combination
of oil streams
YES
normal at boom
up and at arm
extrusion?
NO
YES
Are both LH/RH
travel speeds
NO
low?
NO
YES
Does control
YES
valve spool
move ?
See Note 7
NO
YES
Is not MCV pilot
pressure piping
clogged or is not
NO
there oil
leakage?
NO
YES
NO
Is gear pump
delivering oil?
NO
NO
YES
YES
Is pilot piping
clogged or is oil
leaking from the
NO
piping?
NO
6-19
YES
ⓐ
Are other
attachment
speeds within
ⓑ
standard levels?
NO
YES
Does spool of flow
summation check
valve move lightly
Flow summation
by hand? NO
check valve is
stuck.
Hydraulic pump is
faulty.
YES
ⓒ
Is MCV pilot
pressure within
standard? ⓓ
NO
See Note 3, 4
OK
Does the
Port relief valve is
symptom change
faulty.
when port relief
valve is replaced
Cylinder is faulty.
with other valve?
NO
MCV spool is
stuck.
RCV is defective.
Pilot relief valve is
faulty.
Gear pump is
broken.
Is RCV normal?
RCV is faulty.
NO
Cause Remedy
Normal.
Replace spring
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair or
replace.
Disassemble
and repair.
Disassemble
and repair.
Clean pilot
piping interior or
repair piping.
Disassemble
and repair.
Disassemble
and repair or
replace.
Disassemble
and repair.
Adjust engine
revolution.
Clean orifice in
control valve.
Clean pilot
piping interior or
repair piping.
Disassemble
and repair.