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3)
SWING MOTION IS IMPOSSIBLE IN ONE DIRECTION
Does swing control
YES
valve spool move?
Is MCV pilot
pressure same
for LH and RH?
See Note 2
Check if pilot
piping is clogged
or does have oil
NO
leakage.
4)
MACHINE SWINGS BUT DOES NOT STOP
Does swing spool
YES
move?
Is swing control
valve's return
spring normal?
NO
YES
Does symptom
change when LH
YES
and RH port
relief valves of
swing motor are
NO
exchanged?
NO
NO
Clogged or oil
leak.
YES
Is MCV pilot
YES
YES
pressure within
standard value?
See Note 2
NO
NO
6-11
Swing port relief
valve is faulty.
Shuttle valve is
faulty.
Swing control valve
spool is stuck.
RCV is faulty.
YES
Pilot relief valve is
faulty.
Is gear pump pilot
pressure within
standard level?
Gear pump is
See Note 1
NO
broken.
RCV is faulty.
Swing spool is
stuck.
Return spring is
faulty.
Cause
Remedy
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair.
Clean pilot piping
interior or repair
piping.
Cause
Remedy
Disassemble
and repair or
replace.
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and replace.
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Table of Contents
Troubleshooting
