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NO
NO
5-10
SWING SPEED IS LOW
2)
Is the trouble in
one direction or
in both direction?
Clogged or oil
leak.
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
NO
YES
Does swing control
valve spool move
smoothly by hand?
Is not pilot piping
clogged or is not
it leaking oil?
Is MCV pilot
pressure within
standard level?
Is gear pump pilot
pressure within
standard level?
Is swing motor's
drain rate within
standard value?
YES
Is MCV pilot
pressure same
on LH and RH
sides?
Is dozer speed
within standard
value?
Cause
Remedy
Swing port relief
valve is faulty.
Swing control valve
spool is stuck.
Pilot valve or shuttle
valve is faulty.
ͽ
Swing control valve
spool is stuck.
;
Ϳ
Swing motor is
broken.
Pilot valve or
shuttle valve is
faulty.
Pilot relief valve
is defective.
Gear pump is
broken.
Main relief valve
faulty.
Hydraulic pump
is broken.
Shuttle valve is
faulty.
Pilot relief valve
is faulty.
Gear pump is
faulty.
Disassemble and
repair or replace.
Disassemble
and repair.
Clean pilot piping
interior or repair
piping.
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair.
Disassemble
and repair.
Clean pilot piping
interior or repair
piping.
Disassemble and
repair or replace.
Disassemble
and repair.
Main relief valve
pressure resetting
or repair.
Disassemble
and repair.
Repair or replace.
Repair or replace.
Repair or replace.
ͽ
;
Ϳ
Check that pilot
piping is not
clogged or oil is
not leaking from
it?
Clogged or oil leak.
Is gear pump
delivering oil?
Does the
symptom change
when LH and RH
pilot hoses are
exchanged?
Is gear pump
output pressure
within standard
level?
Is safety valve
pilot pressure
within standard
level?
Both directions
Single direction
Is main relief valve
setting pressure
normal?
YES
YES
Does swing
control valve
spool move
lightly by hand?