Komatsu ecot3 PC300LC-8 Shop Manual page 376

SEN02625-06
Pump Actuator
(Unload)
Service
Boom Hi Arm Hi F main relief valve
Front
Bucket
pump
L.H travel
Boom Lo
Swing
Rear
R.H travel
Arm Lo
pump
(Unload)
3.
Measurement of unload pressure
1) Start the engine.
2) Measure hydraulic oil pressure, when the
engine is running at high idle and all the
control levers are moved to the NEUTRAL
position.
a Hydraulic oil pressure when the unload
valve unloads is displayed.
4. Measurement of work equipment relief pres-
sure
1) Start the engine and move the cylinder to be
measured to its stroke end.
2) Measure hydraulic oil pressure when the
cylinder is relieved while the engine is
running at high idle.
a Except when the boom LOWER is select-
ed, the pressure at which the main relief
valve was relieved is displayed.
a Except when the boom LOWER is select-
ed, releasing the power max. switch intro-
duces the low-pressure relief pressure
and pushing this switch introduces the
high-pressure relief pressure.
a Except when the boom LOWER is select-
ed, keep the swing lock switch in the OFF
position during the inspection. If it is
moved to the ON position, hydraulic oil
pressure is turned to high relief pressure,
as the constant 2-stage relief valve is
moved to the ON position.
a When the boom LOWER is selected, the
pressure at which the safety valve was re-
lieved is displayed.
36
Valve to be relieved
F unload valve
Safety valve
F main relief valve
F main relief valve
RAISE: R main relief valve
LOWER: Safety valve
Swing motor safety valve
R main relief valve
R main relief valve
R unload valve
a When the boom LOWER is selected, the
relief pressure is lower than the main re-
lief pressure.
a When the boom LOWER is selected,
turning off the machine push-up switch in-
troduces the low-pressure relief pressure
and turning it on introduces the high-pres-
sure relief pressure.
5. Measurement of swing relief pressure
1) Start the engine and move the swing lock
switch to the ON position.
2) Measure hydraulic oil pressure when the
engine is running at high idle and the swing
circuit is relieved.
a Hydraulic oil pressure when the swing
motor safety valve is relieved is dis-
played.
a The relief pressure of the swing motor is
lower than the main relief pressure.
6. Measurement of travel circuit relief pressure
1) Start the engine, and lock the travel.
k
Insert pin [2] between the sprocket and
the track frame to positively lock the
travel circuit.
2) Measure the pressure when the engine is set
to high idle and the travel circuit is relieved.
a Hydraulic oil pressure with the main relief
valve in relief condition is displayed. In
the travel circuit relief, the pressure is
high pressure relief all the time.
30 Testing and adjusting
PC300, 350-8