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MAINTENANCE
METHOD FOR BLEEDING AIR FROM HYDRAULIC CIRCUIT
Cancel the automatic warm-up operation, and start the engine to perform the air bleeding.
NOTICE
•
Bleed air according to the following order.
•
Pump (for work equipment and swing)
•
Work equipment circuit
•
Run the engine at the speed 1000 rpm or less. Operate the cylinder slowly.
•
Do not increase the cylinder pressure by sudden braking operation. Do not operate the cylinder to
the stroke end.
•
Operate the cylinder particularly slowly for the first time of operations of each cylinder (extending
and retracting).
•
The work equipment is not operated for 10 seconds or more at the first operation due to a large
amount of air mixed in the circuit. Do not move the lever to the stroke end.
•
Use clean oil which is NAS 7th grade or higher when it is used to be filled in the pump, etc. Use
clean oil jug as well.
1.
Bleeding air from pump
NOTICE
Oil will spurt out from the air bleeding plug (1) hole if the drain hose is installed first.
Abnormal heat will be generated if the pump is operated without filling the pump case with hydraul-
ic oil. It may cause a premature damage to the pump.
1)
Loosen the air bleeding plug (1) and check that oil
oozes out from the air bleeder (2).
2)
If the oil does not ooze out, remove the drain hose
and the elbow from the pump case, and fill the pump
case completely with the hydraulic oil through the
drain port (3).
3)
After completing the air bleeding operation, tighten the
air bleeder (2) and install the drain hose.
2.
Starting engine
Cancel the automatic warm-up operation, and start the en-
gine. Run the engine at low idle for 10 minutes, and then
start the following work
3.
Bleeding air from cylinder
1)
Run the engine at low idle, and extend and retract
each cylinder 4 to 5 times, taking care that a cylinder
is not moved to the stroke end. (Stop the cylinder ap-
proximately 100 mm short of its stroke end.)
2)
Next, operate each cylinder 3 to 4 times to each
stroke end.
3)
Finally, operate each cylinder 4 to 5 times to the end
of its stroke to completely remove the air.
NOTICE
If the engine runs at high speed immediately after the startup, or if a cylinder is pushed up to its
stroke end, the air mixed into the cylinder may cause damage to the piston packing, etc.
4.
Bleeding air from swing motor (Perform it only when the oil inside the swing motor case is drained.)
k
k
CAUTION
MAINTENANCE PROCEDURE
4-37
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