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MAINTENANCE PROCEDURE
BLEEDING AIR FROM HYDRAULIC SYSTEM
For details, see "STARTING ENGINE (PAGE 3-67)". If it is necessary to refer to the items for starting the engine,
moving the machine off, steering, or stopping, see the OPERATION section.
NOTICE
Bleed the air as follows.
1. Pump (work equipment, swing)
2. Work equipment circuit
Run the engine at less than 1000 rpm, and operate the cylinders slowly.
Do not suddenly stop and cause the cylinder pressure to rise or operate to the end of the stroke.
When operating the cylinder for the first stroke (extending and retracting), operate particularly slowly.
When operating the cylinder for the first stroke, there is a large amount of air inside the circuit, so the work equipment will not
move for at least 10 seconds. Be careful not to operate the lever to the end of the stroke.
Use clean oil of NAS7 class or above when filling the pump. Be sure to use a clean oil can.
Bleed the air from the various components in the order below (1 - 6).
1. Bleeding air from pump
1) Loosen air bleed plug (1) and check that oil oozes out from
the air bleeder.
2) If oil does not ooze out, remove the pump case drain hose
and elbow, then fill the inside of the pump case with
hydraulic oil through drain port (2).
If the mouthpiece is lower than the surface of the oil in the
hydraulic tank, oil will flow out from the drain hole when it
is removed, so secure the mouthpiece of the hose at a
position higher than the level of the oil in the hydraulic tank.
3) After completing the air bleed operation, tighten air bleed
plug (1) and install the drain hose.
NOTICE
If the drain hose is installed first, oil will spurt out from plug (1) hole. If the
pump is operated without filling the pump case with hydraulic oil,
abnormal heat will be generated and this may cause premature damage to
the pump.
4 - 34
MAINTENANCE
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