MAINTENANCE MAINTENANCE PROCEDURE
4-49
BLEEDING AIR FROM HYDRAULIC SYSTEM 4
For details, see “STARTING ENGINE (3-189)“. If it is necessary to refer to the items for starting the engine, mov-
ing the machine off, steering, or stopping, see the OPERATION section.
Bleed air from the hydraulic system in the following steps.
1. Hydraulic pump (those for work equipment and hydraulically driven cooling fan)
2. Hydraulic motor (those for swing and travel)
3. Swing holding brake circuit
4. Front idler cushion circuit
5. Pilot piping (those for pilot selector valve circuit and main valve PPC circuit)
6. Work equipment circuit
Run the engine at less than 1000 rpm and operate the cylinders slowly.
Do not use sudden stopping and starting to raise the cylinder pressure; do not operate the cylinder to the
end of its stroke.
Be particularly careful to operate slowly for the first operation of each cylinder (return stroke).
When a cylinder is operated for the first time, there is a large amount of air inside the circuit, so the work
equipment will not move for more than 10 seconds. Do not operate the lever fully to make the work equip-
ment move.
Fill the pumps and other equipment with clean oil of NAS 7 class or above, and use a clean container for
the oil.
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