Bleeding Air From Hydraulic System - Komatsu PC308USLC-3E0 Operation & Maintenance Manual

MAINTENANCE PROCEDURE

BLEEDING AIR FROM HYDRAULIC SYSTEM

For details, see "STARTING ENGINE (PAGE 3-87)". If it is necessary to refer to the items for starting the engine,
moving the machine off, steering, or stopping, see the OPERATION section.
1. Bleeding air from pump
1) Loosen air bleeder (1) and check that oil oozes out from the
air bleeder.
2) If no oil oozes out, remove the drain hose from the pump
case, and add hydraulic oil through drain port (2) to fill the
pump case.
Oil will come out when the drain hose is removed, so
secure the hose mouthpiece at a position higher than the
level of the oil in the hydraulic tank.
3) After completing the air bleed operation, tighten air bleeder
(1) and install the drain hose.
NOTICE
If the drain hose is installed first, oil will spurt out from bleeder hole (1).
If the pump is operated without filling the pump case with hydraulic oil, abnormal heat will be generated and this may cause an
unexpected damage to the pump.
2. Starting engine
Start the engine, referring to "STARTING ENGINE (PAGE 3-87)".
Run the engine at low idle for 10 minutes after starting, then start operations.
3. Bleeding air from cylinders
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 end of its stroke. (Stop the cylinder approx. 100 mm (3.9 in) short of its stroke end)
2) Next, operate each cylinder 3 to 4 times to the end of its stroke.
3) Finally, operate each cylinder 4 to 5 times to the end of its stroke to completely remove the air.
NOTICE
If the engine is run at high speed immediately after startup or a cylinder is pushed up to its stroke end, air taken inside the cylinder
may cause damage to the piston packing.
4. Bleeding air from swing motor
1) Run the engine at low idling, loosen hose (3) at port S, and
check that oil oozes out from port S hose (3).
NOTICE
Do not operate the swing under any circumstances.
2) If oil does not ooze out, stop the engine, remove port S
hose (3), and fill the inside of the motor case with hydraulic
oil.
3) After completely bleeding the air from the swing motor, tighten port S hose (3).
4) Run the engine at low idle, and slowly swing the upper structure at least 2 times uniformly to the left and right.
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MAINTENANCE