Komatsu PC450-8, Operation & Maintenance Manual

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MAINTENANCE
MAINTENANCE PROCEDURE
4-45
BLEEDING AIR FROM HYDRAULIC SYSTEM 4
For details, see “STARTING ENGINE (3-128)“. 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 the oil does not ooze out, remove the drain hose from
the hydraulic pump case and fill the pump case completely
with hydraulic oil through drain port (2).
Hold the removed hose firmly, keeping the mouthpiece
higher than the oil level in the hydraulic tank so that oil will
not spill out of the hose.
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 (3-128)“.
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 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 at least two times uniformly to the left and right. This will automat-
ically bleed the air from the swing circuit.