Komatsu PC2000-8 BACKHOE, Operation & Maintenance Manual, Page: 377 / 504

MAINTENANCE
MAINTENANCE PROCEDURE
4-59
BLEEDING AIR FROM WORK EQUIPMENT CIRCUIT
After changing the oil in the hydraulic tank or replacing the line filters, after removing any hydraulic cylinder or work
equipment piping, or after removing any pump or cushion piping, it is necessary to bleed the air from the hydraulic
circuit. When carrying out the air bleed operation after completing the replacement operation, run the engine at
low idling and do as follows.
1. Extend and retract each cylinder 4 - 5 times without operat-
ing it to the end of its stroke [stop approx. 100 mm before
the end of the stroke].
When a cylinder is operated for the first time, there is a
large amount of air inside the circuit, so the work equip-
ment will not move for more than 10 seconds. Do not oper-
ate the lever fully to make the work equipment move.
2. Keep the engine running at low idling and operate each
cylinder from a point 100 mm before the end of the stroke
to extend the cylinder slowly (take at least 10 seconds) to
the end of its stroke, then hold the work equipment control
lever at the full stroke for 3 minutes.
3. Keep the engine running at high idling and operate each
cylinder from a point 100 mm before the end of the stroke
to extend the cylinder slowly (take at least 10 seconds) to
the end of its stroke, then hold the work equipment control
lever at the full stroke for 1 minute.
q
The operation in Steps 1-3 will bleed the air from inside the cylinder.
q
If the engine is run at high speed from the beginning, and the cylinder is operated to the end of its stroke, the
air inside the cylinder may damage the piston packing.