Komatsu PC290LC-11 Operation & Maintenance Manual page 456

HANDLE MACHINE READY FOR INSTALLATION OF ATTACHMENT
Prepare for the maintenance so that it can be performed as follows.
1.
Lower the work equipment to the ground and stop the en-
gine.
2.
Turn the starting switch to ON (B) position.
3.
Set the lock lever to FREE position (F).
4.
Operate each work equipment control lever and attach-
ment control pedal fully to the front, rear, right, and left a
few times within 15 seconds to release the internal pres-
sure in the hydraulic circuit.
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ATTACHMENTS AND OPTIONS