Hitachi ZAXIS 135US-5B Operator's Manual page 307

IMPORTANT:
 When connecting hydraulic hoses and pipes, take
special care to keep seal surfaces free from dirt and
to avoid damaging them.
 Wash hoses, pipes, and the tank interior with a
washing liquid and thoroughly wipe it out before
reconnecting them.
 Only use O-rings that are free of damage or defects.
Be careful not to damage them during reassembly.
Do not allow high pressure hoses to twist when
connecting them. The life of twisted hoses will be
shortened considerably.
IMPORTANT:
 Do not use hydraulic oils other than those listed in
the table "Brand names of recommended hydraulic
oil".
 When adding hydraulic oil, always use the same
brand of oil; do not mix brands of oil. When using
another manufacturer's hydraulic oil, be sure to
change the full amount.
 The new machine is filled with hydraulic oil of Super
EX 46HN (change interval: every 5000 hours). When
adding or changing the hydraulic oil, continue to use
the Super EX 46HN.
IMPORTANT: Never run the engine without oil in the
hydraulic oil tank.
MAINTENANCE
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