Hydraulic System; Inspection And Maintenance Of Hydraulic Equipment - Hitachi EX27U Operator's Manual

D. HYDRAULIC SYSTEM
INSPECTION AND MAINTENANCE OF HYDRAULIC
EQUIPMENT
CAUTION: During operation the parts of the hy-
draulic system become very hot.
Allow the machine to cool down before beginning
inspection or maintenance.
1. Be sure that the machine is parked on a level, solid
surface before servicing hydraulic equipment.
2. Lower the bucket and blade to the ground and stop
the engine.
3. Begin servicing hydraulic components only after
components, hydraulic oil and lubricants are com-
pletely cooled, and after releasing residual pressure.
a. Bleed air from the hydraulic oil tank to release
internal pressure.
b. Allow the machine to cool down.
Note that servicing heated and pressurized hy-
draulic components may cause hot parts and/or
oil to fly off or escape suddenly, possibly resulting
in personal injury.
c. Keep body parts and face away from plugs or
screws when removing them.
Hydraulic components may be pressurized even
when cooled.
d. Never attempt to service or inspect the travel and
swing motor circuits on slopes. They are highly
pressurized due to selfweight.
4. When connecting hydraulic hoses and pipes, take
special care to keep seal surfaces free from dirt and
to avoid damaging them. Keep these precautions in
mind:
a. Wash hoses, pipes, and the tank interior with a
washing liquid and thoroughly wipe it out before
reconnecting them.
b. Only use O-rings that are free of damage or de-
fects. Be careful not to damage them during re-
assembly.
c. Do not allow high pressure hoses to twist when
connecting them. The life of twisted hoses will be
shortened considerably.
d. Carefully tighten low pressure hose clamps.
5. When adding hydraulic oil, always use the same
brand of oil; do not mix brands of oil. As the machine
is filled with New Landy HN when it is shipped from
the factory, use it as a general rule. When selecting
to use another brand of oil listed in the table "Brand
names of recommended hydraulic oil", be sure to
completely replace the oil in the system.
6. Do not use hydraulic oils other than those listed in the
table "Brand names of recommended hydraulic oil".
7. Never run the engine without oil in the hydraulic oil
tank.
MAINTENANCE
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