Hydraulic System; Inspection And Maintenance Of Hydraulic Equipment - Hitachi ZAXIS 17U-2 Operator's Manual

D. HYDRAULIC SYSTEM

Inspection and Maintenance of Hydraulic Equipment

WARNING: When inspecting and/or maintaining
hydraulic equipment, pay special attention to the
following points.
1. Be sure to park the machine on a level, solid surface.
2. Lower the bucket and blade to the ground and stop
the engine.
3. Begin servicing hydraulic components only after the
components, hydraulic oil and lubricants are com-
pletely cooled, and after releasing residual pressure.
3.1 Bleed air pressure from the hydraulic oil tank.
3.2 Each component, hydraulic oil, and lubricant may
be hot and/or pressurized immediately after opera-
tion. Allow the machine to cool down before begin-
ning inspection or maintenance. Failure to do so
may cause burns caused by contact with hot
component and/or oil, or injury by contacting flying
off of plugs and /or screws. Hydraulic components
may be pressurized even when cooled. Keep body
parts and face away from plugs or screws and
slowly loosen them. Remove plugs and screws
only after thoroughly releasing the residual pres-
sure.
3.3 Never attempt to service or inspect the travel and
swing motor circuits on slopes. Even after air
pressure is released from the hydraulic oil tank, the
machine on a slope will create force to pressurize
hydraulic oil in the travel and swing circuit by its
own weight.
IMPORTANT:
Take special care to keep seal surfaces of hy-
draulic components free from dirt and to avoid
damaging them.
• Wash hoses, pipes, tank and their sur-
rounding areas with a washing liquid and
thoroughly wipe it out before reconnecting
them.
• Only use O-rings that are free of damage or
defects. Never carelessly file O-ring seat
surfaces. Do not allow high pressure hoses
to twist when connecting them. Failure to do
so may considerably shorten the service life
of the hoses.
Do not use hydraulic oils other than those
listed in the table "Brand names of recom-
mended hydraulic oil". When adding hydraulic
oil, always use the same brand of oil. Do not
mix brands of oil. When selecting to use an-
other brand of oil, be sure to completely re-
place the oil in the system.
Never run the engine without oil
the hydraulic oil tank.
MAINTENANCE
present in
7-21