Hydraulic System; Inspection And Maintenance Of Hydraulic Equipment - Hitachi ZAXIS 120-6 class Operator's Manual

D. Hydraulic System
Inspection and Maintenance of Hydraulic
Equipment
IMPORTANT: Never adjust parts of engine fuel system or
hydraulic equipment.
d
CAUTION: When checking and/or servicing the
hydraulic components, pay special attention to the
following points.
1. Be sure that the machine is parked on a level, firm
surface before servicing hydraulic equipment.
2. Lower the bucket to the ground and stop the engine.
3. Begin servicing hydraulic components only after
components, hydraulic oil and lubricants are completely
cooled, and after releasing residual pressure.
3.1 Before checking and/or servicing the hydraulic system,
be sure to release the residual pressure from the
cylinder circuits of the boom, arm and the bucket,
swing piping and pilot piping. An accumulator can be
installed on some models of this machine as an option
to be capable of moving the front attachment for
specified time (around 10 seconds) after stopping the
engine.
3.2 Bleed air from the hydraulic oil tank to release internal
pressure.
3.3 Immediately after operation, all hydraulic components
and hydraulic oil or lubricants are hot and highly
pressurized. Begin inspection and/or maintenance
work only after the machine has cooled down.
Servicing heated and pressurized hydraulic
components may cause plugs, screws and/or oil to fly
off or escape suddenly, possibly resulting in personal
injury. Hydraulic components may be pressurized even
when cooled.
Keep body parts and face away from the front of plugs
or screws when removing them.
3.4 Even after air pressure in the hydraulic oil tank is
released, when the machine is parking on a slope, the
oil pressure in the travel motor and the swing motor
circuits are maintained at high pressure as the reaction
force of the machine's own weight is constantly
applied to the travel motor. Never check and/or service
the machine while parked on a slope.
MAINTENANCE
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