Hitachi ZAXIS 30U-5N Operator's Manual page 220

Bleed Air from Hydraulic System
After changing hydraulic oil, bleed air from the hydraulic
system by following the procedure described below.
Bleed Air from Pump
IMPORTANT: If the engine is started when the pump is
not filled with hydraulic oil, damage to the pump may
result.
1. Connect all hydraulic lines to the hydraulic pump. Fill any
hydraulic components, that can be filled with hydraulic
oil, with as much hydraulic oil as possible at this time.
2. Add hydraulic oil to the hydraulic oil tank to the specified
level.
3. Loosen air bleed plug (1) slightly. Purge air from the
pump casing and suction line. Do not remove as
hydraulic oil may spout out. Tighten air bleed plug (1)
after purging air.
Tightening Torque: 3 0 to 40 N·m (3.0 to 4.0 kgf·m, 22 to
4. Check all line connections for any oil leaks. Set the
engine control dial or lever in the slow idle position.
5. Start the engine. Wait 5 to 10 seconds. Stop the engine.
6. Check the hydraulic oil level at the level gauge located
on the side of the hydraulic oil tank. Add hydraulic oil if
necessary.
7. Restart the engine. Confirm that hydraulic oil level in
the hydraulic oil tank is sufficient. Run the engine for
approximately 1 minute.
8. This is the end of the hydraulic pump air bleeding
procedure.
f
NOTE: If the hydraulic pump is left empty overnight or
longer, be sure to fill the pump with clean hydraulic oil before
performing the air bleeding procedure above.
Bleed Air From Hydraulic Circuits
1. After filling hydraulic oil in the hydraulic oil tank, start
the engine. Evenly operate each cylinder and swing
motor repeatedly for 10 to 15 minutes to purge air from
hydraulic system.
2. Position the machine in the hydraulic oil level checking
position.
3. Stop the engine. Check hydraulic oil level. Add oil if
necessary.
29 lbf·ft)
MAINTENANCE
1
7-40
ZX30U-5N, 35U-5N
1
ZX50U-5N
1
ZX60USB-5N
MADB-07-016
MADB-07-015
MADC-07-011
MADB-07-004