Hitachi ZW 120-6 Operator's Manual page 272

Service Recommendations for Hydraulic Fittings
Two hydraulic fitting designs are used on this machine.
Flat Face O-ring Seal Fitting (ORS Fitting)
An O-ring is used on the sealing surfaces to prevent oil
leakage.
1. Inspect fitting sealing surfaces (6). They must be free of
dirt or defects.
2. Replace O-ring (1) with a new one when assembling
fittings.
3. Lubricate O-ring (1) and install it into groove (3) using
petroleum jelly to hold it in place.
4. Tighten fitting (2) by hand, pressing the fitting joint
together to ensure O-ring (1) remains in place and is not
damaged.
5. Tighten fitting (2) or nut (4) to the torque values shown.
Do not allow hose (5) to twist when tightening fittings.
6. Check for leaks. If oil leaks from a loose connection, do
not tighten fitting (2). Open the connection, replace
O-ring (1) and check for correct O-ring position before
tightening the connection.
Tightening torque:
Tighten fittings to the torque values shown below.
27 mm
Width across flats
N·m
Tightening
(kgf·m)
torque:
(lbf·ft)
MAINTENANCE
36 mm 41 mm 50 mm
(1.1 in) (1.4 in) (1.6 in) (2.0 in)
93 175 205
(9.3) (17.5) (20.5) (33.0)
(68.6) (129.1) (151.2) (243.4)
2
330
7-54
1 4
3
6
M104-07-033
5