Hitachi ZAXIS 17U-5N Owner's Manual page 129

ZX26U-5N
Releasing Overload Relief Valve
• If the front attachment is not loaded
d
WARNING: Loosen overload relief valve slowly. If it is
loosened rapidly, the boom may also lower rapidly. Do
not loosen it more than 3/4 turns, as the hydraulic oil
may spout.
1. Loosen the overload relief valve slowly by checking the
movement of boom.
2. After checking that the boom is completely lowered,
tighten the overload relief valve.
Tightening Torque: 60 to 70 N·m
• If the front attachment is loaded
1. Put the matching marks on lock nut in overload relief
valve and adjusting screw in the boom raise circuit
(cylinder bottom side).
d
WARNING: Loosen the adjusting screw slowly. If it is
loosened rapidly, the boom may also lower rapidly.
2. Loosen the lock nut. Loosen adjusting screw slowly by
checking the movement of boom.
3. After checking that the boom is completely lowered,
align the matching marks and tighten the lock nut.
Torque: 28 to 32 N·m
(2.8 to 3.2 kgf·m, 20 to 23 lbf·ft)
OPERATING THE MACHINE
(6 to 7 kgf·m, 44 to 52 lbf·ft)
5-23
Overload Relief Valve in Boom
Raise Circuit
MABA-05-011
Valve Body
Adjusting screw
Lock Nut
T152-03-03-015