Hitachi ZAXIS 135US-6 class User Manual

TROUBLESHOOTING
11-4
Hydraulic System
When the machine is stored without operation, air mixed in hydraulic oil will become separated and will accumulate
in the cylinder upper sections, causing a delay in the response time of the machine movement or weak power
development.
In case these symptoms appear, repeatedly operate all actuators several times.
Problem Cause Solution
No hydraulic Functions
(Noise from pumps)
Faulty hydraulic pump * Repair or replace
Lack of hydraulic oil Refill
Broken suction pipe and/or hose * Repair or replace
No hydraulic Functions
(Hydraulic pump noise remains
unchanged.)
Faulty pilot pump * Replace
Faulty pilot shut-off solenoid valve * Replace
Faulty wire harness (pilot shut-off solenoid
valve) pilot shut-off switch.
* Repair or replace
The pilot control shut-off lever is in the LOCK
position.
Turn it to the UNLOCK Position.
All actuators have no power. Malfunction due to worn hydraulic pump * Replace
Decreased main relief valve set pressure in the
control valve
* Adjust
Lack of hydraulic oil Refill
Clogged suction strainer in the hydraulic oil
tank
Clean
Absorption of air from the oil suction side Retighten
Faulty pressure sensor. * Replace
Faulty solenoid valve * Replace
Only one side lever is inoperable or has
no power.
Faulty relief valve in the valve * Repair or replace
Broken pipe and/or hose * Repair or replace
Loose pipe line joint Retighten
Broken O-ring at pipe line joint * Replace
Faulty hydraulic pump * Repair or replace
Faulty pilot valve * Replace
Faulty pilot circuit line * Repair or replace
Faulty pilot solenoid valve * Repair or replace
Items with * mark: Consult your authorized dealer.

Hitachi ZAXIS 135US-6 class Specifications

General

Brand	Hitachi
Model	ZAXIS 135US-6 class
Category	Excavators
Language	English