Hitachi ZW20 Wheel Loader Repair Manuals

Service Repair Manual (Troubleshooting) : Vol. No.T4EJ-E-00 (264 Pages)
Workshop Manual : Vol. No.W4EJ-E-00 (220 Pages)
Hitachi ZW20 Wheel Loader Service Manual
The manual is applicable for the Hitachi ZW20 Wheel Loader Model
Service Manual consists of the following:
For Model ZW20 as mentioned above:
Service Manual (Troubleshooting) : Vol. No.T4EJ-E-00 (264 Pages)

Table of Content of the Workshop Manual

SECTION 1 GENERAL

Group 1 Precautions for Disassembling
and Assembling
Group 2 Tightening
Group 3 Painting

SECTION 2 BODY

Group 1 Control Valve
Group 2 Main Pump

SECTION 3 TRAVEL SYSTEM

Group 1 Cab
Group 2 HST Pump
Group 3 HST Motor
Group 4 Reduction Gear
Group 5 Axle
Group 6 Master Cylinder
Group 7 Power Steering
Group 8 Steering Cylinder

SECTION 4 FRONT ATTACHMENT

Group 1 Front Attachment
Group 2 Cylinder

Table of Content of the Technical Manual

SECTION 1 GENERAL

Group 1 Specification
Group 2 Component Specifications
Group 3 Component Layout

SECTION 2 SYSTEM

Group 1 Fuel System
Group 2 Hydraulic System
Group 3 Electrical System

SECTION 3 COMPONENT OPERATION

Group 1 HST Pump
Group 2 HST Motor
Group 3 Axle
Group 4 Brake
Group 5 Orbitroll
Group 6 Control Valve
Group 7 Main Pump

SECTION 4 OPERATIONAL PERFORMANCE TEST

Group 1 Introduction
Group 2 Standard
Group 3 Engine Test
Group 4 Wheel Loader Test

SECTION 5 TROUBLESHOOTING

Group 1 Diagnosing Procedure
Group 2 Failure List
Group 3 Engine
Group 4 Component Layout
Manual guide composition
Hitachi ZAXIS ZW20 service manual consists of the Troubleshooting and the Workshop Manual.

Information included in the Service Manual: Technical information needed for redelivery and delivery, operation and activation of all devices and systems, operational performance tests, and troubleshooting procedures.

Information included in the Workshop Manual: Technical information needed for maintenance and repair of the machine, tools and devices needed for maintenance and repair, maintenance standards, and removal / installation and assemble / disassemble procedures.

DA Valve
The gear pump is coaxially connected to HST pump for the charge and pilot.
The gear pump flow rate is changed in proportion to the engine speed.
All of flow rate flows to the charge circuit through the orifice of DA valve.
DA valve decreases charge pressure to generate control pressure by using the signal based on the pressure difference caused by the flow rate change between the front and rear of orifice.
Therefore, the pump displacement angle is controlled by pressure almost in proportion to the engine speed.
The charging pump delivery flow rate in proportion to the engine speed flows to charging circuit [C] through port [A].

DA valve decreases charging circuit [C] pressure to generate control pressure in control circuit [B] by using the signals based on the spring force by spring (4) and the pressure difference caused by the flow rate change between the front and rear of orifice (6).

1 – Control Cartridge
2 – O-Ring
3 – Set Screw
4 – Adjust Spring
5 – Differential Piston
6 – Orifice
A- DA Valve Primary side (From Charging Pump) B- DA Valve Secondary side (To Control Circuit) C- DA Valve Secondary side (To Charging Circuit) D- DA Valve Drain