Part of the Hitachi Repair Manuals.
This 451-page Hitachi EX120-2 Technical Manual is the factory reference for your Hydraulic Excavator, covering the EX120 platform from General Information straight through Undercarriage, Electrical, and Hydraulic systems. You get full wiring diagrams with pinout tables, hydraulic schematics tracing every circuit, and a dedicated troubleshooting section that pairs symptoms with actual test values instead of guesswork. Open to the fuels and lubricants chapter and you'll find exact service refill capacities, plus a torque specifications section covering the mono-block control valve and pump assembly. Set hydraulic oil replacement at 2500 hours, and confirm pump axial angle runs 2° to 24° before you chase a phantom fault. Stop swapping parts on a hunch when the machine's down money by the hour. Bookmarked by section and fully text-searchable, this PDF opens on your laptop or phone so you can search any spec by keyword and get back under the boom.
What's Inside This Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 1-2 | Safety Alert Symbol, Headline Notation, Technical Manual Updates, How to Use This Manual |
| Safety | 3-13 | High-Pressure Fluid Penetration, Battery Safety, Machine Parking, Burn Prevention, Safe Maintenance Practices |
| Technical Manual: Structure & Function | 14-235 | Specifications, Working Range, Lifting Capacities, Upperstructure, Undercarriage, Hydraulic System, Hydraulic Components, Engine, Electrical System, Attachments |
| Performance Check & Troubleshooting | 236-451 | Operational Performance Tests, Engine Speed and Pump Delivery Checks, Hydraulic Pressure Measurement, Component Troubleshooting, Adjustment Procedures |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Replace Interval for Hydraulic oil | 2500 (Hours) | p. 28 |
| Replace full-flow filter element | 1 | p. 28 |
| Pump axial angle | 2° to 24° | p. 39 |
| Control valve type | mono-block valve with two sections | p. 68 |
| FUSE/5 | 0.5 | p. 143 |
| No.8 fuse | broken | p. 297 |
| Hydraulic oil temperature | 50±5°C (122 ±9°F) | p. 298 |
| Retrial "A" procedure step 3 | After 10 seconds or more have passed, turn ON the key switch or start the engine. | p. 316 |
| Warm-up function will not operate when hydraulic oil temperature is over | 30°C | p. 359 |
| Engine stalls under load | Swash angle at maximum displacement | p. 357 |
| Engine speed for P-mode | 2350±50 rpm | p. 358 |
