Official Hitachi EX120 & EX120-2 Excavator - Technical Manual (Operational Principle & Troubleshooting) 1986-1994
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Models Covered & Key Technical Specifications
- EX120-2 Hydraulic Excavator (1991-1994)
- EX120 Hydraulic Excavator (1986-1990)
Professional Workshop Service Manual & Technical Specifications
Official Hitachi EX120 & EX120-2 Hydraulic Excavator Technical Manual
Master your machine with the definitive technical authority for Hitachi's legendary EX-series. This specialized technical manual provides deep-level engineering insights and operational principles for the Hitachi EX120 and EX120-2 hydraulic excavators. Move beyond basic maintenance and understand the "why" behind your machine's performance with professional-grade documentation used by factory-trained technicians.
Whether you are maintaining a classic EX120 or the advanced EX120-2, this manual provides the specific technical data required to keep your equipment running at peak efficiency in the toughest environments.
Comprehensive Model Coverage
This manual is specifically designed for the following Hitachi models:
- EX120-2 Hydraulic Excavator (1991-1994)
- EX120 Hydraulic Excavator (1986-1990)
Applicable Serial Numbers:
- EX120-2: Serial No. 12N-30001 and up
Technical Value & Shop Benefits
This isn't just a basic guide; it is a deep dive into the excavator’s DNA. Gain a competitive edge with exclusive technical information:
- Advanced Hydraulics: Detailed breakdown of the HPV091DS main pump and HYBZFS11816.8L pilot pump systems. Understand the variable displacement, bent-axis piston technology that powers your machine.
- Electronic Control Systems: Complete guidance on the PVC and EC controllers, including N-sensor (engine speed), P-sensor (pressure), and A-sensor (pump axial angle) functionality.
- Precision Troubleshooting: Utilize the DP-sensor (differential pressure) output data to diagnose load-sensing circuit issues with exact voltage values (e.g., 4.5V at neutral, 2.5V during operation).
- Swing & Travel Dynamics: Full schematics of the swing motor assembly, including the parking brake's negative structure and the anti-cavitation functions essential for preventing system damage.
- Interchangeability Guide: A unique section detailing the compatibility between EX120 and EX120-2 parts, from buckets and arms to engine components like fuel filters and fan belts.
What's Inside - Professional Reference
- Section 01: Specifications
- Detailed working ranges for 2.10m, 2.52m, and 3.01m arms.
- Comprehensive lifting capacities and transport dimensions.
- Precise service refill capacities for fuel (66 US gal), hydraulic system (35.4 US gal), and engine oil (4.3 US gal).
- Section 02: Upperstructure
- Complete layout of the main frame, pump devices, and control valves.
- In-depth look at the mono-block control valve (3-spool and 4-spool sections).
- Detailed operational principles for the boom, arm, and bucket circuits.
- Fuels & Lubricants
- Temperature-specific oil viscosity charts (SAE 10W to SAE 40).
- Recommended grease types for front joint pins and swing bearings (-20 to 40 °C range).
- Mixing ratios for Long-Life Coolant (LLC) and anti-rust agents.
This technical manual is the ultimate toolkit for owners, fleet managers, and mechanics who demand more than just a surface-level understanding. Ensure the longevity of your Hitachi excavator by following the exact specifications and operational principles used at the factory level.
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