This service manual covers the Hitachi EX230LC-5, EX270-5, and EX270LC-5 Excavator models, equipped with ISUZU A-6BG1TQA, A-6BG1 TQA01, or HINO H07D engines. These excavators are engineered for demanding operational environments, offering robust performance and reliability. This manual is designed to provide comprehensive support for maintaining these powerful machines, ensuring their continued efficiency and longevity in various construction and industrial applications. The purpose of this manual is to serve as an indispensable resource for owners, mechanics, and technicians. It provides detailed information on operational principles, troubleshooting procedures, system diagnostics, and component-level repairs. Coverage includes general information, system overviews, operational performance testing, circuit diagrams for hydraulic and electrical systems, and detailed workshop instructions for the upperstructure, undercarriage, front attachment, and engine. This manual facilitates effective maintenance and repair, empowering users to keep their Hitachi excavators in optimal working condition.