The Hitachi Zaxis 225USR-3 Hydraulic Excavator is engineered for robust performance and reliability in demanding construction environments. Featuring a powerful Isuzu AH-6HK1XPN turbocharged diesel engine with a displacement of 7.8 L, it delivers a gross power of 124 kW (166 HP) and a net power of 118 kW (158 HP) at 2000 rpm, meeting Tier 3 / Stage IIIA emission standards. This model is designed with a compact radius for enhanced maneuverability in confined spaces, offering a maximum digging depth of 6.62 m and a maximum digging reach of 9.93 m. Its substantial operating weight of 21,900 kg and a hydraulic motor with planetary gear reduction drive system ensure efficient power transfer and precise control for a wide range of excavation tasks. This Factory Service Repair Manual in English provides comprehensive guidance for the maintenance and repair of the Hitachi Zaxis 225USR-3 Hydraulic Excavator. It covers essential areas including detailed maintenance procedures, troubleshooting common issues, and in-depth technical specifications for all major components, such as the engine, transmission, and hydraulic systems. The manual also includes critical safety guidelines to ensure safe operation and service. By offering detailed information on fluid capacities, operating dimensions, and performance metrics, this resource is an indispensable tool for owners, mechanics, and technicians seeking to maintain the optimal performance, longevity, and safety of their equipment.