The Hitachi Zaxis 225US-3 is a hydraulic excavator from the Zaxis-3 generation, engineered for demanding construction and earthmoving applications. This machine features a robust Isuzu AA-6BG1TRP turbocharged diesel engine, delivering 124 kW (166 hp) and meeting EPA Tier 3 / EU Stage IIIA emission standards. Its hydrostatic transmission and hydraulic motor drive system provide efficient power to the sprockets, enabling precise control and maneuverability. With an operating weight of approximately 22,000 kg and a bucket capacity ranging from 0.8 to 1.2 m³, the Zaxis 225US-3 is designed for reliability and performance in various job site conditions. This Workshop Service Manual (WSM) provides comprehensive technical information for the Hitachi Zaxis 225US-3 hydraulic excavator. It is intended for professional technicians and mechanics to ensure proper maintenance, repair, and optimal operation of the equipment. The manual covers essential areas including detailed maintenance procedures, troubleshooting guides, technical specifications for all major systems, and critical safety guidelines. By following the procedures outlined within this document, users can effectively maintain the Zaxis 225US-3, prolong its service life, and ensure safe and efficient performance.