The Hitachi ZX40U-3 Hydraulic Excavator is engineered for robust performance and reliability in demanding work environments. Featuring a powerful Isuzu 4JG1-P direct injection, water-cooled diesel engine with a displacement of 3.05 L and a net horsepower of 39.3 HP at 2200 RPM, this machine meets EPA Tier 3 and EU Stage IIIA emission standards. Its hydrostatic travel drive system, coupled with a variable displacement hydraulic motor, allows for efficient operation with travel speeds up to 4.7 km/h. With an operating weight of 4,020 kg and a standard bucket capacity of 0.15 m³, the ZX40U-3 is designed for versatility across various construction and excavation tasks. This Workshop Service Manual (WSM) provides in-depth, professional-quality information for the service and repair of the Hitachi ZX40U-3 Hydraulic Excavator. It covers essential areas including detailed maintenance procedures, troubleshooting guides, technical specifications, and critical safety guidelines. The manual is an indispensable resource for owners, mechanics, and technicians, offering the knowledge required to ensure the optimal performance, longevity, and safe operation of the equipment. Its comprehensive scope facilitates efficient diagnostics and repairs, supporting the continued productivity of this advanced hydraulic excavator.