This manual covers the Hitachi ZX40U-3 U-3 Series compact excavator, a versatile machine designed for a range of construction and landscaping applications. Engineered for durability and performance, this model features a robust diesel engine and a hydraulic pilot control system for precise operation. Its compact dimensions, including an operating weight of approximately 3,900 kg and a width over tracks of about 1.74 m, make it suitable for work in confined spaces. The ZX40U-3 offers impressive digging capabilities, with a maximum digging depth of approximately 3.11 m and a reach at ground level of around 5.12 m, supported by a bucket capacity of approximately 0.15 m³. This comprehensive English-language service repair manual provides detailed information essential for the maintenance and repair of the Hitachi ZX40U-3. It covers critical aspects such as engine specifications, hydraulic system components, and maintenance procedures, including fuel tank capacity. The manual is intended for owners, mechanics, and technicians, offering the necessary technical data and guidance to ensure the vehicle's optimal performance and longevity. By following the procedures outlined within, users can effectively troubleshoot issues, perform routine servicing, and carry out necessary repairs.