This manual pertains to the HITACHI HYDRAULIC EXCAVATOR ZAXIS ZX 120 3 SERIES, a robust machine designed for demanding operational environments. Engineered for reliability and performance, this excavator represents a significant advancement in construction equipment technology, offering powerful capabilities and efficient operation for a wide range of tasks. Its construction emphasizes durability and ease of maintenance, making it a dependable choice for professionals in the field. The purpose of this comprehensive manual is to provide detailed information for the maintenance, repair, and understanding of the HITACHI HYDRAULIC EXCAVATOR ZAXIS ZX 120 3 SERIES. It covers essential areas including general information, fuel system, chassis, cooling system, engine components, clutch, lubrication, drive systems, transmission, wheels and tires, final drive, brakes, suspension, steering, frame, and the electrical system, complete with wiring diagrams. This resource is invaluable for technicians, mechanics, and owners seeking to ensure the optimal performance and longevity of their equipment.