This service repair workshop manual covers the Hitachi Zaxis 40U and Zaxis 50U compact excavators from the 5 Series generation. These machines are engineered for reliability and performance in various construction and landscaping applications, featuring robust diesel engines with approximately 40-50 horsepower and hydrostatic transmissions for precise control. Their compact design, with operating weights around 4,000-5,000 kg and rubber track systems, makes them ideal for maneuverability in confined spaces. Notable operational capabilities include swing speeds of 10-12 RPM and travel speeds of 2.5-4.5 km/h, supported by hydraulic systems capable of high flow rates and pressures. The purpose of this manual is to provide comprehensive guidance for the maintenance, repair, and technical understanding of the Hitachi Zaxis 40U and 50U excavators. It details essential maintenance schedules with service intervals typically ranging from 250 to 1000 hours, along with specific fluid capacities for engine oil, hydraulic oil, and coolant. Technical specifications, including engine displacement, transmission types, and hydraulic system parameters, are thoroughly explained. This resource is designed to assist owners, technicians, and mechanics in ensuring the optimal performance, longevity, and safe operation of these Hitachi excavators through clear instructions and detailed information.