This workshop service manual covers the Hitachi Zaxis ZX 225USRK-3, a robust excavator from the Zaxis-3 generation. Engineered for demanding operational environments, this machine features a water-cooled diesel engine and a hydrostatic transmission, designed to deliver reliable performance and efficiency. Its substantial operating weight of 21,700 kg (47,840 lbs) and compact transport dimensions of 9790 mm (32 ft 1 in) length, 2980 mm (9 ft 9 in) width, and 3070 mm (10 ft 1 in) height underscore its versatility for various construction and earthmoving applications. The purpose of this comprehensive English-language manual is to provide detailed information for the maintenance, repair, and technical understanding of the Hitachi Zaxis ZX 225USRK-3. It includes essential data on engine specifications, hydraulic systems, undercarriage components, and maintenance procedures, such as filter types and lubrication system details. With 699 pages of technical guidance, this manual serves as an indispensable resource for owners, operators, and service technicians to ensure the optimal performance, longevity, and safe operation of the equipment.