This manual covers the Hitachi ZAXIS 450-3, 450LC-3, 470H-3, and 470LCH-3 series excavators, representing robust engineering designed for demanding heavy-duty applications. These machines are characterized by their powerful diesel engines, advanced hydrostatic transmissions with electronic control, and substantial operating weights, making them reliable and efficient tools for construction and earthmoving. The 3 Series excavators are built for durability and performance, offering advanced features to enhance productivity and operator comfort in various operational environments. The purpose of this comprehensive official service repair manual is to provide detailed information for the maintenance, repair, and technical understanding of the Hitachi ZAXIS 3 Series excavators. It includes essential data on engine specifications, transmission systems, operational features, and maintenance schedules. This manual is an indispensable resource for owners, technicians, and mechanics, offering guidance on troubleshooting, technical specifications, and proper procedures to ensure the optimal performance, longevity, and safety of these powerful machines.