This manual covers the Hitachi ZAXIS 500LC-3 and 520LCH-3 excavators, part of the LC-3 and LCH-3 Series. These machines are engineered for demanding construction and heavy-duty applications, featuring a powerful Cummins QSX15 diesel engine producing 365 HP and meeting EPA Tier 3 and EU Stage III emission standards. The hydrostatic transmission provides efficient power delivery with travel speeds up to 5.0 km/h, while the robust construction, including a ROPS and FOPS compliant cab, ensures operator safety and machine durability. With an operating weight of approximately 47,000 to 52,000 kg and a standard bucket capacity ranging from 2.0 to 3.0 m³, these excavators are designed for high productivity and reliability in challenging environments. This comprehensive Service and Repair Manual provides essential information for maintaining and repairing the Hitachi ZAXIS 500LC-3 and 520LCH-3 excavators. It details critical maintenance procedures, including fluid capacities and recommended service intervals, along with troubleshooting guides to address potential issues. Technical specifications, operating characteristics, and safety guidelines are thoroughly explained to assist owners, mechanics, and technicians. The manual's complete official coverage ensures that all aspects of the machine's operation and upkeep are addressed, enabling optimal performance and longevity.