This manual covers the Doosan Daewoo DX420LC Hydraulic Excavator, a robust machine designed for demanding construction and industrial applications. Engineered for exceptional performance and durability, the DX420LC offers advanced hydraulic systems and a powerful engine to ensure efficient operation and reliability on any job site. Its design prioritizes operator comfort and productivity, making it a leading choice for heavy-duty excavation tasks. The purpose of this comprehensive service manual is to provide detailed information for the maintenance, repair, and technical understanding of the Doosan Daewoo DX420LC Hydraulic Excavator. It includes essential procedures, diagnostic information, and specifications necessary for owners, technicians, and mechanics to keep the equipment in optimal working condition. By following the guidelines within this manual, users can ensure the longevity and peak performance of their excavator.