This manual covers the Komatsu PC138USLC-2EO Hydraulic Excavator, a versatile machine designed for demanding construction and earthmoving applications. Featuring a robust Komatsu SAA4D107E-1 engine with 4.5 liters displacement and 97.3 horsepower, this excavator is built for reliability and efficiency. Its compact radius design, hydrostatic transmission, and advanced hydraulic system with a maximum pump flow of 212 liters per minute ensure optimal performance and maneuverability in various work environments. The PC138USLC-2EO is engineered to meet Tier 3 / Stage IIIA emission standards, reflecting a commitment to environmental responsibility alongside powerful operation. This Full Service Repair Manual in English provides comprehensive guidance for the maintenance and repair of your Komatsu PC138USLC-2EO Hydraulic Excavator. It details essential procedures, including engine oil, hydraulic oil, and coolant capacities, along with technical specifications for the engine, transmission, and hydraulic system. The manual also outlines safety features, such as the ROPS/FOPS certified cab, and offers troubleshooting information to help diagnose and resolve potential issues. By following the instructions within this manual, owners, mechanics, and technicians can ensure the longevity, optimal performance, and safe operation of the equipment.