This service repair manual covers the Hitachi Dash 3 Series excavators, including the ZX110-3, ZX120-3, and ZX135US-3 models. These diesel-powered excavators feature hydrostatic transmissions and are engineered for robust performance in various construction and earthmoving applications. With approximate operating weights ranging from 10,500 kg to 13,200 kg and powerful diesel engines delivering around 72-73.1 kW, these machines are built for reliability and efficiency. Notable features include ROPS/FOPS certified cabins, a ground clearance of approximately 450 mm, and versatile attachment options such as monoboom or two-piece boom configurations and bucket capacities from 0.5 m³ to 0.8 m³. This comprehensive English-language manual provides essential information for the maintenance and repair of your Hitachi excavator. It details critical procedures, technical specifications, and troubleshooting guidance necessary to keep your equipment operating at peak performance. Topics covered include engine and hydraulic system specifications, fluid capacities, service intervals, and undercarriage components. By following the instructions within this manual, owners, mechanics, and technicians can effectively perform routine maintenance, diagnose issues, and ensure the longevity and optimal functionality of the ZX110-3, ZX120-3, and ZX135US-3 excavators.