This manual covers the John Deere 4050, 4250, 4450, 4650, and 4850 tractors, produced in the mid-to-late 1980s. These tractors represent a significant advancement in John Deere's utility and row-crop offerings, known for their robust construction, reliable diesel engines, and advanced transmission and hydraulic systems designed for demanding agricultural applications. They competed effectively in the market, offering substantial horsepower and operational efficiency, contributing to John Deere's established legacy of durable and dependable machinery. This comprehensive technical service manual provides detailed information for the maintenance, assembly, disassembly, and servicing of these tractor models. It covers all major systems, including the engine, transmission, hydraulics, electrical components, powertrain, and chassis. The manual includes systematic troubleshooting procedures, repair instructions, scheduled maintenance guidelines, and essential technical specifications such as torque values and fluid capacities. Its purpose is to assist owners, mechanics, and technicians in maintaining the optimal performance and longevity of their John Deere tractors.