The John Deere 4640 and 4840 tractors represent a significant era in agricultural machinery, produced approximately between 1977 and 1982. These high-horsepower, versatile tractors were engineered to meet the demands of modern farming operations, offering robust power and performance for heavy fieldwork. They are known for their reliability and durability, built upon John Deere's long-standing heritage in agricultural innovation. Key features include spacious cabs designed for operator comfort and productivity, powerful turbocharged diesel engines, and the advanced John Deere PowerShift transmission, enabling efficient operation across a wide range of tasks. These tractors competed effectively in their market segment, providing farmers with dependable tools for enhanced productivity. This technical service manual provides comprehensive guidance for the maintenance, assembly, disassembly, and servicing of the John Deere 4640 and 4840 tractors. It covers all essential systems, including detailed engine diagnostics and overhaul, transmission repair, hydraulic system servicing, electrical troubleshooting, and chassis maintenance. The manual includes step-by-step instructions for routine maintenance, component repair and rebuild procedures, and diagnostic flowcharts to help identify and resolve common issues. Its purpose is to serve as an indispensable resource for owners, mechanics, and technicians, ensuring the longevity and optimal performance of these powerful agricultural machines through accurate and thorough technical information.