The Fiat Trattori 640 and 640DT are robust tractors introduced in the late 1970s and early 1980s, forming part of Fiat's successful 60-series range. These diesel-powered machines, typically featuring a 3.5-4.0 L engine producing around 60-70 horsepower, were designed for agricultural applications and were available in both two-wheel drive (640) and four-wheel drive (640DT) configurations. Known for their reliable engineering, these tractors represent a significant era in agricultural machinery, offering practical functionality for a wide range of farming tasks. This workshop service repair manual provides comprehensive guidance for maintaining and repairing the Fiat Trattori 640 and 640DT. It covers essential systems including the engine, transmission, fuel, suspension, steering, and brakes, along with detailed sections on bodywork and electrical systems. The manual includes step-by-step repair procedures, diagnostic troubleshooting guides, crucial torque specifications, and detailed illustrations and wiring schematics. Its purpose is to empower both do-it-yourself owners and professional mechanics with the necessary information to keep these tractors in optimal working condition.