The Fiat Trattori 640 and 640DT represent a lineage of robust agricultural machinery, produced primarily in Italy from the late 1970s into the 1980s. These tractors, powered by the reliable Fiat 8000 Series diesel engines, were engineered for demanding farm work, offering substantial horsepower and torque for plowing, PTO operations, and towing. Their design emphasizes durability and straightforward functionality, making them a staple in agricultural settings. The 640DT variant further enhances capability with its Dual Traction (4WD) system, providing superior traction in challenging conditions. Fiat Trattori's heritage is built on delivering dependable and effective solutions for farmers, and the 640/640DT models exemplify this commitment to quality and performance. This comprehensive service repair manual provides detailed information for the Fiat Trattori 640 and 640DT models. It covers all aspects of maintenance, repair, troubleshooting, and diagnostics for the engine, transmission, hydraulics, electrical systems, and chassis. Users will find step-by-step procedures, technical specifications, wiring diagrams, and guidance on common wear items and repair focus areas. The manual is designed to assist professional technicians and experienced DIY mechanics in maintaining the optimal performance and longevity of their tractors. Its extensive coverage ensures that all operational facets of these robust machines can be understood and addressed effectively.