This workshop service repair manual covers Fiat 480, 480DT, 500, 500DT, 540, 540DT, 640, and 640DT agricultural tractors. These robust utility tractors, produced primarily from the late 1970s through the 1980s, were built by Fiat Trattori, a manufacturer known for its durable and reliable machinery. The DT designation indicates the four-wheel drive variant. These models are recognized for their value and have a legacy of dependable performance in general agricultural work. This comprehensive manual provides detailed information essential for maintaining and repairing these Fiat tractor models. It covers a wide range of systems, including the engine (mechanical, fuel, lubrication, cooling), powertrain (clutch, transmission, drivetrain, brakes, axles, hydraulics, PTO), and electrical systems. The manual includes procedures for preventive maintenance, troubleshooting, repair and overhaul, diagnostics, part replacement, and adjustments, along with guidance on special tool usage. It is designed for first-time owners, amateur mechanics, and professional technicians, offering in-depth technical detail to ensure efficient and correct execution of all service procedures.