The 6640 is a robust tractor from the 40 Series line, produced primarily during the late 1980s and 1990s. Known for its reliability and engineering quality, this mid-range utility tractor was designed to meet the demanding needs of agricultural and construction work. Its heritage stems from a long-standing reputation in manufacturing durable equipment. The 6640 offers a blend of practical functionality and operational efficiency, making it a competitive choice within its market segment. This comprehensive factory service repair manual provides in-depth information for the 6640 tractor, covering all styles. It details engine specifications, lubrication, cooling, fuel, and electrical systems, as well as clutch, transmission, drive chain, rear and front axles, brakes, steering, shocks, and body work. The manual includes step-by-step repair procedures, routine maintenance schedules, disassembly and reassembly instructions, and advanced troubleshooting guides with wiring diagrams. Designed for owners, technicians, and mechanics, this English-language manual offers factory-level detail to ensure proper maintenance, repair, and rebuilding of the vehicle.