This technical repair manual covers the John Deere 4055, 4255, and 4455 series tractors, primarily manufactured in the late 1980s through the mid-1990s. These tractors represent a significant evolution in John Deere's utility and row-crop lines, known for their robust engineering, reliability, and operator comfort. With approximate operating weights between 10,000 and 14,000 lbs and horsepower ranging from 75 to 120 PTO HP, these machines were designed for demanding agricultural tasks. John Deere's long-standing legacy, dating back to 1837, underpins the durability and productivity for which these models were recognized. This comprehensive manual provides in-depth technical information essential for the maintenance, diagnosis, and repair of these John Deere tractors. It covers all major systems, including the engine, transmission, hydraulics, electrical system, drive train, brakes, and steering. Detailed procedures for component disassembly, inspection, repair, and reassembly are included, alongside systematic troubleshooting guides and routine maintenance schedules. The manual is intended for John Deere tractor owners, mechanics, agricultural repair shops, and service technicians, offering the knowledge needed to reduce downtime and repair costs.