The John Deere 4055, 4255, and 4455 tractors, produced between 1988 and 1992, represent a significant advancement in agricultural machinery, building upon John Deere's legacy of durability and innovation. These tractors are engineered for demanding agricultural applications, featuring robust construction and reliable performance. Common configurations include John Deere's 400 Series Diesel Engines, offering substantial power, and advanced transmission options such as the QUAD-RANGE and Power Shift transmissions, designed to enhance operational efficiency and operator convenience. Their design prioritizes functionality and longevity, making them a trusted choice for farmers and operators seeking dependable equipment. This comprehensive technical manual, identified as TM1459, provides in-depth operational and testing information for the John Deere 4055, 4255, and 4455 tractors. It covers a wide array of critical systems, including engine operation and tests, fuel and air systems, QUAD-RANGE and Power Shift transmissions, PTO, axles, differentials, steering, brakes, and the hydraulic system. The manual details electrical system operation, operator station diagnostics, and includes a dedicated safety section. With its focus on theory of operation, system diagnosis, troubleshooting, and testing procedures, this manual serves as an essential resource for owners and technicians to maintain, repair, and optimize the performance of these John Deere tractors.