This technical manual covers the 4055, 4255, and 4455 tractor series, primarily produced in the late 1980s and early 1990s. These models represent a significant era for the utility tractor line, known for their power, versatility, and durability in agricultural operations. The manual provides comprehensive technical information, including detailed explanations of system functions, diagnostic procedures, and maintenance guidance, supplemented by actual real photo illustrations and color schemes. It is an indispensable resource for owners and technicians aiming to maintain the optimal performance and longevity of these robust machines. This 840-page English-language technical manual is designed to assist tractor owners, service technicians, and mechanics in understanding, diagnosing, repairing, and maintaining the 4055, 4255, and 4455 models. It comprehensively covers all major systems, including the engine, QUAD-RANGE and Power Shift transmissions, drivetrain, chassis, steering, brakes, hydraulics, electrical systems, and operator station. The manual's scope includes detailed operation and tests, routine failure identification, in-depth system diagnosis, preventative maintenance, component and system testing, and theories of operation, all presented with a focus on practical, hands-on repair with information on dealer-fabricated tools and specialized test equipment.