This manual covers the Caterpillar DP40N, DP45N, DP50N, DP55CN, and DP55N Diesel Forklift Truck models. These industrial vehicles are engineered for demanding material handling applications, offering robust performance and reliability. Their design prioritizes operational efficiency and durability, making them a cornerstone in logistics and warehousing environments. The comprehensive coverage within this service manual ensures that these powerful machines can be maintained and repaired to the highest standards. The purpose of this Factory Service Repair Workshop Manual is to provide detailed technical information and procedures for the maintenance and repair of the specified Caterpillar forklift trucks. It includes extensive coverage of all major systems, including the diesel engine, power shift transmission, cooling, electrical, powertrain, axles, brakes, steering, and hydraulic systems. With step-by-step instructions, easy-to-read text, and highly detailed exploded diagrams and illustrations, this manual is an essential resource for owners, mechanics, and technicians seeking to ensure the optimal performance and longevity of their equipment. Troubleshooting guidance and service data are also included to facilitate efficient problem resolution.