This manual covers Caterpillar (CAT) GP/DP Series Internal Combustion Pneumatic Tire Forklift Trucks, specifically models GP40K, GP40KL, GP45K, GP50K, DP40K, DP40KL, DP45K, and DP50K. These robust industrial forklifts are engineered for demanding material handling applications in warehouses, manufacturing facilities, and distribution centers. Known for their durability, reliable performance, and operator comfort, CAT forklifts are designed for efficiency and longevity in challenging environments. The 'K' designation signifies an internal combustion engine, while 'P' indicates pneumatic tires, and 'D' specifies a diesel engine. These machines are built to meet or exceed industry safety standards, offering a dependable solution for heavy-duty operations. This comprehensive workshop service repair manual provides detailed information for owners, mechanics, and technicians. It covers all essential systems, including the powertrain, transmission, hydraulics, electrical systems, chassis, steering, brakes, mast, and operator station. The manual offers step-by-step procedures for routine maintenance, troubleshooting common issues, and performing complete component repairs and rebuilds. Technical specifications, torque values, fluid recommendations, and wiring diagrams are included to ensure accurate and efficient service. With an estimated 500-800 pages of content, this manual is an indispensable resource for maintaining the optimal performance and longevity of your CAT forklift.