The Hyster Challenger H135XL and H155XL forklifts, generations G006 and F006, are robust machines engineered for heavy lifting and material handling operations. These internal combustion engine-powered forklifts offer a range of engine options, including GM V6 and Perkins Diesel configurations, and are equipped with either manual transmission or a two-speed powershift transmission. Their design emphasizes reliability and efficiency, making them suitable for demanding industrial environments. This Service Repair Manual provides comprehensive guidance for the Hyster Challenger H135XL and H155XL forklifts. It covers essential maintenance procedures, troubleshooting steps, and detailed technical specifications, including information on the hydraulic, electrical, and drive train systems. The manual also includes details on engine control modules, braking systems, and steering mechanisms, along with diagrams and capacities. Its purpose is to assist owners, mechanics, and technicians in maintaining the optimal performance and longevity of these forklifts through routine and preventive care.