This manual covers the Hyster FORTIS S135FT and S155FT compact internal combustion forklifts, model code D024. These robust machines are engineered for demanding industrial environments, offering reliable performance and efficient operation. Their design prioritizes durability and operator comfort, making them suitable for a wide range of material handling applications. The internal combustion engine, compatible with Gasoline/LPG fuel, provides ample power for heavy lifting tasks, while the powershift transmission ensures smooth and responsive control. The Hyster FORTIS S135FT and S155FT Service Repair Manual provides comprehensive guidance for maintenance, repair, and troubleshooting. It includes detailed procedures for scheduled maintenance, fluid capacities, and specifications for critical systems such as the engine, transmission, brakes, cooling, steering, and hydraulic systems. Diagnostic trouble codes, fault code information for the QSB 3.3L engine, and electrical system repair, including wire harness repair, are thoroughly covered. This manual is an essential resource for owners, technicians, and mechanics to ensure the optimal performance and longevity of their Hyster forklifts.