This Service Repair Manual covers the Komatsu WA400-5, a robust piece of equipment designed for demanding operational environments. Engineered for reliability and performance, the WA400-5 is built to handle a variety of heavy-duty tasks. Its advanced hydrostatic transmission system ensures efficient power delivery and precise control, making it a versatile asset for construction, mining, and material handling applications. This manual is an essential resource for understanding and maintaining the integrity of your Komatsu machinery. The purpose of this comprehensive manual is to provide detailed guidance for the maintenance, repair, and technical understanding of the Komatsu WA400-5, serial numbers 70001 and up. It encompasses critical information across various sections, including general operation, structure and function, testing and adjustment procedures, disassembly and assembly, maintenance standards, and other essential technical data. By following the instructions and specifications within this English-language guide, owners, technicians, and mechanics can ensure optimal performance, longevity, and safe operation of their equipment.