The Komatsu WA420-3 and WA420-3LE are robust wheel loaders engineered for demanding construction applications. These machines are recognized for their reliable performance and efficient operation, designed to meet the challenges of various heavy-duty tasks. Their construction reflects Komatsu's commitment to quality and durability, ensuring consistent productivity in challenging environments. This Service Shop Repair Manual provides comprehensive guidance for the Komatsu WA420-3 and WA420-3LE wheel loaders, covering serial numbers A30001 and up. The manual details repair, servicing, technical maintenance, troubleshooting, assembly, and disassembly procedures. It includes essential information on structure and function, testing and adjusting, maintenance standards, and general overviews, supported by diagrams, photos, and schemes to assist owners, mechanics, and technicians in maintaining and repairing these vehicles effectively.