This Operation & Maintenance Manual covers the Komatsu WA420-3 and WA420-3MC wheel loaders, designed for effective, economical, and safe operation. These machines are engineered for reliability and performance in demanding work environments. This manual provides comprehensive information to ensure optimal utilization and longevity of your equipment. This manual is intended for operators and maintenance personnel, offering detailed guidance on a wide range of topics. It includes procedures for operation, handling, lubrication, maintenance, checking, and adjustment. Safety precautions, troubleshooting, technical specifications, and information on optional parts and attachments are also covered. With numerous pictures and diagrams, this document serves as an essential resource for maintaining and repairing your Komatsu wheel loader.