This manual covers the Komatsu WA90-5 Wheel Loader, a piece of heavy equipment designed for material handling applications. Known for its robust engineering and reliability, the WA90-5 features advanced operational systems such as joystick steering and a central lubrication system, ensuring efficient performance and ease of use in demanding environments. This comprehensive guide details its intended use and operational capabilities. The Service Operation Manual provides essential information for maintaining and repairing the Komatsu WA90-5. It includes detailed guides for general operation, maintenance schedules, and specific service procedures, such as injector assembly replacement. Furthermore, the manual specifies fuel, coolant, and lubricant recommendations, as well as tightening torques for bolts and nuts, and outlines the periodic replacement of safety-critical parts. This resource is designed to assist owners and technicians in ensuring the optimal performance and longevity of their equipment.