The Hitachi ZW550 is a robust Wheel Loader designed for demanding applications in material handling, construction, and earthmoving. Engineered for reliability and efficiency, this heavy equipment is built to perform under challenging conditions. Its advanced design focuses on delivering consistent power and operational excellence, making it a valuable asset for any project requiring significant material movement and site preparation. This manual provides comprehensive Operation Principle and Service Repair information for the Hitachi ZW550 Wheel Loader in English. It covers essential areas including the function and structure of various groups such as chassis, power, torque converter transmission, hydraulic, brake, electrical, and operator station. Additionally, it details check and adjustment procedures, performance check measurements, and routine preventive maintenance benefits, aimed at helping owners and technicians save time and money by preventing premature failure and unnecessary repairs.