The coupling flange, code P51113-01, is a solid mechanical interface in the MAN L21/31 engine, enabling the secure joining of rotating shafts. Precision-engineered for torque transmission, it provides structural integrity and alignment between connected machinery elements such as gearboxes or auxiliary equipment. With high resistance to wear and mechanical stress, this flange is essential for maintaining stable and efficient rotational performance, especially under variable loads typical of marine propulsion systems.