Cylindrical pins, code EN1P1228, are precision alignment tools used throughout the MAN L21/31 engine to ensure accurate positioning of components such as housings, covers, and structural subassemblies. These hardened steel pins are essential for maintaining mechanical alignment, preventing rotational slip, and ensuring consistent load distribution across connected parts. By securing the geometry of critical interfaces, cylindrical pins play a vital role in minimizing wear and maintaining the long-term reliability of the engine.