The main bearing cap, code 102985, is a precision-machined structural component that securely retains the main bearing shells and supports the crankshaft within the MAN L21/31 engine. Working together with the cylinder crankcase and tie rods, the bearing cap maintains accurate crankshaft alignment while distributing high mechanical loads generated during engine operation. Manufactured from high-strength materials and engineered to strict dimensional tolerances, it is capable of withstanding continuous vibration, cyclic loading, and elevated operating temperatures. Correct installation and tightening of the main bearing cap are essential for maintaining bearing integrity, minimizing friction and wear, and ensuring the long-term reliability and efficiency of the engine.