The QS cylinder crankcase with code 0743748-6.2 forms the primary structural backbone of the MAN L21/31 engine, housing the crankshaft, bearings, and cylinder assemblies. Designed to withstand high mechanical loads, combustion forces, and continuous vibration, this crankcase ensures precise alignment of all rotating components. Its robust construction and quality specification (QS) compliance are critical for maintaining engine rigidity, reducing deformation, and supporting reliable long-term operation in demanding marine and power generation applications.