The QS Cylinder Crankcase, code 0743748-6.1, refers to a quality-specified version of the engine’s crankcase—one of the most essential structural parts of the MAN L21/31 engine. It provides a strong, precision-machined foundation for housing the crankshaft and other internal moving parts. Designed to withstand extreme loads and vibration, this crankcase is manufactured to the highest quality standards to ensure long-term structural stability in marine propulsion and power generation applications.