Crankcase

The lower part of the cylinder block where used to install the crankshaft is called the crankcase. It includes upper crankcase and lower crankcase. The upper crankcase is cast together with the cylinder block, and the lower crankcase is used to store lubricating oil and seal the upper crankcase, so it is also known as the oil pan. Oil pan bears very little force. It’s generally stamped with thin steel sheet, and its shape depends on the overall layout of the engine and oil capacity. An oil stabilizing baffle is installed in the oil pan, to prevent the oil surface from fluctuating too much when the vehicle shakes. The bottom of the oil pan is also fitted with an oil discharge screw plug, where there is usually a permanent magnet to adsorb metal debris in lubricating oil, thus to reduce engine wear. A bush is installed between the upper and lower crankcase joint surfaces to prevent lubricating oil leakage.