The crankshaft assembly consists of crankshaft, big gear rim, connecting rod, crankshaft bearing and connecting rod bearing (eccentric) etc. It is installed on frame through self-aligning roller bearing.

The crankshaft is an integral cast eccentric shaft. The 3 cranks locate at 360 degrees equally.

The left and right spiral gear rings are integrated to become a herringbone gear rim without cutting groove, which is installed on crankshaft with bolts.

The 3 big end bearings of connecting rod are single row short cylindrical roller bearings installed respectively at three eccentric cranks.

The connecting rod small end is connected to the crosshead pin through double row long cylindrical roller bearing.