The crankshaft is made of alloy steel castings. The crankshaft is equipped with large gear rings, connecting rods, bearings, etc. The tooth shape of the big gear ring is herringbone tooth. The inner hole of the big gear ring is interference fit with the crankshaft, and is fastened with bolts and locknuts. The large end of the connecting rod is installed on the three eccentric cranks of the crankshaft through a single row of short cylindrical roller bearings, while the small end of the connecting rod is installed on the crosshead pin through a double row of long cylindrical roller bearings. The two ends of the crankshaft are double row radial spherical roller bearings.