On the bases of analysis for motion regularity and damage condition, a method for taper machining of cross shaft journal is proposed to reduce journal damage.

Horizontal double sided NC combined drilling machine is specially designed for the machining of main shaft journal hole and crank arm journal straight oil hole of crankshaft with six cylinders.

This paper analyses the reasons causing galvanic corrosion on main shaft journal and main bearings of main diesel engine, and the protection measures are also introduced.