After using roots vacuum unit for a period of time, the problem of crankshaft wear often occurs. The wear is uneven. The radial wear of main journal and connecting rod journal is mainly elliptical, while the axial wear of crankshaft journal is mainly conical. So, how are these crankshaft wear caused?
1. Because the oil passage leading to the connecting rod journal is inclined, under the action of centrifugal force, the mechanical impurities in the lubricating oil accumulate on one side of the connecting rod journal under the action of centrifugal force, which accelerates the wear of the Journal on this side and makes the wear of the connecting rod journal cone-shaped.
2. Because of the bending of connecting rod, the center line of cylinder is not perpendicular to the center line of crankshaft, the axial force on the journal is uneven and the wear deflection is caused.
3. The elliptical wear of the journal is caused by the uneven distribution of the force acting on the journal along the circumference. When roots vacuum unit is working, the combined force on the connecting rod journal always acts on the inner side of the connecting rod journal, and the direction is outward along the radius of the crankshaft, resulting in wear on the inner side of the connecting rod journal.