First, there is a high temperature phenomenon in the hydraulic system. During operation, the piston rod frequently contacts the low temperature environment (in the cold season) (the temperature suddenly drops).
Secondly, the hydraulic oil for the excavator is not replaced during the maintenance period. This phenomenon generally occurs when the piston rod is discolored within a few days of just changing the oil. The reason is that there is a difference in the quality and performance of an extreme pressure anti-wear additive in the hydraulic fluid.
Third, due to the uneven temperature control during the plating process of the piston rod, cracks appear on the surface of the plating layer in the later work. The irregular small crack can be seen by observing the surface of the piston rod with a high magnification magnifying glass.