Post On 2019-10-11

Why does the hydraulic oil of excavation equipment turn black

The Function of Hydraulic Oil

Hydraulic oil plays a lubricating role in hydraulic system. If it is not replaced for a long time, the viscosity of hydraulic oil will decrease and become black. Viscosity reduction will lead to abrasion of parts of hydraulic system such as injection, valve, multi-way reversing valve, oil seal in the main pump of excavator. Abrasion will lead to internal leakage and seriously affect the efficiency of excavator.

Cause of hydraulic oil blackening?

(1) Internal impurities

Metal impurities are the main factors affecting the blackening of excavator hydraulic oil. Because of the high-speed rotation with the pump, the repeated operation of the hydraulic valve spool and the repeated operation of the cylinder, debris will be produced, which will affect the quality of the hydraulic oil if it is not clear for a long time.

In addition, the newly purchased excavator will produce a large number of metal impurities during running-in. When oil is changed, the hydraulic oil in the tank must be completely emptied, and the oil tank must be wiped clean with cotton cloth before adding new oil. If it is not emptied, there may be a large number of iron scraps remaining in the tank, which will also lead to new oil pollution and blackening.

(2) Environmental impact

Excavator working environment is bad, long-term high-strength use is easy to cause oil seal aging, resulting in inadequate pipeline seal; seal ring failure will cause filter plug; dust-proof measures are not in place during cleaning, oil exchange and maintenance, impurities will be brought into the hydraulic system during operation. It is necessary to check whether the hydraulic system of the excavator is closed and whether the breathing hole is intact; check whether the sealing of the exposed parts of the hydraulic part of the equipment is intact, such as the dustproof ring of the cylinder, etc.

(3) Non-standard butter filling

In addition, the reason for the blackening of hydraulic oil may also be that the butter filling is not standardized.

When adding butter to excavator equipped with crusher, the crusher should be lifted up and the steel brazed into the piston. Only half of the standard butter gun is needed for each filling.

If there is no pressure steel brazing when butter is injected, butter will be injected at the upper limit of the brazing groove. When brazing, butter will jump directly to the main oil seal of the crusher. With the reciprocating motion of the piston, butter will be brought into the cylinder block of the crusher, and then the hydraulic oil in the cylinder block of the crusher will be mixed into the hydraulic system of the excavator, which will eventually lead to deterioration and blackening of the hydraulic oil.