Hydraulic system is one of the most common parts of heavy machinery, not only excavators but also lifting equipment, mining machines, and other heavy equipment. There is no denying that the hydraulic pumping system is easy to control and helps machine owners reduce around 80% of oil consumption than pneumatic systems, however, the maintenance costs are very expensive when the hydraulic pump fails.

A hydraulic pump fails is usually symboled by high-pitched noise, high heat, fluid pollution, and leakage.

Contaminated fluid is the main reason for the pump failure and that can be classified as town main types, chemical contaminants, and particle contaminants.

Chemical contaminants

Chemical contaminants mean the fluid is contaminated by water, heat, air, pressure, etc.

Water is the most common contaminant and it can lead to a whole host of problems. When the hydraulic oil is contaminated by the water, the hydraulic pumping system will suffer from both chemical and particle contamination. The diluted hydraulic oil causes rust in the components of the system, resulting in accelerated metal surface wear due to reduced lubrication.

Similar to water contamination, heat can also lead to the deterioration of the oil.

When air passes through the system, a lot of small air bubbles will be produced due to pressure changes and the control of the system will be lost.

Particle contaminants

The most common particle contaminants are metal particles from wear and dirt ingression.

The small size of particle contaminants is usually not going to bing serious damages, as the hydraulic oil protects the parts in the system. Whereas, if the contaminants are too large to pass the clearance between the part surfaces, increased friction will lead to worse damage.

Therefore, if the machine overheats, leaks oil, or makes a loud noise, please check it immediately.


To ensure the hydraulic system works properly, machine owners should check oil levels regularly. If it exceeds or below the required level, owners should do more investigation. Also, be sure the hydraulic oil filter works properly to remove contaminants.

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