Hydraulic System Keeps Failing — What Is the Root Cause?

During excavator repair work, many equipment owners often hear service technicians remind them to bleed air from hydraulic components. However, they remain unclear about the reasons and operating procedures for air bleeding. This article gives a brief explanation.

After disassembly, component replacement or maintenance of an excavator hydraulic system, air is very likely to get trapped inside. Trapped air leads to poor machine performance, faults and abnormal noise. Many owners have questions: Is air bleeding required for hydraulic components? Is it necessary after every maintenance? How to perform air bleeding? Can bleeding be skipped?

Air bleeding must be carried out to prevent component erosion and cavitation. Once air enters the hydraulic system, the air will compress and expand under load. This makes hydraulic components operate erratically and shortens the service life of all hydraulic parts.

A large number of abnormal issues such as noise and sluggish operation in hydraulic systems are caused by trapped air. Operators may spend long hours troubleshooting only to find air as the culprit, resulting in costly downtime and losses.

Therefore, a reminder: whenever hydraulic components are disassembled for repair, or hydraulic oil and other consumables are replaced, air bleeding must be performed properly to avoid severe hydraulic system faults caused by trapped air.