How to Bleed Air From Excavator Hydraulic Cylinder?

How Does Air Get Into Excavator Hydraulic Cylinder?

Installation Mistakes：

During the installation, assembly, or maintenance process of excavators, if the hydraulic cylinder or seals are not properly installed, it may cause air to enter the hydraulic cylinder.

Worn Seals: 

Seals of excavator hydraulic cylinders, such as sealing rings and O-rings, may lose their sealing performance over time due to aging or wear, allowing air to enter the hydraulic cylinder.

Gas Dissolution:

Hydraulic oil in the hydraulic system may absorb air during operation, especially when the temperature of hydraulic oil in the hydraulic system rises, gases dissolved in the hydraulic oil may precipitate and enter the hydraulic cylinder.

Contamination Oil:

The presence of impurities or contaminants in hydraulic oil may affect the normal operation of the hydraulic system, and even cause air to enter the hydraulic cylinder.

Other Faults:

Other faults in hydraulic system components, such as leaks at pump, valve, or pipeline connections, may also cause air to enter the hydraulic cylinder.

How to Know if Air Is in Excavator Hydraulic Cylinder?

Bubbles In Hydraulic Oil:

When there is air in the hydraulic oil, it may cause bubbles to appear in the hydraulic system. When observing the hydraulic oil, if you notice a large number of bubbles or bubbles continuously appearing, this may be a sign of air in the hydraulic cylinder.

Abnormal Noise:

When there is air in the hydraulic cylinder, due to the compressibility of air, abnormal noises may occur in the hydraulic system. These noises are usually generated by the compression or release of gas and can be used as one of the indicators to determine whether there is air in the hydraulic cylinder.

Unstable Hydraulic System Pressure:

When there is air in the hydraulic system, it may cause abnormal pressure in the hydraulic system. For example, during lifting operations, the hydraulic cylinder may not generate enough pressure to lift the object, or during lowering operations, the lowering speed may be unstable.

Vibrations Or Shaking:

When there is air in the hydraulic system, it may cause unstable motion of the hydraulic cylinder. For example, vibrations or shaking may occur during pushing or pulling actions.

Why should bleed air from Excavator Hydraulic Cylinder?

The reason for bleeding air from an excavator hydraulic cylinder is to ensure proper operation of the hydraulic system. Air in the hydraulic system may affect the performance and stability of the hydraulic cylinder, or even cause system failure. Venting a hydraulic cylinder can help ensure that there is only hydraulic oil inside the cylinder and no air.

How to Bleed Air From  Excavator Hydraulic Cylinder?

Bleeding the excavator hydraulic cylinder is one of the key steps to ensure the normal operation of the excavator hydraulic system. During the daily operation and maintenance of the excavator, air may accumulate inside the hydraulic cylinder, which will affect the performance and stability of the hydraulic system. Therefore, regularly bleeding hydraulic cylinders is essential to ensure smooth operation of your excavator. 

Preparation

Before venting the excavator hydraulic cylinder, some preparations need to be done to ensure smooth operation.

Stay safe: When venting a hydraulic cylinder, make sure your surroundings are safe and take appropriate safety measures, such as wearing gloves and goggles.

Shut down the hydraulic system: Before venting the hydraulic cylinder, make sure the hydraulic system is shut down and the hydraulic pump has stopped running.

Locate the hydraulic cylinder: Determine the location of the hydraulic cylinder that needs to be vented and make sure it is easily accessible.

Prepare tools: Have necessary tools ready, such as wrenches, screwdrivers, and hydraulic fluid.

Locate the Exhaust Valve

The first step in bleeding the excavator hydraulic cylinder is to locate the exhaust valve on the cylinder. The exhaust valve is typically located at the top or side of the hydraulic cylinder, and it may be a valve, screw, or plug for releasing air.

Open the Exhaust Valve

Using appropriate tools such as a wrench or screwdriver, gently open the exhaust valve. Before opening the exhaust valve, ensure that a suitable container is placed underneath to collect the expelled hydraulic oil and gas.

Observe the Exhaust

Closely observe the exhaust valve to see if any air bubbles are expelled. Initially, you may see some bubbles, but as the operation progresses, the bubbles should gradually decrease until they are completely expelled.

Close the Exhaust Valve

When hydraulic oil flows out of the exhaust valve without any air bubbles, it indicates that the air inside the hydraulic cylinder has been completely expelled. At this point, close the exhaust valve and ensure it is securely fastened.

Check the Fluid Level

After bleeding the hydraulic cylinder, check the fluid level in the hydraulic oil tank. Add the appropriate amount of hydraulic oil if necessary to ensure the fluid level meets the requirements for normal operation of the hydraulic system.

Test the Hydraulic Cylinder

After completing the bleeding process, test the hydraulic cylinder to ensure its proper operation. Use the hydraulic system controls to test the movement and response of the hydraulic cylinder.

Precautions

When bleeding the hydraulic cylinder, observe the following precautions:

Safety First: Always prioritize safety and ensure that no accidents occur during the operation.

Watch for Hydraulic Oil Splashes: Be cautious of hydraulic oil splashes or gases expelled during the bleeding process, as they may cause harm to the surrounding environment and personnel.

Monitor Hydraulic Cylinder Temperature: Pay attention to the temperature of the hydraulic cylinder during the bleeding process. Elevated temperatures may affect the normal operation of the system and cause damage to the hydraulic cylinder.

Regular Maintenance: Regular maintenance of the hydraulic system is crucial to ensure its stable operation. In addition to regular bleeding, periodic replacement of hydraulic oil and filters is also necessary to ensure the proper functioning of the hydraulic system.

Bleeding the hydraulic cylinder is an important step in hydraulic system maintenance. It ensures the proper operation of the hydraulic cylinder and prolongs its service life.

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