How to design the sealing system of crane hydraulic cylinder to prevent hydraulic oil leakage?

The sealing system of the crane hydraulic cylinders is crucial in preventing hydraulic oil leakage. 

1. Basic Components of the Sealing System
The sealing system of a crane hydraulic cylinders typically consists of sealing rings, dust seals, guide bands, and other components. These components work together to ensure that the hydraulic cylinder maintains excellent sealing performance even under harsh conditions, such as high pressure, high speed, and heavy loads.

2. Selection and Installation of Seals
Types of Sealing Rings:
Depending on the sealing function, sealing rings can be classified into static and dynamic seals. Static seals are mainly used for fixed parts of the hydraulic cylinder, such as the seal between the cylinder head and the cylinder body. Dynamic seals, on the other hand, are used between the piston and the cylinder body, as well as between the piston rod and the cylinder head.

Common types of sealing rings include O-rings, Y-rings, and V-rings. O-rings are suitable for sealing static or rotating motions; Y-rings have good wear resistance and are ideal for reciprocating motion seals.

Materials for Sealing Rings:
Sealing rings should have good elasticity, wear resistance, corrosion resistance, and aging resistance. Common materials include rubber (such as nitrile rubber, fluororubber), polyurethane, and PTFE (polytetrafluoroethylene).

Installation of Sealing Rings:
The installation of sealing rings should ensure tight contact with the sealing surfaces to avoid gaps or twisting. Before installation, the dimensions, shape, and surface quality of the sealing ring should be checked to ensure they meet the design requirements.

During installation, special tools or guide tools should be used. It is important to avoid using metal tools to directly strike or scratch the sealing ring.

3. Dust Protection and Protective Design
Dust Seals:
Dust seals are used to prevent external dust, impurities, and other contaminants from entering the hydraulic cylinder and to protect the sealing rings from damage. Dust seals are typically installed on the outside of the piston rod's extended end, tightly fitting with the piston rod.

Protective Covers and Rubber Boots:
For long-stroke hydraulic cylinders, protective covers or rubber boots can be installed to further protect the piston rod from environmental wear and tear.

4. Guide and Lubrication Design
Guide Bands:
Guide bands are used to ensure smooth movement of the piston rod within the cylinder body and to prevent damage to the seals due to misalignment or oscillation of the piston rod. Guide bands are usually installed on the inner wall of the cylinder body and fit tightly with the piston rod.

Lubrication Design:
To reduce friction and wear between the sealing ring and the sealing surface, a lubrication system should be set up inside the hydraulic cylinder. The lubrication system can either be automatic or manual oiling.

5. Inspection and Maintenance of the Sealing System
Inspection:
After the hydraulic cylinder is manufactured, a sealing performance test should be conducted to ensure that the sealing rings, dust seals, and other components are installed correctly and that there is no leakage.

Maintenance:
During operation, regular checks of the hydraulic cylinder's sealing performance should be carried out. Any leakage should be addressed promptly. Additionally, severely worn sealing rings and dust seals should be replaced regularly.