In the hydraulic transmission system, various components and mechanisms are in a closed state. It is very difficult to troubleshoot problems if they occur, and this kind of failure is mostly due to the failure of one of the components after being damaged. Seal is the key to protect engineering components and hydraulic system, so its reliability often becomes the focus of engineers. The reason why rubber can be used as an important sealing material is that it has strong compression resistance and resistance to change, which can prevent leakage of pressure medium. At present, rubber sealing technology is applied in China's aerospace, petrochemical and other high-tech industries. Therefore, the requirements for rubber's environmental adaptability are very high. To effectively ensure the normal operation of mechanical equipment, staff must attach great importance to the design and development of rubber sealing structures. Because the unreasonable rubber material or structure often leads to seal failure, which has a great negative impact on engineering operations. This paper expounds this problem in detail in order to provide some reference for strengthening the safety and rationality of rubber seal design. 

The main forms of sealing failure of rubber seals are as follows:

 1) Aging, with the passage of time, the strength, compression resistance and resistance of the seals are gradually reduced, and the rubber seals begin to become hard or brittle;

 2) Wear, because the seal is mainly used in the machinery of shaft coupling, there will be scratches on the surface and grooves with different depths;

 3) Damage: the lip of the seal is deformed, the surface is damaged, and local fracture occurs, leading to seal failure;

 4) Twist, local overturning of rubber ring seals, grooves or protrusions;

 5) The lip of the sealing element begins to soften, become sticky or peel locally due to expansion;

 6) Ablation, the lip of the seal is carbonized, the backup ring is ablated, and the rubber seal fails.