Although the oil seal is not big, it is crucial for the normal operation of the shock absorber and can be regarded as the sealing guardian of the shock absorber.

So, what is the most crucial function of an oil seal?

The primary function is to prevent leakage and seal. The hydraulic oil filled inside the shock absorber is the key medium for achieving the damping effect. The oil seal can closely adhere to the piston rod to prevent the leakage of hydraulic oil. Once it leaks, the damping force of the shock absorber will drop significantly, and the vehicle will experience obvious jolts, bouncing, and even the failure of the shock absorber during driving.

Secondly, it is dust-proof and dirt-proof. Through the dual structure of the main lip and the dust-proof lip, it can effectively prevent external dust, sand and moisture from entering the interior of the shock absorber, avoiding wear and corrosion of internal precision components such as pistons and working cylinders, thereby extending the overall service life of the shock absorber.

Apart from dust-proofing and leak-proofing.

What other easily overlooked but very important functions do oil seals have?

There are two key functions:

One is to stabilize the damping performance. The oil seal can maintain the stability of the oil pressure and the cleanliness of the oil inside the shock absorber, ensuring that the damping force remains uniform under different working conditions such as high and low temperatures and high vibration frequencies, guaranteeing the smoothness and comfort of vehicle driving.

The other is to reduce friction and noise. The oil seal lip and the piston rod form a thin layer of oil, which is the lubricating film. Reducing the friction during the reciprocating motion of the two can effectively lower the wear of components and also reduce abnormal noises. Additionally, the oil seal can adapt to high-pressure environments, prevent high-pressure gas from seeping in, and at the same time isolate moisture and ozone, slowing down the rate of its own aging.

So, how to choose an proper oil seal?

The core should be centered around four dimensions: compatibility, temperature and pressure resistance, material and craftsmanship, and brand reputation. Decisions should be made based on the type of shock absorber products, such as automotive hydraulic shock absorbers, motorcycle shock absorbers, and application scenarios like passenger cars, commercial vehicles, and construction machinery. This can be determined from two points. The first is to prioritize matching product specifications with working conditions and dimensional accuracy. The inner and outer diameters and thickness of the oil seal must be exactly matched with the piston rod and the working cylinder; otherwise, oil leakage or excessive wear will occur. When the shock absorber is in operation, it generates frictional high temperatures, and the hydraulic oil has a certain pressure. The recommended temperature range for the oil seal of the shock absorber in passenger vehicles is -40 ° C to +120 ° C. For commercial vehicles and functional machinery, higher temperature and pressure resistance, medium compatibility, and the material of the oil seal must be compatible with the oil used in the shock absorber to avoid swelling and hardening, which may lead to the failure of the shock absorber seal. Different types and specifications of oil seals should be matched according to sedans and off-road vehicles. For example, the reverse lock oil seal has an upper lip for dust prevention and a lower lip for oil sealing. There is a spring on each of the upper and lower lips, and an air sealing lip. When it is used in conjunction with the guide vane, it is in a state of oil and gas separation. This will improve the performance of the shock absorber and extend its service life. Before using the oil seal, it is advisable to apply special lubricating grease for better results.

Some suggestions on oil seal selection and practical application:
In addition to the material selection based on different working conditions mentioned above, attention should also be paid to dimensional accuracy. The thickness tolerance of the inner and outer diameters of the oil seal must be controlled within ± 0.10mm. The surface of the lip should be smooth without burrs; otherwise, it will affect the sealing effect and service life. During installation, it is essential to avoid scratching the lip with sharp tools. A dedicated oil seal sheath can be used for protection.