The main function of a rotary shaft seal, also known as an oil seal, is to prevent the leakage of lubricants, fluids, and other materials between a rotating shaft and a stationary housing. These seals are typically located between a shaft and a bearing, or between a shaft and a gear, and create a barrier that prevents lubricants and other materials from escaping or entering the system.

Rotary shaft seals also help to keep contaminants such as dirt, dust, and moisture from entering the machinery and causing damage. They are designed to provide a tight seal and keep the lubricants inside the machinery, and also help to prevent the mixture of two different mediums such as lubricating oil and water.

In addition to preventing leakage, rotary shaft seals also help to protect the bearing and other components from wear and tear. They are designed to resist wear and tear and to withstand the pressure and temperature variations of the machinery.

Rotary shaft seals are critical components in machinery and are necessary to maintain system efficiency and to prevent leakage and failure. They are used in a wide range of industrial and automotive applications such as motors, pumps, compressors, and are designed to meet the specific requirements of each application. They are also designed to ensure the smooth and efficient operation of machinery and to protect the system against damage and failure.