Glands or oil seals, often called grease, liquid or dirt seals, close the gaps between stationary and moving components of mechanical devices and help prevent oil leakage. They also prevent harmful contaminants from entering the machines, especially in difficult environments. Glands are vital components for practically all types of machines and vehicles in service. The group of oil seals used in dynamics includes radial shaft seals that seal the rotating shaft around its circumference. 

As a rule, glands are used to seal lubricating oil or lubricant and store them in the environment so that moving parts, such as bearings, are constantly with sufficient lubrication. However, such sealants are also used to seal other liquids, gases and solids, such as powders or granules. 

All these types of glands are designed for use without pressure or low pressure up to 0.5 bar for diameters of limited size. With a diameter of 500 mm or more, the maximum pressure is 0.1 bar. For greater pressure, special types of sealants can be used. Oil seals are produced in the most diverse sizes, for shafts from a few millimeters to several meters in diameter.