Radial shaft seals are used to seal rotating axles and shafts. They keep oil or transmission fluid in, and they keep dust and other contaminants out. They can be found in myriad applications, including cars, trucks, gearboxes, pumps, agricultural and construction machinery, and wind turbines.
A radial shaft seal consists of an elastomer bonded to a metal stamping. Two lips are typically molded into the elastomer. The primary lip faces inward to seal in the oil; a secondary lip faces outward to keep contaminants out. A garter spring surrounds the primary lip to supplement the radial force supplied by the elastomer.