Oil seals (grease seals, fluid seals, or dirt seals), are placed on closed spaces between stationary and moving components in a mechanical equipment to prevent lubricant leakage. They halt abrasive or corrosive moisture and also stop harmful contaminants from entering the machinery particularly in severe environments. A vital component of practically every type of machine and vehicle in operation, oil seals protect all types of precision-constructed, close-fitting ball, sleeve, and roller bearings.
In precision bearings, oil seals help prevent lubricants from leaking into the bearings or in a specific area. They also help prevent the mixture of two different medium such as lubricating oil and water.