Radial shaft seals, also known as Oil Seals or Lip Seals, are used to seal rotary elements, such as a rotating bore or a shaft. Common examples include strut seals, hydraulic pump seals, axle seals, power steering seals, and valve stem seals. Early radial shaft seals utilized rawhide as the sealing element, and many elastomeric seal companies today once were tanneries.
The advent of modern elastomers replaced rawhide, industry also added a garter spring which helps the sealing lip compensate for lip wear and elastomer material changes.
The seal construction will consist of a sprung main sealing lip which has a point contact with the shaft. The point contact is formed by two angles, with the air side angle usually less than the oil side angle. Depending on the seal type these two angles are varied to create a pressure distribution at the seal contact point which has a steeper slope on the oil side of the seal. The shallower the slope on the oil side of the seal the wetter the seal will run. The spring is positioned such that axially the centerline of the spring is biased to the air side of the lip contact point.
In order to exclude contaminants numerous types of dust lips or exclusionary lips may be used. In order to resist wear the compounds’ durometer (hardness) is typically 70 to 85 Shore A (between that of an automobile tire and a soft inline-skate wheel).
Here at Townsend Bearings we are a UK based Supplier of a large range of Oil Seals in both imperial and metric sizes.
Oil seals are available in many different materials and configurations. The standard sealing material is Nitrile but other materials such as PTFE, Epdm, Viton and Silicone are also used.
Oil seals also come in differing lip arrangements. the two most common arrangements being the R21 single contact lip and the R23 with a single contact lip and an additional non contact dust lip. It is a combination of these two factors which determine the right oil seal for the application in any industry from engineering to food processing or marine use.
All of our catalogues are available to download in PDF format. To view our catalogues see links to the main Associated Engineering Products catalogue and main Oil Seal sections below.