Radial shaft seal
 | This article may be too technical for most readers to understand. |
Radial shaft seals seal rotary elements, such as a shaft or rotating bore. Common examples include strut seals, hydraulic pumps seals, axle seals power steering seals, 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 angle the air side angle which is typically less than the oil side angle. Depending on the seal type these two angles are varied too 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. Common elastomers are: FKM, ACM, NBR, HNBR, AEM. In order to resist wear the compounds are typically 70 to 85 Shore A.