Radial shaft seals for heavy industrial applications

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Radial shaft seals sit between rotating and stationary components, or two components in relative motion. They have two main parts. One is a cylindrical outer covering with an interference fit that seals statically against the housing bore. The second, a sealing lip, seals dynamically and statically against the shaft. Its sealing edge presses against the counterface surface of the shaft with a defined radial load.Radial shaft seals, also known as lip seals, are used to seal rotary elements, such as a shaft or rotating bore. 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.