Oil Seals - Rotary Shaft Seals
The Rotary Shaft Seal is used for excluding dirt, dust, water or other particles, while retaining lubricant in rotary shaft equipment. It was developed as a means of protecting bearings of rotating shafts. The area between the sealing edge and the shaft is most important. The sealing effect is achieved by preloading the sealing lip making its internal diameter slightly smaller than the shaft diameter. The garter spring ensures constant force to the shaft, flattening the sealing edge to a defined width.
Oil seals prevent internal system fluids from leaking and keep external contamination from entering the system. Leakage and/ or contaminants paths occur between the shaft and the seal lip and between the seal and the housing. Oil seals need to seal both dynamically (on the shaft) and statically (on the outer diameter of the seal).
An oil seal normally consists of three basic components: the rubber sealing element, the metal insert (case) and the garter spring. The purpose of the sealing element is to stop the fluid from leaking between the shaft and housing. The metal insert will give rigidity and strength to the seal while it is being held in the bore or recessed groove. The garter spring will help make the rubber sealing element more effective.