No single physical property of rubbers is responsible for the successful performance of an oil seal or ‘O’ ring. The ultimate tensile strength, breaking elongation, modulus, shore hardness, creep and stress relaxation in tension and compression loads are all important physical properties that characterize a seal or ‘O’ ring. Compression strength and set together with stress relaxation or decay are important for effective sealing. The difference in these properties in a swollen seal is highly critical. An optimum swelling value in a fluid medium is a desirable feature. De-swelling decreases the seal pressure against the wall of the housing where the seal is fixed, leading to leakage. Over swelling minimizes the physical properties of the rubber. Seals made of polysulfide rubbers have extreme fuel resistance but undesirably high compression set. The effect of temperature on the seal is an important factor. Swelling under stress can increase at higher temperatures and a suitable compounding technique should be adopted to reduce this effect.
Significance of Valve Cover Gaskets and Head Gaskets
On some engines you have to remove the clutch-housing cover to reach the rear nuts.


Oil seals are protective elements. They prevent the mixing of water and lubricants within a machine, thereby ensuring optimal machine functionality. Also, oil seals help to prevent lubricant leakage at high pressure like when the machine is working at an extremely high rate. Not only that, radial shaft seals stop foreign components from entering a machine. This is because they can contaminate the lubricant and even damage the machine.
1) Common seal types and their features
4) Allowable total eccentricity

Oil seal type or shape


