- The Half Moon Valve Cover Gasket, named for its distinctive crescent shape that fits snugly around the perimeter of the valve cover, serves as a seal between the cylinder head and the valve cover. Its design, though simple, is engineered to withstand high temperatures and pressures within the combustion chamber, preventing oil leaks and ensuring efficient lubrication of the valvetrain.
Oil seals work by squeezing and retaining lubricant in a thin layer between the lip and the shaft. Perfect sealing is ensured by the hydrodynamic action of the rotating shaft, which in turn produces a slight pump action.
Various materials with unique properties are utilised in the construction of rotary shaft seals, allowing manufacturers to tailor the sealing solution to specific industry requirements and ensure optimal performance.
An overview of the different standard types of oil seals and their main characteristics is shown below.



Several variables, including maximum temperatures, required lubricants, available space, and more, may influence your choice of bearing seal. Each factor can affect the type of bearing best for your application, the amount of material required, and other factors. Although the choice of seals is crucial to the effectiveness of your bearings, you don’t have to make that choice alone. Our experts at NBC bearings can collaborate with you to identify the bearings and bearing seals that provide the best, most affordable solution for your application, environment, and finished product.
By first finding out the dimensions of the inner and outer diameters and the height of the bore, you have all the data for the correct size of the oil seal. Of course, the oil seal must also be able to withstand the pressure, temperature and medium it is exposed to within the seal during the manufacturing process. You can read more about this in our oil seal selection guide.
Where loads are light, the outer skin layer can be made of silicone. It can be made of Fluroelastomer (orViton) to protect under high temperatures (more than 120 degrees Celcius). The skin can also be made of Poly Acrylate or Polytetra-FluroEthylene.
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In addition to preventing oil leaks, the 30-50-10 oil seal also helps to protect the internal components of the machinery or equipment from dirt, dust, and other contaminants. This extends the lifespan of the machinery and ensures its optimal performance.
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Loosen the securing-clamp bolt at the base of the distributor, then carefully withdraw the distributor.

These cassette seals are widely used in wheel-end applications, such as the axles of agricultural machinery or off-road trucks.
A square rubber gasket is a vital component in various mechanical applications, providing a seal between two surfaces to prevent leakage or contamination. These gaskets are commonly used in machinery, engines, piping systems, and automotive applications.