ERIKS type R (type A according to the DIN standard) is identical in shape to type M, but has a rubber outer case with metal reinforcement on the inside. The rubber creates a good seal in the housing, even if the housing has suffered minor damage or is not in its best condition for other reasons. The RST version has a dust lip. These types are often chosen to replace a type with a metal outer case because they are easier to install and can cope with minor damage to the groove, such as scratches.
There are a variety of oil seals used in a variety of applications to help close the space between a stationary and a moving part. By closing the space it prevents any lubricants from escaping. Additionally, oil seals help create a seal that prevents any contaminants from entering machinery which can cause a host of problems. Mechanical equipment and machinery require different size or type oil seals to ensure that there is a superior and precise seal. Because oil seals help reduce contamination or mixing of materials it prolongs the life of machinery and helps ensure a more reliable performance.

What material are oil seals made from?
Atlas
Nitrile rubber offers good durability for general use, while the flexibility of the spring behind the sealing lip keeps the oil seal firmly in place against the moving part.



Auto oil seal Features
Rotary Wheel Of Auto Parts
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Figure 4.6. Rubber reinforced with carbon black and CNT nanocomposite to reduce the accumulation of heat in tyre [42].
Car Iridium Spark Plug: Advantages and Performance
Polyacrylate
Better heat, oil and chemical resistance than NBR
It is recommended for use in oil which contains load bearing additives such as EP gear oils