An oil seal, also known as a radial shaft seal or rotary shaft seal, is used to seal the space between a rotating shaft and a stationary housing. The sealing lip runs over the surface of the shaft and helps keep oil, grease and other lubricants inside the system, while keeping dirt, dust and moisture out.
Techniparts supplies oil seals in a wide range of sizes, materials, designs and brands, in both metric and inch sizes. Common materials include NBR, FKM/Viton, HNBR, EPDM, silicone and PTFE. Oil seals are used in pumps, motors, gearboxes, shafts, agricultural machinery, construction machinery and other industrial applications. See also the complete range of oil seals and rotary shaft seals.
An oil seal is a dynamic seal for rotating shafts. The seal is usually installed in a bore or housing, while the flexible sealing lip makes contact with the rotating shaft. This creates a separation between the inside of the machine and the surrounding environment.
In many designs, the sealing lip is pressed against the shaft by a small tension spring or garter spring. This spring helps maintain the contact pressure throughout the service life of the seal. At the same time, the outside diameter provides the static seal between the oil seal and the housing.
The technical term for a traditional oil seal is often radial shaft seal. The sealing lip makes radial contact with the rotating shaft. Its operation therefore differs, for example, from a V-ring, which rotates with the shaft and seals axially against a stationary surface.
The sealing lip of an oil seal runs directly over the rotating shaft. The elasticity of the sealing material and, in many designs, the tension spring create constant contact pressure between the lip and the shaft surface.
A thin lubricating film between the sealing lip and shaft helps reduce friction and wear. The quality of the shaft surface, lubrication, alignment and circumferential speed are therefore important for performance and service life.
In addition to retaining oil or grease, an oil seal helps prevent dust, dirt and moisture from entering the system from the outside. Some designs feature an additional dust lip or second sealing lip for this purpose.
Oil seals are available in many different profiles and constructions. Differences include the number of sealing lips, outside diameter design, pressure resistance, installation space and protection against contamination.
An oil seal with one main sealing lip is used for general applications where retaining oil or grease is the primary requirement.
Designs with an additional dust or protective lip provide extra protection against dirt, dust and other contaminants from the outside.
Special pressure-resistant oil seals are available for certain applications. One example is the TCN profile. The possible pressure strongly depends on the type, material, rotational speed, shaft diameter and other operating conditions.
The material of an oil seal largely determines its temperature resistance, chemical resistance, wear resistance and friction. The correct material therefore depends on the medium and operating conditions.
NBR is one of the most commonly used materials for oil seals. It offers good properties with many mineral oils, greases and industrial lubricants and provides a good combination of wear resistance and price.
FKM/FPM, often referred to as Viton®, is widely used at higher temperatures and in contact with hot oils, fuels and various chemical media.
HNBR offers better heat, ageing and ozone resistance than standard NBR and can be suitable for higher dynamic or thermal loads.
Silicone / VMQ remains flexible at low temperatures and has a broad temperature range. Its mechanical properties, however, differ from those of NBR or FKM.
PTFE has very low friction and broad chemical resistance. PTFE seals are used, among other applications, at high speeds, with limited lubrication or under chemically demanding conditions.
Oil seals are usually specified using three dimensions: shaft diameter × outside diameter × width. An oil seal measuring 30 × 47 × 7 mm, for example, is suitable for a 30 mm shaft diameter and a 47 mm housing bore and has a width of 7 mm.
The first dimension is the diameter of the shaft on which the sealing lip runs. This dimension must accurately match the application.
The outside diameter determines the housing bore in which the seal is installed. A correct fit is also essential here for reliable static sealing.
The third dimension indicates the width of the oil seal. When replacing a seal, check all three dimensions rather than only the shaft diameter.
Oil seals are used in virtually every industry where rotating shafts and lubricants are present. They protect machines against leakage and help keep contaminants out of bearing and drive systems.
In pumps and electric motors, oil seals are used around rotating shafts to retain lubricants and keep contaminants out.
In gearboxes, transmissions and drive systems, oil seals help prevent oil from leaking along input or output shafts.
Oil seals are also widely used in tractors, excavators, cranes, trucks, earthmoving machinery and other mobile equipment.
The condition of the shaft surface on which the sealing lip runs is important for the performance of an oil seal. Wear, corrosion, scratches or a worn groove can prevent a new seal from sealing correctly.
If the sealing surface is worn, a Speedi-Sleeve can be used in suitable applications to create a new, smooth running surface. This means the complete shaft does not always need to be replaced or remachined.
Techniparts supplies oil seals from a wide range of brands and manufacturers. This means that a suitable original type or technically equivalent alternative can often be found when replacing an existing seal.
Domsel oil seals are available in different designs and materials. Depending on the type, materials such as NBR and FKM are combined with a metal or stainless steel housing.
For specialist rotary sealing applications, you can also explore the Garlock Seals range. The correct design depends on the technical operating conditions.
Do you know which size or design you need? View the complete range of oil seals. Here you will find different types, materials and standard dimensions.
For more information about elastomers and temperature resistance, you can also consult the material information for oil seals.
Is your current shaft damaged or worn? Check whether a Speedi-Sleeve is suitable for repairing the running surface before installing a new oil seal.
An oil seal is a radial shaft seal used between a rotating shaft and a stationary housing. It helps retain oil or grease while keeping dirt, dust and moisture out.
In practice, oil seal and Simmerring are often used for the same type of radial shaft seal. Simmerring was originally a brand/product name that became widely known in engineering.
An oil seal is generally measured as shaft diameter × outside diameter × width. Measure all three dimensions accurately and, if possible, also check the type and material of the existing seal.
The correct material depends on the medium, temperature, speed and operating conditions. NBR is widely used for mineral oil, while FKM is more commonly selected for higher temperatures and more demanding chemical conditions.
Leakage can be caused by a damaged shaft surface, incorrect dimensions, incorrect installation, insufficient lubrication, unsuitable material selection or alignment errors. Therefore, check both the seal and the shaft and housing.
Yes. If mainly the oil seal running surface is worn, a Speedi-Sleeve can be used in suitable applications to create a new, smooth sealing surface.
View the complete oil seal range at Oil-Seal-Stocks for different types, sizes and materials. Specialist Domsel and Garlock designs are also available.
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