A rotary shaft oil seal with a single lip, also known as a single lip seal, is a mechanical component designed to create a barrier between a rotating shaft and a stationary housing.


Retains lubricant: It prevents lubricant, such as oil or grease, from leaking out of the machine where it’s needed for smooth operation.

Excludes contaminants: It stops dirt, water, or other environmental contaminants from entering the machinery, protecting the shaft and internal components from damage.

Single lip rotary shaft oil seals are commonly found in:

  • Engines
  • Transmissions
  • Gearboxes
  • Pumps
  • Compressors
  • Industrial machinery

They are typically made from a combination of materials:

Sealing lips: These are the parts that come into contact with the shaft and are usually made from a synthetic rubber material, such as nitrile rubber (NBR) or fluoroelastomer (FKM), also known as Viton. These materials are chosen for their wear resistance and good sealing properties.

Metal casing: This provides strength and rigidity to the seal and is typically made from stamped steel.

Spring: This keeps the sealing lip in constant contact with the shaft, ensuring an effective seal.

When choosing a single lip rotary shaft oil seal, it is important to consider the following factors:

Shaft size: The seal must have the correct inner diameter to fit snugly on the shaft.

Housing size: The seal must also have the correct outer diameter to fit properly in the housing.

Material: The seal material should be compatible with the lubricant and operating temperature.

Operating speed: Some seals are designed for specific speed ranges.

Chemical resistance: If the seal will be exposed to chemicals, the material should be resistant to those chemicals.