Shields and Seals

Closures, more commonly known as shields and seals are used to protect the internal parts of the bearing against dust, liquid, and gaseous particle contamination. The shields help contain the lubricant in the bearing but are not designed to keep out liquid and gaseous contamination. We manufacture our own shields at WIB to the precise tolerance to minimize the opening gap, thereby offering great grease retention and longer life. On the other hand, seals are designed to keep various types of contamination out, keeping the grease clear of foreign particles and extending the bearing life.


Pressed steel shields (described as Z shield in the nomenclature) are pressed into the bearing and offer some level of protection it against dust and solid particles ingress. Non-contact seals (RSF), constructed of mild steel and rubber material, provide similar advantages as shields, as they have no influence on the friction torque and on the admissible limiting speeds, but do offer enhanced protection.

Contact Seals

Contact seals (RSI, RSR, RSV, RSL, RST) offer better protection against dust, liquid, and gaseous particle contamination. These seals, which are manufactured using synthetic rubber and a zinc-steel core are pressed into the bearings outer ring. The friction at the seal lip on the inner ring increases the drag torque and slightly reduces the admissible limiting speeds. Our application engineers can work with you to determine the right seal architecture and material for your application. If your application goes being common industry designs, we can work to tailor a custom seal design to meet the most demanding needs of your application.

Nitrile seals are limited to a minimum-maximum temperature range of (-30 to +125°C).

For high temperature applications, Viton® seals are commonly used. They can withstand temperatures of up to +230°C.

Seal Design and Nomenclature

Z Z - Mild Steel
  • Low torque
  • High speed
  • High temperature
ZB - Mild Steel, blackened
ZM - Brass Shield
ZS - Copper-Nick
- Stainless Steel
ZP - Plastics
  • Seal without contact 
  • Color blue
  • Low torque
  • High speed
  • Higher tightness than with a Z shield
  • Non-rubbing RSR seal
  • Low torque
  • High speed
  • Higher tightness than with a Z shield
  • Seal
  • Standard color black
  •  Designed to varying degrees of contact pressure
  • Low torque
  • High speed
  • Contactless seal 
  • Standard color blue
  • Low torque
  • High speed
  • Contactless or low-contact seal
  • Low torque 
  • High speed 
  • Prevents water ingress to a higher degree than Z shields
  • Contact seal providing robust protection from outside contaminants
  • Standard color black
  • Standard WIB seal design
  • VITON® seals providing high temperature stability
  • Standard color orange
  • Max operating temperature is 230°C.
  • Special seal with tangential contact on a chamfer of the inner ring
  • Robust protection, especially for extreme environments.
  • Special seal with dual point contact on the inner ring groove.
  • Superior protection, in all environments.
Open No seals applied on bearing
One Side Z, RSR
Same for RSF, RSI, RSV, RST, RSL and others
Both Sides (Identical) Z, RSR
Same for RSF, RSI, RSV, RST, RSL and others
Shield Combinations Z RSR, RSF RSR
All other possible combinations to the extent they are feasible

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