Practical answer
A contact seal generally provides stronger protection against dust and moisture, but it may add friction and temperature. A metal shield normally offers lower friction and higher speed capability, yet it should not be treated as a washdown or heavy-contamination seal.
One-sided and two-sided arrangements also affect relubrication. Check the relevant manufacturer catalog for seal material, contact design, temperature and speed limits rather than selecting from the letters alone.
On-site checks
- One-sided or two-sided protection on the original bearing
- Dust, oil, moisture or washdown at the position
- Temperature, speed and starting-torque requirements
- Whether the bearing must be relubricated externally
Record for enquiry or analysis
- Manufacturer and complete suffix
- Photos of the seal lip or shield
- Operating temperature and maximum speed
- Existing lubrication method and service interval
Suffix rules and allowable values vary by manufacturer. Confirm the final selection against current manufacturer documentation and actual machine conditions. Reference entry points:NSK · Schaeffler medias