At a glance
Sealed bearings
Elastomer closures may touch the ring or run with a controlled clearance. Material and lip geometry are part of the selection.
Use contacting seals for dirt and moisture exposure after checking the permitted temperature and surface speed.
Shielded bearings
Metal shields leave a small clearance and provide a barrier without a sliding sealing lip.
Use shields inside a reasonably clean, protected housing when closure friction needs to remain low.
Key differences
Typical design distinctions. The complete designation and current product specification take precedence.
Swipe the table horizontally to see both options →
| What to compare | Sealed bearings | Shielded bearings |
|---|---|---|
| Barrier | Flexible lip or a designed non-contact gap | Rigid metal gap |
| Moisture | Contact seals usually exclude splash better | Housing sealing is often needed |
| Torque | Varies substantially with contact pressure | Typically lower closure contribution |
| Thermal limit | Elastomer, grease and cage all contribute | Grease, cage and rings still limit temperature |
| Relubrication | Often intended to retain a lifetime grease charge | Access depends on the shield and housing design |
| Suffix examples | 2RS1, 2RSH, DDU, LLU; verify brand | 2Z or ZZ in many product families |
Before you choose
- Select the closure by its stated contact type, not its colour.
- A non-contact seal should not be assigned the torque or speed limit of a contacting seal.
- For contamination control, inspect housing gaps, shaft sealing and the installation environment together.
Check the actual model
Search a full designation, inspect its technical data, then compare candidate records. Similar names or dimensions do not guarantee interchangeability.
Filters show recorded catalogue attributes. Open each candidate to confirm its exact specification.
A few things worth clarifying
Are all sealed bearings contact sealed?
No. Manufacturers also offer low-contact and non-contact seals.
Should I remove a shield to add grease?
Only if the bearing and maintenance procedure permit it. Removing a closure can damage it or change grease retention.
Reference basis & limits
- SKF Evolution — New sealing solutions for deep groove ball bearings
- NSK — Single-row deep groove ball bearings: features and closure designations
Independent explanatory content; not a manufacturer endorsement or approval of a replacement. Verify current product data, fits, lubrication and operating conditions before applying a comparison.