Selecting a bearing

4. Shield and Seal

Compared to the open type, the shielded and sealed bearing types provide better protection from contamination and grease leakage. They are selected based on the application and application environment.

Shield (snap ring type)

NMB part number symbol : ZZ

Components are shield and snap ring.
The shield is secured in the outer ring with a snap ring.
No contact between shield bore and circumference of inner ring

Shield

NMB part number symbol : KK or HH
JIS part number symbol : ZZ

The shield is secured directly in the outer ring.
No contact between shield bore and circumference of inner ring.

Rubber seal

Common symbol : SS and DD

Steel inserted rubber seal is secured directly in the outer ring.
Seals contact circumference of inner ring in DD type, and do not contact in SS type.
DD is highly sealed, but torque increases.