51209
Holding a bearing marked SKF 51209 or NSK 51209 or NTN 51209? Ours is 51209 — the same seat size, the same type and the same sealing and clearance design.
What this bearing is
51209 is a Axial deep groove ball bearing, execution: open. The manufacturer's cross-reference catalogue confirms full interchangeability for 11 designations, including SKF 51209, NSK 51209, NTN 51209.
Designation equivalents
Before you replace it
This is a dimensional and design equivalent: the same seat size, the same bearing type and the same sealing and clearance design. It is not the same product — load ratings, tolerance class and grease may differ between manufacturers. For duty close to the limits or a critical application, check the datasheet of the specific design.
Where these equivalents come from
The base number of a standard bearing is an ISO standard — 6205 is 6205 at every manufacturer. Only the suffixes describing the design differ, and those are what we translate: shields, contact seals, cage and radial clearance. Designations that mean different things at different makers are deliberately omitted.