6311-2RSR
Holding a bearing marked SKF 6311-2RS1 or NSK 6311DDU or NTN 6311LLU? Ours is 6311-2RSR — the same seat size, the same type and the same sealing and clearance design.
What this bearing is
6311-2RSR is a deep groove ball bearing with a 55 × 120 × 29 mm seat, execution: 2RSR seals · clearance CN. The manufacturer's cross-reference catalogue confirms full interchangeability for 10 designations, including SKF 6311-2RS1, NSK 6311DDU, NTN 6311LLU. For 1 designation (FAFNIR 311PP) interchangeability is conditional — the difference usually lies in radial clearance or cage design, so compare the data sheets before fitting.
Designation equivalents
⌀55 × 120 × 29 mm
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.
The same seat in another execution
These items share the mounting size and have cross-reference tables of their own. They differ in sealing, clearance or cage — exactly what decides how the bearing behaves in the seat.
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.