31307-A
Holding a bearing marked SKF 31307J2/Q or NSK 30307D or NTN 30307D? Ours is 31307-A — the same seat size, the same type and the same sealing and clearance design.
What this bearing is
31307-A is a tapered roller bearing, execution: open. The manufacturer's cross-reference catalogue confirms full interchangeability for 16 designations, including SKF 31307J2/Q, NSK 30307D, NSK 31307.
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.
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.