31310-A
Holding a bearing marked NSK 30310D or NTN 30310D or TIMKEN 31310M? Ours is 31310-A — the same seat size, the same type and the same sealing and clearance design.
What this bearing is
31310-A is a tapered roller bearing, execution: open. The manufacturer's cross-reference catalogue confirms full interchangeability for 17 designations, including NSK 30310D, NSK 31310, NTN 30310D.
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.