30310D bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01

Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 30310D model number is decoded

In NTN Ball and Roller Bearings CAT.No.2203E, the NTN order number 30310D denotes the large-OD 30300 family with the steeper contact angle of metric tapered roller bearings, 50 mm bore, 110 mm outside diameter and 29.25 mm assembled width T (1.969 × 4.331 × 1.152 in) to the ISO 355 boundary plan. The last two digits 10 are the ISO bore code, ×5 = 50 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 29.25 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. Individually mounted, 30310D takes axial force in one direction only; two bearings are arranged face-to-face (X) or back-to-back (O) according to the moment stiffness and misalignment the shaft requires. The 30.0 mm section height over the 50 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. Open 4T bearings need application seals; without them the grease at the cone rib of 30310D washes out and the rib/roller-end contact smears on the first wet or dusty shift.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Hub and pinion bearings of this 50 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 30310D.
• The steeper contact angle of the large-OD 30300 family with the steeper contact angle raises axial capacity but lowers the speed ceiling against a 302/322 bearing at 50 mm bore; do not swap to the lighter family without re-checking the 3,200 r/min grease limit and the thrust load split.
• The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 30310D by size alone can deliver the wrong contact-angle execution for a pinion position.
• On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 50 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
• Never fit the 50 mm cone by hammering the 110 mm cup: force for both press fits goes through the ring faces only, or brinell marks release as noise within the first running hours.
• The 126/130 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30310D (ISO 355 7FB); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.