30310-NTN bearing: complete specifications & equivalents
The 30310-NTN is a ISO 355 radial bearing sized 50 x 110 x 29.25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 50 mm |
| Outer diameter D | 110 mm |
| Width B | 29.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 147 kN |
| Basic static load rating C0 | 152 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1310 g |
| Manufacturer designation | NTN 30310 |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
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.
Dimensions in inches & 30300-series range
| Bore d | 1.969 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 1.152 in |
| ISO bore code | 10 |
| Radial section height (D−d)/2 | 30 mm |
| Smallest bore in 30300-series | 15 mm |
| Largest outer diameter in 30300-series | 500 mm |
| Width range across 30300-series | 14.25–105 mm |
| Bore position in 30300-series (smallest first) | 9 of 32 |
| Bore above smallest 30300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30310 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 30310-NTN model number is decoded
30310 is the NTN 4T catalogue entry for a 50×110×29.25 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 2FB, which is the maker-neutral cross-reference for the 50×110 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. NTN adjusts these bearings by cup or cone position rather than shipping a preloaded set; the mounting drawing must state end play or preload for 30310, since running clearance is set during assembly. Selection: C 147 kN against C0 152 kN gives a C0/C ratio of 1.03 for the 50 mm bore, and the equivalent combined load must keep below the rating at the target L10 with the pair counted as one unit. Fillet radii must clear the ring chamfers of the 110 mm cup and 50 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.
Typical equipment & failure modes
Common applications
- truck and bus wheel hubs in paired arrangements
- industrial gearbox and speed-reducer shafts
- bevel and helical pinion drives with high thrust component
- pump and compressor drive shafts carrying combined load
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- false brinelling on a stationary paired set exposed to external vibration
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 30310.
- 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 3,600 r/min grease limit and the thrust load split.
- 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.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 30310 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.
- The 147/152 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30310 (ISO 355 2FB); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 30310?
30310 is a metric 4T tapered roller bearing to ISO 355: 50 mm bore, 110 mm outside diameter and 29.25 mm assembled width T (1.969 × 4.331 × 1.152 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 147 kN, C0 152 kN (2203E prints no Pu for this size), grease limiting speed 3,600 r/min, oil speed 4,800 r/min, mass about 1310 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30310?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (30310); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30310 designation encode the 50 mm bore and what is 2FB?
last two digits 10 are the ISO bore code, ×5 = 50 mm (codes 00–03 use the 10/12/15/17 exception table). The 110 mm OD and 29.25 mm assembled T follow the ISO 355 dimension-series plan. 2FB is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 30310 list two speeds, 3,600 and 4,800 r/min?
The lower figure, 3,600 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30310 at 4,800 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30310 mean?
It is the basic open 4T execution — steel cage, adjusted mounting, no seal or feature suffix. NTN uses U for the uprated design, UTG for ULTAGE large-bearing specs, X for the ISO boundary section, and C/CA/D/A for contact-angle or internal-design variants; all are separate order numbers.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.