30314U bearing: complete specifications & equivalents
The 30314U is a ISO 355 radial bearing sized 70 x 150 x 38 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 70 mm |
| Outer diameter D | 150 mm |
| Width B | 38 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 255 kN |
| Basic static load rating C0 | 272 kN |
| Fatigue load limit Pu | 32 kN |
| Limiting speed (mechanical) | 2600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3050 g |
| Manufacturer designation | NTN 30314U |
| 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 | 2.756 in |
|---|---|
| Outer diameter D | 5.906 in |
| Width B | 1.496 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 40 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) | 13 of 32 |
| Bore above smallest 30300-series size | 55 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30314U | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 30314U model number is decoded
NTN supplies this 70 mm bore tapered roller position as 30314U: one cone assembly, one cup, line-contact rollers and a steel cage, rated 255 kN basic dynamic and 272 kN static on the large-OD 30300 family with the steeper contact angle. The last two digits 14 are the ISO bore code, ×5 = 70 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 38 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. 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 30314U, since running clearance is set during assembly. Speed planning uses both catalogue columns: grease 2,600 r/min is the cage/rib mechanical ceiling for 30314U, oil 3,500 r/min is available with circulating oil — a 900 r/min margin at this size. Mount the 70 mm-bore cone on the shaft first (induction heat, max 120 °C), fit the cup square in its housing, then set preload or end play; never drive the cup home through the rollers of 30314U.
Typical equipment & failure modes
Common applications
- large conveyor and bucket-elevator pulleys
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
- paper-machine press-section rolls
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- 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 damage from a mounting blow delivered through the roller complement instead of the ring face
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- Mount the 70 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 3050 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- 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 70 mm bore; do not swap to the lighter family without re-checking the 2,600 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 30314U by size alone can deliver the wrong contact-angle execution for a pinion position.
- Replacing one half of an adjusted pair without resetting end play negates the 38 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 70 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- The 255/272 kN ratings and 32 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30314U (ISO 355 2GB); 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 30314U?
30314U is a metric 4T tapered roller bearing to ISO 355: 70 mm bore, 150 mm outside diameter and 38 mm assembled width T (2.756 × 5.906 × 1.496 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 255 kN, C0 272 kN, Pu 32 kN, grease limiting speed 2,600 r/min, oil speed 3,500 r/min, mass about 3050 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30314U?
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 (30314U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30314U designation encode the 70 mm bore and what is 2GB?
last two digits 14 are the ISO bore code, ×5 = 70 mm (codes 00–03 use the 10/12/15/17 exception table). The 150 mm OD and 38 mm assembled T follow the ISO 355 dimension-series plan. 2GB 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 30314U list two speeds, 2,600 and 3,500 r/min?
The lower figure, 2,600 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30314U at 3,500 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30314U mean?
Suffix reading on 30314U: U marks the reinforced/uprated internal design of the bare number, a separate order number with higher load capacity than the basic execution; the suffix is part of the order number and the variants are not interchangeable articles.
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.