30314D bearing: complete specifications & equivalents
The 30314D 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 | 214 kN |
| Basic static load rating C0 | 229 kN |
| Limiting speed (mechanical) | 2300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2920 g |
| Manufacturer designation | NTN 30314D |
| 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 |
|---|---|---|---|
| 30314D | 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 30314D model number is decoded
30314D belongs to the NTN metric 4T tapered roller range (large-OD 30300 family with the steeper contact angle); the open bearing leaves sealing to the application and is normally ordered and mounted as an adjustable matched pair. Reading the designation: the leading five digits follow the ISO 355 metric plan (dimension family plus two-digit bore code), and 30314D resolves to 70 mm bore; the NTN factory mark 4T is stamped on cone and cup but is a brand mark, not a size code, so the catalogue sku is printed without it. The pressed-steel cage and surface-finished roller ends are standard 4T execution; ULTAGE-marked variants use upgraded material and internal geometry aimed at longer rating life with the same ISO 355 envelope. The two speed columns differ by a factor of .77 (grease/limiting 2,300 vs oil 3,000 r/min); heat generation at the cone rib decides which lubrication a real 30314D arrangement can sustain. Re-adjustment after bedding-in is standard practice: re-check end play once the paired 30314D arrangement has run in, because initial seat seating relaxes the set preload slightly.
Typical equipment & failure modes
Common applications
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
- paper-machine press-section rolls
- large agricultural and forestry machine axles
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
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 2920 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 2,300 r/min grease limit and the thrust load split.
- Grease packs must leave free volume in the 38 mm-wide set; over-greasing a paired bearing churning at the 3,000 r/min oil-band speed raises temperature and destroys the preload setting.
- The 40.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 30314D or the ring will bottom out on the radius instead of the shoulder face.
- 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.
- The 214/229 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30314D (ISO 355 7GB); 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 30314D?
30314D 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 214 kN, C0 229 kN (2203E prints no Pu for this size), grease limiting speed 2,300 r/min, oil speed 3,000 r/min, mass about 2920 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30314D?
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 (30314D); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30314D designation encode the 70 mm bore and what is 7GB?
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. 7GB 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 30314D list two speeds, 2,300 and 3,000 r/min?
The lower figure, 2,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30314D at 3,000 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30314D mean?
Suffix reading on 30314D: the trailing A/C/D (or E1) letter marks an NTN contact-angle or internal-design revision of the base number, not a seal or clearance code; 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.