30312D bearing: complete specifications & equivalents
The 30312D is a ISO 355 radial bearing sized 60 x 130 x 33.5 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 60 mm |
| Outer diameter D | 130 mm |
| Width B | 33.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 167 kN |
| Basic static load rating C0 | 176 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1950 g |
| Manufacturer designation | NTN 30312D |
| 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 | 2.362 in |
|---|---|
| Outer diameter D | 5.118 in |
| Width B | 1.319 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 35 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) | 11 of 32 |
| Bore above smallest 30300-series size | 45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30312D | 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 30312D model number is decoded
30312D is a metric single-row tapered roller bearing in the NTN 4T programme: a pressed-steel cage guides profiled rollers between a separable cone and cup on the 60×130 mm ISO 355 envelope, with 33.5 mm overall assembled width T. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 30312D by the metric ISO 355 number (ISO series abbreviation 7FB): 60 mm bore, 130 mm OD. NTN grades 4T metric bearings as open bearings without integral seals; at 60 mm bore the application supplies the seals and the grease fill or oil supply to the 7FB ISO 355 assembly. The 2.8 kN-per-mm-bore capacity figure for 30312D summarises the 167 kN rating over 60 mm bore; use it to sanity-check an interchange candidate before swapping brands. When pairing 30312D with a second tapered bearing, keep the matched arrangement clean: a single stray grit particle between cup and housing changes preload faster than the adjustment range can correct.
Typical equipment & failure modes
Common applications
- rolling-mill auxiliary and pinion-stand shafts
- large conveyor and bucket-elevator pulleys
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- indentation of the raceways by hard particles in unsealed open arrangements
Selection pitfalls — read before you substitute
- Mount the 60 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 1950 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 60 mm bore; do not swap to the lighter family without re-checking the 2,700 r/min grease limit and the thrust load split.
- ISO 355 makes the 60×130 mm envelope interchangeable but not the ratings: NTN prints 167/176 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- Grease packs must leave free volume in the 33.5 mm-wide set; over-greasing a paired bearing churning at the 3,600 r/min oil-band speed raises temperature and destroys the preload setting.
- The 35.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 30312D or the ring will bottom out on the radius instead of the shoulder face.
- The 167/176 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30312D (ISO 355 7FB); 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 30312D?
30312D is a metric 4T tapered roller bearing to ISO 355: 60 mm bore, 130 mm outside diameter and 33.5 mm assembled width T (2.362 × 5.118 × 1.319 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 167 kN, C0 176 kN (2203E prints no Pu for this size), grease limiting speed 2,700 r/min, oil speed 3,600 r/min, mass about 1950 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30312D?
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 (30312D); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30312D designation encode the 60 mm bore and what is 7FB?
last two digits 12 are the ISO bore code, ×5 = 60 mm (codes 00–03 use the 10/12/15/17 exception table). The 130 mm OD and 33.5 mm assembled T follow the ISO 355 dimension-series plan. 7FB 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 30312D list two speeds, 2,700 and 3,600 r/min?
The lower figure, 2,700 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30312D at 3,600 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30312D mean?
Suffix reading on 30312D: 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.