30307C bearing: complete specifications & equivalents
The 30307C is a ISO 355 radial bearing sized 35 x 80 x 22.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 22.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 73.5 kN |
| Basic static load rating C0 | 68.5 kN |
| Limiting speed (mechanical) | 4800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 517 g |
| Manufacturer designation | NTN 30307C |
| 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 | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.896 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 22.5 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) | 6 of 32 |
| Bore above smallest 30300-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30307C | 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 30307C model number is decoded
30307C is the NTN 4T catalogue entry for a 35×80×22.75 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 30307C by the metric ISO 355 number: 35 mm bore, 80 mm OD. Individually mounted, 30307C 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. Selection: C 73.5 kN against C0 68.5 kN gives a C0/C ratio of 0.93 for the 35 mm bore, and the equivalent combined load must keep below the rating at the target L10 with the pair counted as one unit. After mounting check the contact pattern with marking blue: a pattern biased to the large or small roller end means the 35 mm pair is misadjusted and the 22.75 mm T set will edge-load in service.
Typical equipment & failure modes
Common applications
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
- truck and bus wheel hubs in paired arrangements
- industrial gearbox and speed-reducer shafts
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- 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
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 35 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 30307C.
- 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 35 mm bore; do not swap to the lighter family without re-checking the 4,800 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 30307C 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 22.75 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Never fit the 35 mm cone by hammering the 80 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 73.5/68.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30307C; 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 30307C?
30307C is a metric 4T tapered roller bearing to ISO 355: 35 mm bore, 80 mm outside diameter and 22.75 mm assembled width T (1.378 × 3.15 × 0.896 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 73.5 kN, C0 68.5 kN (2203E prints no Pu for this size), grease limiting speed 4,800 r/min, oil speed 6,400 r/min, mass about 517 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30307C?
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 (30307C); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30307C designation encode the 35 mm bore?
last two digits 07 are the ISO bore code, ×5 = 35 mm (codes 00–03 use the 10/12/15/17 exception table). The 80 mm OD and 22.75 mm assembled T follow the ISO 355 dimension-series plan.
Why does 30307C list two speeds, 4,800 and 6,400 r/min?
The lower figure, 4,800 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30307C at 6,400 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30307C mean?
Suffix reading on 30307C: 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.