30315U bearing: complete specifications & equivalents
The 30315U is a ISO 355 radial bearing sized 75 x 160 x 40 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 75 mm |
| Outer diameter D | 160 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 283 kN |
| Basic static load rating C0 | 305 kN |
| Fatigue load limit Pu | 35 kN |
| Limiting speed (mechanical) | 2400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3610 g |
| Manufacturer designation | NTN 30315U |
| 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 | 2.953 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.575 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 42.5 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) | 14 of 32 |
| Bore above smallest 30300-series size | 60 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30315U | 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 30315U model number is decoded
For a 75 mm shaft with a thrust component, NTN lists 30315U, a metric 4T tapered roller bearing of 283 kN C and 305 kN C0 inside the 160 mm OD, 40 mm-wide assembled set. Digit by digit, the bare number identifies the large-OD 30300 family with the steeper contact angle and a bore code resolving to 75 mm; 160 mm OD and 40 mm assembled T are the matching ISO 355 boundary dimensions shared with other makers of the same dimension series. At 283 kN C the bearing offers about 3.8 kN of dynamic capacity per millimetre of the 75 mm bore — compare any substitution on this ratio and the 40 mm assembled T, not on bore alone. The fatigue load limit Pu printed for 30315U is 35 kN; in the adjusted-life equation that is the equivalent-load floor below which high reliability is expected even under contamination. When pairing 30315U 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
- 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
- rolling-contact fatigue after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Mount the 75 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 3610 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 75 mm bore; do not swap to the lighter family without re-checking the 2,400 r/min grease limit and the thrust load split.
- The 42.5 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 30315U or the ring will bottom out on the radius instead of the shoulder face.
- Never fit the 75 mm cone by hammering the 160 mm cup: force for both press fits goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Open 30315U units have no seals: a wheel-hub or gearbox application needs external sealing or the 2,400 r/min grease figure is meaningless once water reaches the cone rib.
- The 283/305 kN ratings and 35 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30315U (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 30315U?
30315U is a metric 4T tapered roller bearing to ISO 355: 75 mm bore, 160 mm outside diameter and 40 mm assembled width T (2.953 × 6.299 × 1.575 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 283 kN, C0 305 kN, Pu 35 kN, grease limiting speed 2,400 r/min, oil speed 3,200 r/min, mass about 3610 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30315U?
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 (30315U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30315U designation encode the 75 mm bore and what is 2GB?
last two digits 15 are the ISO bore code, ×5 = 75 mm (codes 00–03 use the 10/12/15/17 exception table). The 160 mm OD and 40 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 30315U list two speeds, 2,400 and 3,200 r/min?
The lower figure, 2,400 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30315U at 3,200 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30315U mean?
Suffix reading on 30315U: 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.