30328UUTG bearing: complete specifications & equivalents
The 30328UUTG is a ISO 355 radial bearing sized 140 x 300 x 67.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 300 mm |
| Width B | 67.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 945 kN |
| Basic static load rating C0 | 950 kN |
| Fatigue load limit Pu | 91.5 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 21100 g |
| Manufacturer designation | NTN 30328UUTG |
| 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 | 5.512 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 2.667 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 80 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) | 24 of 32 |
| Bore above smallest 30300-series size | 125 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30328UUTG | 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 30328UUTG model number is decoded
30328UUTG 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 140×300 mm ISO 355 envelope, with 67.75 mm overall assembled width T. Reading the designation: the leading five digits follow the ISO 355 metric plan (dimension family plus two-digit bore code), and 30328UUTG resolves to 140 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 printed contact-angle geometry gives the large-OD 30300 family with the steeper contact angle its characteristic load split — at 945/950 kN (C/C0) the static rating is about 1.01× C, typical of tapered bearings proportioned for heavy combined duty. Catalogue mass of the 30328UUTG set is 21100 g (0.831 lb cone + cup); abutment and shaft shoulder design must carry that mass square to the axis. Open 4T bearings need application seals; without them the grease at the cone rib of 30328UUTG washes out and the rib/roller-end contact smears on the first wet or dusty shift.
Typical equipment & failure modes
Common applications
- wind-turbine gearbox and main-shaft arrangements
- offshore crane and drawworks drums
- heavy haul railway traction gearboxes
- large marine propulsion reduction gears
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- 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 fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- At 140 mm bore the 30328UUTG set is adjusted with hydraulic nuts on large mill and wind positions; follow the drive-up angle/end-play procedure, because manual torque methods cannot control preload at the 945 kN C level.
- 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 140 mm bore; do not swap to the lighter family without re-checking the 1,300 r/min grease limit and the thrust load split.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 140 mm shoulder geometry, because retrofitting flips the cups.
- Grease packs must leave free volume in the 67.75 mm-wide set; over-greasing a paired bearing churning at the 1,800 r/min oil-band speed raises temperature and destroys the preload setting.
- Minimum load matters at high speed: an unloaded 30328UUTG at a large fraction of 1,300 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- The 945/950 kN ratings and 91.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30328UUTG (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 30328UUTG?
30328UUTG is a metric 4T tapered roller bearing to ISO 355: 140 mm bore, 300 mm outside diameter and 67.75 mm assembled width T (5.512 × 11.811 × 2.667 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 945 kN, C0 950 kN, Pu 91.5 kN, grease limiting speed 1,300 r/min, oil speed 1,800 r/min, mass about 21100 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30328UUTG?
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 (30328UUTG); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30328UUTG designation encode the 140 mm bore and what is 2GB?
last two digits 28 are the ISO bore code, ×5 = 140 mm (codes 00–03 use the 10/12/15/17 exception table). The 300 mm OD and 67.75 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 30328UUTG list two speeds, 1,300 and 1,800 r/min?
The lower figure, 1,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30328UUTG at 1,800 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30328UUTG mean?
Suffix reading on 30328UUTG: the UUTG suffix marks the ULTAGE specification for large NTN tapered rollers — upgraded material and internal design for longer life inside the unchanged ISO 355 envelope; 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.