30238UUTG bearing: complete specifications & equivalents
The 30238UUTG is a ISO 355 radial bearing sized 190 x 340 x 60 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 190 mm |
| Outer diameter D | 340 mm |
| Width B | 60 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 920 kN |
| Basic static load rating C0 | 1000 kN |
| Fatigue load limit Pu | 91.5 kN |
| Limiting speed (mechanical) | 1000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 21500 g |
| Manufacturer designation | NTN 30238UUTG |
| 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 & 30200-series range
| Bore d | 7.48 in |
|---|---|
| Outer diameter D | 13.386 in |
| Width B | 2.362 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 75 mm |
| Smallest bore in 30200-series | 15 mm |
| Largest outer diameter in 30200-series | 580 mm |
| Width range across 30200-series | 11.75–104 mm |
| Bore position in 30200-series (smallest first) | 30 of 37 |
| Bore above smallest 30200-series size | 175 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30238UUTG | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 30238UUTG model number is decoded
30238UUTG belongs to the NTN metric 4T tapered roller range (standard-section 30200 family); 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 30238UUTG resolves to 190 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. At 920 kN C the bearing offers about 4.8 kN of dynamic capacity per millimetre of the 190 mm bore — compare any substitution on this ratio and the 60 mm assembled T, not on bore alone. Selection: C 920 kN against C0 1000 kN gives a C0/C ratio of 1.09 for the 190 mm bore, and the equivalent combined load must keep below the rating at the target L10 with the pair counted as one unit. When pairing 30238UUTG 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
- large marine propulsion reduction gears
- cement-plant kiln and mill drive trains
- rolling-mill roll-neck and gearbox positions
- large crusher and SAG/AG-mill drive shafts
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- edge loading when shaft deflection exceeds the few arc-minutes of misalignment the adjusted pair allows
Selection pitfalls — read before you substitute
- At 190 mm bore the 30238UUTG 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 920 kN C level.
- The standard-section 30200 family at 190 mm bore (340×60 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 1,400 r/min oil ceiling.
- Never fit the 190 mm cone by hammering the 340 mm cup: force for both press fits goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Never fit the 190 mm cone by hammering the 340 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 30238UUTG units have no seals: a wheel-hub or gearbox application needs external sealing or the 1,000 r/min grease figure is meaningless once water reaches the cone rib.
- The 920/1000 kN ratings and 91.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30238UUTG (ISO 355 4GB); 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 30238UUTG?
30238UUTG is a metric 4T tapered roller bearing to ISO 355: 190 mm bore, 340 mm outside diameter and 60 mm assembled width T (7.48 × 13.386 × 2.362 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 920 kN, C0 1000 kN, Pu 91.5 kN, grease limiting speed 1,000 r/min, oil speed 1,400 r/min, mass about 21500 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30238UUTG?
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 (30238UUTG); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30238UUTG designation encode the 190 mm bore and what is 4GB?
last two digits 38 are the ISO bore code, ×5 = 190 mm (codes 00–03 use the 10/12/15/17 exception table). The 340 mm OD and 60 mm assembled T follow the ISO 355 dimension-series plan. 4GB 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 30238UUTG list two speeds, 1,000 and 1,400 r/min?
The lower figure, 1,000 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30238UUTG at 1,400 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30238UUTG mean?
Suffix reading on 30238UUTG: 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.