323128 bearing: complete specifications & equivalents
The 323128 is a ANSI ABMA 19.2 radial bearing sized 140 x 225 x 68 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 | 225 mm |
| Width B | 68 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 435 kN |
| Basic static load rating C0 | 650 kN |
| Fatigue load limit Pu | 66 kN |
| Limiting speed (mechanical) | 1200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 9820 g |
| Manufacturer designation | NTN 4T-323128 |
| Standard | ANSI ABMA 19.2 |
| Catalog version | NTN 2203E 2026-09-25 |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN 2203E 2026-09-25) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN 2203E 2026-09-25); 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 & 4t-432-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 8.858 in |
| Width B | 2.677 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in 4t-432-series | 40 mm |
| Largest outer diameter in 4t-432-series | 790 mm |
| Width range across 4t-432-series | 46–266 mm |
| Bore position in 4t-432-series (smallest first) | 18 of 39 |
| Bore above smallest 4t-432-series size | 100 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 323128 | 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 323128 model number is decoded
NTN supplies this 140 mm shaft position as 4T-323128: a factory-adjusted double-row tapered roller bearing whose two roller rows share one double cup, overall width 68 mm. Large sizes continue the plans under different leading digits: 4130/4131 and 4230/4231 belong to the 430-family dimension plan, while 3230/3231 continue the 432 heavy plan — 323128 reads accordingly. The fatigue load limit Cu printed for 4T-323128 is 66 kN — the equivalent-load floor below which high reliability is expected even under contamination in the adjusted-life equation. TDO construction means the two cone assemblies of 4T-323128 face away from each other inside one double cup: the load lines diverge outward, giving a wide effective spread and high moment stiffness for the 140 mm shaft. Mount 4T-323128 as one article: lift on the double cup, never on a single cone, or the preset alignment of the two rows is disturbed.
Typical equipment & failure modes
Common applications
- cement-plant mill and kiln drive trains
- port-crane hoist and luffing gearboxes
- heavy press and forging-machine drives
- large shredder and recycler main shafts
Known failure patterns
- roller large-end smearing against the cone ribs when one row of the unit runs starved of lubricant
- overheated running after a field attempt to "tighten up" the factory-set internal clearance
- one-row flaking when a bent shaft concentrates the combined load on a single row of the pair
- cage fatigue after continuous running near the grease limiting speed without oil cooling
- water-induced pitting when washdown reaches the open unit without external seals
Selection pitfalls — read before you substitute
- At 140 mm bore the 4T-323128 unit needs hydraulic or crane-assisted fitting and a verified oil supply; manual methods cannot control seating at the 435 kN C level.
- The 432 heavy plan gives 4T-323128 its 68 mm width and 435 kN rating at the 140 mm bore; do not downgrade to a 430-family unit of the same bore without re-checking C, C0 and the 66 kN Cu.
- The internal clearance of 4T-323128 is factory-set: no end-play adjustment exists at mounting, and any attempt to set preload with a shaft nut overloads one row.
- Order by the full 323128 code including suffixes — U, X, DX, E1 and UTG variants share the 140 mm bore but are different articles with different internal geometry.
- An unloaded 4T-323128 near 1,200 r/min lets rollers skid; ensure a minimum load or light spring preload on high-speed positions.
- The 435/650 kN ratings and 66 kN Cu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-323128; internal geometry legitimately differs between manufacturers, so re-verify ratings, clearance class and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 4T-323128?
4T-323128 is a double-row tapered roller bearing of TDO (back-to-back) construction: 140 mm bore, 225 mm outside diameter and 68 mm overall width. From NTN Ball and Roller Bearings CAT.No.2203E: C 435 kN, C0 650 kN, Cu 66 kN, grease limiting speed 1,200 r/min, oil speed 1,700 r/min, mass about 9.82 kg. It is an open, preset-clearance unit with pressed-steel cages.
What is the difference between the NTN 430 and 432 double-row series at 140 mm bore?
Both are TDO double-row tapered roller units, but 430 is the light plan and 432 the heavy plan: at the same bore the 432 execution is wider and heavier with higher load ratings. 4T-323128 belongs to the heavy-duty 432-family TDO double-row series. Large sizes continue the plans as 4130/4131/4230/4231 (430 family) and 3230/3231 (432 family).
Can the internal clearance of 4T-323128 be adjusted at mounting?
No. The TDO unit — two cone assemblies against one double cup — is ground and set by NTN at the factory, and the 68 mm overall width is the finished dimension. Mounting sets no end play: seat the unit square, clamp the cup uniformly and verify free rotation. Field re-adjustment overloads one row.
What do the suffix letters on 323128 mean?
With no letter suffix, 323128 is the basic open double-row execution: steel cages, factory-set internal clearance, no feature suffix in the order code.
Why does 4T-323128 list two speeds, 1,200 and 1,700 r/min?
The lower figure, 1,200 r/min, is the grease-lubricated limiting speed for the two rows and their cages. With oil lubrication NTN rates 4T-323128 at 1,700 r/min because oil removes heat from both roller rows better — the housing feed must reach both rows through the double cup.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN 2203E 2026-09-25 on 2026-10-01. Read our editorial & correction policy.