23256EMKD1 bearing: complete specifications & equivalents
The 23256EMKD1 is a ISO 15 radial bearing sized 280 x 500 x 176 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 280 mm |
| Outer diameter D | 500 mm |
| Width B | 176 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass, machined (M1) |
| Basic dynamic load rating C | 3770 kN |
| Basic static load rating C0 | 5340 kN |
| Fatigue load limit Pu | 193 kN |
| Limiting speed (mechanical) | 740 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 148000 g |
| Manufacturer designation | NTN 23256EMKD1 |
| Standard | ISO 15 |
| 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 & 23200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 6.929 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 110 mm |
| Smallest bore in 23200-series | 90 mm |
| Largest outer diameter in 23200-series | 1360 mm |
| Width range across 23200-series | 52.4–475 mm |
| Bore position in 23200-series (smallest first) | 16 of 34 |
| Bore above smallest 23200-series size | 190 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 23256EMD1 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 23200-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 23256EMD1 — mounting (adapter/withdrawal sleeve or tapered seat, drive-up) differs. Verify shaft arrangement. |
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 23256EMKD1 model number is decoded
The NTN order number 23256EMKD1 identifies a 280×500×176 mm (11.024 × 19.685 × 6.929 in) spherical roller bearing, 1:12 tapered bore (K), to the ISO 15 boundary plan. On the NTN nameplate the suffix cluster after the size reads in order: cage design (EM), bore (K), lubrication feature (D1); 23256EMKD1 is assembled exactly in that order. The 1:12 tapered bore mounts on an adapter/withdrawal sleeve (or tapered seat); drive-up sets the residual radial clearance and fixes the axial position of the 280 mm bore assembly. Pu 193 kN against C0 5340 kN anchors the contamination derating; for dirty mining duty the adjusted life of 23256EMKD1 moves with cleanliness far more than with small C variations. Fillet radii on shaft and housing must clear the ring chamfers of the 176 mm-wide set; use the NTN shoulder/withdrawal-groove table rather than copying a ball-bearing layout.
Typical equipment & failure modes
Common applications
- large SAG/ball-mill trunnion and pinion shafts
- heavy vibrating screens and grizzly feeders
- offshore and marine propulsion shaftlines
- large wind-turbine main-shaft arrangements
Known failure patterns
- lubricant starvation at the centre rib area when the D1/W33 groove is not connected to a relubrication supply
- pressed EA cage fatigue under sustained vibration when minimum load is not maintained
- roller-end smearing during skidding starts under light load and high viscosity grease
- water-induced pitting in washdown or outdoor duty without effective external seals
- hard-particle indentation through the open arrangement in dusty mining duty
Selection pitfalls — read before you substitute
- At 280 mm bore 23256EMKD1 is normally mounted on adapter/withdrawal sleeves with hydraulic assistance; follow the NTN drive-up angle or oil-injection procedure — manual nut tightening cannot set the multi-tonne seating correctly.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 3770 kN rating no longer applies.
- Do not confuse EA and EM at the same number: 23256EMKD1 carries EM machined-brass-cage; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 280×500 mm envelope is identical.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 280 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K seats.
- Do not confuse EA and EM at the same number: 23256EMKD1 carries EM machined-brass-cage; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 280×500 mm envelope is identical.
- The 3770/5340 kN ratings, 193 kN Pu and 148000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 23256EMKD1 (EM machined-brass-cage/D1); another maker's same-envelope part revises internal geometry, so re-verify ratings and cage before substitution on vibrating or rated drives.
Frequently asked questions
What are the dimensions and catalogue data of 23256EMKD1?
23256EMKD1 is an NTN double-row spherical roller bearing to ISO 15: 280 mm bore, 500 mm OD and 176 mm width (11.024 × 19.685 × 6.929 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 3770 kN, C0 5340 kN, Pu 193 kN, grease limiting speed 740 r/min, oil 950 r/min, mass about 148000 g. It is open, with one-piece machined brass cage (EM high-capacity design) and a 1:12 tapered bore.
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
K denotes a 1:12 tapered bore. 23256EMKD1 mounts on an adapter sleeve (or tapered shaft seat) and is driven up to the specified residual clearance; its cylindrical-bore counterpart in the same envelope and ratings is 23256EMD1.
What do EA and EM mean on NTN spherical roller bearings?
EA is the NTN standard-capacity/high-capacity execution with a pressed sheet-steel window cage; EM is the high-capacity execution with a one-piece machined brass cage. Both use the optimised symmetric-roller design, but cage identity changes mass, speed behaviour and suitability for duties like vibrating screens, so they are separate order numbers. 23256EMKD1 is the EM machined-brass-cage execution, listed with the ＊ ULTAGE new-generation mark.
What do D1 and W33 mean on 23256EMKD1?
D1 is NTN's outer-ring lubrication feature: an annular groove with oil holes around the outer ring, aligned with a housing grease port so lubricant reaches both roller rows directly. 23256EMKD1 carries D1; W33 is the equivalent industry-spelled annular-groove-and-holes feature seen on other executions.
How much misalignment and axial load can 23256EMKD1 take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 23200 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 3770 kN C / 5340 kN C0 — but sustained pure axial load is not recommended because it unloads one row.
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.