231-900B bearing: complete specifications & equivalents
The 231-900B is a ISO 15 radial bearing sized 900 x 1420 x 412 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 900 mm |
| Outer diameter D | 1420 mm |
| Width B | 412 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 18700 kN |
| Basic static load rating C0 | 38000 kN |
| Fatigue load limit Pu | 2030 kN |
| Limiting speed (mechanical) | 150 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2500000 g |
| Manufacturer designation | NTN 231/900B |
| 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 & 23100-series range
| Bore d | 35.433 in |
|---|---|
| Outer diameter D | 55.906 in |
| Width B | 16.22 in |
| ISO bore code | 31 |
| Radial section height (D−d)/2 | 260 mm |
| Smallest bore in 23100-series | 100 mm |
| Largest outer diameter in 23100-series | 1420 mm |
| Width range across 23100-series | 52–412 mm |
| Bore position in 23100-series (smallest first) | 36 of 36 |
| Bore above smallest 23100-series size | 800 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 231-900BK | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 23100-series envelope, cage and ratings; this is the cylindrical-bore execution of the tapered-bore 231-900BK (K/K30 sleeve or tapered-seat mounting). 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 231-900B model number is decoded
231/900B is an NTN double-row spherical roller bearing: two rows of symmetric rollers on a sphered outer raceway, 900×1420×412 mm to ISO 15, with pressed-steel cage (standard execution). Digit by digit the code reads as spherical-roller dimension series plus 900 mm bore; the 412 mm width is the wide ISO 15 section, which is why spherical rollers interchange dimensionally but not in cage or rating detail. The bearing accepts predominantly radial load with a moderate axial share, but is not a pure thrust bearing: sustained axial-only load skids the unloaded row and damages the basic cage. Catalogue mass 2500000 g (2500.00 kg) for the 900×1420×412 mm execution includes the basic cage and both roller rows; shaft and housing shoulders must support that ring squarely. Fillet radii on shaft and housing must clear the ring chamfers of the 412 mm-wide set; use the NTN shoulder/withdrawal-groove table rather than copying a ball-bearing layout.
Typical equipment & failure modes
Common applications
- heavy vibrating screens and grizzly feeders
- offshore and marine propulsion shaftlines
- large wind-turbine main-shaft arrangements
- steel-mill and heavy crusher main shafts
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
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- rolling-contact fatigue after the catalogue L10 life at the actual load
- brinelling from static overload or a hammer blow during sleeve mounting
Selection pitfalls — read before you substitute
- At 900 mm bore 231/900B 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.
- Minimum load must be maintained even at rest under vibration: an unloaded 231/900B on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The cylindrical-bore 231/900B and its tapered-bore counterpart 231/900BK share envelope and ratings but not mounting: do not order the K variant unless the drawing specifies a sleeve or tapered seat.
- Minimum load must be maintained even at rest under vibration: an unloaded 231/900B on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- Never substitute 231/900B by envelope alone: the 38000 kN C0 and 2030 kN Pu are specific to the NTN basic execution, and vibrating duty depends heavily on cage identity.
- The 18700/38000 kN ratings, 2030 kN Pu and 2500000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/900B (basic); 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 231/900B?
231/900B is an NTN double-row spherical roller bearing to ISO 15: 900 mm bore, 1420 mm OD and 412 mm width (35.433 × 55.906 × 16.22 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 18700 kN, C0 38000 kN, Pu 2030 kN, grease limiting speed 150 r/min, oil 200 r/min, mass about 2500000 g. It is open, with pressed-steel cage (standard execution).
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
231/900B has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 231/900BK (K = 1:12, or K30 = 1:30 on the wide series), intended for adapter/withdrawal-sleeve mounting.
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. 231/900B is the basic execution.
What do D1 and W33 mean on 231/900B?
231/900B is listed without a D1/W33 outer-ring groove in 2203E; lubrication is supplied from the ring sides. D1 (NTN spelling) and W33 add the annular groove plus holes and are ordered as distinct suffixed executions of the same envelope.
How much misalignment and axial load can 231/900B take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 23100 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 18700 kN C / 38000 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.