231-630B bearing: complete specifications & equivalents
The 231-630B is a ISO 15 radial bearing sized 630 x 1030 x 315 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 630 mm |
| Outer diameter D | 1030 mm |
| Width B | 315 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 10700 kN |
| Basic static load rating C0 | 19900 kN |
| Fatigue load limit Pu | 1190 kN |
| Limiting speed (mechanical) | 250 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1050000 g |
| Manufacturer designation | NTN 231/630B |
| 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 | 24.803 in |
|---|---|
| Outer diameter D | 40.551 in |
| Width B | 12.402 in |
| ISO bore code | 31 |
| Radial section height (D−d)/2 | 200 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) | 30 of 36 |
| Bore above smallest 23100-series size | 530 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 231-630BK | 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 231-630BK (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 231-630B model number is decoded
231/630B is an NTN double-row spherical roller bearing: two rows of symmetric rollers on a sphered outer raceway, 630×1030×315 mm to ISO 15, with pressed-steel cage (standard execution). Numbering ties 231/630B to its envelope and execution: same-number EA versus EM or plain variants share the 630 mm bore but differ in cage and sometimes mass, so they are quoted as separate articles. Open by design, 231/630B requires application seals and a grease or oil system; NTN vibrating-duty executions of this envelope are selected with cage and clearance choices that are separate order codes. With about 17.0 kN of C per millimetre of the 630 mm bore, 231/630B screens interchange candidates quickly — then verify cage (EA/EM), bore (K/K30) and lubrication feature (D1/W33) suffixes. Never mount 231/630B by striking the outer ring through the roller set; drive through ring faces (or the adapter sleeve nut) and support the ring square to avoid brinelling the 1030 mm race.
Typical equipment & failure modes
Common applications
- steel-mill and heavy crusher main shafts
- mining shovel and dragline swing shafts
- cement-rotary-kiln support and trunnion rolls
- large SAG/ball-mill trunnion and pinion shafts
Known failure patterns
- raceway spalling at the roller ends when misalignment or deflection concentrates the line contact
- cage damage when a mounting force is applied through the roller set instead of the ring face
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- false brinelling on stopped machines exposed to screen or crusher vibration
- rolling-contact fatigue after the catalogue L10 life at the actual load
Selection pitfalls — read before you substitute
- At 630 mm bore 231/630B 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 231/630B on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 10700 kN rating no longer applies.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 630 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K30 seats.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 10700 kN rating no longer applies.
- The 10700/19900 kN ratings, 1190 kN Pu and 1050000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/630B (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 231/630B?
231/630B is an NTN double-row spherical roller bearing to ISO 15: 630 mm bore, 1030 mm OD and 315 mm width (24.803 × 40.551 × 12.402 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 10700 kN, C0 19900 kN, Pu 1190 kN, grease limiting speed 250 r/min, oil 320 r/min, mass about 1050000 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?
231/630B has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 231/630BK (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. 231/630B is the basic execution.
What do D1 and W33 mean on 231/630B?
231/630B 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 231/630B 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 — 10700 kN C / 19900 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.