231-630BK bearing: complete specifications & equivalents
The 231-630BK 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 | 1020000 g |
| Manufacturer designation | NTN 231/630BK |
| 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 |
|---|---|---|---|
| 231-630B | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 23100-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 231-630B — 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 231-630BK model number is decoded
231/630BK 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). On the NTN nameplate the suffix cluster after the size reads in order: cage design (—), bore (K), lubrication feature (none); 231/630BK is assembled exactly in that order. The 200.0 mm radial section over the 630 mm bore carries two roller rows; capacity per millimetre of bore is about 17.0 kN/mm, among the highest of rolling bearings for the ISO 15 envelope. Pu 1190 kN against C0 19900 kN anchors the contamination derating; for dirty mining duty the adjusted life of 231/630BK moves with cleanliness far more than with small C variations. Never mount 231/630BK 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
- 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
- raceway spalling at the roller ends when misalignment or deflection concentrates the line contact
- 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
- false brinelling on stopped machines exposed to screen or crusher vibration
- hard-particle indentation through the open arrangement in dusty mining duty
Selection pitfalls — read before you substitute
- At 630 mm bore 231/630BK 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.
- Oil relubrication toward 320 r/min needs drain and level design; flooding the 315 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- 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.
- Do not confuse EA and EM at the same number: 231/630BK carries basic; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 630×1030 mm envelope is identical.
- The 1:12 tapered bore is the only difference from the cylindrical-bore 231/630B: envelopes and ratings match, but drive-up tooling, sleeve and seat do not — never mix the two mounting methods.
- The 10700/19900 kN ratings, 1190 kN Pu and 1020000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/630BK (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 231/630BK?
231/630BK 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 1020000 g. It is open, with pressed-steel cage (standard execution) 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. 231/630BK 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 231/630B.
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. 231/630BK is the basic execution.
What do D1 and W33 mean on 231/630BK?
231/630BK 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 231/630BK 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.