231-500BK bearing: complete specifications & equivalents
The 231-500BK is a ISO 15 radial bearing sized 500 x 830 x 264 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 500 mm |
| Outer diameter D | 830 mm |
| Width B | 264 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 7700 kN |
| Basic static load rating C0 | 13700 kN |
| Fatigue load limit Pu | 875 kN |
| Limiting speed (mechanical) | 330 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 566000 g |
| Manufacturer designation | NTN 231/500BK |
| 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 | 19.685 in |
|---|---|
| Outer diameter D | 32.677 in |
| Width B | 10.394 in |
| ISO bore code | 31 |
| Radial section height (D−d)/2 | 165 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) | 26 of 36 |
| Bore above smallest 23100-series size | 400 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 231-500B | 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 231-500B — 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 231-500BK model number is decoded
231/500BK is an NTN double-row spherical roller bearing: two rows of symmetric rollers on a sphered outer raceway, 500×830×264 mm to ISO 15, with pressed-steel cage (standard execution). The leading digits are the ISO 15 dimension series (23100 series); the bore code resolves to 500 mm (two-digit code ×5, with the 00–03 exception table), and 830 mm OD / 264 mm width follow the general plan. 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. 500 mm bore is 19.685 in and 830 mm OD is 32.677 in; the ISO 15 envelope swaps between brands, but the 7700/13700 kN ratings and cage design are NTN 2203E values. Mount 231/500BK on its adapter or withdrawal sleeve on the 500 mm plain shaft: oil the sleeve, fit the lock nut, drive up to the NTN-specified residual clearance (or use oil injection on large seats), then lock the tab washer.
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
- machined EM cage wear from inadequate oil film at the cage-guiding surfaces
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
- rolling-contact fatigue after the catalogue L10 life at the actual load
Selection pitfalls — read before you substitute
- At 500 mm bore 231/500BK 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.
- K and K30 are different tapers — K is 1:12 and K30 is 1:30 on the wide series; an adapter sleeve for one will not mount the other 500 mm bearing, and drive-up procedures differ.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 7700 kN rating no longer applies.
- The 1:12 tapered bore is the only difference from the cylindrical-bore 231/500B: envelopes and ratings match, but drive-up tooling, sleeve and seat do not — never mix the two mounting methods.
- Never substitute 231/500BK by envelope alone: the 13700 kN C0 and 875 kN Pu are specific to the NTN basic execution, and vibrating duty depends heavily on cage identity.
- The 7700/13700 kN ratings, 875 kN Pu and 566000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/500BK (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 231/500BK?
231/500BK is an NTN double-row spherical roller bearing to ISO 15: 500 mm bore, 830 mm OD and 264 mm width (19.685 × 32.677 × 10.394 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 7700 kN, C0 13700 kN, Pu 875 kN, grease limiting speed 330 r/min, oil 430 r/min, mass about 566000 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. 231/500BK 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 231/500B.
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. 231/500BK is the basic execution.
What do D1 and W33 mean on 231/500BK?
231/500BK 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 231/500BK 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 — 7700 kN C / 13700 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.