231-500B bearing: complete specifications & equivalents
The 231-500B 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 | 584000 g |
| Manufacturer designation | NTN 231/500B |
| 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 |
|---|---|---|---|
| 231-500BK | 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 231-500BK (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 231-500B model number is decoded
231/500B is the basic execution of NTN's spherical roller range for a 500 mm shaft — 7700 kN basic dynamic capacity in a 584000 g, open ISO 15 envelope. 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. Two symmetric roller rows share the load: C 7700 kN, C0 13700 kN (C0/C ≈ 1.78), with useful axial capacity in either direction alongside the dominant radial load. Pu 875 kN against C0 13700 kN anchors the contamination derating; for dirty mining duty the adjusted life of 231/500B moves with cleanliness far more than with small C variations. Supply grease through the outer-ring feature during commissioning and at the calculated interval, rotating the 500 mm bore assembly by hand to distribute it across both rows.
Typical equipment & failure modes
Common applications
- large wind-turbine main-shaft arrangements
- steel-mill and heavy crusher main shafts
- mining shovel and dragline swing shafts
- cement-rotary-kiln support and trunnion rolls
Known failure patterns
- lubricant starvation at the centre rib area when the D1/W33 groove is not connected to a relubrication supply
- machined EM cage wear from inadequate oil film at the cage-guiding surfaces
- sliding wear and heat when relubrication intervals ignore the groove (D1/W33) supply path
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
- water-induced pitting in washdown or outdoor duty without effective external seals
Selection pitfalls — read before you substitute
- At 500 mm bore 231/500B 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 7700 kN rating no longer applies.
- Oil relubrication toward 430 r/min needs drain and level design; flooding the 264 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 264 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 500 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K30 seats.
- The 7700/13700 kN ratings, 875 kN Pu and 584000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/500B (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 231/500B?
231/500B 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 584000 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?
231/500B has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 231/500BK (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. 231/500B is the basic execution.
What do D1 and W33 mean on 231/500B?
231/500B 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 231/500B 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.