231-800B bearing: complete specifications & equivalents
The 231-800B is a ISO 15 radial bearing sized 800 x 1280 x 375 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 800 mm |
| Outer diameter D | 1280 mm |
| Width B | 375 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 16000 kN |
| Basic static load rating C0 | 31000 kN |
| Fatigue load limit Pu | 1780 kN |
| Limiting speed (mechanical) | 180 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1890000 g |
| Manufacturer designation | NTN 231/800B |
| 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 | 31.496 in |
|---|---|
| Outer diameter D | 50.394 in |
| Width B | 14.764 in |
| ISO bore code | 31 |
| Radial section height (D−d)/2 | 240 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) | 34 of 36 |
| Bore above smallest 23100-series size | 700 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 231-800BK | 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 231-800BK (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 231-800B model number is decoded
NTN lists 231/800B with a cylindrical bore and plain outer ring (no D1/W33 groove): 800 mm bore, 1280 mm OD, 375 mm width, rated 180 r/min on grease. Reading the full code: the number gives the 800×1280 mm envelope, — names the cage/capacity execution, no bore suffix means cylindrical bore for a direct shaft seat, and plain outer ring (no D1/W33 groove) completes the order number. The sphered outer raceway lets the inner-ring assembly pivot, accommodating shaft deflection and housing misalignment (around 1–2° for this class; use the 2203E value for the exact series) without edge loading the rollers. Selection: the C0/C ratio of 1.94 (31000/16000 kN) reflects the heavy static and shock proportioning of 231/800B; size the equivalent load at the required L10 with shock factor for the application. Fillet radii on shaft and housing must clear the ring chamfers of the 375 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
- 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
- brinelling from static overload or a hammer blow during sleeve mounting
- water-induced pitting in washdown or outdoor duty without effective external seals
Selection pitfalls — read before you substitute
- At 800 mm bore 231/800B 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.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 375 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 375 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- The cylindrical-bore 231/800B and its tapered-bore counterpart 231/800BK 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 231/800B on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The 16000/31000 kN ratings, 1780 kN Pu and 1890000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 231/800B (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 231/800B?
231/800B is an NTN double-row spherical roller bearing to ISO 15: 800 mm bore, 1280 mm OD and 375 mm width (31.496 × 50.394 × 14.764 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 16000 kN, C0 31000 kN, Pu 1780 kN, grease limiting speed 180 r/min, oil 240 r/min, mass about 1890000 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?
231/800B has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 231/800BK (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. 231/800B is the basic execution.
What do D1 and W33 mean on 231/800B?
231/800B 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 231/800B 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 — 16000 kN C / 31000 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.