232-670BK bearing: complete specifications & equivalents
The 232-670BK is a ISO 15 radial bearing sized 670 x 1220 x 438 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 670 mm |
| Outer diameter D | 1220 mm |
| Width B | 438 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 17900 kN |
| Basic static load rating C0 | 32000 kN |
| Fatigue load limit Pu | 1770 kN |
| Limiting speed (mechanical) | 220 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2200000 g |
| Manufacturer designation | NTN 232/670BK |
| 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 & 23200-series range
| Bore d | 26.378 in |
|---|---|
| Outer diameter D | 48.031 in |
| Width B | 17.244 in |
| ISO bore code | 32 |
| Radial section height (D−d)/2 | 275 mm |
| Smallest bore in 23200-series | 90 mm |
| Largest outer diameter in 23200-series | 1360 mm |
| Width range across 23200-series | 52.4–475 mm |
| Bore position in 23200-series (smallest first) | 32 of 34 |
| Bore above smallest 23200-series size | 580 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 232-670B | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 23200-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 232-670B — 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 232-670BK model number is decoded
232/670BK is an NTN double-row spherical roller bearing: two rows of symmetric rollers on a sphered outer raceway, 670×1220×438 mm to ISO 15, with pressed-steel cage (standard execution). Digit by digit the code reads as spherical-roller dimension series plus 670 mm bore; the 438 mm width is the wide ISO 15 section, which is why spherical rollers interchange dimensionally but not in cage or rating detail. Pu 1770 kN is the catalogue fatigue load limit for 232/670BK, used in the adjusted-life equation at contaminated or partial-film conditions typical of mining and vibrating duty. With about 26.7 kN of C per millimetre of the 670 mm bore, 232/670BK screens interchange candidates quickly — then verify cage (EA/EM), bore (K/K30) and lubrication feature (D1/W33) suffixes. On vibrating-duty shafts verify the radial clearance class and cage choice at order time; the open 232/670BK leaves sealing and the C3/C4 clearance decision to the application drawing.
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
- pressed EA cage fatigue under sustained vibration when minimum load is not maintained
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- fretting corrosion between adapter sleeve and tapered bore when the drive-up is insufficient
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
Selection pitfalls — read before you substitute
- At 670 mm bore 232/670BK 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.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 670 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K30 seats.
- The 1:12 tapered bore is the only difference from the cylindrical-bore 232/670B: envelopes and ratings match, but drive-up tooling, sleeve and seat do not — never mix the two mounting methods.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 17900 kN rating no longer applies.
- The D1/W33 groove only helps if the housing has a matching grease passage; mounting a grooved 232/670BK in a solid block with no port wastes the feature and leaves the centre rows under-lubricated.
- The 17900/32000 kN ratings, 1770 kN Pu and 2200000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 232/670BK (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 232/670BK?
232/670BK is an NTN double-row spherical roller bearing to ISO 15: 670 mm bore, 1220 mm OD and 438 mm width (26.378 × 48.031 × 17.244 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 17900 kN, C0 32000 kN, Pu 1770 kN, grease limiting speed 220 r/min, oil 280 r/min, mass about 2200000 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. 232/670BK 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 232/670B.
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. 232/670BK is the basic execution.
What do D1 and W33 mean on 232/670BK?
232/670BK 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 232/670BK take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 23200 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 17900 kN C / 32000 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.