240-670BK30 bearing: complete specifications & equivalents
The 240-670BK30 is a ISO 15 radial bearing sized 670 x 980 x 308 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 | 980 mm |
| Width B | 308 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 9650 kN |
| Basic static load rating C0 | 20600 kN |
| Fatigue load limit Pu | 1040 kN |
| Limiting speed (mechanical) | 250 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 781000 g |
| Manufacturer designation | NTN 240/670BK30 |
| 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 & 24000-series range
| Bore d | 26.378 in |
|---|---|
| Outer diameter D | 38.583 in |
| Width B | 12.126 in |
| ISO bore code | 40 |
| Radial section height (D−d)/2 | 155 mm |
| Smallest bore in 24000-series | 65 mm |
| Largest outer diameter in 24000-series | 1580 mm |
| Width range across 24000-series | 35–462 mm |
| Bore position in 24000-series (smallest first) | 33 of 42 |
| Bore above smallest 24000-series size | 605 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 240-670B | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 24000-series envelope, cage and ratings; this is the tapered-bore execution (K30, 1:30) of the cylindrical-bore 240-670B — 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 240-670BK30 model number is decoded
240/670BK30 belongs to the 24000 series of NTN spherical rollers: self-aligning, high radial capacity, moderate axial load in either direction. Reading the full code: the number gives the 670×980 mm envelope, — names the cage/capacity execution, K30 marks the 1:30 tapered bore for sleeve mounting, and plain outer ring (no D1/W33 groove) completes the order number. Pu 1040 kN is the catalogue fatigue load limit for 240/670BK30, used in the adjusted-life equation at contaminated or partial-film conditions typical of mining and vibrating duty. Grease/oil ratio: the 250 r/min limiting value is .78 of the 320 r/min oil value; heavy 308 mm-wide cages run hot in churning grease, so quantity and groove supply both matter. Check the self-aligning movement after fitting: the housing should pivot freely around the sphered outer raceway; a pinched outer ring removes the alignment capacity the bearing was selected for.
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
- lubricant starvation at the centre rib area when the D1/W33 groove is not connected to a relubrication supply
- cage damage when a mounting force is applied through the roller set instead of the ring face
- sliding wear and heat when relubrication intervals ignore the groove (D1/W33) supply path
- hard-particle indentation through the open arrangement in dusty mining duty
- brinelling from static overload or a hammer blow during sleeve mounting
Selection pitfalls — read before you substitute
- At 670 mm bore 240/670BK30 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 308 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- The 1:30 tapered bore is the only difference from the cylindrical-bore 240/670B: 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 9650 kN rating no longer applies.
- The D1/W33 groove only helps if the housing has a matching grease passage; mounting a grooved 240/670BK30 in a solid block with no port wastes the feature and leaves the centre rows under-lubricated.
- The 9650/20600 kN ratings, 1040 kN Pu and 781000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 240/670BK30 (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 240/670BK30?
240/670BK30 is an NTN double-row spherical roller bearing to ISO 15: 670 mm bore, 980 mm OD and 308 mm width (26.378 × 38.583 × 12.126 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 9650 kN, C0 20600 kN, Pu 1040 kN, grease limiting speed 250 r/min, oil 320 r/min, mass about 781000 g. It is open, with pressed-steel cage (standard execution) and a 1:30 tapered bore.
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
K30 denotes a 1:30 tapered bore (the wide 24000 series). 240/670BK30 mounts on a matching adapter or withdrawal sleeve on a plain 670 mm shaft and is driven up to a measured radial clearance; the cylindrical-bore counterpart is 240/670B.
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. 240/670BK30 is the basic execution.
What do D1 and W33 mean on 240/670BK30?
240/670BK30 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 240/670BK30 take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 24000 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 9650 kN C / 20600 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.