240-670B bearing: complete specifications & equivalents
The 240-670B 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 | 794000 g |
| Manufacturer designation | NTN 240/670B |
| 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 |
|---|---|---|---|
| 240-670BK30 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 24000-series envelope, cage and ratings; this is the cylindrical-bore execution of the tapered-bore 240-670BK30 (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 240-670B model number is decoded
NTN lists 240/670B with a cylindrical bore and plain outer ring (no D1/W33 groove): 670 mm bore, 980 mm OD, 308 mm width, rated 250 r/min on grease. Digit by digit the code reads as spherical-roller dimension series plus 670 mm bore; the 308 mm width is the wide ISO 15 section, which is why spherical rollers interchange dimensionally but not in cage or rating detail. The 155.0 mm radial section over the 670 mm bore carries two roller rows; capacity per millimetre of bore is about 14.4 kN/mm, among the highest of rolling bearings for the ISO 15 envelope. Pu 1040 kN against C0 20600 kN anchors the contamination derating; for dirty mining duty the adjusted life of 240/670B 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 670 mm bore assembly by hand to distribute it across both rows.
Typical equipment & failure modes
Common applications
- offshore and marine propulsion shaftlines
- large wind-turbine main-shaft arrangements
- steel-mill and heavy crusher main shafts
- mining shovel and dragline swing shafts
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
- roller-end smearing during skidding starts under light load and high viscosity grease
- false brinelling on stopped machines exposed to screen or crusher vibration
- brinelling from static overload or a hammer blow during sleeve mounting
Selection pitfalls — read before you substitute
- At 670 mm bore 240/670B 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 9650 kN rating no longer applies.
- Oil relubrication toward 320 r/min needs drain and level design; flooding the 308 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- The cylindrical-bore 240/670B and its tapered-bore counterpart 240/670BK30 share envelope and ratings but not mounting: do not order the K variant unless the drawing specifies a sleeve or tapered seat.
- The cylindrical-bore 240/670B and its tapered-bore counterpart 240/670BK30 share envelope and ratings but not mounting: do not order the K variant unless the drawing specifies a sleeve or tapered seat.
- The 9650/20600 kN ratings, 1040 kN Pu and 794000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 240/670B (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 240/670B?
240/670B 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 794000 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?
240/670B has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 240/670BK30 (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. 240/670B is the basic execution.
What do D1 and W33 mean on 240/670B?
240/670B 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 240/670B 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.