240-850BK30 bearing: complete specifications & equivalents
The 240-850BK30 is a ISO 15 radial bearing sized 850 x 1220 x 365 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 850 mm |
| Outer diameter D | 1220 mm |
| Width B | 365 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 13900 kN |
| Basic static load rating C0 | 31500 kN |
| Fatigue load limit Pu | 1490 kN |
| Limiting speed (mechanical) | 180 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1390000 g |
| Manufacturer designation | NTN 240/850BK30 |
| 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 | 33.465 in |
|---|---|
| Outer diameter D | 48.031 in |
| Width B | 14.37 in |
| ISO bore code | 40 |
| Radial section height (D−d)/2 | 185 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) | 37 of 42 |
| Bore above smallest 24000-series size | 785 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 240-850B | 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 240-850B — 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 240-850BK30 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 240/850BK30 denotes the 850 mm bore spherical roller bearing (13900 kN C / 31500 kN C0) in the 24000 series, the self-aligning choice for heavy combined load. Digit by digit the code reads as spherical-roller dimension series plus 850 mm bore; the 365 mm width is the wide ISO 15 section, which is why spherical rollers interchange dimensionally but not in cage or rating detail. Suffix reading on 240/850BK30: the bare number is the standard open execution; K30 marks the 1:30 tapered bore of the wide series; B marks the standard large-bore internal design on slash-size 230–232 series; quote the full code because each suffix is a distinct article. Pu 1490 kN against C0 31500 kN anchors the contamination derating; for dirty mining duty the adjusted life of 240/850BK30 moves with cleanliness far more than with small C variations. 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
- 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
- raceway spalling at the roller ends when misalignment or deflection concentrates the line contact
- machined EM cage wear from inadequate oil film at the cage-guiding surfaces
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- false brinelling on stopped machines exposed to screen or crusher vibration
- false brinelling on stopped machines exposed to screen or crusher vibration
Selection pitfalls — read before you substitute
- At 850 mm bore 240/850BK30 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.
- Do not confuse EA and EM at the same number: 240/850BK30 carries basic; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 850×1220 mm envelope is identical.
- K and K30 are different tapers — K is 1:12 and K30 is 1:30 on the wide series; an adapter sleeve for one will not mount the other 850 mm bearing, and drive-up procedures differ.
- Minimum load must be maintained even at rest under vibration: an unloaded 240/850BK30 on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 365 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- The 13900/31500 kN ratings, 1490 kN Pu and 1390000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 240/850BK30 (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 240/850BK30?
240/850BK30 is an NTN double-row spherical roller bearing to ISO 15: 850 mm bore, 1220 mm OD and 365 mm width (33.465 × 48.031 × 14.37 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 13900 kN, C0 31500 kN, Pu 1490 kN, grease limiting speed 180 r/min, oil 240 r/min, mass about 1390000 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). 240/850BK30 mounts on a matching adapter or withdrawal sleeve on a plain 850 mm shaft and is driven up to a measured radial clearance; the cylindrical-bore counterpart is 240/850B.
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. 240/850BK30 is the basic execution.
What do D1 and W33 mean on 240/850BK30?
240/850BK30 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 240/850BK30 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 — 13900 kN C / 31500 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.