239-850K bearing: complete specifications & equivalents
The 239-850K is a ISO 15 radial bearing sized 850 x 1120 x 200 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 | 1120 mm |
| Width B | 200 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 6500 kN |
| Basic static load rating C0 | 15100 kN |
| Fatigue load limit Pu | 1080 kN |
| Limiting speed (mechanical) | 220 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 532000 g |
| Manufacturer designation | NTN 239/850K |
| 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 & 23900-series range
| Bore d | 33.465 in |
|---|---|
| Outer diameter D | 44.094 in |
| Width B | 7.874 in |
| ISO bore code | 39 |
| Radial section height (D−d)/2 | 135 mm |
| Smallest bore in 23900-series | 160 mm |
| Largest outer diameter in 23900-series | 1820 mm |
| Width range across 23900-series | 45–315 mm |
| Bore position in 23900-series (smallest first) | 29 of 38 |
| Bore above smallest 23900-series size | 690 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 239-850 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 23900-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 239-850 — 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 239-850K model number is decoded
239/850K is the basic execution of NTN's spherical roller range for a 850 mm shaft — 6500 kN basic dynamic capacity in a 532000 g, open ISO 15 envelope. On the NTN nameplate the suffix cluster after the size reads in order: cage design (—), bore (K), lubrication feature (none); 239/850K is assembled exactly in that order. Pu 1080 kN is the catalogue fatigue load limit for 239/850K, used in the adjusted-life equation at contaminated or partial-film conditions typical of mining and vibrating duty. Pu 1080 kN against C0 15100 kN anchors the contamination derating; for dirty mining duty the adjusted life of 239/850K 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 850 mm bore assembly by hand to distribute it across both rows.
Typical equipment & failure modes
Common applications
- cement-rotary-kiln support and trunnion rolls
- large SAG/ball-mill trunnion and pinion shafts
- heavy vibrating screens and grizzly feeders
- offshore and marine propulsion shaftlines
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
- roller-end smearing during skidding starts under light load and high viscosity grease
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
- fretting corrosion between adapter sleeve and tapered bore when the drive-up is insufficient
Selection pitfalls — read before you substitute
- At 850 mm bore 239/850K 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.
- Oil relubrication toward 290 r/min needs drain and level design; flooding the 200 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- The D1/W33 groove only helps if the housing has a matching grease passage; mounting a grooved 239/850K in a solid block with no port wastes the feature and leaves the centre rows under-lubricated.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 850 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K30 seats.
- The D1/W33 groove only helps if the housing has a matching grease passage; mounting a grooved 239/850K in a solid block with no port wastes the feature and leaves the centre rows under-lubricated.
- The 6500/15100 kN ratings, 1080 kN Pu and 532000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 239/850K (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 239/850K?
239/850K is an NTN double-row spherical roller bearing to ISO 15: 850 mm bore, 1120 mm OD and 200 mm width (33.465 × 44.094 × 7.874 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 6500 kN, C0 15100 kN, Pu 1080 kN, grease limiting speed 220 r/min, oil 290 r/min, mass about 532000 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. 239/850K 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 239/850.
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. 239/850K is the basic execution.
What do D1 and W33 mean on 239/850K?
239/850K 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 239/850K take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 23900 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 6500 kN C / 15100 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.