239-1250K bearing: complete specifications & equivalents
The 239-1250K is a ISO 15 radial bearing sized 1250 x 1630 x 280 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 1250 mm |
| Outer diameter D | 1630 mm |
| Width B | 280 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 13400 kN |
| Basic static load rating C0 | 33500 kN |
| Fatigue load limit Pu | 1810 kN |
| Limiting speed (mechanical) | 120 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1550000 g |
| Manufacturer designation | NTN 239/1250K |
| 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 | 49.213 in |
|---|---|
| Outer diameter D | 64.173 in |
| Width B | 11.024 in |
| ISO bore code | 39 |
| Radial section height (D−d)/2 | 190 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) | 36 of 38 |
| Bore above smallest 23900-series size | 1090 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 239-1250 | 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 239-1250 — 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 239-1250K model number is decoded
239/1250K is the basic execution of NTN's spherical roller range for a 1250 mm shaft — 13400 kN basic dynamic capacity in a 1550000 g, open ISO 15 envelope. Digit by digit the code reads as spherical-roller dimension series plus 1250 mm bore; the 280 mm width is the wide ISO 15 section, which is why spherical rollers interchange dimensionally but not in cage or rating detail. The sphered outer raceway lets the inner-ring assembly pivot, accommodating shaft deflection and housing misalignment (around 1–2° for this class; use the 2203E value for the exact series) without edge loading the rollers. Equivalent-load planning keeps a radial plus moderate axial combination on 239/1250K; if the axial component dominates, pair with a thrust bearing rather than running one roller row unloaded. Supply grease through the outer-ring feature during commissioning and at the calculated interval, rotating the 1250 mm bore assembly by hand to distribute it across both rows.
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
- sliding wear and heat when relubrication intervals ignore the groove (D1/W33) supply path
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
- false brinelling on stopped machines exposed to screen or crusher vibration
Selection pitfalls — read before you substitute
- At 1250 mm bore 239/1250K 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 160 r/min needs drain and level design; flooding the 280 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- 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 1250 mm bearing, and drive-up procedures differ.
- Oil relubrication toward 160 r/min needs drain and level design; flooding the 280 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- Minimum load must be maintained even at rest under vibration: an unloaded 239/1250K on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The 13400/33500 kN ratings, 1810 kN Pu and 1550000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 239/1250K (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 239/1250K?
239/1250K is an NTN double-row spherical roller bearing to ISO 15: 1250 mm bore, 1630 mm OD and 280 mm width (49.213 × 64.173 × 11.024 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 13400 kN, C0 33500 kN, Pu 1810 kN, grease limiting speed 120 r/min, oil 160 r/min, mass about 1550000 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. 239/1250K 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 239/1250.
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. 239/1250K is the basic execution.
What do D1 and W33 mean on 239/1250K?
239/1250K 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 239/1250K 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 — 13400 kN C / 33500 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.