QJ-309-N2PHAS bearing: complete specifications & equivalents
The QJ-309-N2PHAS is a ISO 15 radial bearing sized 45 x 100 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer |
| Basic dynamic load rating C | 100 kN |
| Basic static load rating C0 | 83 kN |
| Fatigue load limit Pu | 3.55 kN |
| Limiting speed (mechanical) | 12000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1050 g |
| Manufacturer designation | QJ 309 N2PHAS |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & QJ300-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in QJ300-series | 17 mm |
| Largest outer diameter in QJ300-series | 400 mm |
| Width range across QJ300-series | 14–78 mm |
| Bore position in QJ300-series (smallest first) | 7 of 27 |
| Bore above smallest QJ300-series size | 28 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7309-BE-2RZP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 55.9/37.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-BEP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 55.9/37.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-BECBP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 61/40.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-BEGAPH | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 61/40.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-BECBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 61/40.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-BECBY | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 64/45 kN) — boundary dimensions match, not a load-rating equivalent. |
| 7309-ACCBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×25 mm envelope, but catalogue C/C0 differ between executions (100/83 kN vs 68/45.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| QJ-309-N2MA | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×25 mm envelope with catalogue ratings within 10 %; QJ 309 N2MA is the brass cage, open arrangement, four-point split-inner-ring execution of this size — boundary dimensions interchangeable, execution differs. |
| QJ-309-MA | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×25 mm envelope with catalogue ratings within 10 %; QJ 309 MA is the brass cage, open arrangement, four-point split-inner-ring execution of this size — boundary dimensions interchangeable, execution differs. |
| QJ-309-PHAS | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×25 mm envelope with catalogue ratings within 10 %; QJ 309 PHAS is the PEEK cage, open arrangement, four-point split-inner-ring execution of this size — boundary dimensions interchangeable, execution differs. |
| 7309 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | SKF SKF 7309 BEP shares the 45×100×25 mm angular-contact envelope, but catalogue C/C0 differ (100/83 kN vs 55.9/37.5 kN) — envelope match, not a load-rating equivalent. |
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 QJ-309-N2PHAS model number is decoded
QJ 309 N2PHAS is SKF's 45 mm-bore QJ four-point contact ball bearing of the QJ300 series, 45×100×25 mm, with a two-piece inner ring for bidirectional axial location beside a radial bearing. QJ identifies a four-point contact ball bearing with a two-piece inner ring: the gothic-arch raceways seat each ball at four points, giving axial location in both directions while a paired radial bearing carries the radial load. N2 marks two locating slots, 180° apart, in one outer-ring side face: pins or dogs engage the slots to stop the outer ring turning in its radially-clear housing bore. glass-fibre reinforced PEEK cage, outer-ring-centred with lubrication grooves in the guiding surfaces (suffix PHAS), for very high-speed oil-air or grease lubrication. Envelope 45×100×25 mm (1.772×3.937×0.984 in), 27.5 mm radial section height, C 100 kN, C0 83 kN, Pu 3.55 kN.SKF publishes only the 12,000 r/min limiting speed for this execution, catalogue mass 1050 g. Sizing arithmetic on the 45 mm bore: 100 kN C divided by the 27.5 mm radial section height gives 3.6 kN per section millimetre; the 1050 g mass and 4 % Pu/C share frame the light-load floor for the adjusted-life check. The 3.55 kN fatigue load limit is the equivalent-load floor for long-life adjustment; with 100/83 kN ratings and 1050 g mass this execution carries about 2.22 kN of C per millimetre of bore. Speed-ratio note for this exact unit: no thermal reference speed is listed (seal/grease life governs), so the 12,000 r/min limiting value is the single published ceiling. Locating-slot execution: the two N2 notches are milled into one outer-ring side face exactly 180 degrees apart and engaged by housing dogs or headed pins during assembly; verify dog engagement by hand before the cover goes on, deburr the slot edges after any housing rework, and re-inspect the slot roots for fretting marks at each overhaul because a dog that rides only one slot lets the outer ring walk. The slots identify this order number unmistakably: the plain MA/PHAS execution of the same bore has no notches and must be secured differently.
Typical equipment & failure modes
Common applications
- textile machinery traverse drives
- gearbox shafts where one QJ locates axially in both directions beside a radial bearing
- screw and worm drives
Known failure patterns
- two-piece inner-ring separation damage if the split ring is pressed or heated unevenly during mounting
- false brinelling while the shaft stands with pure radial load and no minimum axial load
- locating-slot root fretting or dog wear when only one N2 notch carries the anti-rotation torque
- fretting corrosion on a loose rotating shaft seat
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- Engage the N2 slots with housing dogs at assembly — a radially loose outer ring without positive anti-rotation creeps its seat
- Provide a minimum axial load (spring preload is common) so the balls stay correctly seated at speed and light-load conditions; otherwise they skid.
- Engage the N2 slots with housing dogs at assembly — a radially loose outer ring without positive anti-rotation creeps its seat
- Anti-rotation is built into QJ-309-N2PHAS: check the two N2 slot faces and the engaging housing dogs at every refit, and never rely on cover friction to stop the radially loose outer ring.
- The PHAS PEEK cage of QJ-309-N2PHAS is outer-ring-centred with lubrication grooves: feed clean oil-air or appropriate grease to the guide land and inspect groove filling at overhaul.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for QJ 309 N2PHAS as the qj slotted execution; the other order numbers of the QJ 309 size are different products and may carry different ratings — always quote the full designation when purchasing.
Frequently asked questions
What are the dimensions and catalogue data of QJ-309-N2PHAS?
QJ 309 N2PHAS measures 45 mm bore × 100 mm OD × 25 mm width (1.772 × 3.937 × 0.984 in), mass about 1050 g. SKF 17000 ratings: C 100 kN, C0 83 kN, Pu 3.55 kN, SKF publishes only the 12,000 r/min limiting speed for this execution.
What does the N2PHAS suffix mean?
QJ identifies a four-point contact ball bearing with a two-piece inner ring: the gothic-arch raceways seat each ball at four points, giving axial location in both directions while a paired radial bearing carries the radial load. N2 marks two locating slots, 180° apart, in one outer-ring side face: pins or dogs engage the slots to stop the outer ring turning in its radially-clear housing bore. glass-fibre reinforced PEEK cage, outer-ring-centred with lubrication grooves in the guiding surfaces (suffix PHAS), for very high-speed oil-air or grease lubrication.
How is a QJ four-point bearing mounted?
As a thrust/locating bearing with radial clearance in the housing, paired with a separate radial bearing (commonly a cylindrical roller bearing): the QJ locates the shaft axially in both directions, the radial bearing carries radial load. Keep the outer ring unclamped with a small end-play gap; N2 slot executions use dogs to stop the outer ring turning.
What does QJ mean in QJ 309 N2PHAS?
QJ is SKF's four-point contact design: a two-piece inner ring and gothic-arch raceways so each ball contacts at four points, giving bidirectional axial location with limited radial capacity — it must see Fa/Fr ≥ 1,27 for correct ball contact.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.