QJ-306-N2PHAS bearing: complete specifications & equivalents

Specification table

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.

Cross references & equivalents

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-306-N2PHAS model number is decoded

QJ 306 N2PHAS is SKF's 30 mm-bore QJ four-point contact ball bearing of the QJ300 series, 30×72×19 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 30×72×19 mm (1.181×2.835×0.748 in), 21.0 mm radial section height, C 53 kN, C0 41.5 kN, Pu 1.76 kN.SKF publishes only the 17,000 r/min limiting speed for this execution, catalogue mass 420 g. Envelope economics: the 19 mm width over a 21.0 mm section yields 0.90 mm of ring width per section millimetre, and the bearing weighs 420 g for 53 kN of dynamic capacity — about 8 g per rated kN. Mass and section check: 420 g inside the 30×72×19 mm outline leaves a 21.0 mm radial section, and the 41.5 kN static rating is 0.78× the dynamic rating — plan static safety and minimum load against those numbers rather than against sister executions. Bore-to-OD planning: OD 72 over bore 30 is a 2.40× step for this size, and the 19 mm width gives a bore/width ratio of 1.58; use these ratios when housing space around the 30 mm shaft is the first constraint. 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

Selection pitfalls — read before you substitute

• The inner ring is two-piece: handle both halves together, mount square, and do not separate the split ring unless the fitting procedure requires it.
• Apply the Fa/Fr ≥ 1,27 condition: at lower ratios the balls contact both sides of a raceway, increasing friction and shortening life — the paired radial bearing should carry the radial share.
• Apply the Fa/Fr ≥ 1,27 condition: at lower ratios the balls contact both sides of a raceway, increasing friction and shortening life — the paired radial bearing should carry the radial share.
• Anti-rotation is built into QJ-306-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-306-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 306 N2PHAS as the qj slotted execution; the other order numbers of the QJ 306 size are different products and may carry different ratings — always quote the full designation when purchasing.