QJ-307-MA 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-307-MA model number is decoded

QJ 307 MA is SKF's 35 mm-bore QJ four-point contact ball bearing of the QJ300 series, 35×80×21 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. machined brass cage, outer-ring-centred (suffix MA), which guides on the outer ring rather than on the balls. Envelope 35×80×21 mm (1.378×3.15×0.827 in), 22.5 mm radial section height, C 64 kN, C0 51 kN, Pu 2.16 kN.SKF publishes only the 15,000 r/min limiting speed for this execution, catalogue mass 570 g. Selection figures for QJ 307 MA: the static-to-dynamic ratio C0/C is 0.80, Pu 2.16 kN is about 3 % of C, and catalogue mass works out to roughly 16 g per millimetre of bore. Load balance: C0 51 kN against C 64 kN gives a 0.80 ratio, typical of a four-point thrust-oriented design; Pu 2.16 kN enters the SKF adjusted-life equation rather than the basic rating life. Bore-to-OD planning: OD 80 over bore 35 is a 2.29× step for this size, and the 21 mm width gives a bore/width ratio of 1.67; use these ratios when housing space around the 35 mm shaft is the first constraint. Plain outer-ring execution: this order number is delivered without N2 locating slots, so anti-rotation is solved in the housing instead — a shoulder dog, a spring-loaded key, a cover feature or an interference-free circlip arrangement. Because the outer ring deliberately runs with radial clearance and a small axial float gap, omitting positive anti-rotation invites seat fretting; the slotted N2 order number is the alternative when the housing can provide engagement pins.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep a small axial gap between the outer ring and the cover flange so it can accommodate thermal movement; never clamp the outer ring solid.
• The MA machined brass cage is outer-ring-centred — inspect its guide clearance when servicing
• 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.
• Anti-rotation is NOT built into QJ-307-MA: without N2 slots the housing must provide a dog, keyed cover or other positive stop, since the outer ring runs radially loose by design.
• The MA brass cage of QJ-307-MA is outer-ring-centred: its guide land needs an uninterrupted oil film, so check lubricant reach when the bearing is used purely as a thrust location.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for QJ 307 MA as the qj plain execution; the other order numbers of the QJ 307 size are different products and may carry different ratings — always quote the full designation when purchasing.