NU306 bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings) · extracted 2026-09-26

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings); 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 NU306 model number is decoded

In SKF catalogue PUB BU/P1 17000, NU306 appears as NU 306 ECP: an open, single-row cylindrical roller bearing in the NU300 series, with glass-fibre reinforced polyamide cage and line-contact geometry for high radial capacity. Reading the designation: the leading NU marks a single-row cylindrical roller bearing with separable inner ring, the 3 is the ISO 15 diameter/width series (standard), and the last two digits encode the 30 mm bore; the 72 mm OD and 19 mm width follow the ISO 15 general plan. The SKF catalogue adds the ECP suffix for the standard glass-fibre reinforced polyamide cage; ECJ (pressed steel) and ECM (machined brass) are alternative executions with different speed and temperature ratings. At 11,000 r/min reference speed the 21.0 mm-section NU306 is governed thermally by cage material and lubricant flow; oil or grease selection should be made against that value, with 12,000 r/min as the mechanical ceiling. Fit selection follows the rotating ring — interference on a rotating inner ring — and the outer ring is free to slide axially in the housing; a 30 mm shaft typically takes a k5 seat with an H7 housing bore.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• On this 30 mm bore, thermal expansion of the shaft can preload the inner ring if the fit is too tight; calculate the residual interference at operating temperature and confirm the outer ring can still slide axially in the housing.
• The NU300 series at 30 mm bore (72×19 mm) is the standard-section cylindrical roller envelope; stepping to a wide-section 22/23 variant changes OD, width and heat generation — it is not a drop-in swap when the housing and speed are fixed.
• The ECP polymer cage is rated for standard industrial service up to 120 °C; sustained running above the limiting speed or with degraded lubricant softens the cage — inspect at every relubrication interval.
• The ECP polymer cage is rated for standard industrial service up to 120 °C; sustained running above the limiting speed or with degraded lubricant softens the cage — inspect at every relubrication interval.
• The 58.5/48 kN ratings are SKF catalogue 17000 values for the ECP polymer-cage execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
• SKF lists several executions of NU306 (ECP polymer cage, ECJ pressed steel, ECM machined brass); they are not interchangeable order numbers — quote the full NU 306 ECP designation when purchasing and match the execution to the speed and temperature requirements.