NCF2338-ECJB-PEX bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.2 high-capacity 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. 6.2 high-capacity 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 NCF2338-ECJB-PEX model number is decoded

In SKF catalogue PUB BU/P1 17000, SKF NCF 2338 ECJB/PEX denotes a high-capacity cylindrical roller bearing on the ISO 15 190×400×132 mm envelope, dimension series 23 (medium-section, wide), with catalogue mass 78000 g. The NCF configuration means the high-capacity caged partner execution (ECJB pressed-steel cages with displaced cage bars for extra rollers), matching the NUH bearing in the same dimension envelope; functionally the bearing is the non-locating member of the paired high-capacity arrangement, absorbing axial displacement while carrying the full high radial rating. Reading the order-string suffix ECJB/PEX: the high-capacity execution with pressed-steel cages (the /PEX mark denotes the pinion-shaft special build with its own catalogue rating line). With C 2240 kN and C0 2750 kN, size the bearing on the 190×400 mm ISO 15 envelope and check the 255 kN Pu against the equivalent-load floor; the catalogue lists 1,700 r/min thermal reference speed and 2,200 r/min mechanical limiting speed. Mounting: used opposite the NUH locating bearing on wind-gearbox and heavy industrial pinion shafts; fit the inner ring with interference and let this bearing float axially. A 190 mm seat normally takes a m6 interference with an H6 housing bore when the inner ring rotates. The /PEX mark identifies the pinion-shaft build: it is the execution developed for the pinion position in wind-turbine and heavy industrial gearboxes, and SKF publishes its own rating line (C 2240 kN / C0 2750 kN here) because the roller complement and internal profiling differ from the standard execution. Treat NCF2338-ECJB-PEX as a separate service part: do not substitute the standard NCF 2338 bearing against the /PEX loads, and refit pinion arrangements with the same /PEX order number to preserve the calculated L10 and peak-torque margin.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• High-capacity NUH and NCF bearings are designed as a locating/non-locating PAIR on the same shaft; fitting two locating NUH bearings can preload the arrangement thermally.
• The /PEX pinion build and the standard NCF 2338 bearing are separate service parts with different internal profiling and rating lines; replacing the /PEX part with the standard execution silently erases the peak-torque margin the gearbox was designed for.
• Press-fit force goes through ring faces only; driving a ring home through the rollers brinells the 400 mm raceway.
• Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
• The 2240/2750 kN ratings are SKF catalogue 17000 (2018) values for the ECJB/PEX execution; re-verify against the current catalogue for critical drives and keep the catalogue version with the specification.