NU311EA bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01

Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.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 NU311EA model number is decoded

NU311EA is an NTN NU cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 55×120×29 mm ISO 15 envelope. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU311EA floats or locates; the numeric remainder is the ISO 15 series and 55 mm bore reference, not a fit or clearance instruction. NTN ships these bearings open with normal (CN) radial clearance and P0 tolerance as standard; precision classes and C3/C4 clearance are separate order suffixes, not part of NU311EA. Rating life at 162 kN C assumes clean oil and adequate film; the 17.4 kN Pu floor means contamination derating — not the C rating alone — governs adjusted life in dusty gearboxes. Heat the inner ring to max 120 °C for the 55 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• On this 55 mm bore, shaft thermal growth can preload the inner ring if the fit is too tight; verify residual interference at temperature and confirm the float ring still slides after mounting NU311EA.
• If the shaft must be located both ways, do not use NU311EA alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
• Do not replace NU311EA with a deep-groove ball bearing on rating alone: line contact gives 162 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
• Do not replace NU311EA with a deep-groove ball bearing on rating alone: line contact gives 162 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
• Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 120 mm race brinells and releases as vibration within hours.
• The 162/143 kN ratings, 17.4 kN Pu and 1430 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU311EA (EA pressed-steel-cage execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.