N311 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 N311 model number is decoded

N311 belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E, under the ＊ ULTAGE new-generation specification: line-contact rollers between ground raceways for a 123 kN dynamic rating in the 55 mm bore. Numbering ties N311 to its envelope: type code N, series N300, 55 mm bore; the 120×29 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. the bare number is the standard-capacity open execution with the normal pressed-steel cage; the ＊ symbol printed before the number in 2203E marks the ULTAGE new-generation specification — upgraded material/geometry and longer rating life, not part of the order code; quote the full N311 designation when purchasing. The 2.2 kN-per-mm-bore figure (123 kN over 55 mm) lets a N311 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. Keep the open bearing wrapped until fitting: the line-contact raceways of the 55 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.

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 N311.
• The N rib arrangement is not interchangeable with another prefix on the same 55 mm seat: inner ring ribbed, outer ring ribless. Swapping NU for NJ changes axial location behaviour even though the 120×29 mm envelope matches.
• Open N311 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 55 mm contact.
• Do not replace N311 with a deep-groove ball bearing on rating alone: line contact gives 123 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
• The 29 mm width and abutment faces must be square to the axis; a tilted spacer concentrates load across the roller set and shows as uneven raceway polish on the 55 mm inner ring.
• The 123/111 kN ratings, 13.6 kN Pu and 1420 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for N311 (standard 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.