NUP311EA bearing: complete specifications & equivalents
The NUP311EA is a ISO 15 radial bearing sized 55 x 120 x 29 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 55 mm |
| Outer diameter D | 120 mm |
| Width B | 29 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 162 kN |
| Basic static load rating C0 | 143 kN |
| Fatigue load limit Pu | 17.4 kN |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1430 g |
| Manufacturer designation | NTN NUP311EA |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
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.
Dimensions in inches & NUP300-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 4.724 in |
| Width B | 1.142 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 32.5 mm |
| Smallest bore in NUP300-series | 20 mm |
| Largest outer diameter in NUP300-series | 580 mm |
| Width range across NUP300-series | 15–108 mm |
| Bore position in NUP300-series (smallest first) | 8 of 32 |
| Bore above smallest NUP300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NUP311EA | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 NUP311EA model number is decoded
The NTN order number NUP311EA denotes a 55×120×29 mm (2.165 × 4.724 × 1.142 in) cylindrical roller bearing in the NUP300 family, the EA high-capacity pressed sheet-steel cage. Reading the code: NUP for the two-direction-locating type, then the ISO 15 diameter/width series and the bore code — ×5 = 55 mm (00–03 use the 10/12/15/17 exception table). The 32.5 mm radial section ((120−55)/2) frames the roller complement; capacity per millimetre of bore is about 2.9 kN/mm before application factors. Mass 1430 g for the 55×120×29 mm NUP311EA execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. 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
Common applications
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
- machine-tool gearbox and spindle radial sets
- material-handling drum and wheel shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage distortion after a mounting blow carried through the roller set
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- electrical pitting on VFD-driven motor shafts without grounding protection
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 NUP311EA.
- The NUP rib arrangement is not interchangeable with another prefix on the same 55 mm seat: inner ring two ribs + loose L-ring. Swapping NU for NJ changes axial location behaviour even though the 120×29 mm envelope matches.
- Grease limiting speed 5,300 r/min and oil 7,600 r/min are different limits for NUP311EA: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Wide (22/23) and light (10/49) executions at 55 mm bore share bore but not OD/width; check the full NUP300 series code before substituting, because housing and shoulder geometry will not interchange.
- The 32.5 mm section at 55 mm bore leaves a narrow oil path; with the EA pressed-steel-cage cage the relubrication groove and oil-level design must keep grease from churning in the 29 mm-wide cavity.
- The 162/143 kN ratings, 17.4 kN Pu and 1430 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NUP311EA (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.
Frequently asked questions
What are the dimensions and catalogue data of NUP311EA?
NUP311EA is an NTN NUP single-row cylindrical roller bearing to ISO 15: 55 mm bore, 120 mm OD and 29 mm width (2.165 × 4.724 × 1.142 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 162 kN, C0 143 kN, Pu 17.4 kN, grease limiting speed 5,300 r/min, oil 7,600 r/min, mass about 1430 g. It is open, with the EA high-capacity pressed sheet-steel cage.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
The prefix states the rib arrangement: NU has two outer-ring ribs and a ribless inner ring (float, no axial load); NJ adds ribs for one-direction location; NUP adds a loose L-ring to locate both directions; N has two inner-ring ribs and a separable outer ring; NF has one rib per ring for one-direction guidance. NUP311EA is the NJ rib arrangement plus a loose L-shaped rib ring on the inner ring — it locates the shaft in both axial directions.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. This page's bearing carries the EA pressed-steel-cage execution.
Can NUP311EA take axial load and locate a shaft?
the NUP design provides two-direction axial location via its loose rib ring, for light/moderate thrust guidance. The loose rib ring still only suits light/short-duration axial guidance; heavy thrust belongs to a dedicated thrust bearing.
What do Fw and Ew mean for NUP311EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 70.5 mm, Ew 106.5 mm. The nominal bore/OD remain 55/120 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 5,300 r/min grease / 7,600 r/min oil.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.