N311EA bearing: complete specifications & equivalents
The N311EA 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 N311EA |
| 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 & N300-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 N300-series | 17 mm |
| Largest outer diameter in N300-series | 580 mm |
| Width range across N300-series | 14–108 mm |
| Bore position in N300-series (smallest first) | 9 of 33 |
| Bore above smallest N300-series size | 38 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| N311EA | 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 N311EA model number is decoded
For pure radial duty on a 55 mm shaft NTN supplies N311EA: two integral ribs on the inner ring and a ribless separable outer ring; the open execution is rated 5,300 r/min on grease and 7,600 r/min on oil. On the NTN nameplate N states which ring carries the ribs, which determines whether N311EA floats or locates; the numeric remainder is the ISO 15 series and 55 mm bore reference, not a fit or clearance instruction. The separable ring comes off without removing the roller assembly from the other ring, which eases inspection and lets the non-locating arrangement accommodate thermal shaft growth. The 55 mm (2.165 in) bore and 120 mm (4.724 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 29 mm-wide ring. Provide axial location with an adjacent locating bearing rather than expecting the float cylindrical set to hold thrust on the 55 mm shaft.
Typical equipment & failure modes
Common applications
- industrial gearbox input and output shafts
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
- machine-tool gearbox and spindle radial sets
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- rolling-contact fatigue after the catalogue L10 life is exceeded
- hard-particle indentation of raceways in unfiltered oil or open arrangements
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 N311EA.
- 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.
- Wide (22/23) and light (10/49) executions at 55 mm bore share bore but not OD/width; check the full N300 series code before substituting, because housing and shoulder geometry will not interchange.
- If the shaft must be located both ways, do not use N311EA alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 162/143 kN pair here belongs to N311EA as printed, not to the bare size.
- The 162/143 kN ratings, 17.4 kN Pu and 1430 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for N311EA (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 N311EA?
N311EA is an NTN N 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. N311EA is two integral ribs on the inner ring and a ribless separable outer ring — equivalent float behaviour with the separable ring on the housing side.
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 N311EA take axial load and locate a shaft?
the N design is non-locating like NU but floats with the separable outer ring in the housing. Provide axial location with an adjacent locating bearing (angular-contact, deep-groove or a paired NJ/NUP set).
What do Fw and Ew mean for N311EA?
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.