NU211-NTN bearing: complete specifications & equivalents
The NU211-NTN is a ISO 15 radial bearing sized 55 x 100 x 21 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 | 100 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 64.5 kN |
| Basic static load rating C0 | 62.5 kN |
| Fatigue load limit Pu | 7.6 kN |
| Limiting speed (mechanical) | 6900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 626 g |
| Manufacturer designation | NTN NU211 |
| 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 & NU200-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 0.827 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 22.5 mm |
| Smallest bore in NU200-series | 15 mm |
| Largest outer diameter in NU200-series | 580 mm |
| Width range across NU200-series | 11–92 mm |
| Bore position in NU200-series (smallest first) | 10 of 36 |
| Bore above smallest NU200-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU211 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 55×100×21 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 NU211-NTN model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NU211 appears as a 55 mm bore single-row cylindrical roller bearing (64.5 kN C / 62.5 kN C0) with a pressed sheet-steel cage, listed to the ISO 15 boundary plan. Digit by digit, NU211 reads as NU (outer ring ribbed, inner ring ribless), ISO 15 series, and bore 55 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. With C 64.5 kN and C0 62.5 kN (C0/C ≈ 0.97) the bearing is proportioned for heavy radial load; the NU design carries no axial load and floats axially on both sides. With the inner ring rotating, catalogue practice is a k5/m5 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NU arrangements. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NU211 non-locating position preloads the bearing when the shaft grows.
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
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- brinelling from static overload or impact during handling
- 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 NU211.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NU211 skids at 6,900 r/min and fails by smearing long before L10 fatigue.
- The NU rib arrangement is not interchangeable with another prefix on the same 55 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 100×21 mm envelope matches.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 64.5/62.5 kN pair here belongs to NU211 as printed, not to the bare size.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NU211 skids at 6,900 r/min and fails by smearing long before L10 fatigue.
- The 64.5/62.5 kN ratings, 7.6 kN Pu and 626 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU211 (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.
Frequently asked questions
What are the dimensions and catalogue data of NU211?
NU211 is an NTN NU single-row cylindrical roller bearing to ISO 15: 55 mm bore, 100 mm OD and 21 mm width (2.165 × 3.937 × 0.827 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 64.5 kN, C0 62.5 kN, Pu 7.6 kN, grease limiting speed 6,900 r/min, oil 8,200 r/min, mass about 626 g. It is open, with a 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. NU211 is two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially.
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. NU211 is listed among the ＊ ULTAGE-marked executions in 2203E.
Can NU211 take axial load and locate a shaft?
the NU design carries no axial load and floats axially on both sides. 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 NU211?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 66.5 mm, Ew 88.5 mm. The nominal bore/OD remain 55/100 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 6,900 r/min grease / 8,200 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.