NUP221 bearing: complete specifications & equivalents
The NUP221 is a ISO 15 radial bearing sized 105 x 190 x 36 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 190 mm |
| Width B | 36 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 223 kN |
| Basic static load rating C0 | 241 kN |
| Fatigue load limit Pu | 26.1 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3870 g |
| Manufacturer designation | NTN NUP221 |
| 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 & NUP200-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.417 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in NUP200-series | 17 mm |
| Largest outer diameter in NUP200-series | 580 mm |
| Width range across NUP200-series | 12–92 mm |
| Bore position in NUP200-series (smallest first) | 19 of 35 |
| Bore above smallest NUP200-series size | 88 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NUP221-ECP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 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 NUP221 model number is decoded
The NTN order number NUP221 denotes a 105×190×36 mm (4.134 × 7.48 × 1.417 in) cylindrical roller bearing in the NUP200 family, a 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 = 105 mm (00–03 use the 10/12/15/17 exception table). Line contact between rollers and raceways gives NUP221 high radial capacity but no tolerance for misalignment: beyond roughly 3–4 arc-minutes the roller ends edge-load and fatigue accelerates. Speed ratio check: limiting 3,600 r/min is .84 of the 4,300 r/min oil value for NUP221; grease-churn heating closes that gap as fill quantity rises. Mount the separable inner ring + roller assembly on the shaft first and slide the outer ring into the housing; never press the outer ring through the rollers of NUP221.
Typical equipment & failure modes
Common applications
- large electric-motor and generator rotors
- cement and mining conveyor drive pulleys
- heavy industrial gearbox and reducer shafts
- large pump, turbine and compressor rotors
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- fretting corrosion on a loose rotating shaft seat
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- Induction-heat the 105 mm inner ring (max 120 °C) and mount it before fitting the outer ring; the ring mass makes square guidance essential — driving through the rollers brinells the 190 mm raceway.
- Open NUP221 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 105 mm contact.
- If the shaft must be located both ways, do not use NUP221 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- Open NUP221 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 105 mm contact.
- Wide (22/23) and light (10/49) executions at 105 mm bore share bore but not OD/width; check the full NUP200 series code before substituting, because housing and shoulder geometry will not interchange.
- The 223/241 kN ratings, 26.1 kN Pu and 3870 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NUP221 (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 NUP221?
NUP221 is an NTN NUP single-row cylindrical roller bearing to ISO 15: 105 mm bore, 190 mm OD and 36 mm width (4.134 × 7.48 × 1.417 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 223 kN, C0 241 kN, Pu 26.1 kN, grease limiting speed 3,600 r/min, oil 4,300 r/min, mass about 3870 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. NUP221 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. NUP221 is supplied in the standard open execution shown in the table.
Can NUP221 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 NUP221?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 126.8 mm, Ew 168.8 mm. The nominal bore/OD remain 105/190 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,600 r/min grease / 4,300 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.