7021-NTN bearing: complete specifications & equivalents
The 7021-NTN is a ISO 15 radial bearing sized 105 x 160 x 26 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 | 160 mm |
| Width B | 26 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 88.5 kN |
| Basic static load rating C0 | 81.5 kN |
| Fatigue load limit Pu | 4.95 kN |
| Limiting speed (mechanical) | 4100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1860 g |
| Manufacturer designation | NTN 7021 |
| 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 & 7000-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.024 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 7000-series | 10 mm |
| Largest outer diameter in 7000-series | 420 mm |
| Width range across 7000-series | 8–65 mm |
| Bore position in 7000-series (smallest first) | 22 of 36 |
| Bore above smallest 7000-series size | 95 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7021 | GENERIC-ISO | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per 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 7021-NTN model number is decoded
NTN 7021 belongs to the standard-section 7000 single-row family: the catalogue boundary dimensions read 105 / 160 / 26 mm (bore / OD / width). Decoding 7021: 70 is the single-row dimension series (standard-section 7000 single-row family), with 21 encodes the 105 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. With C 88.5 kN and C0 81.5 kN, each mm of bore carries about 0.84 kN of dynamic rating. The 105/160/26 envelope is an ISO 15 boundary plan, so dimensional interchange with other makers holds — ratings and internal geometry do not automatically follow. Heat-mounting to 80-90 deg C is the clean route onto a 105 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- large pump, fan and compressor rotor shafts
- crane and hoist gearbox shafts
- paper-machine roll and calendar drives
- extruder and mixer gearbox output shafts
Known failure patterns
- impact brinelling dents on the 30 deg contact path after a shaft-side hammer blow during mounting, because axial shock travels straight through the contact angle
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
Selection pitfalls — read before you substitute
- Bearings of 105 mm bore arrive heavy enough that handling damage (dents from slings, tilting on the shaft) is a real failure precursor — use proper lifting and heating kit.
- The standard 30 deg bearing and its B (40 deg) sibling share the envelope; picking between them is a load-direction decision, not a quality upgrade.
- A 7021 mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- On a 105 mm shaft, an interference fit eats internal clearance; skipping the clearance/preload recalculation is the classic cause of a new bearing running 20 deg C hotter than the drawing suggests.
- The 88.5/81.5 kN ratings and 4.95 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7021; internal geometry legitimately differs between manufacturers, so re-verify ratings, contact angle and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 7021?
7021 is a single-row angular contact ball bearing to ISO 15: 105 mm bore, 160 mm outside diameter, 26 mm width (4.134 x 6.299 x 1.024 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 88.5 kN, C0 81.5 kN and a 4.95 kN fatigue load limit Pu; the grease limiting speed is 4,100 r/min and the oil rating 5,500 r/min; mass about 1860 g.
How is the 7021 designation structured?
70 is the single-row dimension series (standard-section 7000 single-row family); 21 encodes the 105 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. The 160 mm OD and 26 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7021 support?
One 7021 alone takes thrust in one direction only, along its 30 deg contact angle; reversing thrust calls for a second bearing or a factory-matched DB/DF/DT pair (the catalogue right-hand columns list the paired ratings). Radial load is always carried as a combined load through the angled contact.
What lubrication speeds does NTN print for 7021?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 4,100 r/min and the oil rating 5,500 r/min. These are catalogue ceilings for a correctly mounted bearing with the stated lubricant; preload, fill quantity, ambient heat and paired arrangements all move the real limit.
What should be checked before substituting another make for 7021?
The 105/160/26 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 88.5 kN / C0 81.5 kN, the speed figures, contact angle and suffix meaning against the donor catalogue before swapping on a rated drive.
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.