7028 bearing: complete specifications & equivalents
The 7028 is a ISO 15 radial bearing sized 140 x 210 x 33 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 210 mm |
| Width B | 33 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 133 kN |
| Basic static load rating C0 | 133 kN |
| Fatigue load limit Pu | 6.85 kN |
| Limiting speed (mechanical) | 3100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3960 g |
| Manufacturer designation | NTN 7028 |
| 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 | 5.512 in |
|---|---|
| Outer diameter D | 8.268 in |
| Width B | 1.299 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 35 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) | 26 of 36 |
| Bore above smallest 7000-series size | 130 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7028-BGM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 140×210×33 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 7028 model number is decoded
7028 is an NTN single-row angular contact ball bearing: standard-section 7000 single-row family, listed in NTN Ball and Roller Bearings CAT.No.2203E at 140 x 210 x 33 mm. Reading the code: 70 is the single-row dimension series (standard-section 7000 single-row family), 28 encodes the 140 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. Catalogue mass is about 3960 g, which at this 35.0 mm radial section keeps the bearing comfortably inside high-speed spindle weight budgets. Choose the standard-section 7000 single-row family when the shaft needs a stiff locating support and the axial component is known to act mostly one way. Set preload or end-play with the pair as a unit and lock the adjustment; a single angular-contact bearing cannot run free like a deep-groove one.
Typical equipment & failure modes
Common applications
- large pump and turbine auxiliary shafts
- steel-plant conveyor and table roll drives
- wind-turbine and heavy-machinery auxiliaries
- heavy industrial gearbox main shafts
Known failure patterns
- false brinelling on the raceway contact ellipses when a preloaded spindle sits vibrating at standstill — visible as evenly spaced flute-like wear at ball pitch
- loss of preload after housing-fret or shaft creep, leaving the pair loose — ball skidding, cage rattle and a falling natural frequency follow
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
Selection pitfalls — read before you substitute
- At this size the shaft fit, shoulder geometry and preload procedure dominate the outcome; a 140 mm bore bearing forgives nothing in a poorly machined housing.
- 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 7028 mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- The 3,100 r/min speed figure assumes the catalogue lubrication state and a correctly set pair; real limits drop fast with excess grease fill or heavy preload.
- If the application vibrates at standstill (transport, idle machine next to a running line), specify protection: the contact ellipse of a preloaded bearing false-brinells faster than a loose one.
- The 133/133 kN ratings and 6.85 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7028; 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 7028?
7028 is a single-row angular contact ball bearing to ISO 15: 140 mm bore, 210 mm outside diameter, 33 mm width (5.512 x 8.268 x 1.299 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 133 kN, C0 133 kN and a 6.85 kN fatigue load limit Pu; the grease limiting speed is 3,100 r/min and the oil rating 4,100 r/min; mass about 3960 g.
How is the 7028 designation structured?
70 is the single-row dimension series (standard-section 7000 single-row family); 28 encodes the 140 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 210 mm OD and 33 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7028 support?
One 7028 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 7028?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 3,100 r/min and the oil rating 4,100 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 7028?
The 140/210/33 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 133 kN / C0 133 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.