7208B bearing: complete specifications & equivalents
The 7208B is a ISO 15 radial bearing sized 40 x 80 x 18 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 40 mm |
| Outer diameter D | 80 mm |
| Width B | 18 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 35.5 kN |
| Basic static load rating C0 | 23 kN |
| Fatigue load limit Pu | 1.8 kN |
| Limiting speed (mechanical) | 8300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 375 g |
| Manufacturer designation | NTN 7208B |
| 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 & 7200-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.709 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in 7200-series | 10 mm |
| Largest outer diameter in 7200-series | 540 mm |
| Width range across 7200-series | 9–85 mm |
| Bore position in 7200-series (smallest first) | 9 of 36 |
| Bore above smallest 7200-series size | 30 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 7208B model number is decoded
From the medium-duty 7200 single-row family, 7208B measures 40 mm across the bore, 80 mm over the outer ring and 18 mm across the faces. NTN builds the number from 72 is the single-row dimension series (medium-duty 7200 single-row family), then 08 encodes the 40 mm bore (bore code x 5), and the trailing B marks the 40 deg contact-angle execution (the no-letter standard bearing works at 30 deg). The oil rating of 11,000 r/min sits 2,700 r/min above the 8,300 r/min grease figure — a 1.33x step that says how much headroom oil cooling buys. Where the same envelope must also be sealed, or where mounting mistakes are likely, compare with the double-row 52/53 catalogue pages before fixing the bill of materials. Shaft and housing shoulders must clear the ring corners yet support enough face — the catalogue abutment diameters for the 40 mm bore give the working limits.
Typical equipment & failure modes
Common applications
- conveyor drive and tension-drum shafts
- agricultural gearbox and PTO shaft supports
- printing-press cylinder and folder shafts
- machine-tool spindle cartridges and driven tooling
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
- thermal runaway from excessive preload: the pair runs hot, grease darkens and the contact ellipse spreads until the raceways smear
- machined-cage land scoring when a high-speed spindle runs past its grease rating and the cage runs dry on its guidance surface
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
Selection pitfalls — read before you substitute
- In this size class the common miss is lubrication interval, not fit — a 40 mm spindle at the catalogue speeds needs a calculated relubrication plan, not a calendar one.
- The 40 deg B-execution raises axial capacity but lowers the speed ceiling — do not copy the standard-bearing speed and preload settings onto it.
- Substituting the B (40 deg) execution for the standard 30 deg bearing changes the axial/radial load split — the shaft position and the mating bearing see different forces even though the envelope is identical.
- Substituting the B (40 deg) execution for the standard 30 deg bearing changes the axial/radial load split — the shaft position and the mating bearing see different forces even though the envelope is identical.
- Grease rated for deep-groove motor duty is not automatically right at 8,300 r/min with preload; check the grease speed factor against the catalogue figure.
- The 35.5/23 kN ratings and 1.8 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7208B; 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 7208B?
7208B is a single-row angular contact ball bearing to ISO 15: 40 mm bore, 80 mm outside diameter, 18 mm width (1.575 x 3.15 x 0.709 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 35.5 kN, C0 23 kN and a 1.8 kN fatigue load limit Pu; the grease limiting speed is 8,300 r/min and the oil rating 11,000 r/min; mass about 375 g.
How is the 7208B designation structured?
72 is the single-row dimension series (medium-duty 7200 single-row family); 08 encodes the 40 mm bore (bore code x 5), and the trailing B marks the 40 deg contact-angle execution (the no-letter standard bearing works at 30 deg). The 80 mm OD and 18 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7208B support?
One 7208B alone takes thrust in one direction only, along its 40 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 7208B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 8,300 r/min and the oil rating 11,000 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 7208B?
The 40/80/18 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 35.5 kN / C0 23 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.