7307B bearing: complete specifications & equivalents
The 7307B is a ISO 15 radial bearing sized 35 x 80 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 | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 40.5 kN |
| Basic static load rating C0 | 24.2 kN |
| Fatigue load limit Pu | 1.89 kN |
| Limiting speed (mechanical) | 8400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 469 g |
| Manufacturer designation | NTN 7307B |
| 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 & 7300-series range
| Bore d | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.827 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 22.5 mm |
| Smallest bore in 7300-series | 10 mm |
| Largest outer diameter in 7300-series | 420 mm |
| Width range across 7300-series | 11–80 mm |
| Bore position in 7300-series (smallest first) | 8 of 32 |
| Bore above smallest 7300-series size | 25 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7307B | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the 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 7307B model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 7307B appears as a heavy-duty 7300 single-row family bearing of 35 mm bore, 80 mm outside diameter and 21 mm width. The designation breaks down as 73 is the single-row dimension series (heavy-duty 7300 single-row family); 07 encodes the 35 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 40 deg contact angle is the lever that turns the 24.2 kN static rating into useful one-direction thrust capacity. The 35/80/21 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 35 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- electric motor shafts with axial locating duty
- conveyor drive and tension-drum shafts
- agricultural gearbox and PTO shaft supports
- printing-press cylinder and folder 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
- resin-cage cracking on the 7900-series sizes after hot, dry running or solvent attack on the polymer
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
Selection pitfalls — read before you substitute
- In this size class the common miss is lubrication interval, not fit — a 35 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.
- Grease rated for deep-groove motor duty is not automatically right at 8,400 r/min with preload; check the grease speed factor against the catalogue figure.
- A 7307B mounted the wrong way round still turns smoothly by hand; the failure shows up weeks later as raceway flaking on the unloaded-looking side.
- A 7307B 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 40.5/24.2 kN ratings and 1.89 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7307B; 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 7307B?
7307B is a single-row angular contact ball bearing to ISO 15: 35 mm bore, 80 mm outside diameter, 21 mm width (1.378 x 3.15 x 0.827 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 40.5 kN, C0 24.2 kN and a 1.89 kN fatigue load limit Pu; the grease limiting speed is 8,400 r/min and the oil rating 11,000 r/min; mass about 469 g.
How is the 7307B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 07 encodes the 35 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 21 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7307B support?
One 7307B 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 7307B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 8,400 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 7307B?
The 35/80/21 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 40.5 kN / C0 24.2 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.