7301B bearing: complete specifications & equivalents
The 7301B is a ISO 15 radial bearing sized 12 x 37 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 12 mm |
| Outer diameter D | 37 mm |
| Width B | 12 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 11.7 kN |
| Basic static load rating C0 | 4.95 kN |
| Fatigue load limit Pu | 0.39 kN |
| Limiting speed (mechanical) | 19000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 45 g |
| Manufacturer designation | NTN 7301B |
| 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 | 0.472 in |
|---|---|
| Outer diameter D | 1.457 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 12.5 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) | 2 of 32 |
| Bore above smallest 7300-series size | 2 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7301B | 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 7301B model number is decoded
At 12 x 37 x 12 mm, NTN 7301B sits in the heavy-duty 7300 single-row family of the angular-contact programme. Decoding 7301B: 73 is the single-row dimension series (heavy-duty 7300 single-row family), with 01 encodes the 12 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 radial section height here is 12.5 mm, and the catalogue couples that with C 11.7 kN / C0 4.95 kN. Choose the heavy-duty 7300 single-row family when the shaft needs a stiff locating support and the axial component is known to act mostly one way. Shaft and housing shoulders must clear the ring corners yet support enough face — the catalogue abutment diameters for the 12 mm bore give the working limits.
Typical equipment & failure modes
Common applications
- bicycle and motorcycle wheel and steering positions
- small gearbox pinion shafts with helical gears
- precision instrument and encoder support shafts
- small machine-tool spindle and live-centre positions
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
- edge loading and early spalling from housing bores that are out of round or shoulders that are too small for the ring face
- current-erosion pitting on VFD-driven motor shafts, first visible as a grey frosted band across both raceways
Selection pitfalls — read before you substitute
- At 12 mm bore the rings are thin-sectioned: press force must go through the ring being fitted, never through the balls, or the first damage is already in the raceway before the machine runs.
- 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.
- Grease rated for deep-groove motor duty is not automatically right at 19,000 r/min with preload; check the grease speed factor against the catalogue figure.
- A single-row angular contact left loose on the shaft to "help assembly" will fret the seat: the contact angle keeps driving the ring axially under load.
- The 11.7/4.95 kN ratings and 0.39 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7301B; 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 7301B?
7301B is a single-row angular contact ball bearing to ISO 15: 12 mm bore, 37 mm outside diameter, 12 mm width (0.472 x 1.457 x 0.472 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 11.7 kN, C0 4.95 kN and a 0.39 kN fatigue load limit Pu; the grease limiting speed is 19,000 r/min and the oil rating 26,000 r/min; mass about 45 g.
How is the 7301B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 01 encodes the 12 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 37 mm OD and 12 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7301B support?
One 7301B 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 7301B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 19,000 r/min and the oil rating 26,000 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 7301B?
The 12/37/12 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 11.7 kN / C0 4.95 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.