7300B bearing: complete specifications & equivalents
The 7300B is a ISO 15 radial bearing sized 10 x 35 x 11 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 10 mm |
| Outer diameter D | 35 mm |
| Width B | 11 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 10.5 kN |
| Basic static load rating C0 | 4.6 kN |
| Fatigue load limit Pu | 0.36 kN |
| Limiting speed (mechanical) | 22000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 41 g |
| Manufacturer designation | NTN 7300B |
| 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 | 0.394 in |
|---|---|
| Outer diameter D | 1.378 in |
| Width B | 0.433 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) | 1 of 32 |
| Bore above smallest 7300-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7300B | 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 7300B model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, 7300B appears as a heavy-duty 7300 single-row family bearing of 10 mm bore, 35 mm outside diameter and 11 mm width. Reading the code: 73 is the single-row dimension series (heavy-duty 7300 single-row family), 00 encodes the 10 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). Because the contact line is angled, one bearing of this type takes radial load plus thrust from one direction only — the opposite direction needs a second bearing or a matched set. When axial load reverses, specify the bearing as a matched pair (DB, DF or DT) instead of two random singles — the catalogue right-hand columns give the paired ratings for exactly this reason. Heat-mounting to 80-90 deg C is the clean route onto a 10 mm shaft; drive-fits through the balls transmit force through the contact ellipse and can brinell it.
Typical equipment & failure modes
Common applications
- servo and stepper motor shafts with axial preload
- bicycle and motorcycle wheel and steering positions
- small gearbox pinion shafts with helical gears
- precision instrument and encoder support 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
- thermal runaway from excessive preload: the pair runs hot, grease darkens and the contact ellipse spreads until the raceways smear
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- 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 10 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.
- Never use a four-point or double-row bearing as a like-for-like swap for a single 7300B without re-checking axial float, heat and housing width — the kinematics differ.
- The C0 of 4.6 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- The 22,000 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.
- The 10.5/4.6 kN ratings and 0.36 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7300B; 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 7300B?
7300B is a single-row angular contact ball bearing to ISO 15: 10 mm bore, 35 mm outside diameter, 11 mm width (0.394 x 1.378 x 0.433 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 10.5 kN, C0 4.6 kN and a 0.36 kN fatigue load limit Pu; the grease limiting speed is 22,000 r/min and the oil rating 29,000 r/min; mass about 41 g.
How is the 7300B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 00 encodes the 10 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 35 mm OD and 11 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7300B support?
One 7300B 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 7300B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 22,000 r/min and the oil rating 29,000 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 7300B?
The 10/35/11 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 10.5 kN / C0 4.6 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.