7303B bearing: complete specifications & equivalents
The 7303B is a ISO 15 radial bearing sized 17 x 47 x 14 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 17 mm |
| Outer diameter D | 47 mm |
| Width B | 14 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 16.4 kN |
| Basic static load rating C0 | 8.05 kN |
| Fatigue load limit Pu | 0.63 kN |
| Limiting speed (mechanical) | 15000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 109 g |
| Manufacturer designation | NTN 7303B |
| 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 | 0.669 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 0.551 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 15 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) | 4 of 32 |
| Bore above smallest 7300-series size | 7 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 7303B | 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 7303B model number is decoded
The heavy-duty 7300 single-row family entry 7303B carries a 17 mm bore in a 47 mm outside diameter, 14 mm wide envelope. Two fields make up the code — 73 is the single-row dimension series (heavy-duty 7300 single-row family) and 03 encodes the 17 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 static margin, C0 8.05 kN versus C 16.4 kN, is what supports slow oscillating duty and shock without immediate brinelling. Selection starts from the thrust share: as axial load grows past roughly half the radial load, an angular-contact position of this section usually outlives a deep-groove one. A 17 mm shaft typically takes a j5/k5 fit for rotating inner-ring load; keep the housing bore to G6/H6 class so the contact geometry is not distorted.
Typical equipment & failure modes
Common applications
- precision instrument and encoder support shafts
- small machine-tool spindle and live-centre positions
- high-speed router, grinder and woodworking spindles
- small pump and compressor shafts with combined load
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
- pressed-steel cage pocket wear and rivet loosening after repeated ball skid at light load and high speed
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- contamination-induced denting — hard particles rolled into the contact ellipse become the initiation points for surface fatigue
Selection pitfalls — read before you substitute
- At 17 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.
- The C0 of 8.05 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- 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.
- Do not pair two random 7303B bearings from stock and expect catalogue paired ratings — matched-set grinding is what makes DB/DF/DT preload behave, and NTN sells those as separate order numbers.
- The 16.4/8.05 kN ratings and 0.63 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7303B; 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 7303B?
7303B is a single-row angular contact ball bearing to ISO 15: 17 mm bore, 47 mm outside diameter, 14 mm width (0.669 x 1.85 x 0.551 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 16.4 kN, C0 8.05 kN and a 0.63 kN fatigue load limit Pu; the grease limiting speed is 15,000 r/min and the oil rating 20,000 r/min; mass about 109 g.
How is the 7303B designation structured?
73 is the single-row dimension series (heavy-duty 7300 single-row family); 03 encodes the 17 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 47 mm OD and 14 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7303B support?
One 7303B 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 7303B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 15,000 r/min and the oil rating 20,000 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 7303B?
The 17/47/14 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 16.4 kN / C0 8.05 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.