7303-NTN bearing: complete specifications & equivalents
The 7303-NTN 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 | 17.7 kN |
| Basic static load rating C0 | 8.65 kN |
| Fatigue load limit Pu | 0.68 kN |
| Limiting speed (mechanical) | 18000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 107 g |
| Manufacturer designation | NTN 7303 |
| 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 | 03 |
| 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 |
|---|---|---|---|
| 7303 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×47×14 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7303-BE-2RZP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×47×14 mm envelope per ISO 15; seal variant (OPEN vs RSR) and load ratings differ — confirm sealing and rating before substituting. |
| 7303-BECBP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×47×14 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 7303-BEP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 17×47×14 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 7303-NTN model number is decoded
7303 is the 17 mm bore member of NTN's heavy-duty 7300 single-row family, with a 47 mm outside diameter and 14 mm section width. Reading the code: 73 is the single-row dimension series (heavy-duty 7300 single-row family), 03 encodes the 17 mm bore (bore code x 5); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. At roughly 15.0 mm of radial section, the catalogue still quotes 17.7 kN dynamic capacity for the 17 mm bore. For a 17 mm shaft with combined load, the practical shortlist is this series, its 7200-series lighter section, and — where thrust reverses — a back-to-back pair rather than a single row. Shaft and housing shoulders must clear the ring corners yet support enough face — the catalogue abutment diameters for the 17 mm bore give the working limits.
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
- 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
- lubricant starvation scoring at the ball/raceway contact when grease volume or relubrication interval is guessed instead of calculated
- 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 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 standard 30 deg bearing and its B (40 deg) sibling share the envelope; picking between them is a load-direction decision, not a quality upgrade.
- 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.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- Catalogue mass and ratings belong to the open execution; shields, seals and resin cages change both the speed ceiling and the thermal behaviour of the same basic size.
- The 17.7/8.65 kN ratings and 0.68 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7303; 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 7303?
7303 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 17.7 kN, C0 8.65 kN and a 0.68 kN fatigue load limit Pu; the grease limiting speed is 18,000 r/min and the oil rating 24,000 r/min; mass about 107 g.
How is the 7303 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); with no letter after the digits it is the standard 30 deg contact-angle execution — the 40 deg version carries a B. The 47 mm OD and 14 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7303 support?
One 7303 alone takes thrust in one direction only, along its 30 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 7303?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 18,000 r/min and the oil rating 24,000 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 7303?
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 17.7 kN / C0 8.65 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.