7203B bearing: complete specifications & equivalents
The 7203B is a ISO 15 radial bearing sized 17 x 40 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 | 17 mm |
| Outer diameter D | 40 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 | 12.2 kN |
| Basic static load rating C0 | 6.1 kN |
| Fatigue load limit Pu | 0.48 kN |
| Limiting speed (mechanical) | 17000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 66 g |
| Manufacturer designation | NTN 7203B |
| 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 & 7200-series range
| Bore d | 0.669 in |
|---|---|
| Outer diameter D | 1.575 in |
| Width B | 0.472 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 11.5 mm |
| Smallest bore in 7200-series | 10 mm |
| Largest outer diameter in 7200-series | 540 mm |
| Width range across 7200-series | 9–85 mm |
| Bore position in 7200-series (smallest first) | 4 of 36 |
| Bore above smallest 7200-series size | 7 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 7203B model number is decoded
7203B is the 17 mm bore member of NTN's medium-duty 7200 single-row family, with a 40 mm outside diameter and 12 mm section width. NTN builds the number from 72 is the single-row dimension series (medium-duty 7200 single-row family), then 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). Catalogue dynamic rating C is 12.2 kN against C0 6.1 kN — a C0/C ratio of 0.50 that is typical of an angular-contact contact ellipse. 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. 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
- 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
- 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
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
- flaking that starts at the raceway shoulder on the thrust-loaded side when axial load repeatedly exceeds the design share
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.
- Grease rated for deep-groove motor duty is not automatically right at 17,000 r/min with preload; check the grease speed factor against the catalogue figure.
- The C0 of 6.1 kN is a static rating, not a permissible running thrust — sizing continuous axial load from C0 alone is a recurring drawing-office error.
- 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.
- The 12.2/6.1 kN ratings and 0.48 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 7203B; 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 7203B?
7203B is a single-row angular contact ball bearing to ISO 15: 17 mm bore, 40 mm outside diameter, 12 mm width (0.669 x 1.575 x 0.472 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 12.2 kN, C0 6.1 kN and a 0.48 kN fatigue load limit Pu; the grease limiting speed is 17,000 r/min and the oil rating 22,000 r/min; mass about 66 g.
How is the 7203B designation structured?
72 is the single-row dimension series (medium-duty 7200 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 40 mm OD and 12 mm width follow the ISO 15 boundary-dimension plan for that series.
Which axial direction does 7203B support?
One 7203B 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 7203B?
Per NTN Ball and Roller Bearings CAT.No.2203E, the grease limiting speed is 17,000 r/min and the oil rating 22,000 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 7203B?
The 17/40/12 mm envelope is ISO 15 interchangeable, but internal geometry — contact angle, osculation, cage and shoulder details — is maker-specific. Re-verify C 12.2 kN / C0 6.1 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.